Paddleducks
Paddler Modelling => Construction => Topic started by: bundyrap on November 01, 2006, 07:55:51 AM
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Hi Everyone
I'm about to start building the Sergal kit of the Mississippi 1870 as my first paddle wheeler. Altho I've been building RC planes most recently large scale electric warbirds for 20 something years, this will be only my 3rd boat. The Dumas' kit of the Chris Craft Barrel Back was the first - a very rewarding project and goes well and a Model Slipway's Al Khubar tug half way thru and a different sort of challenge in a glass hull and plastic structure.
In posting my progress here I am looking for advice and answers to some basic (dumb?) questions as I learn. Am I in the right place?
My first challenge is adapting what is basically a static model of the Mississippi into a working RC model. This latest versions of the kit now come with the option of balsa planking the first layer instead of lime wood. Since I plan on having a painted lower hull and not the varnished planking I'm thinking I might just do one layer of planking out of 3mm balsa instead of the supplied 1.5mm balsa and glass the finish. Is this a workable alternative with a coating of resin on the inside for water proofing?
Attached are some pics of what you get. First impressions are of a very high quality kit with passable instructions. Looks like a lot of fun anyway :)
Richard
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Hi Everyone
In posting my progress here I am looking for advice and answers to some basic (dumb?) questions as I learn. Am I in the right place?
Yes your in the right place Richard...
My first challenge is adapting what is basically a static model of the Mississippi into a working RC model. This latest versions of the kit now come with the option of balsa planking the first layer instead of lime wood. Since I plan on having a painted lower hull and not the varnished planking I'm thinking I might just do one layer of planking out of 3mm balsa instead of the supplied 1.5mm balsa and glass the finish. Is this a workable alternative with a coating of resin on the inside for water proofing?
I haven't built this model, but the normal paddler problems are those of top weight/stability and wether the hull will be of sufficient draught to support it and the necessary drive gear, RC gear and ballast etc.
Balsa is a perfectly good material to use on a hull, but it must be thoroughly waterproofed. I'd suggest a coat of epoxy resin inside and out before painting.
The hull on all sternwheelers is very shallow, so I'd be looking at increasing it's depth by 1/2" or so to support the items mentioned above. Most people will never know it's been altered, and you have to be practical...
Finally (for now) I'd also look at how you can save weight on the superstructure - By replacing the supplied materials with thinner stuff, or using plasticard maybe? Are the fittings resin, white metal castings, brass? Again, look at replacing anything that is heavy with a lighter alternative. The top weight is always going to be one of the major problems with this model, so you should look at saving weight wherever possible.
Attached are some pics of what you get. First impressions are of a very high quality kit with passable instructions. Looks like a lot of fun anyway :)
Richard
It looks very good quality from the photos Richard - I wish you every success with it...
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Anyone else with more experience of sternwheelers care to make a comment? I've only built two sternwheelers, so I'm no expert on them, and I'm happy if you want to say I'm wrong with the comments I've made so far... :wink:
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Hi PD's & as Eddy says..... welcome Richard to the only & :no1 Paddler WEB site in the world
If I could humbly :angel suggest, just spend as many hours as you have available reading our PD postings........ you won't regret the hours & ask as many questions as you wish... someone from our world wide group will offer constructive comment :D
Oh BTW PD's...... Richard is from our northern OZ city of Bunderberg.... which is also the home of that famous OZ drink BUNDI+Rum :beer which I believe is EXPORTED :bravo to most or many Countries.... but possibly not yet to SCOTLAND :hehe :music :rant - Derek in Wollongong.... just down the :arrow: :arrow: :arrow: east coast by some 2300 km from BUNDI
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David ,
Welcome to the group, great to see another Aussie joining this great paddler hobby, as regards to weight saving and waterproofing balsa I have been using balsa for a few years now and found the about 5 to 6 coats of nitrate dope, progressively thing and rubbing down between each coat will achieve a very waterproof hull and is cheaper than epoxy resin. Don't forget to download Skype so all us Aussies can chat and plot together. I hope I spelt the boat name right.
Peter Webster
A bit further south than Derek
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Hi Everybody
And thanks for the replies.
I like the idea of making the hull 12mm deeper to help cope with the weight of the working bits to be added. Easy to do at this stage - see attched pic. Thanks Eddy.
I like the varnished planked wood look but in moderation so with all the planked decks. windows and doors I'm going to do a plain black hull. My warbird heritage is coming thru here but planked 3 mm balsa with 1oz cloth and epoxy with a brushed coat on the inside is the plan.
Superstructure on the Mississippi is all wood and some brass. Light ply frame with vertical planking and laser cut details is the order. Doing it out of plastic would be lighter but not a whole lot for the trouble so I might stick with the kit's super structure as is. Besides I like working in wood!
Next looming Rc question is the rudders as supplied. Wood with wooden dowel running in brass tube. I haven't fully gone in to this yet but it seems unusual. Is it sound?
