I can't think of any reason he would have done that, unless he was attempting to make a repair on structural damage.

No structural damage. After thinking about it and thinking about, I think the previous owner was trying to extend the running surface to gain more Stern lift. Mostly likely due the additional weight of the old kicker. The boat now has a much lighter new Yamaha 9.9.

For now I am just going to leave it, it's been on for 4 years I've owned and the boat planes quite well. I ended up through bolting two pieces of angle iron and mounting my transducers to that. Was able to mark bottom up to about 25 mph. So have a little adjustment to do. But an overall improvement to my previous tranducer location.

Those are trim tabs. You are correct they are for stern lift to help get on plane easier. Just make sure that any penetration through the fiberglass and into the transom are properly sealed. Any leakage will result in the transom plywood rotting. 3m 5200 is a great permanent below waterline sealer for the mounting fasteners.

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I enlarged the pic on the laptop. I see the plate now, not the trim tabs. My mistake. I would check out the install and make sure there isnt any
Water leakage through the hull at the fasteners. Just speaking from experience. I am in the process of restoring a hull that had rotted transom and stringers.

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