New motor sprays water up, too big?

[tunez96]

I have a 14' Lund with a 15" transom. I recently upgraded my 9.9 Mercury to a 1973 Johnson 25, model 25EL73A. When I hit about 10 MPH or so, water sprays up the back of the transom, arcing out and then hitting the handles on the sides. It's enough that I actually had to pull the plug out. I tried all the tilt setting and nothing has worked. It appears to be a short shaft like the mercury, the measurement from transom to cavitation plate is about 17". Is it possible that the shaft itself is too wide around for my boat? Any help is appreciated.

 

[AMD Rules]

Re: New motor sprays water up, too big?

Where is the antiventilation plate sitting in comparison to the bottom of the transom? Should be level, or just slightly higher than the bottom of the hull. You may have too much of the lower end in the water causing excessive drag and resultant spray.<br /><br />Any bolt on attachments(doelfins)?

 

[tunez96]

Re: New motor sprays water up, too big?

The antiventilation plate is about 3 inches lower than the bottom of the transom. It doesn't seem to be much lower than my old outboard, but the shaft has a much bigger girth. The new motor has no bolt ons of any kind. I did notice that on the closest trim setting to the boat that the exhaust was hitting the water.

 

[Barnacle_Bill]

Re: New motor sprays water up, too big?

To start, you need to raise the motor at least 3 inchs.

 

[JB]

Re: New motor sprays water up, too big?

Fifteen inches is a short shaft transom. 25EL73A is a long (20") shaft engine.<br /><br />I would put a setback plate on it that raises the engine 5", or swap the engine for a short shaft engine.

 

[KIGuy52]

Re: New motor sprays water up, too big?

Mine does the same thing, even though I built up my transom up to 20". I'm going to shim it up another inch tomorrow. I'll let you know how it works. (9.9 to a 25...I did that too...boat feels like I got a Hemi now.) I think you'll like it once you get it set up right.

 

[tunez96]

Re: New motor sprays water up, too big?

Thanks for your help everybody. I now realize that my old outboard was also a long shaft, which would explain why it would hang up in the weeds so bad. I'm going to be taking the motor back and looking for another, something at least newer than the boat (a 75). If anyone knows where to start looking, a 25 hp short shaft with electric start, mid 80s or newer. I can already tell I'm looking for a needle in a haystack.