is my motor too high-- problems?

[stuee]

Hi, i have a 21ft glass halfcab and just put a 235hp Johnson on the back. I seem to get alot of spray from the lower leg when traveling, also i do get a little purposing when going over 55kph. could this be a issue being too high, i can life with the spray a bit.
The image looks like its angles but its straight, the few beers before didnt help
thanks

 

[ondarvr]

Those symptoms are normally from the motor being mounted too low, and from the pic it looks like it could be.

 

[stuee]

oops just noticed the image upside down ?? dont know how that happened, I thought the cavitation plate was supposed to be level with the keel? its about 1 1/2inch higher than the keel.

 

[bonz_d]

I find this interesting in that I have a much smaller Johnson on an aluminum boat that I picked up this summer that has this same issue. In my case the engine is a 1994 30hp. When I 1st installed this and ran it the plate was about 1/2" below the keel and at speed the spray was coming up about 2' higher than the engine. Almost looked like a rooster tail. I finally got the engine raised to the point that at speed I was cavitating and blowing out the prop on straight runs and it was still spraying from the deflection plate. Still haven't found a cause or solution.

 

[ondarvr]

It's an anti ventilation plate, and it looks to be an inch or so below the keel. You need to back up and take another pic with the camera level with bottom of the transom so we can get a better idea of the relationship of the AV plate and keel.

 

[jbcurt00]

It's an anti ventilation plate, and it looks to be an inch or so below the keel. You need to back up and take another pic with the camera level with bottom of the transom so we can get a better idea of the relationship of the AV plate and keel.

Yep, ^^^ the pix is upside down, so in the pix as posted the anti-cav/vent plate is above your ruler. It extends out over the prop.

The part of the motor that has 2 bolts thru it, just below the ruler, isnt the anti-vent/cav plate, its the mount for the lower unit onto the mid leg.

Right?

Perfect example of why I prefer using photobucket instead of uploading pix..

Edit: odd, when viewed in your post pix is upside down. When I click it and it opens in an attachment window its upside down. When I right click the open attachmentand choose VIEW Image, its right side up. Strange...

 

[ondarvr]

The pic is right side up on my iPad.

 

[jrttoday]

too much stern weight was the answer I found for mine - 252lb motor on a 15'4" hull. Corrected itself after installing 24V bow mount trolling motor w/batteries up front. Also stowed 15lb anchor in the nose. Your problem might be as simple as weight distribution

 

[Woodonglass]

Based on what I'm seeing, if that bar is dead level with the keel, if anything, it's a bit low!!!!

 

[stuee]

No Title

Sorry for the late reply, here is a photo more wider view of it all.

 

[ondarvr]

It looks too low, plus the fin, foil, or whatever you want to call it, allows the motor to be even higher, if it drags in the water it may create all sorts of odd side affects.

Your performance will most likely improve by raising the motor.

 

[jbcurt00]

Yep, low and the hydrofoil probably makes the too low and spray worse....

 

[sphelps]

+ 1 too low ...

 

[stuee]

Thanks all, So currently from the first photo you can see the keel is roughly just below the bolt heads, if i raise the motor 1 hole is should be enough or 2 holes?

 

[jbcurt00]

Go up 1 or 2 and run it. See if it improves. If it doesn't, change it again.

May need to change tilt angle too

 

[ondarvr]

Thanks all, So currently from the first photo you can see the keel is roughly just below the bolt heads, if i raise the motor 1 hole is should be enough or 2 holes?

There is no way to tell until you try it, move it up one hole, if works well move it up another hole, do that until it doesn't work like you want it to and then move it back down one hole.