Boat Engine/Motor size question

I thought the same..but then I start looking at boats and they list a max HP...on 23 and 24 ft boats. That was the confusing part.

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How are maximum HP ratings for boats calculated? Weight? Length? Combination of both? Is there an "unlimited" class? What kind of boats are in that class?

Thanks.

Don't own a boat personally..but trying to learn a bit before I start looking...I'm still years out from ownership.

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I think its based more upon what they offer from the factory.

As far as how much you can put on it, it depends on your wants and needs(gas usage, cost, etc...), coupled with a safety aspect.

As far as safety, weight is the real concern. However you can put too much engine and have an unsafe max speed for the boat. although you can limit your speed

Not sure how its calculated but I have a 22' blazer bay which has an unlimited HP rating on the sticker. Wouldn't want to see what would happen with a 557 on the back

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What about the USCG max HP ratings placard on the boats? How is that calculated?

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Im pretty sure those ratings are subject to what the manufacture and their lawyers wish to post on them

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commercial built have no rating

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What do you mean by this? My boat was commercially built and has a 175 rating on it. Although it has a 150 and still does just over 60, not sure I'd want the 175

You can get new motor decals to read any horsepower rating you want.

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then I start looking at boats and they list a max HP...on 23 and 24 ft boats. That was the confusing part.

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The manufacturer did that based on their own number crunching, but the general formula for a boat less than 20ft is (L x W x 2) - 90 = max HP, you can add up to 5HP to get a round number. All measurements are in feet and width is of the actual transom, not beam.

LINK

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What do you mean by this?

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A boat that is used as in commercial use. They also don't have to have floatation.