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[Captin Jimmy]

Hi all i need some help

I'm planing on scratch building an all wooden speed boat Riva Aquarama  (just so you can see the boat) http://www.cornwallmodelboats.co.uk/acatalog/amati_riva.html  but i need some advice on how to make it waterproof. I want to have a wood finish so fiber glassing the out side is no good but i was thinking of maybe doing the inside is that a good idea?

What should i use to finish to wood with?  Would a clear aerosol varnishes make the wood waterproof and protect it from roting ?

Also what type of glue should i use i like working with PVA type glues more so i was thinking of using Titebond II Premium Wood Glue as it is "water-resistance" does that mean that it will be good to use for the planking ? (I wouldn't want to have the boat fall apart in the water   ) Or do i have to use a CA glue (what ever that means  )

I also plan on giving the boat a sing layer of planking in Mahogany Strip 2x5mm as this will be a lot cheaper than double planking is mahogany easy to plank with ?

Thanks or any helpful advice in advance 

[derekwarner]

Captin Jimmy.......a few observations & have you previously built a plank on frame hull?

1. the design of the Riva Aquarama model does not really lend itself to being able to build the vessel & THEN coat the internals with epoxy resin....or certainly not epoxy resin & glass cloth
2. POF and using one layer of 2.0 mm planking is also a challange unless you have a near perfect set of lines...as maintaining see thru wooden planking precludes the use of fillers to even out the usual unevenness created during planking
3. one alternative to this is double planking with the first layer sandable & fillable ....then the second layer is the cosmetic external skin
4. another alternative would be to plank in say 4.0 mm thick material & you have plenty of parent material for truing up sanding
5. you could consider the internal epoxy resin & glass cloth at this stage just prior to adding the deck planking
6. your requirement of viewable external planking also has an influence of the choice of glue used.......white PVA glue is not water resistant, but dries clear, certain alternate glues will provide certainly a greater water resistance but may stain the planking & hence ruin your best efforts
7. there are a number of polyurathane single pack aersol sprays that will provide a lusterous build of coats & display the natural beaurty of the timber planking and still provide a water tight integrity & reasonable impact resistance
8. some may sugget that polyurathane single pack will absorb water

Others will offer alternate constructive comment....but if it were my choice...... I would opt for 3 or 4 +5+6+7  ....Derek

[Captin Jimmy]

Thanks for the advice

What if i coated the hull in Yacht Varnish such as http://www.amazon.co.uk/Ronseal-Exterior-Yacht-Varnish-Satin/dp/B001GU8A4G would that create a clear waterproof layer over the wood? if so would it matter what type of glue is used ?

Or maybe someone knows of some other nice clear material which can be used.

Also does anyone know what Titebond II glue drys like? is it clear or yellow.

As for the fiber glassing i was thinking of building the bottom part of the hull then fiberglassing the in side and then adding the top with an opening hatch in it to get at the batteries ect.

[Sandy]

If it helps to know, Tietbond II dries yellow.

[john44]

Why are you against fibreglass matting the outside if the boat.
  I have made 3 Aquaramas of different sizes, all fibergassed and lacquered
and polished up to mirror finish. As stated above you will need double planking/cross planking, the first being sanded to take out any
unevenness of the profile. Mahogany is good to use but it can be quite brittle. When I made my boats I finished the planking, gave
it a coat of fibreglass resin diluted with propan 10% by volume to seal the fibres after sanding. Then I gave them 2 layers of fiberglass
fine woven cloth, and then 2 coats of undiluted resin. After sanding lacquering and polishing the results are worth the time taken.

[w3bby]

I agree with John, use a fine cloth and epoxy to seal the outside and use just brush on epoxy on the inside. You will not see the cloth when the boat is finished, you will however see your wonderful mahogany planking in all it's glory  I prefer to use West Systems epoxy. You can check out there how to's here http://www.westsystem.com/ss/boat-building/

[John W E]

Hi there Captin Jimmy

I myself am unsure of the method you are using to plank the hull on your model.   There are 2 methods you could use - for double planking - they are

Double plank Carvel - this is where the planks run from the stern to the stem parallel with the keel up to the gunnel and they are butt jointed (edge to edge).  This layer of planking is then corrected by sanding and filling to remove any hollows or bumps.   Then, the 2nd layer is applied over the top ensuring that the joints between the planks do not coincide with the plank edge joints of the first set of planks. The outer layer of planks can then be sanded and finished with various grades of sand paper and sealed with either polyester resin coating or an epoxy.   There is no real need to add matting or a woven roven in this layer, because all we need from the finishing layer is to create a barrier to create a suitable barrier to prevent moisture from reaching the planking.  The strenth is already built in to the structure by the planking method you have used and it is a reasonably strong and tough structure.

Double diagonal - follows the same pattern as double plank carvel - but the planks run from the keel at a 45 degree angle to the chine - from stem to stern and also run from the chine to the gunnel at the opposite 45 degree angle - for your first layer of planking.   This again, once again completed, is sanded and filled to correct any mis-shapes.
Then the outer layer of planking is applied in the opposite direction on top of the first layer of planks.    

When this planking procedure is completed it can be finished off in either of the above methods.

Of the two methods of planking the double diagonal one is a stronger one because it becomes a form of plywood as the grain of the planks run at 90 degrees to each other.
Therefore, as mentioned above, it is the stronger one - so only requires the minimum of barrier between the water and the planking and therefore it would be suggested that an epoxy finishing resin would be used.

The main thing is though to seal the inside of the hull as well; with either a polyester or an epoxy resin as this stabilises the planking and structure and prevents moisure entering the planking causing it to swell and break away from the outer layer.

For a better view of this have a look at the 63 ft Whaleback Build on this forum - this build does use a very fine layer of tissue matting - along with polyester resin and also if you look in the warships section at the Vosper RTTL 2751 build, this only uses epoxy on the outside.

These are eventually painted, but, you will be able to see the standard of finish achieved by polishing with wet'n'dry.

Hope this helps
http://www.modelboatmayhem.co.uk/forum/index.php?topic=9758.0

http://www.modelboatmayhem.co.uk/forum/index.php?topic=20758.0
aye
john