Thanks for the input guys
Richard
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Hi PD's - Bundyrap wrote
Wood with wooden dowel running in brass tube
Richard - if it is intended to contact water, the wood will swell :sob & you wont't be happy :rant as it will sieze :crash
All/most Model supply shops have the American range of K & S metal tubes, flats & other sections - eg., a 1/8" OD tube [0.125"] runs perfectly in the next telescoping tube size being 5/32" OD - the differing profiles of round, square, rectangular, flat, plate, angle...... & with a bit of thought compliment each other perfectly to construct whatever
Soft soldering is not a difficult :hammer task & brass solders easly, naturally does not rust & can be polished to a :great shine.... so much you need :sunglasses & the running surfaces can be lapped with Sandy's favourite drink BRASSO :hehe - Derek
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Hi All
Pics show my progress to date. The hull is planked and glassed, lower deck is on and planked, the supplied wooden rudders and arms have been replaced with brass ( thanks Dereck) and the lower storage and engine rooms are nearly finished.
I'm still keen to have a go at making working Pitman rods with a belt drive as plan B. What rpm should I be aiming at for a sternwheeler? The MFA/Como Drills ad is suggesting their 810:1 gearbox giving 19 rpm on 12volts is ideal for sternwheelers but would have thought the 148:1 ratio giving 106 rpm would be closer to the mark.
My next challenge is to split the second level deck horizontally so as to make the upper levels removable to allow access to the workings. I have just finished a HobbyCNC 3 axis cutter so its first job in anger will be to cut a copy of the second level deck shape. Could be done by hand where is the fun in that!
Richard
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It's looking really good Richard - Nice work!
I'd go for the 148:1 motor/gearbox, 19RPM may be about right for the full size vessel, but it's never going to work in a model...
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For a model you're going to need to be able to turn the wheel around 100 to 150 rpm max. It sounds excessive, but you'll need it to fight cross winds.
My Verity will turn over just a little more than 100 rpm and it has a hard time with wind. It's a heavy boat too, but with shallow draft and three decks of cabins, the wind loves it.
With such a beautiful boat I would paint the hull white.
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Hi there Richard.
Regarding the speed of the paddle.
As Eddy correctly says 19RPM ain't never ever going to work on a model!
How fast do you want it to go in say feet per minute?
Take the circumference of the paddle in feet.
Assume say 20% slip (X1.2) between the water and the paddle when cruising.
1mph = 88 ft/minute.
Circumference is PI X D
Say paddle is 6" dia. 3.142 X 0.5 = 1.6ft
Speed of ship required say 2mph
RPM = 2 X 88 / 1.6 = 110
Correct for slip 110 X 1.2 = 132 RPM required.
(Say 150RPM to be safe for the above case!!)
This way there shouldn't be too much guess work about what gearbox to use.
All the best
David
It's looking really good Richard - Nice work!
I'd go for the 148:1 motor/gearbox, 19RPM may be about right for the full
size vessel, but it's never going to work in a model...
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Regards
Eddy>
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Thanks for help Guys :)
I'm starting to look at ways to make scale, working Pitman rods to drive the wheel. The kit comes with a 6mm solid brass shaft and plain bearings for the paddlewheel with everything being glued to the shaft.
So two questions at this stage - are the plain bearings adequate to cope with 150 rpm workload and is glueing the wheel frames and cranks to the shaft the best way to go?
My feeling is the bearings should be alright but I'd be looking at soldering/screwing brackets and cranks to the shaft. Any advice?
Thanks as always
Richard
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Hi PD's & I assume Richard, the bearings you mention are as per the snap....
1) I agree, soft soldering is far better than any form of gluing when brass is concerned...you may need to make a compromise somewhere as you will need to secure brass to wood... a brass disk the size of a ten cent coin... soft soldered to the paddle shaft but pre drilled for 10 BA brass metal thread screws?.... around the OD & secured back to the wood
2) In a perfect world we would never design & use the same materials in a bearing application... having said this... brass on brass @ 150 RPM would be fine with acceptable lubrication.... considered pre drilling a 2mm diameter hole at the 12.0 o'clock position in the bearings :?: - from there you could inject :hammer a dollop of RUBBER grease prior to each steaming/motoring/paddling :oops: :shock:
This rubber grease will not disolve @ the speeds/temperatures you will experience and will not leave those :nono tell tail rainbow polution drops in the water
You are doing a great job. :trophy ...................Derek
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Hi Derek
Would proper stainless steel bearings such as from Stock Drive Products ( https://sdp-si.com/eStore/ ) all round be the better option?
Thanks
Richard
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Hi PD's & funny you should ask that Richard.............I initally installed 1/4" ID Sintalite bushes to PS Decoy in Y2002, but found the tension deflection in the 1/4" paddle shaft [when electric & belt driven] not to my liking :sob
So with the current refit :hammer :towel :clap to steam, I purchased four X SR3C-ZZMC3 [3/16" ID X 1/2" OD] stainless steel roller bearings (ZZMC3 = also S/S shielded] from the same https://sdp-si.com/eStore/ ) source & @ $4.80 AUD each was very in expensive
If you have the design/means/location of floating your paddle shaft in S/S sealed roller bearings, they willl out last you by 1000,000 years :terrific
Is there never any end to PD modeling :?: :arrow: :evil: :angel - Derek
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I used flanged bearings for r/c cars for my wheel and to build a realistic operating pitman drive.
EDIT: Found the updated drawing....
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To be authentic the cranks on the paddele wheel need to be quartered. That is they need to be 90 degrees off set from each other. I think this would be kind of hard to do with a single motor on a single shaft.
