Stretchy skin on frame model

[alan craig]

This experiment was inspired by a post on this forum which I cannot find now; it was a model made to test a stretchy covering and was vaguely speedboat shaped.
I'm building a double ended model yacht hull with a stretch covering (an old tee shirt) just to see if it's a viable way of making a boat. If it seems successful I'll carry on and make it radio controlled. Size 34" long x 10" maximum beam and made of s**thousedoorwood as my old boss would have said. The wood quality cost far more in time spent compensating for warps, knots etc. than I saved in pounds by not buying anything. At least I have a pleasing shape.(not me, the model.)

skin frame

• alan craig
• Nov 19, 2018

first assembly

skin frame

• alan craig
• Nov 19, 2018

stretchy tee shirt material

 

[upchurchmr]

Neat looking test. That looks like a much better model than I would manage
Your tee shirt material is 100 times as stretchy as a real desirable fabric. Polyester (un heat shrunk).
I think I have some as scrap - send me an address and I'll ship it to you.
For your next level test.

How long is the model?

OOps, I just saw you are in England.
I'd probably send it anyway.

 

[alan craig]

Thanks upchurchmr. 34" x 10". I've still got enough polyester left over from a 14ft skin on frame boat Skin on teak boat https://www.boatdesign.net/threads/skin-on-teak-boat.61282/ to do a small canoe. Although tee shirt fabric is too stretchy to add any strength to the structure i'm hoping it will be stiff enough after painting to be viable. It's so easy to cover as it stretches on with only a single cut at the stern. I've just given it the first coat of paint and it's very slow drying (especially in a wet November) so it will be a few days before I report back.
p.s. Very nice strip plank boat in your profile!

 

[upchurchmr]

I assume then you don't need more. Tell me if I'm wrong.
I made the assumption that you had no experience with actual SOF skinning.
Sorry.

 

[alan craig]

No I don't need any more fabric, and thanks very much for the kind offer. Don't be sorry; I feel like I've upset you!

 

[upchurchmr]

Not upset at all. I've tried pushing my scraps on others, mostly because I assumed a lack of experience. And I'm not planning SOF again, but I save everything.

That really reflects on myself.

Good luck.

 

[Barry]

Older fabric airplanes used a material called Ceconite, this might be a trade name.
A family friend used to fly spotter flights for water bombers with a supercub and this the fabric the plane was wrapped with.
You can glue the edges and then iron the fabric and it tightens up like a drum. Then coat it with a paint and you have a waterproof membrane
50 years ago, in the days of no money, my friends and I built 18 - 20 foot kayaks and they worked fine. We just put a thin coat of resin over the ceconite
You can google something like " applying fabric to airframes" to find threads on the application.

 

[upchurchmr]

Ceconite is a trade name for Polyester fabric, in lighter weights than normally used for boats.
But as Barry said, it can be used for lighter boats.
Even aircraft don't use resin for a coating.

 

[alan craig]

I'ved used a tee shirt because that's what I wanted to try; I'm aware of the coverings for fabric airframes.
Picture here of the hull with two coats of wood primer (I'm only using the old paints that are filling up my garage). I've now added two undercoats and the weave still isn't completely filled (Hammerite garage door paint!), next is gloss from a local DIY shop.

stretch skin

• alan craig
• Nov 25, 2018

first two coats

I think I knew when I started that this wouldn't be viable for a full size boat, but if it doesn't leak in the bath test I will probably carry on and make it radio controlled.

 

[alan craig]

My last post here was a while ago. I couldn't decide wether to bin the model or carry on making it into a radio controlled model. Finally decided to continue so I will document it here.
It floated fine in the bath without leaks and the sash weight I had lying around immersed it to a sensible waterline so I decided to carry on. No plans, just keep going. Slowly. So the boat now has a keel (awaiting paint and a sealing gasket), a cambered deck, rudder and cabins. and an aluminium mast. Next step is a few more spars, a gaff cutter rig and standing rigging.

Stretchy SOF

• alan craig
• Apr 24, 2019

Cabin roofs removable. Aft cabin houses steering servo.

Model yacht on work/carry stand. Ballast just fits inside stand.

Stretchy SOF

• alan craig
• Apr 24, 2019

Removable keel. Ballast weight is a sash window counterbalance.

Even a toy needs a cambered deck and a nice sheer line.