Mike- you're pretty much stuck with a 17 because of the backstay, which limits any extra area in the area of the batten. You can get more area (which is not your goal) with ALL full battens because you can pick up roach down low. if full battens are tuned perfectly there might be a small advantage aside from more roach, but I wouldn't bet money on it. My Sage (backstay) has a full batten on top. It came that way; I told the sailmaker (Harry Pattison) to make it like Dave's (Scobie) and in a drifter it sometimes hangs up on the backstay when I tack, but it has the same area as the ones with regular battens and hangs up because there is little give in it. I always draw the roach on my sailplans, but really leave it to the sailmaker as to the amount. Note that the M-17, also the Sage and many others, sail best upwind with some mast rake, and mast rake increases the amount of permissible roach. Note that battens are considered one-design by the rating groups, and any increase in length or number should be reflected in the rating. I see "fathead" sails on M-15's (a very long top batten, which makes the sail more of a rectangle as opposed to a triangle, and has about 10%+- more area) entered in races and racing head-to-head with stock 15s but it ain't fair. The sailor of these boats should be honest and fess up to the race committee when he enters, who will adjust the rating. I had the prototype SageCat, which was designed with a fathead main, here for several months and entered it in several races. I liked the fathead; it has plenty of sail area in light and moderate air, and in a blow the top of the head bends off, reducing heeling moment. it took me a while to learn to make it go fast. Once I got past the stupid stage it really sailed. Gary O, whom many of you know, had the same experience; he sailed it in the Wrinkleboat race a year ago (he won) and did better the second day. So far I haven't gotten any feedback from owners, but I'm pretty sure it's going to be a really good boat. Time will tell. Note that the Sagecat was designed with a fathead, so there will be no problem with ratings. Hope this helps. -----Original Message----- From: Mike Barnett via montgomery_boats Sent: Friday, April 06, 2018 11:24 AM To: montgomery_boats@mailman.xmission.com Subject: M_Boats: Full Length Top Batten Is anyone using a main with a full length top batten? I'm not particularly trying to increase the roach (although if I can, let me know... we haven't sailed ours yet so I have no way to guess re: backstay interference), just trying to get the best sail shape possible.