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Not only authentic, but if they're not at 90 degree from one another it would create a dead spot and the pitmans would lock up. I noticed this was an old drawing i uploaded that did not show the 90 degree cranks for the pitmans. Somewhere I have misplaced the correct drawing, but this setup does work well with a single motor and the pitmans push back and forth.
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I can certainly vouch for the fact that Joes system works and allows for the arms to be quartered Bill. It does need to be built accurately as I'm sure he would agree...
Basically it takes the rotary motion of the motor and converts it to recipricating motion - The pitman arms are then attached to the recipricating output and the wheel at which point its converted back into rotary motion.... That made a lot more sense before I wrote it honest! ;)
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That made a lot more sense before I wrote it honest! --------------------------- :music
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I'm glad you said it! HELP! I'm confused??
I found the updated drive drawing so edited the post on it.
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I have seen that mechanism some where. Joe do you have it posted on another site? I think that would really make the model stand out. Add in valve eccentrics and Wow!
Richard. You really scored on that kit. Would loved to have had it myself. Is teh hull plastic or did I miss something along the way? I still have to design (and build) mine for the City of Eugene.
Your boat is going to be a very nice looking one when done.
Bill
Edit: Sorry about the misspelling etc. My spell check isn't working and my club hands are really bad this morning. Can't get in to see neuroligist untill next month.
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Bill, i have the drawing and photos in the miscellenous page on my web site http://www.towboatjoe.com/mscl_.htm
I could be somewhere else, I can't remember and things sure seem to have a way of getting around on the net.
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Yep, that is where I saw it. was wracking my brain to remember where. Wanted top post it here but you beat me to it. :lol: Some how I remembered two motors but I see now how you use the channel to make it work.
Nice looking padeel wheeler. Unusal float arangement. Haven't seen that style before.
Bill
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Here's the helical wheel ofthe real boat. It's also referred to as a herribone design.
Now how about some more photos of the Mississippi build? :yeah
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Hi All
And thanks for all the input :)
Building is progressing nicely. This is a well thought kit of a fine looking boat lacking only in the instructions. It is basically all there in the instruction sheet with some amusing translations - like most instructions it pays to read them well and understand what they intend before doing it your own way!
I've managed to make a split deck at the first deck level so everything above the lowerdeck will lift off to allow access to the workings. This has caused a few headaches with more to come trying to keep all the deck posts straight and in line.
Thanks for the diagrams and pics ToeBoatJoe. I've had a go at making a similar drive but friction and alignment issues has seen me take the simpler ( less pure - please don't shoot me! ) approach which works well in as far turning the wheel and looking good but the first water test has highlighted some real problems.
The first is with the rudders in front of the wheel - it just doesn't steer going forwards at all and this was with the top decks off and a large lump of lead along with battery to bring it down to it's water line. Backwards was good even with the breeze blowing but forwards the rudders might as well not have been there.
Second problem is the amount water shipped into the engine room while under way. Reverse was really bad nearly drowning the rudder servo in very short time.
This is a lovely looking boat and a great fun build but I don't want to end up with a show pony. I'm sure there are answers to these running challenges.
My current thinking is to make a split wheel and have a form of 'tractor' steering similar to my Al Khubar tug which will turn on the spot with it's 2 engines run through a mixer. This would mean running each half of the wheel via a pulley and having dummy pitman rods because they just look so good doing their thing.
Any ideas??
Thanks Guys
Richard
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The real vessels had the same problem with steering which is the reason for inventing monkey rudders.
The way they would steer is with the current. They would drift into a bend and reverse the wheel to swing the stern into the turn.
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One possible solution would be to make the rudders reach deeper below the hull, it doesn't look too good if you display the model on a stand (between sailings) and they could catch on things in shallow water, but it should help.
I've seen on some models where the owner has made detatchable extensions for the rudders which clip on for sailing and are removed for display/transportation, but I don't know how it was done :?
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Hi PD's - TBJ.... what is the typical arc of rudder movement for stern wheelers :?: .... we have read by 'Ronald Parsons'... 'that many OZ paddlers could bring the rudder 90 degrees to the vessel axis'... but this was to shorten the vessel when in a "Lock"
When we think the axis of a rudder divides the flow path of water equally...one half of flow is un impeaded & wants to propel the vessel in the direction of flow, & the rudder accepts the half of the water flow and bounces the flow back off the rudder face at a 90 degree included angle..... :rant ... & the result is the turning motion...not rocket science but thinking - and having said this Richard you could consider a similar concept - Derek
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Hi All
I've been playing with the rudder shape and yep it makes an enormous difference even with just one rudder modified. The one in the pic is just a 'concept' version after talking about the best shape with a yachtie mate and it really does work well.
Cutting it from clear polycarbonate on the CNC machine and painting just the original shape somewhat hides the extension. A folding extension is certainly another option. Any thoughts on what might be the best ideal shape and balance area in front of the pivot?
Bottom line is steering is very fixable with a deeper rudder and is just a matter of deciding on the least obtrusive looking method. Working the angles more will also be another area to look at Derek. 90 degrees will take some doing but I'll see how much I can get.
My next project will be a 16th scale PS Adelaide. 90 degree rudder travel should be easier to organize there and with a motor per wheel mixed electronically, steering I hope will not be such a problem.
Hey Derek do you know any details of the 2 paddlers built for Expo 88 in Brisbane? They are the Kookaburra Queens I & II and now work as restaurant and tourist boats on the Brisbane river. I hope to get down and get to go on them early in the new year but would love to find some drawings of them. They have a beautiful hull shape and would make a fine pair of models.
