Trim Tab issue, or ... ??

I have a 2000 SeaRay Sundancer with an Alpha II outdrive and Mercruiser 5.0L. Obviously it is an I/O.

I have the trim tabs all the way up but still am now getting this great deal of flat spray in front of my rooster tail off the back of the boat ... that would seem like the tabs were all the way down and causing a great deal of drag. The tabs are all the way up. I do not recall this ever occurring before and I just cleaned the heck out of the boat to remove the barnacles, etc. there is nothing hanging or dragging and on the most flat days on the Intracoastal I can get rid of most of it by trimming the prop way up but still getting this flat spray.

Please and thanks for any input - I am at a loss for what may be causing it.
Ron
rjklein@roadrunner.com

 

To the top ...

 

Now that your bottom is "Clean", perhaps the Trim tabs are below the bottom causing Drag?
Make sure your Tabs are straight out from the bottom - not Up or Down.

 

Depending on how your tabs are mounted, in the full up position they'll cause you to get some spray. Jango is right, insure the tabs are straight out, following the bottom of the boat.

 

negative angle

According to all major manufacturers of trim tabs when fully retracted the tabs should be above the plane of the bottom, this is called negative angle by Bennett. For a 9" chord tab a straightedge off the bottom should indicate 1/2" between the trailing edge of the tab and the straightedge. This ensures that when retracted the tabs are not affecting the vessel and when in a following sea this can be very important.

keysdisease

 

If you don't want spray behind the boat just turn off the engine...

Seriously, spray is difficult to eliminate and making sure the tabs are not dragging is just one thing. Make sure your bottom to transom transition edge is sharp is another, the sharper the better. Then you have a good starting point. Measurements show that water rises about the same as your bottom trim angle. So if your boat is trimming at say 4 deg at medium to high speed you should make sure the tabs can handle 4 deg angle of water rise without touching the surface when fully retracted.