Send me your address and I would be glad to send you a small sample of foam board. You can take this sample and go scouting for it in Mysore. You should get it easily. Ask a cobbler (Mochi) show him the sample and he should be able to guide you. They use it, sometimes for making insoles. Or else, you should draw some leads from photo framers.

Economy?

Balsa : 750mm X 100 mm X 3 mm = Rs.150/- approx.

Foam Board : 1000 mm X 1000 mm X 3 mm  = Rs. 200/- approx.

Strength:

The largest that I have built with foam is the RAF FIRE Boat. If your bulkheads and formers are spaced closely, there is no reason that you can't build bigger with PVC Foam. The inner skeleton has to be built strong.

I am seriously considering building the 950 mm Speedboat Aastha out of PVC foam. I can save a lot of cheap Balsa / Japonica. Balsa sands better and dents and dings can be made to disappear with a smooth sand. PVC Foam (the dust, you are right, is unhealthy) needs a coat of automotive putty, followed by sanding for a REALLY smooth finish. However, after that is done it is very solid!

Forget fibreglass and all the hassles involved - get hold of Wembleys Quickfix. Dilute that with 50% thinner and brush it on. Wait for the first coat to dry hard and then apply a second layer. Now sand it smooth with 150 and then 250 grade emery paper - wet/dry (black paper). Voila! Rock solid.

Thanks sir, that is really helpful. I have planned catamaran with gas engine. Ordered drive hardware ant will order engine in next cc cycle. It would be 42" boat. I had planned with balsa which would be around 6000 - 7000 rs. But now I will first try sunboard.

Thanks for all the information. Please keep it coming.

Will send you the samples tomorrow.

Sir can you be kind enou to send me a small peice for a sample to go about shops searching for it?
Even I want to get into boats... will start with a tugboat

topalle,
I ll send the same peice once I get it from VC sir. Send me PM with your address.

Uh Oh! Now I have send Amit a bigger sample!

Good. Thread. VC some more posts from your experience? Worthy of sticky

Now please discuss about material construction techniques step by step like building the hull,waterproofing, adding electronics, deck ,detailing, etc

Topalle, trying to do something like that here:

http://www.rcindia.org/boats/aastha-scratchbuilt-speedboat/

Here are some pics for reference. It is a simple way to construct any boat or ship structure.

1) final the design
2) calculate the size
3) final the material to be used
4) take design on butter paper or get ito done on autocad
5) if doing manual cutting then trace it on material
6) if on cnc or laser cut then it will give you a perfect cut 1 to 1000 pcs and more
7) fix it on keel
cover it with sheet or strip

I think will be able to upload many thing from my current project. But my first and for most preference is balsa. No matter what is the cost