how deep should a transom be to hold 200 horsepower engines and up?

[Islandboy]

i need some help

[marshmat]

Care to elaborate? What is the situation you're talking about?

[Guillermo]

Power (For planning boats) is more related to breadth astern than with deepness of hull there. Could you be more specific about your question?

[Islandboy]

ok ive designed a NEW boat hul that has never been made and i jus need to know the calculations of certain parts of the boat its a planning hull more of a power skiff i need to know if the transom have to be a certain measurement to hold a engine over 200 horsepower

[dougfrolich]

hmmmm. I think a better question might be; What should the LCG be for the speed I expect to achive for a given horsepower, chine beam, dead rise, lwl and displacement.

[Willallison]

I think what Islandboy means, is how thick does the transom need to be.
I don't have the info here at work - but someone else may do. There is much more to engineering a hull structure than simply the thickness of the transom however...

[gerard baladi]

Go to marinepower.com, they have diagrams of engine installation requirements for various o/b (surf through the downloads)

[fede]

Transom for most Mercury sterndrives has got to be between 51 and 57 mm.

[Ike]

I think he wants transom height. Most outboard motors have a standard shaft length of 20 inches (50.8 cm). So your transom height from the bottom of the hull to the top of the transom where the motor mounts, should be 20 inches (50.8 cm) for most outboards. However, these big block outboards generally have a long shaft. I looked on Mercury's site for the shaft length of their 225 EFI Four Stroke. It's 25 inches (63.5 cm) or you can specify a 30 inch (76.2 cm) shaft. Yamaha is the same for their 225 fourstroke. I would go for 25 (76.2). All the outboard manufacturers usually use the same standards shaft length so this should accommodate any 200 HP or up outboard

[Ike]

Oops, I goofed on my metric conversion. 25 inches is 63.5 cm. I've got to proofread before I post!

[antonfourie]

Have a look at the PDF in this thread for Yamaha outboard dimensions

http://www.boatdesign.net/forums/showthread.php?t=10461

[dereksireci]

CODE OF FEDERAL REGULATIONS – TITLE 33 – NAVIGATION AND NAVIGABLE WATERS

PART 183—BOATS AND ASSOCIATED EQUIPMENT

Subpart D—Safe Powering

((Length of boat in feet x width of transom in feet) x 2) - 90 = max HP

For a boat with remote steering and transom height 20" or more

http://www.uscgboating.org/safety/boatbuilder/part1/reg33_183_4a.htm

djs