Richard
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Hi PD's ..... Richard
1) got to be your call with the sizing/positioning/arc of the rudders, but it is good to know that you have achieved an increase/improvement in such short time :D :D :D
2) 16th Scale PS Adelaide.... :respect2 .. two motors & mixing ????????? :sorry but Tony from NZ & I both went down the :sob track where we found the MIXING to be more ROBOT like [a Sherman Tank]... other PD's may have had more recent & happier experiences
3) Kookaburra paddler on the Brisbane river... yes some 10 years ago Karina & I spent an evening... good food... great experience..... both PS Kooka's are diesel, but still good fun - Derek
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Hi there.
Just a mad idea. I was wondering if you could hide a bow thruster across
the stern. Could be linked to the rudder electrics so that it would
produce a strong turning effort when the rudder control was operated.
Maybe could hide the inlet/outlets with very shallow scoop/louvres under
each side of the hull? I just thought that that way it maybe be less
intrusive than extra large rudders.
Turning both rudders at 90 degrees would I believe simply produce drag
rather than very much steering effort. If you turned one rudder at 90
degrees on the inside of the turn, while the other was at say 60 degrees,
I believe would help it round. Clever linkage needed, like on a car where
the inside wheel turns at a much greater angle than the outside wheel.
Good luck and let us know what the answer finally turns out to be.
All the best
David
Hi All
I've been playing with the rudder shape and yep it makes an enormous
difference even with just one rudder modified. The one in the pic is just
a 'concept' version after talking about the best shape with a yachtie mate
and it really does work well.
Cutting it from clear polycarbonate on the CNC machine and painting just
the original shape somewhat hides the extension. A folding extension is
certainly another option. Any thoughts on what might be the best ideal
shape and balance area in front of the pivot?
Bottom line is steering is very fixable with a deeper rudder and is just a
matter of deciding on the least obtrusive looking method. Working the
angles more will also be another area to look at Derek. 90 degrees will
take some doing but I'll see how much I can get.
My next project will be a 16th scale PS Adelaide. 90 degree rudder travel
should be easier to organize there and with a motor per wheel mixed
electronically, steering I hope will not be such a problem.
Hey Derek do you know any details of the 2 paddlers built for Expo 88 in
Brisbane? They are the Kookaburra Queens I & II and now work as restaurant
and tourist boats on the Brisbane river. I hope to get down and get to go
on them early in the new year but would love to find some drawings of
them. They have a beautiful hull shape and would make a fine pair of
models.
Richard>
Attachments:
http://www.paddleducks.co.uk//forum/files/boats_182.jpg
http://www.paddleducks.co.uk//forum/files/false_rudder_004_590.jpg
http://www.paddleducks.co.uk//forum/files/false_rudder_001_917.jpg
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Hi PD's - TBJ.... what is the typical arc of rudder movement for stern wheelers :?:- Derek
I think the most pitch I have seen on an old stern wheeler is about 75 to 80 degree.
Here's photos of the rudders on the Verity.
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A simple way to produce a thruster is to use a car windscreen washer pump and flexible pipes. A simple nipple type fitting on both sides of hull ,connect pipes and hey prest its finished. Use a servo opperated double microswitch and it sucks water from one side and squirts it out the other. Reverse sevo and it works the opposit way. Runs on 12 volt. One at the bow and one at the stern and you can turn on the spot. Alternatively use the fuel filler pumps that aeromodellers use. Regards, Walter.
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Richard,
Your photos of your rudders tell the whole story. They are way too small for the boat. Most stern wheel rudders I have seen and those in drawings are much larger. The top of the rudder nearly conturs to the paddle wheel with very little space between them. The front of the rudder also contours to the hull. Towboat Joe gives a good example of a rudder profile. When you position your rudders think of them as thrusters.
I was fortunate to be able to spend over an hour at the helm of the stern wheeler Columbia Goarge. She was fitted with threeregular rudders and three monkey rudders. On a hard turn she could spin 180 degrees in place with the pilot house as a pivit point. The captain explaind to me that it is not the movement of the rudders through the water that caused the boat to turn as with a prop boat but it is the movment of the water through the chute formed by the rudders that turns a stern wheeler. The paddle wheel serves as a giant pump impeller. The fun part was docking. The rudders were set opposite of each other. This formed a side thrust and the boat moved side ways to the dock.
Bill
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Wow what great ideas there! Thanks everybody.
The way my rudders attach is via a brass pin so it is only a 30 second job to swap rudders so first up I'll make bigger, closer contoured ones and see what that does. I'll also have a go at fitting a third rudder in there.
The monkey rudder idea makes an awful lot of sense creating in effect a tunneled thruster. The problem there will be making the bracket behind the wheel in aesthetic harmony with the rest of boat but no doubt it can be done. Am I right in thinking the main rudders and monkey rudders are controlled independently from each other for greater flexibility?
Hope to have a few pictures of the modifications by the weekend.
Richard
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Wow what great ideas there! Thanks everybody.
The monkey rudder idea makes an awful lot of sense creating in effect a tunneled thruster. The problem there will be making the bracket behind the wheel in aesthetic harmony with the rest of boat but no doubt it can be done. Am I right in thinking the main rudders and monkey rudders are controlled independently from each other for greater flexibility?
