OK, now that makes sense as to why use backstay tension up wind, to tighten the forestay. And, because of the lower shrouds (both fore and aft) the mast does not rake when the backstay adjuster is tightened only the top portion is pulled back.
Joe McCary Aeolus II #4795 West River, MD [EMAIL PROTECTED] On Behalf Of Sneddon, Keith I agree with Tom on most of this, except; on mast head rigs (like a C27), the backstay adjuster is mostly to adjust the sag of the forestay, which influences the width of the "slot" between the headsail and mainsail, whereas on a fractional rig (like most J- Boats), the backstay adjuster will really bend the upper tip of the mast aft, particularly if the mast section is tapered up high. The difference is that, on a masthead rig, the forestay directly resists the backstay tension, and on a fractional rig, it reacts the force of the backstay from a lower attachment point, which bends the mast. Keith Sneddon #4760 "Are We There Yet?" _____ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, August 27, 2007 2:21 PM To: [email protected] Subject: RE: catalina27-talk: a whole week! We really need Tim or Chris or Phil or someone to comment on this, but ... I don't think you can really get a C27 mast to curve by adding tension to the backstay adjuster. The thing is just too think an extrusion. My understanding, which has undoubtedly has as much opportunity to be wrong as yours, is that rake and backstay do two different things. Rake adjusts the turning moment of the sail combination to the turning moment of the hull. It's kind of a dynamic thing since the turning moment of the hull changes with healing, and the turning moment of the sails changes with what sails you have up and how they are trimmed. So you're trying to hit an average. The idea of using the backstay adjuster to bend the top part of the mast backwards is to change the shape of the main. Why you do that and what it accomplishes I'll leave to others. Tom Well, Tom, You asked for a week to take you mind off other things as well as your tie. So you can't complain except for the shredding bimini and sail cover. I am glad your mast rake has helped your performance. I am wondering along the same lines if using the adjustable backstay adjuster if it has some of the same effects? Going to weather my understanding is to add on more backstay tension (moving the mast aft and adding weather helm) and when off the wind to release tension. To me this seems counter intuitive and backwards. Am I wrong (would not be the first time)? Joe McCary Aeolus II #4795 West River, MD [EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Well, for a midwest August it was sure a windy week. Couldn't even sail Monday. Tuesday and Wednesday I was rail down at hull speed with just a working jib up. Thursday I actually used the main. Friday a storm came through and shreaded my bimini and main sail cover at the dock. Weekend was back to typical August sailing ... i.e., hot and slow. Re a previous post on mast rake ... I finally got the opportunity to retune the mast. Pulled it forward a good bit, and she sure sails a lot better. I think I need to go another inch, but till I can get out in conditions where I'm healed at 15-20 degrees with BOTH a main and jib, I can't really tell. It's been a funny midwest season. I bought a new 135 this year so I could sail better in light air. It's been up twice. I've mostly been using an old working jib, and often a reefed main. Tom 6219 Different Drummer
