Underpowered or not?

brooksk

Seaman Apprentice
Joined
Aug 15, 2002
Messages
44
Looking to buy a new/used 20-21 ft sized I/O cuddy, with weight around 3400-3600lbs. Is there a guideline for determining what hp engine should be matched so the boat is not underpowered?<br />A dealer suggested anything over 2500lbs should have a V-8. What about actual hp of motor?
 

Oldsaltydog

Petty Officer 1st Class
Joined
Jan 27, 2004
Messages
322
Re: Underpowered or not?

You could find the web site of a boat manufacturer (Bayliner, Sea Ray, etc.) and see what the weight and motor ratios are for specific models.
 

Jdeagro

iboats.com Partner
Joined
Jul 30, 2003
Messages
1,682
Re: Underpowered or not?

The most common opinion is the more HP the better. I do not subscribe to that theory as it is too simplistic. Boat design, and balance dictate the performance as much or more than HP. In fact in our testing of identicle boats, a v6 performed as well as a v8 if not better. <br /><br />The theory that a bigger motor work less and therefore consumes less is also suspect. The cubic inches and engine running RPMs dictates the fuel consumption. Assuming that the engines are performing correctly. Bigger cylanders suck in more fuel, so even if the throttle is opened less, the cylander requires more.<br /><br />Anyway; the typical power to weight ratio for boats in this size is between 10 lbs per HP and 14 Lbs per HP. Easy enough to calulate. Simply devide the weight by the HP. <br /><br />Now you should consider the load that you carry is heavy then you should compensate for that as well. If the load is to the stern then the balance is not as good and you need to compensate for that as well. The absolute best thing you can do for a boat is install trim tabs which will help keep the boat in balance at all the veriying conditions. <br /><br />Do a search on trim tabs and Smart Tabs for performance information.
 

mattttt25

Commander
Joined
Sep 29, 2002
Messages
2,661
Re: Underpowered or not?

nautijohn provided good info.<br /><br />i'd guess a 220hp mercruiser i/o would match nicely to that boat.
 
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