Stern strength

[max50]

I'm new at this so help please.
Can somebody tell me how to determine what kind of outboard horsepower can a powerboat stern take,some pictures,text would be nice,forces involved etc,everything!?(powerboat types like the skater 21)
How much strength does kevlar add,plywood,honeycomb materials etc,reccomend books etc?
Thanks!

[jimslade]

Check out a book that Glen-L sells. Its called fiberglass boatbuilding.

[marshmat]

Hi Max,
The power rating for an outboard boat is a function of several parameters. Hull volume and how that volume is distributed are the main points. Transom width is a factor, so is the shape of the running surface and the hull weight. In smaller vessels the location of the controls (tiller or wheel, and where in the boat the wheel is) are considered as well. These factors plus a few more are mathematically combined to determine the maximum power that the hull can safely handle; the result is the capacity plate rating. I don't know if there's any legal requirements for this in Croatia, but in Canada we're pretty meticulous with safety and legal stuff.
In terms of construction, it is the responsibility of the designer and the builder to engineer the hull and motor mount structures to withstand the forces involved. If you can find the company that built the hull, or the designer, they should be able to tell you what kind of power it should be used with.