Brothers new boat has a lot of spray from transom

[JohnVH]

I know typically I've read the motor is too low? But the plate is a over the bottom of the boat. The transducer we've raised but have not gone out yet, but sure has a lot! Of spray. Help?

Campion 185

 

[jbcurt00]

Looks like the AV plate is below the hull in pix #2

 

[JohnVH]

Look at the 4th picture from a better angle, it's above the bottom, but is it not enough?

http://forums.iboats.com/filedata/fetch?photoid=10258464

 

[jbcurt00]

The fin directly over the prop and just above the trim tab, looks like its below the transducer body, or at least appears to be

So 1in +/- too low....

 

[JohnVH]

Oh, I was going off the fin above that. Got it! Thanks! I'll let him know.

 

[jbcurt00]

I'd try it as is, if you"ve relocated the transducer already.

The AV plate even w the bottom of the boat isnt a hard, always correct rule, but it is based on typical results.

May even perform best w the AV plate a little above the bottom, wont know w out testing and tuning.

 

[funk6294]

I would suspect with the notched area on the bottom the motor will need to come up so the cav plate is above the bottom. That notch out works to set the motor back when on a plane, this would have the water up a little higher when it meets the motor.

 

[alldodge]

Thing it will always spray with the step in the rear. Water comes out of the bottom of the hull then comes up and hits the bottom of the hull then the AV plate. Kind of like having an extension box but no way to adjust height. The AV plate will be like an anchor when trimmed up.

 

[JohnVH]

Ok, so the motor should come up, should we make some sort of splash guard or something above that step? The spray is crazy and blows into the boat, that can't be normal

 

[alldodge]

I don't know how to fix the issue without a transom redesign, or installing some kind of splash guards.

Maybe install a jack plate

Edit: but I think you will still have splash with a jack plate

 

[JohnVH]

Others don't do it, so not that step, must just be a low motor

https://youtu.be/3k0TLlP8zLQ

 

[alldodge]

Others don't do it, so not that step, must just be a low motor

https://youtu.be/3k0TLlP8zLQ

Just my opinion but here is how I see it. Water flows under hull and then reaches step which is a low pressure area that is flat, so water sprays upward contacting the flat hull. This spray now hits the drive and splashes against it above the CAV plate. A boat with a Vee hull clear back to the end of the transom will be below the CAV plate and is airborne with no contact

 

[JohnVH]

He has lifted the motor two mounting holes, picked up speed, lost the spray, better economy.

 

[GA_Boater]

Hey John - Thanks for the update. Sprayback isn't an uncommon problem here and it's good to see a fix for your brother.

Go boating and fishing.

 

[ajgraz]

Good to see a follow-up post to document a fix to a problem...so rare that people do so!

Say, how's that transducer working out, being positioned so close to that step? I'd imagine it must be seeing some disturbed water there...maybe 6" to port would be better?

 

[Old Ironmaker]

He has lifted the motor two mounting holes, picked up speed, lost the spray, better economy.

Good move. Just a tip for others. I had installed a new Humminbird transducer a few years back. The Rooster tail from the transducer was 6 feet high. Humminbird supplied a rubber insert you popped in to close the gap that is between the transducer and the bracket. Problem solved.