Freshwater

[mjt60a]

There's been a serious lack of progress on the ship lately, this is due to me running out of money (hence making the newspaper boat using materials I already have lying around...)
I'm now working at the local dump (this may or may not be temporary) and should soon be able to buy necessary items to continue, but of course I don't have as much free time to actually work on it  :x
Progress since last update is...
completed planking promenade deck and mostly completed the engineroom skylight (don't know if there's supposed to be one, there appears to be some structure there but could be a container for life jackets - or even folding deck chairs!) Made it as a skylight for now, could change it later if need be. It opens on hinges and will be where the power and reciever switches are.
Made the top rear section of sponson deck both sides (at prom-deck level) where the lifeboats go, these 'foul' the bulkhead lights when the aft saloon is removed (for access to battery/electrical items) so also had to make the bulkhead lights spring loaded so they can be pushed inside and will return to original positions.
Fitted windows in aft saloon and begun the tricky job of attaching the wooden frames, that's about half done, I may do some more tonight.
Acquired 'material' for one of the masts this is a (fairly) inexpensive beginners fishing rod, it's the only thing I could think of to make the mast as thin as it looks in photos yet not fragile. I need to make it detatchable but with connections for the navigation light (I'm thinking two short lengths of styrene tube which fit one inside the other, the largest glued into the deck the other to the end of the mast - and a headphone plug and socket fitted in each.....remains to be seen if I can make that work...)
Then I'll need to make another one... :roll:
I'll take pictures as soon as it looks any different to last time...

[mjt60a]

...Oh, yes I almost forgot - floatation tests!
I haven't been able to do that yet with the full hull. I don't know if I ever mentioned this or you can see from any of the pictures but the hull is in two sections, the forward 'about one-third' of the total which just has some lights inside and the remaining two-thirds which contain all the electrical stuff and can basically sail by itself, pushing the bow section around in front of it. The back of the forward section has four holes in so it can be bolted to the rear with wing nuts which screw onto coach bolts epoxied into the rear, but water can enter through these holes. It won't sink as there's a watertight bulkhead in front of it and it is intended to flood but I will need to fibreglass the inside of that area the same as the outer hull to protect the wood before it can be flooded.
However, it does float OK with the holes blocked with 'blu-tack' and the aft (main) section also seem to be OK (I tried them in the bath)

[Eddy Matthews]

Sounds like things are coming along nicely Mick - Looking forward to the photos.

...However, it does float OK with the holes blocked with 'blu-tack' and the aft (main) section also seem to be OK (I tried them in the bath)

Bath??? You meant Test Tank surely? :-)

[Eddy Matthews]

Oh, I forgot to ask, why is the hull in two sections? Seems like a strange way of doing things, but I'm sure there's a reason for it...

[mjt60a]

I made it in two sections so it could fit into a case for transportation. As I don't have a car I intended to transport it by bus/train to either southend (no reply from southend model power boat club though    ) or bluewater (waiting list for members but they allow visitors to pay £1 on the day if there's a channel free) - However......the model is now much heavier than I expected even without ballast (requires the equivalent weight of six pints of water) so transportation could still be a problem... :?

[derekwarner_decoy]

Hi Mick - you mentioned a void space between the two sections that you plan to fiberglass - have you considered intentionally using this space a ballast tank?

With the six pint ballast requirement this is a pretty big number 6x750= 4500 ml or 4 1/2 kg or 4 1/2 litres of water space

I am going to be in a similar but lessor situation with PS Decoy requiring approx 3 kg of ballast - I have considerd making a mould of a number of the lower hull profiles between the frames, then casting lead countours & epoxy cementing them in - advantage is lower mass & stability, dis-advantage is lifting & lowering a vessel that is 3kg heavier than before

I suppose the only real advantage with lead ballast is that it can be  fixed or removable & it is 11.3 times smaller in volume that water - please  let us know how you proceed -   because    this ballast is heavy - Derek

[Khephre]

Derek, if you are casting your ballast to the shape of the hull would you also need to epoxy the castings into Decoy? Wouldn't the hull/frame surrounds, gravity, inertia and friction all help keep then in place?

Or is there some threat of movement - like are you planning to emulate Waverley crossing St Ives Bay in that storm?

If you have reasonable access to the 'bilges' in Decoy then here's an option for your castings.

Try putting a layer or two of cling film into the hull so that it nestles into the contour of the hull between the frames, then pour lead shot into the cavity. Follow that with enough epoxy to fill the cavity to the top of the lead shot. Complete this by embedding an eye-bolt and ring or similar part-way into the resin/shot mix and leave all to set.

Once set you should be able to lift the cast ballast out of the hull using the nifty little handle you've made. Strip off the cling film and Robert's your father's brother.

If the hull is contoured then you might need to 'careen' your model to work on it - lay it over, cast one side at a time and work the ballast into an acceptable shape before it goes off, then do the other side. 5 minute epoxy shld do fine and keeps the time lags to a minimum.