Hope to have a few pictures of the modifications by the weekend.
Richard
Go to the photo gallery and look at the stern wheel picture of the Portland. You will see how the deck is wrapped around behind the wheel to accomodate the monkey rudders. And yes the two different rudders are indipendent in controll. On the Columbia Gorge the rudder controlls were hydraulic. both were leavers on the same mount. Rather than a ships wheel the main rudders controll is tow handles on top of a stand. The main is a longer handle and the monkey rudders is shorter and on top.
For general steering only the main rudder is used. For quicker manvers or a strong curent both rudders are used. Full right with the main and full left with teh monkey and the boat wil move sideways. Of course you have ot adjust the turns (engine speed) to a slow turn.
Bill
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On the work boats, like the Verity, Lady Lois, Major, etc, the steering rudders and monkey rudders are fixed together. Hence the reason they were called monkey rudders. "Monkey see monkey do"
In the photo is how I done the Verity. It has chain for steering cable so I found soldered link chain that has worked well for years. I used sheaves to build pulleys and ball & socket connectors used for airplane linkages as the connecting rods.
Here's a typical monkey setup. A rectangle with support brackets at each end. Pipe welded on for bearings and rudder shafts. Two rigid conduits from pulleys at each corner through back splash for steering cable to channel through. The cable connects to the steering rudders just like they do on the monkey rudders. All you need now is a connecting rod to go from one monkey rudder to the other.
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Hi All
You guys sure do know your stuff :)
All I've done is increase the 2 existing rudders not in depth like before but backwards to follow the contours of the wheel and the resulting steering control now is brilliant. Although it will require a deal of butchery I think I will still fit monkey rudders as in TowBoat's pics just to see how much control is possible. Hopefuly I'll get a bit of time over Xmas to give this a go. Thanks again!
Work on the superstructue is still heading upwards. I've struct a few concerns here the biggest one being not enough 1.5mm x 5mm wood for all the top and bottom railings. What I plan to do here is take the oportunity and cut my own banisters with a less 'chunky' pattern and cut my own railings from thin ply on the CNC machine with a 1mm slot to accept the new banisters. I'll post some pics of this as work progresses.
Another question regards the top deck/roof railings. Decks 2 and 3 have railings 22mm high which is a scale 1100mm but the top deck is only 18mm which represents real life 900mm. Is there a reason for this lower railing on the top deck? To my eye it would look better if all the railings are the same height.
Richard
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My word, you've certainly been busy! It's really starting to look like a very nice model, and something to be extremely proud of.... I hope you'll soon be getting some photos of her on the water? I'd certainly like to see them.
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Two reasons for the railing being shorter on the Texas deck is to allow better visability for the pilot and to give a more balanced look overall to the boat. The shorter cabin with the windows just below the wheel house adds to the height of the hand railing, so with standard railing on the Texas deck they would look taller than normal and out of place.
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Well Richard, I'm full of envy. Great job so far. The rudders look much better.
I am confused about the stacks though. They look to only stop at the Texas deck. I would think they would go on down to the engine room.
I really like the looks of that boat. makes me want to drop everything I'm working on and get started on the City of Eugene. All my model building, commissions and personal, will come to a halt today as I am going in to the hospital this morning to have surgery on my left hand. Once I recover from that, about six weeks, I go in again for the right hand. I doubt you will hear mucn from me for a while.
Bill
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Here are some pics on the water. Still a tremendous amount of work to do or is that fun to be had building. I know those stacks look funny just sitting there at the moment but when finished there is a planked 'elbow' under the deck leading inside.
I'm still a little confused reguarding these rail heights TowBoat. Am I right in thinking there is a difference between a Texas deck and a promenade deck? From your explaination which makes a lot of sense, I'm thinking my concern is with the railing height of the promenade deck which runs all the way round the top just below the Texas deck (which is the deck on the roof of the raised cabins?) which on the design has no rail at all. If it were to have a rail, a shorter one like you say would look much better.
I've hooked up a belt drive just to see how it would work and I must admit I like it. Using the Pitman rods that came with the kit which have a small slot at one end to allow for small inaccuracies ( I'm guessing), I got slight jerkiness as the pins slid back and forth through the slots. With the belt there is none of this and with less friction there is a noticable increase in the amount of power available. I know this says more about my setup than the practicalities of working Pitman rods as Towboat has shown but for the moment I'm happy with a belt and a dummy rod. I will certainly revisit working rods in the future tho as per towboat's diagram.
I've also hooked up a sound system which plays a loop of calliope and Dixieland jass music. This is controlled via a spare servo, a 12 volt 50 watt amp and a 200mm light weight car speaker. I wasn't sure how this would work but it really does work well. It adds another whole dimension so much that even my wife Patsy wanted a go at driving it! That is a real win!
Monkey rudders and a start on the railings is the plan for the next few days. I hope to post a video on PutFile.com if I can capture the atmosphere.
Have a great Christmas all
Richard
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Hi All
My Mississippi had her first real day on the lake today with mixed results. If you want to attract a crowd this does the trick with people appearing from nowhere when it hit the water and the sound system started up. There is no doubt it looks and sounds good on the water.
The downside was when a gust of wind hit her, the loose ballast which was only trial fitted moved causing a dramatic list which resulted in the top decks/hatch coming off. The partly finished Al Khubar saved a swim and after a quick drying all is good again.
