What gage is the aluminum? Looks pritty thick. You'll be hard presed to get any real performance out of a .40 size boat out of aluminum. The other thing you need to consider is radio glitching with metal. It's been done without glitching but you have to take precautions. As far as performance with an aluminum hull, that can be done too, but on a larger scale. A guy could make his formers say out of 18-22 gage aluminum using I-beem construction and using lightning holes. Then skin it with VERRY VERRY thin aluminum like a pop can is made out of. Then you could exced the strength to weight ratio of the usual miterials used. (bulsa, ply, fiberglass, ect) To do this you'd need to build this around a 1.00 ci. motor or larger and not the cheepies eather. Most plane 1.00 ci. motors run about 3-5 hp stock. You need something outrageously powerfull like a motor that'll run like 40-60% nitro ($$$) with a turbo or something like this;
http://www.geocities.com/ramair1968/...ito.html?20073
(also $$$).
The point is, to build and get performance with aluminum you need to get a high power to weight ratio and it's hard to do on a small scale.
Shawn