Of course the first "prevention" is to avoid getting knocked down.
Now you don't have to say that.
This discusses a inflated masthead bag for the F-27, and also examples
of righting procedures for the F-27.
The F-27 is a trimaran, which affords it huge advantages for righting.
Maybe my favorite boat.
Right up there with the Mac 26X/M, but for different reasons.
http://www.f-boat.com/pages/backgrou...zearticle.html

Monohulls can be so equipped too, but if hatches aren't sealed, most
will just sink like a rock when knocked down unless equipped with
positive buoyancy foam.
Like the Mac 26M/X is.
Sure, some owners have retro-fitted their boats with foam, but those
aren't properly engineered and tank-tested.
Amateur stuff and probably just more food for Davy Jones.
But it's skiffs that got me thinking about this, because open boats
are easily swamped, whereupon they are prone to rolling over
Sure, a bit of hull sticks out of the water when the boat is
constructed with positive buoyancy.
Doesn't mean you can roll it back over, or that it's a good platform
for survival.
The NFL players lost off Tampa a while back are a good example.
Four very strong men couldn't right that boat, which was well
designed, and level floating when capsized. They tried.
Had they been able to, they could have bailed and survived.
So for typical open powerboats which might be subject to swamping and
capsize, I'm thinking inflatable airbags on both gunnels..
Activation could be manual and/or automatic upon immersion.
Keep that boat from rolling over when swamped.
The engineering is straightforward and easily accomplished.
The system would be lightweight and not affect boat performance.
What's the problem? A number.
1. Cost. Might add a couple/few grand to the boat cost.
2. Cosmetics - some bulkiness or bumps on the gunnels.
3. Liability - if you sell it, it has to work - every time.
Maybe there's disclaimers for that - I'm not a lawyer.
4. Safety ain't no fun.
5. But the biggest problem by far - I don't have my own boat
manufacturing company.
Somebody could market these systems to clamp onto the gunnels
of any boat. Add some cupholders to ensure sales. Maybe an iPod
option. Be creative.

--Vic