boat motor sizing

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hall0743

Cadet
Joined
Aug 26, 2011
Messages
15
I know this has been asked a lot from the searching I have done, but I can't seem to find a specific answer for my question...

I have a 1989 Bluefin Super Hawk 1606 with a max hp rating of 50hp
I found a 1988 Bluefin Super Hawk with a max hp rating of 90hp

I measured my boat and used the US Coast Guard formula for safe hp, and I come up with 111hp on my boat...
Length: 15.833ft
Transom width: 6.375 ft
Transom Height: 20" (old brochure I found claims it is 21.5")

So I am confused as to why it is rated at 50hp? If I constructed my own boat to the same dimensions, the formula would tell me my max hp is far higher than 50.
 
delta229

delta229

Seaman Apprentice
Joined
Aug 15, 2011
Messages
43
Re: boat motor sizing

Maximum HP ratings for boats are based on several things. One part of the formula used by boat builders is the distance from the center axis or balance point to the motor (Moment). The weight of the engine effects the balance of the boat. Two exact hulls, one with a forward console and one with a more rear console will balance different. Too much weight to the rear will make the boat stern heavy. Building a boat that isnt properly balanced around its center axis will cause instability. The rating stated on the placard that was installed in the boat is the proper guideline. Also be careful that there is a significant amount of difference in the weight of outboards, even wit the same horsepower.
 
H

hall0743

Cadet
Joined
Aug 26, 2011
Messages
15
roscoe

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,764
Re: boat motor sizing

According to NADA Guides, both the 1988 and the 1989 Superhawk weigh 677#, and are rated for 50 hp.

I'd bet the one you found with the higher rating, has had a bogus capacity placard attached.
 
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