The obvious answer is to fix the ballast in place. My question is should this almost 2kg of lead be fixed along the center line of the keel or being a completly flat bottom be spread out evenly?
The CNC machine did an excellent job of cutting railings from old reject ID cards. I also cut all the hand rails from 2 mm ply stained teak as these were missing in my kit. This is my only problem with what has been an excellent kit. It pays to be frugal with the other supplied wood as there is very little room for error but still just enough.
The monkey rudders work well in the confines of the pool but out on the open water the normal rudders work fine. Still I think I'll leave the monkeys on and tidy their linkages up.
Work now moves onto the finer details.
Richard
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Richard
What a truly brilliant looking model. Your CNC machine really does the
business. No way could they be cut by hand! She looks really great when
upright on the water.
I really don't think that there is much to choose between the distribution
of the ballast either centrally along the bottom or spread evenly over the
bottom. I think that it really depends on where the framing is inside the
hull and keep it close to that (or on it) so as not to stress the skin
when handling out of the water.
One small comment. The monkey rudders look very efficient but a little
subject to damage when out of the water. I was wondering if a small skeg
fitted from the hull back to the bottom of the rudders would provide some
added strength. This would also provide some protection under the rudders
in front of the paddle wheel as they have quite long blades.
Congratulations on an absolutely brilliant job.
All the best
David A
Hi All
My Mississippi had her first real day on the lake today with mixed
results. If you want to attract a crowd this does the trick with people
appearing from nowhere when it hit the water and the sound system started
up. There is no doubt it looks and sounds good on the water.
The downside was when a gust of wind hit her, the loose ballast which was
only trial fitted moved causing a dramatic list which resulted in the top
decks/hatch coming off. The partly finished Al Khubar saved a swim and
after a quick drying all is good again.
The obvious answer is to fix the ballast in place. My question is should
this almost 2kg of lead be fixed along the center line of the keel or
being a completly flat bottom be spread out evenly?
The CNC machine did an excellent job of cutting railings from old reject
ID cards. I also cut all the hand rails from 2 mm ply stained teak as
these were missing in my kit. This is my only problem with what has been
an excellent kit. It pays to be frugal with the other supplied wood as
there is very little room for error but still just enough.
The monkey rudders work well in the confines of the pool but out on the
open water the normal rudders work fine. Still I think I'll leave the
monkeys on and tidy their linkages up.
Work now moves onto the finer details.
Richard>
Attachments:
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http://www.paddleducks.co.uk//forum/files/cnc_railings_024_991.jpg
http://www.paddleducks.co.uk//forum/files/boats_over_north_jan_07_027_162.jpg
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Yep, it looks magnificent Richard! You've certainly done a superb job, and I hope your happy with the results?
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With a bit of care you can tune a model to the conditions by distributing ballast around the hull in different ways.
You can minimize pitching by putting your ballast at bow and stern. This helps keep the hull stable and helps to cut through waves instead of riding them.
If your model is relatively top heavy or has a lot of weight high up and outboard (e.g. a side paddler or a shallow draft stern wheeler) , then you can achieve the strongest righting effort by concentrating the ballast along the centre line.
However if your model is relatively light in the superstructure, then you might be able to spread the ballast across the beam to give an easier roll and more realistic handling.
cheers
Tony
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Hi All
Not a good day on the pond.
After securing 2kg of lead down low along the centerline of the hull ( thanks for input guys) I thought I would be in business but it was not the case. With a bit more of the rigging and assorted poles added I found that this 2kg was not enough to hold her up in anything above dead calm conditions. No more ballast could be added with water lapping the decks with 2kg of lead in the bottom.
Drastic action was needed. Out came the ballast and a .5m long, 1.5kg keel was slung 200mm below the hull! This gave me a little more free board and certainly stiffened her up but very unscale. Out onto the open lake and moderate conditions of 5 - 10 knotts and the first gust tipped her over!
Doing the sums, at this size the Mississippi displaces about 5-6kg. If I made her half as big again giving her a length of about 1.4 metres she would displace nearly 20kg.
My thinking is that a boat of this style, amount of superstructure and detail built to a scale giving a sub metre length is not a practical model in anything other then dead calm conditions - great for the shelf though.
So this is where my Mississippi project ends for now. It has been great fun, I've learnt so much but I haven't ended up with very sailable model which was my main aim. Time to move onto a lower, bigger boat with new challenges.
Thanks for everyone's input over this build and look forward to the new one.
Richard
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Hi PD's & as 'bundyrap' says....
Doing the sums, at this size the Mississippi displaces about 5-6kg. If I made her half as big again giving her a length of about 1.4 metres she would displace nearly 20kg.
Michael...if I may suggest
1) you have completed a superb looking scale model & with the :bravo accolades of many PD members
2) we cannot scale mother nature, so the cube root of wind = any model vessel with high potential will suffer from WINDAGE
3) last week we had Brett S Hallet repost after two years in the desert.......if you go back to the old PD postings you will find many communications from Brett & others on what not to build... like our PS GEM or PS Captain Stuart...... all due to the :darn above water superstructure WINDAGE issue etc
Have :beer & then GOOGLE 'Float a Boat Plans' & :news you will be happy
regards Derek
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OK :oops ...& appologies....the communication was to Richard.....who the the bloody hell is Michael :rant anyway :?: :?: :?: :?: Derek :nono :hehe
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OK, the fog has lifted......Bundyrap... :thinking again.. have you considered increasing the actual draft of your Missi....
