115HP on a 100hp rated boat

[sasanm]

Guys,
Another question. I have a buddy that is willing to give me his 115 HP Merc which is a 1988 model. The question I have is I had a 72 60HP johnson on the back of it and I am wondering if my boat can handle the 115? It is a 63 alominum starcraft holiday that I am rebuiding and I believe it is only rated for 100HP. Will the 15 HP make that big of a difference. I am also thinking that a 100HP motor in 1963 probably weighs more than a 88 115HP. Last I am rebuiding the tansom so maybe I can do something there to help.
Thanks again,
James

 

[oops!]

Re: 115HP on a 100hp rated boat

its illeagal......

the uscg rules determine the hp rating of the boat......

legnth x beam

having said that...........


id do it...but im crazy....

 

[wavrider]

Re: 115HP on a 100hp rated boat

In 1985 or 1986, depending on the source
the hp rating was changed from crank to prop
prior to 1985 it was crank rated
after 1985 it was prop rated
so any engine prior to 1985 is 10% less hp that the newer engines after 1985
so a 115 built in 1988 is 115 hp at the prop
your 1972 is 60hp is 60hp at the crank
understand the difference?

now the difference in 15 hp? never really know the difference until there is an accident or insurance issue, if it is only rated at 100hp then that is manufactures reccomendation, some states adhere to this as the law and is illegal to go above that rating.
other states could care less what you hang on the back of the transom.
Just always keep in mind the owner is responsible for all passengers on his vessel so if ever a situation occurs where accident or injury arises the over horsepower could come into effect
with that said

Rebuild that transom, make it super strong, mount the 115 and drive it like you stole it
really just cause you have it does not mean you are going to use the extra hp, weight i believe is around 315 lbs of engine give or take a few lbs
so if your transom will handle it, and you do not worry about legal issues, go for it

 

[kevincoe]

Re: 115HP on a 100hp rated boat

Someone installed a 200 hp Merc on my old 1977 Grady in 97...the boat was rated for 230 hp...boat sits in the water a lot lower in the rear end but the transom seems to be holding.... If you can somehow make the transom stronger like wavrider said I think it sounds like a steal.

 

[Bondo]

Re: 115HP on a 100hp rated boat

Ayuh,.......

Go for It.......

 

[reelfishin]

Re: 115HP on a 100hp rated boat

So long as your not adding weight it won't be all that noticeable. I've turned several smaller motors into their bigger versions over the years just to get around the rules and regulations. I have a 120 Evinrude that was built on a 90HP lower and mid with a 90 cover and tag, although my boat is rated for a 120, I doubt the average person would notice or really bother to check.

 

[imported_stump jumper]

Re: 115HP on a 100hp rated boat

I bought my boat with a 130 Evinrude. Replaced that motor with a 200 Mariner. It has it's disadvantages. I have attached a pictures to show how she sits in the water.

 

[Solittle]

Re: 115HP on a 100hp rated boat

You know that attorney's love you guys who overpower your boats come lawsuit time. They will clean your clock.

 

[imported_stump jumper]

Re: 115HP on a 100hp rated boat

I, for one, am judgement proof. Can't get blood out of a turnip.