Oh cool, Vis Smeed had a little electric submarine named
Sprat
.
Okay, I've not built this and didn't even know of the fellow before this post.
With that out of the way, I've been playing in Google and it appears the answer to the built of balsa question is - that balsa covered with at least one layer of model airplane tissue and cellulose dope was a common construction method. Even for that submarine.
Found an article where alternate materials were used for an enlarged version of a Vic Smeed plan,https://iansmodelboats.weebly.com/veleta.html
For the first time, as the boat was built mainly of balsa and lit-ply, I skinned the hull with nylon stocking and a product called Poly-C, which is designed to skin aircraft wings. It is a water based acrylic resin which is much easier and pleasant to use than epoxy. The coats can be applied quickly as it dries sufficiently within 20 minutes and, of course, clean up is quick and easy too.
However, do note,
There were quite a few things I wouldn't do again after building this model such as;
1. I would revert to the use of epoxy for hull finish. The water based resin I used here was great- easy to apply, finish an clean up but still prone to dents when handling the model.
I will offer no value assessment of that input, but there it is and fun was had in doing the Googling.
