What is the truth about 9.9 and 15 hp outboards, t

E

ellshu

Member
Joined
Dec 29, 2015
RO Number
33902
Messages
11
Engine rating for a dinghy 9.6' is 10 hp max , engine weight at max weight 206 lb

Engine rating for same manufacturer dinghy 10.6 ' is 15 hp max. , with sae engine weight load at 206 lb

Actual engine weight if existing johnson 8 hp is 85 lb, and
9.9 hp motors seem to have max weigh at 115 lb on 2 cycle or slightly more if they are 4 stroke

I can get from the anchorage to the pickup dock with the 8hp alone in 5 minutes, but returning to the same spot with my two guests is 25-30 minutes because it just cant get up on plane on the soft bottom tender.
Will a 9.9 hp either 2 pr 4 cycle make a difference in speed and plane ,and thereby keeping it legal without going to a 15 hp, or changing the whole kit for a RIB AND 15.
I have done so much reading about the 9.9 being an actual 15 if the opening plate behind the carb is removed from the cylinder intake etc etc etc.
 
If you intend to move 3 to 4 people on plane, you should be thinking about more HP and a RIB. We had an 18 hp 4 stroke Tohatsu and it was on a 11 foot Avon RIB. It was ok for three people maybe 4 but getting on plane would be a challenge. We had to lean forward regularly to get on plane with that set up.
25HP would have been much better.
 
agreed, soft bottoms generally don't plane well.
 
Two strokes are significantly lighter. Many 9.9's can be changed to 15 with a change of the carburetor.
 
I wouldn't expect much improvement from a 9.9 over an 8; maybe, but the soft bottom is more likely the biggest inhibitor.

Used to be 9.9 and 15 2-strokes were often built on the same platform. More recently 15 and 20 4-strokes have been the same platform, with 8s and 9.9s on a smaller block.

Oddly Suzuki now makes their 9.9/15/20 fuel-injected 4-stroke all on the same platform.

-Chris
 
Even some RIB`s can be hard to plane, I had a 10ft merc dink with the hard plastic bottom, 15 hp two stroke couldnt plane w/ 3 people. I retired the whole set up and went w/ a 8 ft inflatable keel with a 8 hp two stroke. The same 15 hp 2 stroke merc is now on a 14 ft Starcraft aluminum , planes 5 people esay.
 
An aluminum dink is going to be better hands down. I was going to suggest one since we almost went that route.

AB has a pretty good line of aluminum dinks. Easy on the transom and they require less HP.
 
You must log in or register to reply here.
Back
Top