I was looking at the big static model shark that I built a few years ago, and I was wondering whether it would be possibly to build a similar-sized model from balsa/ply, BUT instead of plank-on-frame, I was thinking planks of balsa butt-joined together (with another piece of wood glued into the corners for strength), then sanded to shape, liberally covered in perhaps varnish or fibreglass resin, and finally painted.

What do you guys think?

(Remember, it's just an idea! )

I personally think that the way that someone choose to build their sub is personnaly up to them, I mean, every way has its advantages and disadvantages. DazDaman, are you planning to build your sub so that it goes deep? Installing braces along the inside of the hull or builkheads, can be usefull.

Not that deep - maybe a couple of feet or so. Maximum of five feet, but that's not necessary. I fully intended on building braces and bulkheads into the body to maintain strength, and using 10mm balsa for the majority of the build.

I would think that would be a super bouyant vessle though. Am I wrong here? But it seems like you would be adding alot of weight just to keep it down in the water. Unless I am missing a detail.

I was intending on adding a fair bit of weight to it, anyway, including a removable belly section for more ballast if necessary.

wow, it has been a long time since my last visit to the rc subs forum... anyways, i think with thick balsa, and some fiberglass covering, you probly wont need to worry about it being light. that should be fine. first, you will want to figure out the size, and if it will be dry-hull or with a watertight cylinder. it looks like you will want a dry-hull, as you will have wood on the inside. this will complicate the building of the hull, but then its alot easier to put the electronics in. i am most likely repeting stuff you already know though.

benthehen

I'm aiming for a model about 45" long (same size as the big shark in the pic), that will be about 7" deep/6" across.

In what way will the building of it be complicated?

Daz',
I don't see why building the Shark out of wood wouldn't be possible. It might be more trouble, water proofing the insides as well as the outside, but certainly 'do-able'. If it's going to be a 'dry' hull you'll have to give some thought to the internal bracing (more required than for a 'wet' hull) and so it would be more complicated.
I wonder if there would be any advantage to finishing the thing with the PVC, or the liquid plastic stuff used for coating tool handles? I know it would be more expen$ive than the usual finishs, but wouldn't it be 'neat'? [A local company does that sort of thing, big vats of the stuff, just dunk it!]
- 'Doc

Doc

I never thought of the plastic finish - we used to do that kind of thing in high school!

I intend on fitting internal bracing across the body, and also was thinking of plywood "stiffeners" (the only way I could describe them!) up the sides of the shark.

hmm. the biggest thing is propulsion- i think you are planning on just a prop, although it could use the tail movement... that would be a challenge. i would say the hardest part of getting it to be dry hull with the wood, is were the linkages from the servos, and the prop shaft exit the hull.

on the other hand, a water tight cylinder is expensive, cause it takes time to build one and they are made by hand, in low numbers. so i suppose that making it dry hull would suite your needs better.

benthehen

Well, my original idea was a prop as the working tail would be considerably difficult to do. The shark in the attached pic has a working tail. The mechanism is far too complex for me!!