David, To Wilson's advice I would add--then add about 7 feet to the length. You will need line length to add a splice and you will need some extra length to handle the line at the cockpit end of things. This advice comes from someone who bought a 25' rope/wire halyard for a Montgomery 17 in 1982, at great expense and then cut it 25 feet long for a mast that was 25 feet tall. Think about that. This from a fellow that lost his whole rig because the outhaul line he used was two feet too short and he had to stand up in the stern of his boat in rough water to reach the cleat to adjust it, fell overboard, grabbed the only thing he could, the end of that outhaul line and pulled the whole mast in after him with a nifty 75 degree bend right at the spreaders. Moral, better several feet too long than even an inch too short. Tom B, Mont.17 (the second) #258, 77'