Rating plates (HP Specifically)

[egclassic]

Sorry if this is the wrong place to post this question, but what do they base the HP rating of a boat on?
I have a 20' pontoon that currently has a 35hp Merc on it, but it has a max HP rating of 65HP.
I have an opportunity to get a 70hp Johnson (1977) to put on it.
I have searched the NADA site for weights of motors, this particular motor weighs in at 231lbs.
I also checked the weights of 65HP motors on their site. I found that some years of 65hp motors weigh as much as this 70hp.
Would I be safe to go just 5hp over max? I know alot of people go to extremes on over powering, and thats not my intent.
Thanks!

 

[boobie]

Re: Rating plates (HP Specifically)

I wouldn't go over the max rating on the boat. Between insurance companys, the DNR and lawyers you could have troubles if you ever got in an accident. You may want to check with your insurance company and local law enforcement and see what they say.

 

[BonairII]

Re: Rating plates (HP Specifically)

How old is the pontoon boat?

Going over max hp capacity is a hot-button issue here on iboats.

Going 5hp over max is nothing IMO. Go for it.

Putting a 1986 or newer 65hp on it would technically be within capacity, but would yield more hp than the 70 horse you're contemplating. If you put a 65hp 4-stroke....you'd also be much heavier too.

 

[egclassic]

Re: Rating plates (HP Specifically)

How old is the pontoon boat?

Going over max hp capacity is a hot-button issue here on iboats.

Going 5hp over max is nothing IMO. Go for it.

Putting a 1986 or newer 65hp on it would technically be within capacity, but would yield more hp than the 70 horse you're contemplating. If you put a 65hp 4-stroke....you'd also be much heavier too.

The boat is a 1988 Bass Buggy.
I didn't think 5hp over would be that big a deal either. I actually passed up a deal on a real nice 75Hp Johnson because I did not want to go over by 10 hp. But when you are looking at used motors, you choices are somewhat slim.
BTW, I have already replaced the transom with new wood and checked all the existing bolts/fasteners.

 

[BonairII]

Re: Rating plates (HP Specifically)

If the transom is new....you're in great shape. Remember anything older than 1986(when they started rating hp at the prop instead of at the powerhead), is going to produce about 10-15% LESS hp than the motor states it is. If the 75horse was pre-1986....you would've been well within safe limits.

Don't let the "max capacity zealots" here dissuade you from going over Max Capacity.

It's MUCH safer to a be tad over limit with a new transom.....than to be right at max with a 30yr old "suspect" transom.

Common sense is the key.


Too many here talk about lawsuits and tickets....yadda yadda yadda. Unless, a person is overpowering.....AND.....driving like a idiot....there aren't grounds for a lawsuit solely based on the extra hp.

A lawyer would have to PROVE that it was the extra horses caused the accident.

There's more legal liability IMO with the folks here(and all over the country) that are knowingly operating boats with old/weak transoms.....than a guy/gal running a little more power on a rock solid transom.