Along the way in my attempts to re-turn the boat, I tried the pre-bend thing. The mast acts like a telephone pole, and anybody that can induce a pre-bend in the thing has more trust in their rig tension and chainplate strength than I.
Tom "Sneddon, Keith" <[EMAIL PROTECTED]> Sent by: [email protected] 07/11/2007 11:32 AM Please respond to [email protected] To <[email protected]> cc Subject RE: catalina27-talk: how much rack to you set in your mast? Weather helm is also very sensitive to heel angle, because with increased heel you get more lateral offset between the center of driving force (on the sail) and the center of drag (more or less on the keel), which makes the boat want to rotate into the wind. If the boat is heeling more than 20-25 degrees, you are probably going to have a bunch of weather helm. That is also part of the reason that where and how you sail is going to affect optimum rake. If it is predominately windy where you sail, or if you sail shorthanded or solo (or your crew refuses to sit out on the high side), you probably will want a little less rake than someone who sails in lighter air or with a full crew of enthusiastic hikers. I read an article online that recommended mast pre-bend even for deck-stepped mast-headed rigs like a C27. Does anybody on this list buy into that? From the rig tension stuff going around a couple of weeks ago, I would guess no (evidenced by all lowers having about the same tension). Keith Sneddon #4760 “Are We There Yet?” From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Sailor Chef Sent: Wednesday, July 11, 2007 12:07 PM To: [email protected] Subject: Re: catalina27-talk: how much rack to you set in your mast? Tom, A little change will make a difference, not a whole lot but a difference. And don't try to take out all the weather helm, It'll make the boat very hard to steer. You won't be able to tie off the tiller and duck below for that beer because the boat will seemingly have a mind of it's own w/out at least some weather helm. Plus, at the extreme, no (or lee) helm can be very dangerous in a blow. As far as taking measurements it's much more accurate to measure the forestay length from pin to pin when you get the rig where you want it so as to be able to repeat the setting after a lay-up. Using the main halyard hanging slack method will be different almost every time due to changes in the boat's trim (empty tanks vs. full tanks, ect.) As far as understanding the theory, you are correct. The center of effort should be just aft of the center of lateral resistance but understand, the center of effort moves around a lot as you ease the sails, change to a smaller (or larger) headsail or reef the main so you are dealing w/ an average. First I would suggest you make sure the rig is centered side to side. An easy way to do this is take the cleated off main halyard and pull it down to the pin on the upper shroud and see if it matches both sides. Once you have done this just go sailing and make small adjustments till you have what you like, then measure the forestay. Mark, "Gratis" (6115) and others Want to keep your WHOLE PAYCHECK? PLEASE VISIT http://www.fairtax.org ----- Original Message ----- From: [EMAIL PROTECTED] To: [email protected] Sent: Wednesday, July 11, 2007 9:45 AM Subject: Re: catalina27-talk: how much rack to you set in your mast? OK, thanks, that helps a lot. I used to have less weather helm before I stored the boat for a year. When I stored it, I had to drop the forestay when they pulled it to its cradle. Then when I launched again this year, I thought I remembered somewhere that the main halyard hanging still should hit the boom about 4 inches back, so I set her up that way. I did note that the forestay turnbuckle was not screwed in as far as it used to be. Let me see if I understand the theory here. If I have excessive weather helm, I stand the mast up straighter (less aft rake), thereby moving the center of effort forward to match the turning moment of the boat? Oh ... does a little change make a lot of difference .... or is it a lot of change makes a little difference? Tom "Sailor Chef" <[EMAIL PROTECTED]> Sent by: [email protected] 07/10/2007 02:52 PM Please respond to [email protected] To <[email protected]> cc Subject Re: catalina27-talk: how much rack to you set in your mast? Thanks for the kind words Phil. I started on my advanced mast rake/tune degree when I acquired my first J-24. I couldn't afford new sails for a little while, so I ended up with my rig twisted up like a pretzel to be able to get any sort of shape out of my blown out sails. One of my buddies looked at it one day after I beat him and asked me if I'd used a tuning guide, I told him "sure, I average the North, Sobstad and UK guides then did the opposite"! When the penny jar got big enough I bought a set of "one regatta" North's. For the first couple of races I was as slow as I'd ever been 'till I got the rig sorted out. It still didn't look like most of the other's in the fleet but was real close to the perennial fleet leader's rig and I was fast again! Mark Want to keep your WHOLE PAYCHECK? PLEASE VISIT http://www.fairtax.org ----- Original Message ----- From: Phil Agur To: [email protected] Sent: Tuesday, July 10, 2007 2:03 PM Subject: RE: catalina27-talk: how much rack to you set in your mast? Well said Mark. I’ve been in one design fleets that try to pass all the exact rig settings back and forth between the boats, and that’s good until you want to finish above mid-pack, after that it’s unscripted. Mast rake is indeed used to balance the helm but curiously I’ve found prevalent recommendations for a heavy amount of rake in the C22 racing fleet. On the whole it was observed the boats made better progress to windward in heavy air with heavy rake. What was really happening was when hit with a puff (in heavy air) the boat not the skipper reacted by feathering up (the start of a round-up if you will) due to the heavy weather helm. To understand why that would be advantageous you have to subscribe to the theory that racing to windward is like climbing a ladder, so any motion (i.e. like feathering in a puff) that moves the boat to the next rung is a huge instantaneous gain. The fleet winners compete with very neutral helms, since weather helm creates drag throughout the leg, and manually feather up in the puffs thereby making both gains. Wining is often just stringing a succession of small gains together. My last race boat would actually reverse to negative weather helm if you over tightened the backstay. However, it would do a good imitation of a complete knock down in that condition without rounding up. Cruisers (those who want to sail comfortably without focusing like a championship racer) therefore should leave in sufficient weather helm to avoid the uncomfortable down stay maneuver. Phil Agur s/v Wing Tip Secretary/Treasurer Call Sign WCW3485 IC27/270A MMSI 366901790 www.catalina27.org Vessel Doc# 1039809 -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Sailor Chef Sent: Tuesday, July 10, 2007 10:58 AM To: [email protected] Subject: Re: catalina27-talk: how much rack to you set in your mast? Tom, Mast rake is used to "balance" the helm and is largely a boat by boat thing. Some of the factors determining the amount of rake needed (or not needed) are the size and type of sails, weight distribution in the boat, primary wind conditions in your area and your sailing style. Generally, if you have a lot of weather helm, you need less rake (more straight), If you have no (or lee) helm, you need more rake (leaning back). Hope this helps Mark, "Gratis" (6115) and others Want to keep your WHOLE PAYCHECK? PLEASE VISIT http://www.fairtax.org ----- Original Message ----- From: [EMAIL PROTECTED] To: [email protected] Sent: Tuesday, July 10, 2007 11:44 AM Subject: catalina27-talk: how much rack to you set in your mast? I was reading an article on another board, and it caused me to wonder ... how much rack do those of you who have tall rigs set up in your mast with the backstay tensioner off? Mine has about four inches of aft rack, as determined by where the main halyard crosses the boom. Does that seem about right? Tom Monroe 6219 Different Drummer Internal Virus Database is out-of-date. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.9.14/885 - Release Date: 7/3/2007 10:02 AM Internal Virus Database is out-of-date. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.9.14/885 - Release Date: 7/3/2007 10:02 AM Internal Virus Database is out-of-date. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.9.14/885 - Release Date: 7/3/2007 10:02 AM
