Trim Tab Questions?
 

I am looking at getting the Eddie Marine k-plane style trim tabs, but I have some space issues on my transom. How close can the tabs be mounted to the outdrive. I have attached a picture with the approximate location the tabs would go. The tabs are 17 inches long and taper from 12 inches to 8 inches. I think it will just fit, any opinions. Thankshttp://members.aol.com/jlstang95/transom.jpg

You will definitely want the opinion of some more experienced guys, but I don't think you want them mounted even with the bottom of the boat. If they are too low, when the water comes off the transom and it will "turns up" it will push against the tabs even if they are raised all the way up. This will cause a nose down attitude and probably slow you down.

Check with Dana and see how far above the transom line they suggest.

Just an observation but if you intend to put 18" long tabs on it that close to the drive you better check to see if you'll have clearance with the drive turned full left/right. Doesn't look like you will from the pic.

The picture is a little decieving. I made a template of the tabs and I don't think the drive will hit the tab at full turn. Since the tabs tapper down to 8 inches it will mis the tab by a couple of inches. Even though it won't touch, is there any ill effects from putting the tab so close to the drive, or will it not matter.

Some theories have you placing the trim tabs in as close to the drive as possible, that way when you are running up on plane the tabs are more effective ? Not sure if that makes any cense or not but it did work on my 251 Convinsor.

I am all for that theory then because the tabs are going to get as close as you can get without hitting the drive. I think the tab will be 5-6 inches from the drive at full turn.

The only thing you may sacrifice is the ability to level the boat from side to side if you had some uneven loads in the cockpit. The further out, the more leverage.

#1. Check not only clearance side to side, but also clearance when the drive is trimmed out. You may find that your prop will hit the drive. Ovbiously you don't run the drive that high, but what if you're in shallow water and trim up and have to turn?

#2. The closer to the keel CL of the hull, the more reactive the hull will be to tab adjustment. What may have required two inches of travel if they were installed further out, may only require a 1/2 inch movement when mounted as close as yours will be. This mkes the boat super sensitive to tab adjustment, maybe moreso than you would desire??

We've tried them from very close to keel CL all the way out to the chine line, and find the further out the better the overall handling.
You may want to call Will Smith at Phantom powerboats in Sarasota. His new SV light hull has them extremely close in and he can share with you his reasoning and the applicability on a pleasure boat VS a race boat.

Take care