PS Mary Ann by Jeff

[jeff1949]

More work done. Have got the side 'planks' on now, and hull very roughly shaped, well, bow at least. Stern is going to take some time to get the hull curves looking OK. One more row of planks to do, then time to start planning for location of the couple of beams that will run across the hull to support the wheel boxes and sponsons? (the decking bits that extend past the hull sides around the paddle boxes).

Gorilla Glue is great stuff. I have quite black fingers (as pre-warned by others) but have discovered that the magic WD40 removes wet glue from hands, tools, the bottle, etc with ease - but not apparently once it has dried. Have also been following the instructions re storage, ie remove all air from the bottle, wipe tip very clean, and store bottle upside down - seems to work as the glue hasn't shown any signs of going stiff yet.

Will get a pic up tomorrow night if I can. Purists will shudder!
Jeff

[DamienG]

There'll be no shudders from me Jeff Just praise for doing the best you can.

[jeff1949]

Well, had a half day off, so sanded the hull to a decent shape. Used the 90mm angle grinder with a coarse disc, and a palm sander also with coarse paper. Hull now looking pretty presentable compared to last  Sunday. I am have some pics, but also having trouble uploading them from this end, so maybe tomorrow evening.
Time now to start planning the innards and how the deck is going to look. I am using a 12 v 7.2 amp hour battery for power - heavy. So will maybe need to wrap Mary Ann in glad wrap and put her in the bath to see how balance will work out - and also see what sort of displacement I might have. I have a feeling she is going to sit fairly high and not be terribly stable until I get the wheels on.
More as time permits.
Jeff

[jeff1949]

Here there be progress pics. Should be up-front - the patches in the hull are Plasti Bond. Had to fill in a few gaps but I am not too worried about the final appearance at this stage. As an aside, I mentioned elsewhere that a couple of years ago I finished the scale cabin cruiser that I started when I was 15. It was largely held together with Plasti Bond, which must have been a fairly new product way back then (50 years ago!). The hull has stayed firmly held together all these years and didn't need structural repairs when I decided to complete it - a brilliant product I reckon!

I have cleaned up the inside of the hull (angfle grinder and palm sander again) since I took these pics. Have worked out a deck plan to put into action.
Jeff

[jeff1949]

Another pic

[jeff1949]

and another

[jeff1949]

Something of a quandary. The hull is pretty well done. Should I test just the hull in water to check balance and stability with the battery fitted before I proceed with fitting the other structures for decking and the out-rigger type decks (around the wheels - don't know the proper term), or should I do the other structural stuff first and figure out balance etc afterwards?

Suggestions appreciated.

I think I will make the rudder assembly next before floating.
Jeff

[derekwarner_decoy]

Jeff..........it is always best to know what you have to work with....

1. you could estimate the displacement of the hull by the block coefficient calculation method

[eg.,.......  lets say your hull is 1000 mm long x 200 mm wide and sits 50 mm deep in the water
1000x200x50 ..so in cubic mm ~~ this is approximately 10 litres of water or 10 kg of mass required to get the vessel down to it's 50 mm draft line ~ well that is for a plain pontoon shape.........you will need to make some estimations of the reduction in volume with the pointed bow & stern...so depending on the form of the hull......this same 100 x200x50 may be reduced in volume by say 1.2 kg?]

2. slap a few coats of wood primer or varnish on the hull & perform a physical displacement test.....simply adding cans of anything....beer, beetroot, pineapple + batteries  ....until the hull is resting at the desired waterline......then weigh all of the temporary ballast + the hull by itself, then the sum of both = the hulls displacement

Some have attempted cling wrap, but this is fraught with danger ......

From there you can understand the required positioning of the battery & motor + ancillaries' to give you the desired fwd & aft trim

Single story Australian style paddlers didn't really suffer from stability/windage issues, however naturally SLA type batteries can be laid on their sides to offer lower centre of gravity

Saying this, there is a short documentary on PS Marion [3 stories high above the waterline]......and the skipper equates the wind against the superstructure as being similar to an ocean going yacht under sail............ Derek

[jeff1949]

Thanks a heap Derek. I will do as you say over the weekend and report back when I can.

