Steel or Aluminum? And I love both.
Originally we had planned on building in aluminum but the price of aluminum would have required waiting another year for us to have enough cash. Cost was the most important factor to us because the other differences in the end were a wash.
Originally thinking in aluminum it is ideal to get the plates wide enough to avoid as much welding as possible. In aluminum everything would be 3/8 inch except the pilot house which would be 1/4 inch.
Hull: 15 wide x 75 long x 2 sides; 16 plates – 8 x 20ft
Deck 16 x 70; 8 plates – 8 x 20ft
Bulkheads 8’x 16′ x 5; 5 plates – 8 x 20ft
Keels 20′ long x 2 deep x 2 sides x 2 keels; 2 plates – 4 x 20ft
Skeg & Rudder 15 long x 8 deep x 2 sides; 4 plates 4 x 20ft
Pilot House: 15 x 16 roof + 4 x 62′ perimeter; 2 – 8 x 20 and 4 – 4 x 20
When converting to steel, the wide plates are no longer important but steel comes off a roll so lengths up to 65 feet are available if you don’t mind paying extra for the oversize truck to deliver them. If I could get 75 foot long sheets it might be worth considering, but I chose 45 ft sheets because they fit on a standard truck and allowed the butt joints in the hull to be staggered.
The pilot house will still be aluminum on a steel boat; so to convert the aluminum sizes to steel I just took the square footage for all of the 3/8 inch plate which came to 5,120 and divided that by 6 ft, which is currently the widest steel plate available without having to pay extra and that comes to 854 feet. Divide that by 45 ft plates and it comes to 18.9, but 20 is a nice round number. In July of 2008 the price was 61 cents a pound delivered, plus tax. It would have been half that cost if we had purchased in January, but that is spilled milk.
In addition to plate we also need 1000 feet of 2 1/2″ to 3″ Sch40 for the bulwark and for rounding the corners. We chose to go with 3 inch. It’s considerably more but I have bent 2 1/2″ pipe and never bent a 3 inch pipe yet. Also 800 ft of 1/4 inch, 2 x 2 inch angle that will be used for ribs and stiffening the deck. We could go with 1/4 thick, 3 inch flat bar too, but I think banging your head against the flat of an angle is much nicer that the edge of a flat bar.