1) go to the fruit market, get an empty polystyrene brocilli box [580 x290 = 168200 sq mm]
2) fill the bath with water, get the kitchen scales & trial the required force [mass = extra displacement] to get the box to draw say 25mm
3) go the a surfboard manufacturer & get a 60 mm thick off cut of board foam
4) epoxy resin the board foam to the hull of Missi.... & then blend it in
5) after the desired displacement increase has been trialed [2 to 4 kg?] it's a simple matter sanding, blending & filling then glass matting & epoxy resin
A simple alternative to the Missi.... just collecting dust & the vessel will not look out of keeping.....
Some time back our cousin, Tony [M] from NZ suggested :computer using granulated lead shot [available from gun shops] as ballast - insert a few layers of cling wrap into the hull cavities, pour :hammer the pre calculated amounts of lead & then flood with epoxy resin.... then this provided ballast blocks that would not move and are removable :terrific etc....
From memory some of the plans for OZ paddlers from Float a Boat are listed as having the draft incresed for scale stability... I did the same in Y2000 when I drew the lines for my PS Decoy, but :ohno as I need extra ballast - [Decoy I mean] - Derek :music
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Hi Derek
Interesting idea that - love the way you think.
So I strapped a 500 x 150 x 70 chunk of foam on the bottom with 2.5 kg of lead imbedded in it. This brings the water line up to where it should be but the C of G is still too high.
My problem is the top decks weigh all of 1.8kg and sits nearly 300mm above the water line and this is with only 2 of the 4 funnels fitted. I need way more than 2.5kg of lead and much deeper than 70mm to counter this in a static sense let alone to counter windage out on the water.
I'm very happy though with it. I've learnt heaps, had great fun building her and the design intrigues me enough to have another go in the future at a multideck, rearwheeled Mississippi style boat.
For now I'm looking at the PS Adelaide or the Zulu. My thinking is they are lower and bigger with more displacement. Would either of these be a reasonable choice?
Richard
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I can't comment on the Adelaide Richard, but certainly the Zulu makes a superb working model....
One othe rsolution to your stability problem is to use Dereks idea of adding to the bottom of the hull to give more bouyancy, but then add a removeable drop keel (a smaller version of a yacht keel) to get the COG even lower - Lots of models have been built using this method, and if you have it as a bolt on attachment it can be removed for static display...
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Adelaide would have very little deck housin which means (depending on materials used) it wouldn't really be too heavy on the top.
She has her wheel house and a small cabin on top, the sunken cabin in the stern, the two sponson boxes and that is all, well apart fromt he incredibly large engine and boiler!
If you want any photos feel free to ask...I just seperated all my adelaide potos into a seperate folder.
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I have so far built the Pevensey, Adelaide and Captain Sturt and am currently building a larger Pevensey, the first on was only 1/32 scale and this one is from the Float A Boat plan at 1/24 scale, and the other boat is a bit of fun and is a Blockade Runner based on Glynn Guest's boat and is scaled up 1 1/2 times with a different bow and stern and some aother mods and additions but all of these models have been or are being built of mainly balsa hulls and superstructure and doped with usually 4 coats of progressively thinned dope. No problems so far and that is after about 2-3 years of heavy use. The only problem I have encountered is windage with the Captain Sturt so that is relegated to calmer days, so try using balsa andif you choose the Adelaide just keep the weight low.
Peter Webster
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Hi All
I think I will build both the Zulu and Adelaide. I'm spoilt with two big work benches from plane building days and I tend to 'bog down' just building one thing for months so two it is.
The Zulu's engineering is captivating and it is proven design. The problem is getting a plan. I've had one on order from Taubmans since October but the last email from Don says he should have it on the way to me this week so we will see. Meanwhile I'll start finding out about a lathe and how to hook it up to the CNC software.
The history and local flavour of the Adelaide make it a must build. Again as Peter has found it seems a good design to model with relatively low superstructure and if I scale up the Float-a- Boat plan one and a half times to 1.5 metres there should be plenty of displacemnet to play with. Did you increase the hull depth Peter with any of your Murray River models?
Pictures of the PS Adelaide would FANTASTIC and the more the merrier! Would it be alright to post them in here or should I start another thread on the building of the PS Adelaide? I'm guessing pictures of the Adelaide would be as it is today with the round paddle guards and lowered rear cabin. My current thinking would be to build it in this form as it was originally built and not the modified square box version.
Lots of reading and sums to do.
Richard
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Wherever you want me to place them I will. Square box Adelaide definately isn't as exciting as the 'original' round box version.
The Float-A-Boat plans are for the square box aren't they?
You can get plans for all three of the Port of Echuca's boats from their gift shop and I assume this is round box Adelaide.
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Richard,
No , I didn't increase the hull depth but did use the foam method as outlined by
Derek as an increase in buoyancy and a safeguard against sinking , if needed, but
thankfully this has not been required as yet.
Peter W
( In smokey Melbourne)
Hi All
I think I will build both the Zulu and Adelaide. I'm spoilt with two big work benches from plane
building days and I tend to 'bog down' just building one thing for months so two it is.
