H.P. ratings for boats

[jvc45]

HI got a simple question here about hp ratings on boats.
I have a 1988 sylvan rated for a 40hp motor.
could I put an older motor pre 1980's that is bigger than the hp rating of the boat?
Let say a 50hp 1975 merc or johnson.
I have herd that the older motors were rated different before the 80's so an older 50 is like a 80's 40.
any thoughts or sugustions is welcome.

 

[tashasdaddy]

Re: H.P. ratings for boats

you can put anything you want on it, but. insurance will not cover it. if you have an accident you will be at fault.

 

[jtexas]

Re: H.P. ratings for boats

Most bass tournaments won't allow it. And talk to your insurance agent, if insurance coverage is important to you.

Your '75 motor is rated at the powerhead which as a rule of thumb is 10% or so higher than at the propshaft, which an '88 motor would be rated for. So a '75 50 is somewhere neighborhood of an '88 45.

The extra 10hp wouldn't cause me any safety concerns. Disclaimer: I'm no lawyer, engineer, or boat expert either, and I'm not affiliated with iboats, yada yada yada at your own risk, etc....

 

[Chief101]

Re: H.P. ratings for boats

you can put anything you want on it, but. insurance will not cover it. if you have an accident you will be at fault.

How do you know this? I've talked to my agent and he has never heard of this rule you so speak. Even the Coast Guard Aux. here didn't know this rule. Tho they did say it may not bode well for you in a civil case. Chief Chief .)

 

[jvc45]

Re: H.P. ratings for boats

My concern was getting pulled over bye the DNR and getting a ticket for having a 50hp motor on a 40hp boat.
My thoughts are would i be gaining anything with a older higher hp motor? thinking the extra weight of the older motor vs the hp gain. would I loose or gain from it, I think that it would be about equal because of the extra weight.

 

[croSSed]

Re: H.P. ratings for boats

I say put as much power on it as you legally can... to a POINT. I've been around power boats all my life. In my experience when you put the rated power on a boat (say, a boat rated for 125 and you put a 125 on it) it still seems under-powered.

Example: My dad once had an old boat that was rated for a crankshaft 125. At one time he had a '68 Merc 125 on it. It did okay - had enough power for skiing, but had yawnable performance at top speed. Then, he bought a propshaft rated Suzy 140 and put it on the same boat. NOW it started to become fun! Had more torque for skiing and at WOT nearly flew! Keep in mind that a propshaft rated 140 is more like 155 or160 crankshaft h.p. He effectively went from a 125 to a 160! The power difference was amazing. When you ran that boat at WOT with the engine trimmed out, it didn't throw a wake. The only thing coming out the back was prop blast. It did an easy 50 mph. With the old 125 you'd have to be going down hill somehow to reach 45. Earlier I said, "to a POINT." To me a V-6 150 or 175 would be CRAZY on that boat.

Some would say, "Isn't it dangerous to overpower a boat?" Not if you know what you're doing, and you don't WAY overpower it. And just because you have that extra power doesn't mean you have to use it. People do this all the time with cars and never think, "gee, I wonder if this is overpowered now." You have your stock '69 SS Camaro with a S.B. 350. Then you have your bored out, cammed, heads ported, huge Holley, blown, etc., '69 SS Camaro. I've never heard anyone wonder aloud if they have too much power with a car like that...

TG

 

[Silvertip]

Re: H.P. ratings for boats

The reason you don't worry about it in a car is that there is no plate indicating the maximum horsepower the car will handle. But you can guess who will lose if that non-standard car is in an accident with a minivan driven by a mom hauling a bunch of kids. They will own your stuff. With a boat there are lots of factors affected by overpowerering but in a nutshell, it all boils down to what happens if you have an accident and the lawyers find the boat had a larger engine than the boat was designed to handle. Your insurance company (if you have one) will certainly deny coverage (or you could pay a higher premium). Of course you can take a chance. Only you can determine what risk you want to take.

 

[croSSed]

Re: H.P. ratings for boats

The reason you don't worry about it in a car is that there is no plate indicating the maximum horsepower the car will handle. But you can guess who will lose if that non-standard car is in an accident with a minivan driven by a mom hauling a bunch of kids. They will own your stuff. With a boat there are lots of factors affected by overpowerering but in a nutshell, it all boils down to what happens if you have an accident and the lawyers find the boat had a larger engine than the boat was designed to handle. Your insurance company (if you have one) will certainly deny coverage (or you could pay a higher premium). Of course you can take a chance. Only you can determine what risk you want to take.