Many thanks,Jeff

[jeff1949]

Busy weekend - no float test yet. BUT - got the hull painted with 3 coats of polyurethane, and got the rudder assembly built. Will have about 50 degrees each way of centre - probably sufficient - it will have to be! Will post some pics later, but basically the rudder has a top and bottom brass tube as a bearing and the stern post has one, in the middle (should have made it the other way around), with another tube which is a smooth fit inside the 'bearings' going the full length of the rudder. This inner tube will swing the rudder, via an arm to the servo and a long pin which will sit down inside the rudder and be soldered to the inner tube and servo arm.
Made it this way so I can easily remove the rudder if I have to (the inner tube will just pull out and the rudder will separate from the boat). But a picture is worth 1000 words so I will post a picture later on.
Not real bad progress since this time last Sunday!
Jeff

[jeff1949]

Some progress pics - hoping they upload together!

[jeff1949]

Think I have the rudder/servo set-up worked out so that I can get full rudder swing. Not installed yet, will leave that for a few days until I get some more structural stuff done. Have fitted motor mounts (removable in case those tiny motors don't drive hard enough) and about to start making a frame for the paddle decks.
The motors will drive a brass tube as an axle, housed in a snug fit outer brass tube as a bearing. Will mount a tube-bearing on the top of the hull, with another at the outer end of the wheel, and 2 bearings on the motor mount. I am pretty sure that this will give sufficient support for the axle. The drive gear is held to the axle with a tiny split pin, and the wheels will also use split pins to hold them to the axle. This will make wheel and motor removal fairly simple, if needed.
As you all know, time is the critical ingredient.
Must say it is really nice having to build in weight, as opposed to building in lightness as with R/C gliders!
Jeff

[jeff1949]

Had a spare hour so have fitted the frames for the paddle decks, made the bushings for the drive shafts. I will be using both motors initially, and if they seem to work in unison - i.e. same speed - and the rudder will swing the boat, I may leave them at that. Although at a later date I will fit the reversing switches as in Brett's article. By the way, the motors draw about 240 ma running free, and about 500ma when the shaft is held firmly between fingers.

This is a contrast to my model cabin cruiser, which has a 12 volt drill motor in it, driving about an 1 1/4 prop. Haven't measured the current draw, but it will blow a 40 amp fuse if I put too much power on too quickly, through the ESC.

Pics will appear in next day or two, of progress.
Jeff

[jeff1949]

Hello again!

I am pleased to say that Mary Ann is almost ready for the water. Very briefly, after my last post some 18 months ago, I got stuck on the paddle wheels - that is, how to make them quickly. I didn't want to go to the trouble of spending hours creating intricate wheels that may not have worked. About 2 weeks ago I decided to make some thin sheet metal discs, and use Loctite Epoxy Weld to glue the paddles into place between them. With a brass tube as the bearing (pinned to the brass tube axle) the wheels are now done and fitted to the boat.
Had a trial run in the bath to see if the tiny motors would drive them without stalling, and the boat very near leapt out! Plenty of power, no sign of stalling - and between them they only draw about 240ma.

Since then I have completed the decking, permanently installed the drive system, and given the decking a coat of polyurethane. I am now ready to start installing the ESC - which I will need because the boat is going to be too fast - and the rest of the electrical stuff. Intending to run 2 servos with a Y lead for rudder and wheel steering. One servo turning the rudder, the other servo to operate a micro switch for each wheel - to turn one motor off on turns.

And just this evening I realized that the wheels will probably cause stability problems, and have decided on a method to fairly quickly make some timber wheels. Current wheels have 16 paddles - I think the new ones will only have 9. But will decide this once I have had the boat in the water to see how she handles.

Will post some pics in the next couple of days. Just wanted to say it is good to be back on the forum and to see what others have been doing.

I should add that these tiny motors, apart from being very cheap, appear to be really appropriate for paddle boats, and pretty easy to set up. An ESC should control speeds well, and the way I see it, the motors already come with a pretty good reduction ratio and it seems a lot less fiddling around with belts and pulleys, etc.

More to come. Best wishes to all. Jeff

[DamienG]

Welcome back Jeff good to hear the Mary Ann build has progressed.

Damien.