The Zulu's engineering is captivating and it is proven design. The problem is getting a plan. I've
had one on order from Taubmans since October but the last email from Don says he should have
it on the way to me this week so we will see. Meanwhile I'll start finding out about a lathe and how
to hook it up to the CNC software.
The history and local flavour of the Adelaide make it a must build. Again as Peter has found it
seems a good design to model with relatively low superstructure and if I scale up the Float-a- Boat
plan one and a half times to 1.5 metres there should be plenty of displacemnet to play with. Did
you increase the hull depth Peter with any of your Murray River models?
Pictures of the PS Adelaide would FANTASTIC and the more the merrier! Would it be alright to
post them in here or should I start another thread on the building of the PS Adelaide? I'm
guessing pictures of the Adelaide would be as it is today with the round paddle guards and
lowered rear cabin. My current thinking would be to build it in this form as it was originally built and
not the modified square box version.
Lots of reading and sums to do.
Richard
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> If your model is relatively top heavy or has a lot of weight
> high up and outboard (e.g. a side paddler or a shallow draft
> stern wheeler) , then you can achieve the strongest righting
> effort by concentrating the ballast along the centre line.
>
> However if your model is relatively light in the superstructure,
> then you might be able to spread the ballast across the beam
> to give an easier roll and more realistic handling.
This statement and the pictures are somehow misleading, so let me
please try to put it right:
If you take the same amount of lead ballast (i.e. to achieve the correct
draft) and either concentrate on the centerline, concentrate it at the
chines, or distribute it evenly over the beam:
The righting torque and the stability will be always exactly the same
(as long as you don't change the height of the ballast).
If you list the ship with a given angle under static conditions,
it will malke absolutely difference in righting lever and -torque.
What however changes is the moment of inertia, which doesn't
affect the static stability at all, but the dynamic properties:
If you concentrate the ballast right under the center, you get the
smallest inertia; if you spread it wide, the biggest.
Large inertia and same righting torque result in a slow frequency
of the rolling motion; small inertia in a high frequency.
The same applies for the pitching motion if you distribute the ballast
to bow and stern: The pitching gets slower, and you get the impression
that the vessel cuts through the waves. Concentrated ballast results
in a smaller inertia and thus faster pitching, allowing the ship to
follow or ride the waves better.
But again: Concentrated ballast does NOT result in a stronger
righting lever. Static listing angle and capsizing tendency stay the same.
Only thing you get is a faster rolling motion under dynamic conditions.
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...The righting torque and the stability will be always exactly the same (as long as you don't change the height of the ballast).
If you list the ship with a given angle under static conditions,
it will malke absolutely difference in righting lever and -torque.
What however changes is the moment of inertia, which doesn't
affect the static stability at all, but the dynamic properties ...
:shock:
Many thanks for your corrections Gretzschel, although I think that Richard's problem is all about dynamic effects of wind and wave action and I wonder about the relevance of static stability? After all the model (great looking model, Richard) floats upright and any tendency to list can be trimmed....
My lack of grasp of physics and my misuse of the words used to describe righting effort, moments of inertia, centroids and concentration/dispersion of mass is why I'll stick to building and sailing models and avoid designing them in future!!!! :idea:
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My thinking is that a boat of this style, amount of superstructure and detail built to a scale giving a sub metre length is not a practical model in anything other then dead calm conditions - great for the shelf though.
Seems you're right. Unfortunately:
Not wanting to bore you with mathematical similarity laws,
just a rough calculation I just made and which I found quite
interesting:
All of you know that mass or displacement are scaled by the
power of three.
As the lever on which the righting forces act on a listing boat
is scaled simply with the scale of length. The righting torque
at a given list angle therefore is scaled by the power of four
(By the way, the same scale factor also applies to the torque
of the drive if we want to reach scale speed).
Now for the wind: The lateral area of the boat on which the wind
acts is scaled by the square of the length scale.
The listing torque caused by the wind and acting on the boat is
proportional to the lateral area (square of length scale)
times the height of of the center of that lateral area (length scale)
times the square of the wind speed.
The scale of the listing torque is therefore the cubic of the
length scale times the square of the scale of wind speed.
Pfff - so much for the theoretical background....
But now it gets interesting:
Every model ship builder knows the scale speed according to Froude,
which means that a speed scaling factor of the square root of the
length scale leads to a similar wave pattern.
If we assume a "Froude wind", for example only 1/7 of the original
wind speed for a 1:50 scale model, we would get an identical
listing angle as the prototype:
The listing torque caused by the wind would scale by the power
of four, just as the righting torque does.
So even the wind makes no exception to Froude's law regarding
the similarity of liquid behaviour.
But as we experience on our pond the SAME REAL wind speed
given by mother nature, a moderate 20 kph wind would act on a
1:50 model boat in the same way as a 140 kph gale on the real boat!
And I wouldn't like to be on the ocean on a high rising wooden
riverboat during such a gale!
Therefore, the theory can fully underline what you experienced
the hard way: High rising riverboats are very prone to wind
problems, which get worse with miniaturisation.
Small models of riverboats unfortunately seem to be restricted to
fair weather or even indoor use, even if measures such as very
light cabins or ballast keels are taken. Unless you find ways to
increase the righting torque by the factor of 50.
Looks like I will have to rethink my sternwheeler plans, and
concentrate on low sitting river carferries, providing a minimal
amount of lateral area and height.
So much for that, Moritz