Hi David, I have the same system which I have improved with a better block system but there is not even a hint of over-stressing the transom. Of note: As per one of the prior comments I always set the adjustment back to loose before leaving the boat.
I use it / pull it all the way down pretty much every time I sail as the dominant winds dictate being close hauled when going the length of the lake. It seems to me you should take a look at the pre-load on your mast and make sure it's not excessive. Unless something else is amiss you potentially have too much mast pre-load and are over-stressing the mounts. You can check that by having the main halyard attached to the gooseneck, pull it tight, and go in the cabin then look up through one of the small hatches above the table. You should see the halyard being about 2-3 inches off the mast at the deepest pat of the curve ( roughly mid way up the mast ) with the backstay adjustment loose. Adjusted that way you'll also see that the top of the mast moves about 6 inches when cranking on the backstay which seems plenty to get the desired effects going up-wind. I literally see the boat point-up a few degrees and accelerate when I crank on the backstay. I hope that helps -Francois 1990 34+ "Take Five" Lake Lanier, GA
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