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View Full Version : Floor/hull strength question



fkeys
04-03-2004, 09:57 PM
From what i've read, boats without full length stringers rely on the floor for the majority of the hull strength and stiffness. Well I learned this after chopping the s**t out of the floor.

http://www.hotboatpics.com/pics/data/500/5776DSC01332-med.JPG

I don't want to put full length stringers, and I don't want to replace the floor (as it existed previously.) To get hull strength and stiffness, I was thinking of "filling" the bottom sponsons (sp?) with a 1" to 1-1/2" thick woven roven or directional reinforcement laminate. I'll tie the existing stringers into this laminate and continue it all the way up under the deck.

I'm questioning the adequacy of this "beam" with respect to strength and stiffness. I'd sure appreciate anyones thoughts and suggestions. Thx

bulldogdaddy
04-04-2004, 10:11 AM
what the hell does the motor sit on?
seems to me for a jet boat you'd want full length stringers just for the motor torque.

fkeys
04-04-2004, 10:37 AM
The engine is mounted to stringers (bunks) that are only 6-8 ft long. Here's a pic showing them.

http://www.hotboatpics.com/pics/data/500/5776DSC00414-med.JPG

The boat hull (in the area of the bunks) is about 5/8" thick. I'm told that is pretty d**n thick for a boat - dunno. Never had structural problems as indicated by cracking, hull delamination, etc. The floor in non-stringer boats may well help with torque too.

Techno
04-04-2004, 11:40 AM
I would think a foam or balsa cored 2nd skin would be much better than armour plate added to the sponsons.
That much glass is 'spensive, heavy and still requires several layups to do so heat build up don't ruin it.

Even better idea is find out if your floor is even a structural part. A test in Hot boat compared 2 OBs rigged and an IO, the IO didn't have a floor installed to save weight. All 3 boats were the same model, but built for IO or OB.
I assume the hull was identical except for bunk/transom diffs since the floor was left out to save weight.