Max Hp rating verses OB Weight?

9

96720

Seaman
Joined
Apr 22, 2010
Messages
60
Doing a transom rebuild and was wondering if I finish it to the original thickness and construction will I be able to mount twin outboards that weigh more but have less horsepower than the factory specs.? The boat is rated for a maximum horsepower of 80hp. (that?s about 265 lbs for that vintage motor) and I want to put twin 30hp 4 strokes that weigh about 160 lbs each (320 lbs. total). Will the transom be able to handle the weight? Thanks.
 
saltwaterbluefish

saltwaterbluefish

Petty Officer 2nd Class
Joined
Dec 14, 2010
Messages
156
Re: Max Hp rating verses OB Weight?

First, off adding more weight to the transom will cause the bow to lift up more when sitting in idle so you may need to put more weight up front to get it balanced. Second, the newer motors do weigh heavier, so look at the year of the boat and then the weight of 80 hp motors from that year to get an idea of exactly what kind of weight you can add. Without knowing the boat name and alot more research there is no answer. IMHO I would call the manufactor of the boat and ask them for advice, if they give the go ahead then go, if not don't. One other thing you may consider is that running two engines is alot more expensive than one, more maintence, more drag, etc. If you just want an extra motor for safety install a kicker bracket. I know that didn't really answer the question, but it should get you started.
 
H

havingfun2

Cadet
Joined
Mar 18, 2009
Messages
29
Re: Max Hp rating verses OB Weight?

Weight difference is a only 55 pounds. If it has a swim platform etc, try having a child etc that weights the same and you will get an idea on how that weight changes the c of g on that haul. Does not sound like a speed demon setup, so that can give you some leway. On a boat rated for 80 hp, I doubt that extra bit of weight will affect much. 2 engines will in theory actually even out the total engine load across the whole transom rather than a single weight hanging in the middle.
With proper spacing there are prop efficiency gains for dual versus single
One old vintage motor versus 2 new 4 strokes? After intial purchase, your costs should drop!
 
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