HP question on a 310RIB

[Cherman]

Finally getting around to purchasing the engine for our West Marine 310 RIB with the fixed floor and transom. It's max rated HP is 15. The Suzuki DF15 and DF20 HP Engines are identical engines. Same bore, stroke, length, and most important, weight. The difference is the 20 has a higher max. rpm.

So without getting into the:

• Why Suzuki instead of _______________
• The fact I am over the maximum recommended HP.

Wouldn't you get the higher HP being it's the same weight as the lower HP?
The operator is either myself or my wife. (not kids)
Isn't hp recommendations usually directly related to engine weight when rating these smaller boats?

I think the extra 5hp would be helpful when loaded with four persons to maintain a plane.
And will probably get the electric start for the Admiral.

Your thought? Thanks, Chris

 

[John bouy]

I would definetly go with the 20hp, especially since the weight is the same. With 4 people the 15 will be working pretty hard to plane out.

 

[La Maddalena]

I would go with the extra horsepower too. That being said, we never had a problem on plane with our Zodiac 310 w 15 HP Honda, fully loaded.

 

[endless seas]

20 hp Tohatsu

 

[northern]

If you over HP a boat what does that do to your insurance.
If the Coast Guard finds you over HP your boat is there any fines or charges you can face.

 

[Sea Gull]

20 HP, but replace the decals on the engine cowling with 15 HP.

 

[tc410]

20 HP, but replace the decals on the engine cowling with 15 HP.

Ditto.

 

[k9medic]

If you over HP a boat what does that do to your insurance.
If the Coast Guard finds you over HP your boat is there any fines or charges you can face.

You might see some civil hassles but the CG wont mess with you. Even most states have HP exemptions for RIB or inflatable boats.

 

[Cherman]

Thanks for everyone's opinion on this.
Most likely going the decal swap direction. My insurance didn't care about the HP. probably cause the RIB is a rider on top of the main boat insurance. (rider might be the wrong terminology)

So I dug into how they determine the max HP for a specific model boat. Here is one link of many that I found on that subject. http://continuouswave.com/whaler/reference/ratedHP.html
So I took the length and width right out of the specifications in the manual that came with the boat and actually came up with 20hp being the max for this model. The most important part of the equation being

"The rated horsepower may be rounded up to the nearest "5".