Thom: with the sliding gooseneck you need to have a line that keeps the 'mast end' of the boom from rising. you also need a vang to keep the boom from rising when off the wind. the vang is also used when going to weather based on the conditions and your preferences in adjusting sail shape. be sure to review the information shared by JudyB ... i agree with all she said (yes, it is true that as sail become older than five or so years need to be replaced even if not heavy used). a sail original to your boat is way past replacement date. :: Dave Scobie -------------------------------------------- On Tue, 3/11/14, Thom Loftus <thom_loftus@yahoo.com> wrote: Subject: Re: M_Boats: proper boom placement To: "W David Scobie" <wdscobie@yahoo.com> Date: Tuesday, March 11, 2014, 7:04 PM Hi Dave.Not sure who made my mainsail, but I'll check.Is it safe to say that the boom should sit wherever it wants to naturally sit on the mast when the sail is fully raised? I guess I'm also wondering if a boom vang is sufficient for keeping downward tension on the boom, or if you advise also rigging some kind of downhaul from the bottom of the gooseneck to the deck (i.e. some means of locking the gooseneck in place).Thanks,Thom From: W David Scobie <wdscobie@yahoo.com> To: Thom Loftus <thom_loftus@yahoo.com> Sent: Tuesday, March 11, 2014 2:36 PM Subject: Re: M_Boats: proper boom placement Thom: was your main made by McKibben (sic)? my M15's ('84) and my M17's ('83) mains were/are McK sails. both set the aft end of the boom low (good for hitting heads). when i talked to Harry Pattison, with E/P sailmakers, about this his guess (besides the sails being old and blow out) is McK cut the sails this way to gain a few extra square feet of sail area. when Harry made the new main for my M15 it was cut so the boom was 'flat'. i had Harry re-cut the foot of my M17's blown out old main to be loose foot and set the boom flat. :: Dave Scobie -------------------------------------------- On Tue, 3/11/14, Thom Loftus <thom_loftus@yahoo.com> wrote: Hi Dave.1987. The main is older I think, but in good shape. The previous owner didn't sail much and there's no indication that it's blown out. From: W David Scobie <wdscobie@yahoo.com> Sent: Tuesday, March 11, 2014 2:26 PM Thom: what year is your M15? how old is the main? :: Dave Scobie -------------------------------------------- On Tue, 3/11/14, Thom Loftus <thom_loftus@yahoo.com> wrote: Hello All. I've recently replaced the mast on my M15 and have noticed that when my mainsail is hoisted as far as it will go up the mast, and the luff is relatively taught, that the end of the boom droops at a downward angel from the gooseneck when the topping lift is eased. It's almost as if the foot of my mainsail is cut at an angle, but I can't confirm that at the moment. In looking at pictures online, it is difficult to tell if this is the way the boom is supposed to sit, or if there is something wrong with my rig. I have not yet installed a boom vang and I don't actually know how high off of the deck the boom should sit at the gooseneck. I have no cunningham rigged and to keep the boom from inching up in the mast, I usually tie it to the deck from a loop in the gooseneck. Can anyone enlighten me as to how hight off the deck my boom should sit and whether or not the boom should angle down as it moves aft? Thanks Thom