I see the point you guys are making but considering the dynamics feel safe with what I have for this boat. I'd do something different on the Endeavour. The Mac's life line is only 16 inches off the deck and if I'm tethered in I'm going forward on my hands and knees, so my center of gravity is very low and I wouldn't be going very far on this tether to gain much momentum.
If someone else feels different then run the jack lines along the bases of the stanchions where there would be no leverage on the attach points. The way they are made you could run the lines through the base.
I personally can't see a mac user putting D-rings in but if they want to that is their choice. Also we are not out in 8+ foot waves in these boats and I wonder what percentage of these boats even have jack-lines, tethers and harnesses. Unless I'm in some really freak situation I'm still safer than doing nothing.
The main point I was trying to make in the first post was that tether you can get from West Marine and probably other places is a great width for our boats and keeps you in the center of the boat,
Sumner
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1300 miles to The Bahamas and Back in the Mac...
Endeavour 37 Mods...
MacGregor 26-S Mods...
Mac Trips to Utah, Idaho, Canada, Florida, Bahamas