Join Date: Jul 2000
Thanked 165 Times in 154 Posts
Rep Power: 16
First of all, those 'rust blooms in the tang and pin area are 'highly suggestive' of severe crevice corrosion and I would recommend 'soon' that you inspect for the potential of 'sudden catastrophic' failure.
Weather Helm ---
Before you alter the rigging geometry, etc., I would most strongly suggest that you evaluate the mainsail shape and condition of the 'boltrope' - if in fact it is a woven dacron boltroped mainsail). There are 2 EXTREMELY common mainsail conditions and 1 very common rig tension condition that promote so-called 'weather helm':
1. The mainsail is not being 'raised' on the mast properly. On a boltroped woven dacron main, the sail will NOT take its proper shape unless you *additionally stretch out that boltrope* by approx. 1" additional 'stretch' for every 11 ft. of luff length .... all done by additional halyard (+/or cunningham) strain. If you dont additionally stretch out the boltrope when raising .... the sail will be over-draft, draft aft, and the leech will be 'hooked up' to weather --- all causing significant weather helm. "Setting" such a sail for proper 'weather helm' includes: stretching out the luff by an *additional* 1" for every 11ft. of luff length, then going onto a hard beat and releasing the helm; if the boat heads up, increase halyard tension until the boat's helm 'goes dead-fish neutral' ... then release a wee bit of halyard strain until the boat s-l-o-w-l-y heads up (and the rudder is held at about 2-3° of angle).
2. Shrunken bolt rope. On a windless day, at the dock, raise the sail, apply the correct amount of ADDITIONAL halyard strain (1" additional luff strain for each ~11ft. of luff length), and measure the angle that the TOP side of the boom makes with the mast. Most mainsail's 'tack angle' will be 88-90 degrees, never greater than 90·. If that angle is 'much' more that that 90°, and the end of the boom is still LOWER on the horizontal plane than the gooseneck connection, then take pics. of the sail up and fully raised and then take the sail to a sailmaker and have the boltrope either adjusted or replaced. Every time you tension/release a boltrope it becomes microscopically shorter and fatter .... and ultimately the boltrope will become 'noticeably' shorter and will take gross amounts of extra halyard strain to get the sail into proper 'shape'.
Dacron Mainsails usually dont become 'baggy' or get 'blown-out' --- 99.9% of the time its either the boltrope has become 'shortened' due to age or the sailor simply doesnt know HOW to raise/set a sail with a boltrope.
3. Insufficient backstay tension. Most rec. boats should be operating with the backstay at about 15-18% tension (for winds up to 15Kt.).... the backstay tension causes the forestay tension. If this forestay tension is insufficient the 'sag' in the luff of the jib/genoa will be too great and the result in the jib/genoa will be 'draft-aft', too much overdraft, hooked up leech, the mid portion of the luff will be operating 'well off to leeward' !!! ..... and the boat will 'aggressively' heel over, be will be skidding off to leeward (felt as helm pressure), slower than crap, 'cranky' , and 'wont point worth a damn'. A boat that is well heeled and is 'skidding off to leeward ' will have the wake coming off the stern at a noticeable angle (greater than 3°) - 'skidding off to leeward' is erroneously felt in the tiller/wheel to be 'weather helm'.
BTW - A jib sheet that is 'overtightened' by a winch will do the exact same thing and cause the exact same 'shape effects' on a jib/genoa.
Only as a **VERY LAST RESORT** and after correcting #1 #2 #3 above should a mast be 'raked' to remedy 'weather helm'.
I make the claim that improper mainsail raising/shaping and mainsail (w/ boltroped woven dacron) luff tensioning is ~90% the cause of 'weather helm', ~9% of the time the rig is too loose, & ~1% of the time its 'mast rake'. ~ most cruising sailors never 'stretch out that boltrope when raising a 'dacron' mainsail, ... and most cruisers will have the aft end of the boom 'drooping down' toward the cockpit and will be experiencing 'weather helm'.
Last edited by RichH; 12-12-2010 at 03:24 PM.