Ageed. However, recently I was checking with my insurance company about insuring a different boat I'm considering picking up. The h.p. plate on the boat says 125. I told him I was going to put a 140 on it (just to see what he would say). He didn't bat an eye. Said my coverage would cost no more than it presently does.

TG

 

[tashasdaddy]

Re: H.P. ratings for boats

Florida and others states have laws to covering this. in Florida you cannot not exceed the capacity, persons or HP, displayed on the capacity plate. if you do this makes you automatically guilty.

 

[deejaycee_2000]

Re: H.P. ratings for boats

find a place that will make you a new plate exactly the same but with a higher hp rating ..... for the record, you didn't get this from me ... lol

 

[Texasmark]

Re: H.P. ratings for boats

My insurance agent had 2 blanks on my application for insurance. One was for hp rating, the other for size of engine installed. Since I was well under my max rating I got a discount.

Mark

 

[deejaycee_2000]

Re: H.P. ratings for boats

I don't think anyone would insure any of my boats .... I have a high risk life insurance though ... hahaha ..... i'm 175hp over the max rating on my fastest boat ....

 

[jvc45]

Re: H.P. ratings for boats

Thanks for all your input guys, I am a little worried about putting anything way over what the tag says because I did that with my last boat and now the transom is cracked where you bolt it on. I put a merc 1500 150 hp on the boat and it was rated for 125hp sure it gave me more speed but i paid in the long run, now the boat is sitting in my back yard, its to bad i have another 150hp merc in the guarage for back up but i have no back up transom. so I bought a smaller boat just for fishing and if i do go over max hp rating it would be just the next step up from 40hp. now i got to figure out what to do with all the extra motors i have that i no longer use, sell trade??
I have like 5 i no longer need.

 

[croSSed]

Re: H.P. ratings for boats

There's no way the 150 cracked your transom. The 25 h.p. is related to top end speed power. If we are talking about 2 I-6 Mercs (a 1500 and a 1250) the 1250 would be harder on the transom than the 1500. In my experience the 1250 has way more torque and speed out of the hole. The 1500 is kind of a pig in comparison. The only place the 1500 outdoes the 1250 is in all-out top speed. Even if it was a V-6 150 it wouldn't crack a solid transom. I'd say the problem was with the transom and not with the power you were using.

deejaycee - I like your way of thinkin'! 8)

TG

 

[Texasmark]

Re: H.P. ratings for boats

Now why doesn't that surprise me dee. 8) 8)

Mark

 

[jvc45]

Re: H.P. ratings for boats

TJ I think you have a good point there I never thought about it like that, The boat is a 1972 and you could tell there has been a couple of other motors on it besides the one i put on so maybe your right the transom was weak from the get go. I have thought about pulling the motor off and fixing it pulling out all the old wood and using a product that is pre-mixed and pour it in, Its 3 times stronger than wood and has a shelf life of 3 months.

There's no way the 150 cracked your transom. The 25 h.p. is related to top end speed power. If we are talking about 2 I-6 Mercs (a 1500 and a 1250) the 1250 would be harder on the transom than the 1500. In my experience the 1250 has way more torque and speed out of the hole. The 1500 is kind of a pig in comparison. The only place the 1500 outdoes the 1250 is in all-out top speed. Even if it was a V-6 150 it wouldn't crack a solid transom. I'd say the problem was with the transom and not with the power you were using.

deejaycee - I like your way of thinkin'! 8)

TG

 

[bassboy1]

Re: H.P. ratings for boats

Change the number on the motor cowling. Some brand motors have the same size cowlings on 40s and 50s. Just get a forty cover.


You didn't hear this from me. If you ever get in trouble for that, email me so I can delete this post before I get busted.8)

 

[Bob_VT]

Re: H.P. ratings for boats

An interesting point is some newer boats are being advertised with max hp AND max engine weight. Sundance skiffs is a company doing this.

The slight differance in HP should not be too much for your boat as long as you are adult about it.

Many many many bassboats are running significantly higher hp motors but labeled as 150. BASS had a max hp rule.

 

[Rancherlee]

Re: H.P. ratings for boats

The engine HP rating was made for engine weight anyway and is kinda out dated. MOST transoms get wrecked from hauling the boat down the highway without a transom saver device.

What are you looking to get ou fo your boat, more hole shot or more topend speed. Going up to a 50/60hp engine thats based on a 40hp block isn't going to do anything for holeshot power. works great for topend speed though and its easy to put a 40hp cowl/decals on it and if you get in trouble and they question the 50 or 60hp tag on the engine (which they won't) just say you blew your engine and used the 50/60hp block which is the same to replace your 40hp block.