The amount of Gluvit you need to seal a 14 ft. aluminum boat depends on freeboard, hull shape, etc. For example, let's say the boat is 14' long, 16" freeboard, and 6' wide. Conservatively, 14 x 6 x .85 (the bottom profile is calculated like bottom paint) = 71.4 sq ft. Then conservatively, each side would be about 14' x 16" (yes, it flares and tapers—this is just a rough estimate) = 16.3 sq. ft. per side x 2 = 32.66 sq. ft. plus the transom of 6' x 16" = 7 sq. ft.