Max engine HP rating?

[311Hemi]

What is all involved in the max HP rating on boats?

I have an 1985 Bass Tracker 16'v tiller that is rated to 40hp. Looking to upgrade the Merc 20hp that is on there now to a 40hp 4 stroke. I am just curious if that should be fine weight wise...or is it other reasons for the max HP.

I have seen a lot more 50hp engines available....would I be asking for trouble looking at those? For instance I found a 2001 Merc 50hp tiller that weighs 199 lbs and the same year Merc 40hp 4 stroke that weighs 204 lbs. The current 20hp Merc only weighs about 105 lbs.

[Ralph Wiggum]

I know if your plate says 40 and you get stopped with a 50 on it, you can get a ticket!

[311Hemi]

Yea, I would assume so. Only problem is that the number has actually been scraped away over the years (not on purpose) along with other parts of the plate. I just remember that it said 40hp for the max.

[iffy]

weight difference is negligible between a 4 stroke and a 2 stroke. The horsepower rating is there for what the transom can likely handle horsepower wise. I'd guess that your boat could handle the 50HP but if you ever had an insurance claim on your boat or motor, your company could refuse to pay, being you exceeded the HP limit. Its your boat, do as you wish, but consider the consequences.

[pfluemis]

Quote:

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What is all involved in the max HP rating on boats?

I have an 1985 Bass Tracker 16'v tiller that is rated to 40hp. Looking to upgrade the Merc 20hp that is on there now to a 40hp 4 stroke. I am just curious if that should be fine weight wise...or is it other reasons for the max HP.

I have seen a lot more 50hp engines available....would I be asking for trouble looking at those? For instance I found a 2001 Merc 50hp tiller that weighs 199 lbs and the same year Merc 40hp 4 stroke that weighs 204 lbs. The current 20hp Merc only weighs about 105 lbs.

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Take 100lbs of weight and put it in the back, center, of the transom, and see how you like the extra weight. Seriously. No need to get up on plane and WOT, but just how the boat feels while using it. Like anchored, trolling, or manuvering with the trolling motor. A modern 40 hp motor is about 50lbs more than the 80's motors, and about 100lbs more than what you have now. While it may not seem like much, when you look at the percentage of increase, it's a lot different. You'll be doubling the weight you have on it now, and adding 25% more weight than any motor on the market at the time the boat was designed and built.

At least you're sitting better than the situation I'm in. If I would want to go to a new four stroke on my boat, I will be adding 94% more weight than any of the motors that were built before, or 20 years after, my boat was built. About 192 LBS!

As far as going to a 50hp motor goes, adding 25% more hp than the boat was rated for might drastically shorten the life of the hull/transom. When you figure in the 25% weight increase too, it really starts to look bad. Personally, I wouldn't do it, but, in the end, it's your call.

[311Hemi]

Thanks for the info. I have decided to not go with a 50, I will be looking for a 40. I will also throw a couple weights in the back to see what 100 more pounds feels like. I found one 40 today...just not sure whether or not I am ready to jump on it. Might wait until this fall to upgrade the outboard to see what deals come around.

[MOWalleyeguy]

Putting a larger motor on a boat then was rated for it is NOT a good idea. You should maybe call the coast guard first and find out from them the penalties if/when caught. I know its not something I would do. Insurance companies wont cover any accidents or claims if you do this. But if your going to do it... I wish you luck.