I use 10 or 12 gauge shot that comes in ten kilo plastic containers from the local huntin', shooting' and fishin' shop here, but most any gauge of shot should work fine. Just avoid the steel shot that is gradually replacing lead - it's specific gravity is much less so is not as effective as ballast.

Pluses:
- cold-cast in-situ avoids the dangers of heating and handling molten lead
- no need to build a mould of the hull beforehand
- major timesaving
- good ballasting down low = stable
- removeable for easy transportation

Minuses:
- the specific gravity of a lead/epoxy mix is lower than pure lead so requires a larger space for the same weight of ballast
- not as easily recycled as pure lead
- epoxy solvents have safety issues of their own

Hope this is a thought provoker for you
cheers
Tony

[mjt60a]

I have in fact considered not only using that space but building in some more in the mostly empty bow section and  behind the boiler/engine (battery/motor) room, with holes in the bottom, a ceiling a little below the waterline and perhaps connected to cowl vents or such like above deck to form watertight (airtight, even - apart from the vents) self filling ballast tanks. The only thing that puts me off a little is that the centre of gravity won't be as good (presumably) with water-filled areas as with a 'lump of metal' right in the centre of the lowest part of the hull.

[Khephre]

Mick,

I'd be inclined to get some ballast fore and aft as well as right in the centre of the model.

I reckon that a bit of ballast towards the bow and stern helps stiffen the movement a little and helps reduce any tendency for a model to pitch in "heavier seas". Likewise spreading the weight a little across the bilges from side to side helps reduce a tendency to roll.

Concentrate the weight in one spot dead centre and you run the risk of building in a pendulum-like effect.

Tony

[mjt60a]

Mick,

I'd be inclined to get some ballast fore and aft as well as right in the centre of the model....

Sorry, what I meant was 'along the centreline of the hull' like a long metal bar (cut into suitable lengths as the frames that shape the ply around the bow are solid walls up to main deck level forming compartments...)
I didn't know about balasting across the width of the hull though, I'd have thought keeping the weight near the centreline was best...
...if that's the case, the 'lead shot in resin' idea would probably be the best way...

[derekwarner_decoy]

Yesterday Tony wrote

Derek, if you are casting your ballast to the shape of the hull would you also need to epoxy the castings into Decoy? Wouldn't the hull/frame surrounds, gravity, inertia and friction all help keep then in place?>>>>>

If you have reasonable access to the 'bilges' in Decoy then here's an option for your castings.

Try putting a layer or two of cling film into the hull so that it nestles into the contour of the hull between the frames, then pour lead shot into the cavity. Follow that with enough epoxy to fill the cavity to the top of the lead shot. Complete this by embedding an eye-bolt and ring or similar part-way into the resin/shot mix and leave all to set.

Once set you should be able to lift the cast ballast out of the hull using the nifty little handle you've made. Strip off the cling film and Robert's your father's brother

Thanks Tony - [no you got that one wrong, Robert was my grandfather, but how did you know?] - I like the idea of removable ballast that is cast on site so will be stable & not move etc as you noted above [& no splattered lead & burnt skin]

Naturally the smaller the shot size the smaller the glue gap & if I know I need 3020 grams just measure it & glue it [in cling wrap]

However if we want to recheck the calcs just go to Google & search on the word density then choose the site
www.nyu.edu/pages/mathmol/textbook/density.html -   fasinating reading - Derek

[mjt60a]

This is the most recent picture (it's a bit wide if you look at it full size.... :?  );

since taking it, I've glazed the windows and added the frames, the same as the front ones, and the black protective strip around the hull.

[Eddy Matthews]

It's definately looking good Mick - Maybe we should try to have a get together for all the UK modellers on the forum that have a paddler? It would make a great day I'm sure....

[Khephre]

Good onyer Derek,

good to avoid molten lead if possible - as you say, skin doesn't respond well to lead at 330+ degrees C. And despite all the care in the world handling the lead pot, any moisture at all in the mould will result in a terrific steam explosion. If you use a cold ladle in the lead pot then this can cause a similar outcome so heat that ladle up first!

Don't forget that the epoxy you add will have a weight component all of its own and that your 3020 g of ballast is a combination of lead and epoxy resin. A complicating factor admittedly if absolute accuracy is sought...


Fair point re the centreline Mick, although I'm still cautious about a pendulum effect being set up. Perhaps other more experienced modellers than me can add their two cents worth?

Freshwater's really looking a treat. Well done.

Cheers
Tony

[mjt60a]

Maybe we should try to have a get together for all the UK modellers on the forum that have a paddler? It would make a great day I'm sure....

That'd be great, I haven't done that since the PSPS rallies at blackheath (I don't think they have them anymore, last time I saw the pond - last year - it looked un-navigable to models...) only problem for me would be lack of transport for larger models at the moment as I can't afford a car until I get a job again....