I waited to reply in hopes that someone knew the answer in inches. If all else fails... On a calm day with the mast down, feed the sail with attached halyard onto the mast. When it reaches its limit then back it down an inch or two and put your BB (swage?) on the halyard at the hook point. I would suggest the extra inch or two since changing conditions may make it difficult to raise the main to the extreme top position.
<br>Good luck, I hope someone can tell you the exact measurement. My 81 hobie has the double pully system on top of the mast, so a simple measurement won't suffice.
<br>Get it done soon. Sailing's great!
<br>Greg H14,H16 <br><br>