Sean, I went down today and did a rough measurement of the centerboard thickness. I was unable to drop the board but I could lay underneath and look up. Because the exposed edge is a tapered leading-edge I could not get a direct measurement but I could look up into the cavity and approximate it against the ruler in my hand. It is thinner than I had thought probably 3/4" to 1". Also, I was thinking about your need to minimized time on the sling. A couple of thoughts came to me: If the pivot pin is not exposed do it in advance, expose it. I remember thinking I knew just where it was on my old M15 only to end sanding a fairly large area to locate it. Also, could you remove the centerboard stop-pin before they got there (though it could be touchy with the crane guy to allow you to let got the winch while still in the sling). That way maybe you could sling the boat over a flat surface lower it down, loosen the winch, knock out the pivot pin, raise the boat, unfasten the pendant, lay the board over, set the boat down, and move the centerboard about with one of those hydraulic engine hoists. No matter how you do it, have a few guys there to stabilize that centerboard...Wish I could help. I'm sure you have given all of this a great deal of thought and have got a plan...But what the Hell, being an armchair quarterback is irresistible...HA! Besides I get to learn from you the best way to do this!!! Talk to ya soon, Rick