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My Brother in Law and I were doing a sea trial of 2 similar 13' Sports, both with 40 HP Mercs, but one was a 4 stroke and the other a 2 stroke, both 3 cylinder types.

We were on flat water with minimal current and no wind. When full throttle, the 2 stroke boat would start to list, best described as severe, that would inevitably end in a flip if not throttled back. A very strange feeling.

Similarly to last year, when the boat was on a plane the wake would splash back onto the transom indicating poor planning performance. Since it was missing the steering anode tab thingy (a technical term) and the screen filter that is under it, we added the tab and adjusted it to almost center hoping it would improve things.

This is when the list started. After adjusting the tail of the tab to the starboard, the list was notably lessened. In talking to the Merc dealer, he said that the tab was only for steering adjustment and he had never heard of it causing a list or a flip. Regardless, let’s not forget that the tab adjustment definitely reduced the list.

THEN things got more interesting when we went back to playing with our Whalers (in public, no less: ... )

My Brother in Law in the 2 stroke decided to jump my wake. He was fine going to my port but when he went over my wake to my starboard (which would have a tendency to lean his boat to starboard as he comes over my wake), over the boat went. Complete turtle - What a rush.

After collecting all that floated, we beached, flipped, bailed and towed it back to the dock. After spraying it off and purging water from the cylinders, he got it running again. Kudos to Mercs.

Then off we went to the Merc dealer again to ask questions. Again nobody had heard of the steering tab causing a boat to flip, but they advised that the sloppy wake with water splashing back on the transom was unquestionably a result of the motor being too low.

Back at the rivah, we lifted the motor by about an inch and went back to the water trial again. Now the wake was clean and the list gone.

My theory - because 1) the tab is curved in a hydrofoil shape, and 2) the motor was too low, I theorize that the steering tab was deeper in the water than designed resulting in a force that was pushing the motor clockwise (with respect to looking at the transom from behind), which in turn cause the boat to list to starboard, and ultimately flip.

Any other similar experiences out there?

Or any discussion on my theory and/or other theories

Matt A