9.9 water intake concern

[JSGOLD]

We are replacing an old tired 55hp with a 9.9 remote Mercury motor on our old StarCraft boat deep V. We use it almost always at 10hp max lakes so speed is not a concern. Just tired of dragging the 55 along and having to use a 8hp tiller so much. My question is this...The transom on this boat is between 19-20" in center. The 9.9 I have is a long shaft but I notice that the water intake on it is a bit higher than either the 55 or the old 8hp long shaft and the cavitation plate may be even or slightly above the bottom most point. This area has to be submerged since the water intake is under it. Now on this boat the bottom of the transom is always about 5-6" below water anyway. But, am going from a 240 lb motor to one about 100 so unsure how far below it will go. I can always install the motor off center but am pretty sure it will be OK. Do any of you have a similar situation? I guess if it raises up enough I can add weight back there.

 

[steelespike]

If its a long shaft motor and the 55 is a long shaft motor it should work fine.
The boat will tend to squat whether it planes or not.The water coming out from under will seek the level of the water around it.
Observe the operation. Is the impeller fresh? They do suggest a new impeller if you don't know the age of the present one.

 

[Sea Rider]

Small OB will push much better working at middle transom than off center. Sit engine at 90 deg, perpendicular to water level when boat floats alone. A 9.9 won't plane a boat rated for a 55 HP engine, but will achieve nice displacement speed provided that engine matches the sweet transom height required to extract all those 9.9 ponies out of that engine. You could go for a prop maximization if in need to push the boat much better than with factory delivered prop. Will need an induction tach for that.

Happy Boating

 

[JSGOLD]

Thanks! I will be double checking some things on the motor as we go. It looks like it has been well maintained. It pumps water pretty well and is very smooth. I plan on checking impeller and replacing fuel filter etc. I will place in center and see how it sits as soon as I can get the 55 removed. Hope to have it sold by days end. The hull is actually rated for 90hp but since we use the boat at 10hp lakes most of the time I will have to settle for whatever speed I get. Don't need much although I will miss having a bigger engine when do go to Stonewall Jackson one-two times a year. But I think the 9.9 will do OK. I have been using a 8hp long shaft and even dragging the 55 around it has done OK. Thanks again! Will advise when I have swapped them out.