New Project - Underbuilt transom?

R

rschnack

Petty Officer 3rd Class
Joined
Oct 29, 2002
Messages
94
I am finally planning to start repairing my 1969 16' Alumicraft Sea Aira. I need to replace the transom. I have read Jim Anderson's "Runabout Renovation" cover to cover a couple of times. In it he mentions that some of the early fiberglass boat builders way over estimated the horsepower rating for their boats. I measured the transom on my boat and found it to be 1.5" overall, including metal cap. Subtracting for the metal cap and fiberglass on both sides this only leaves about one inch for wood. The boat is rated for 100 hp and it has an 85 hp Johnson on it. This seems thin for the transom. Should I trust the hp rating?<br /> Your opinions would be greatly appreciated.<br /><br />Best regards,<br />RCS
 
J

JasonB

Lieutenant
Joined
Feb 10, 2003
Messages
1,455
Re: New Project - Underbuilt transom?

My '76 boat is rated for 100hp and the original transom was 1.5" thick solid plywood +fiberglass and trim. The new one I just put is is 1/16-1/18" thicker as I reinforced mine with a layer or two of woven roven. My 85 won't be able to budge it. Your transom should be in the 1 1/4" range which I would think would be ok. Are you replacing the transom? If so, glass it and it should be plenty strong.
 
R

rschnack

Petty Officer 3rd Class
Joined
Oct 29, 2002
Messages
94
Re: New Project - Underbuilt transom?

Thanks for the input JasonB. I will be replacing the transom. I can't make the top part of the transom any thicker because the way the splash well fits to it. I may add another layer of plywood to the inside of the transom below the splash well to reinforce it. It seemed pretty strong with some rot in it. The new transom will definately be stronger than the original.<br /><br />Best regards,<br />RCS
 
JasonJ

JasonJ

Rear Admiral
Joined
Aug 20, 2001
Messages
4,163
Re: New Project - Underbuilt transom?

My transom wood was only one inch as well. It had a 3/8th thick piece of plywood between the transom wood and the splashwell, so when I put in the new transom, I layered 3/4 with 5/8 and it worked out perfectly, and the transom is rock solid. My boat was rated for 145 horsepower.
 
K

Ken G

Petty Officer 2nd Class
Joined
Feb 28, 2003
Messages
158
Re: New Project - Underbuilt transom?

Horsepower ratings are based on the size of the boat not the thickness of the transom. It correlates length, beam, and width of transom. <br /><br />You could build up your transom to 3" thick and mount a 300 hp outboard. It may not break but I wouldn't ride in it. Well, I might ride once. LOL
 
You must log in or register to reply here.
Top