Quote:
Originally Posted by Bigshrimpin
Each sq ft of foam is equal to roughly 60lbs of flotation. Submerged weight of fiberglass (.33 k factor) and aluminum (.63 k factor) is very different from the weight on land. This manual explains how to calculate your flotation needs. Page 20 (or page 24 of the pdf)
http://www.uscgboating.org/regulatio.../FLOTATION.pdf
On a 23ft seacraft each stringer is roughly average of 15 inches deep x 2 stringers x 16ft +/- . . . that's a LOT of flotation just in the stringer foam. If you round it to 1 cubic ft for each foot of stringer . . . that's approx 32 cubic ft x 60lbs = 1920lbs of flotation.
If the hull is solid glass (which it isn't) but just for the explanation let's say the hull weight 2600lb was solid glass . . . the submerged weight would be 2600 x .33 = 858lbs of flotation would be needed to float the hull. When you factor in plywood cores and balsa cored decks . . . it'll weigh even less. Even the motor (assuming it's a 50/50 mix of steel (.88) and aluminum (.63) = 1.51/2 = .755 k ) so a motor underwater only weighs 75% of what it does when it's not submerged. A 600lbs motor would only weigh 450lbs underwater. My point is that the stringers full of DRY foam is PLENTY of flotation for 23 with motor and people. |
When lost, the hulls are found.