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  #1  
Old 01-04-2014
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Evaluating sails in off season

Can an experienced sail maker evaluate a sail off the boat, or does he (or she) really need to see it set on the boat?

The reason I ask is that some owners claim to not reef until much higher wind speeds than I do. At about 16-17 knots (true), no matter how much I flatten the sail my boat develops a lot of weather helm. Not sure if it's me, the fact that my version of the boat is a shoal draft, or my sail. I'm trying to eliminate / understand the causes and differences with other boats. (Of course, maybe the other sailors are um, shall we say, stretching the truth?)

Could a sail maker tell me whether the sail condition is contributing?
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Old 01-04-2014
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Re: Evaluating sails in off season

Talk to your local loft and see. The loft that I've worked with most can check sail fabric condition off of the boat, but can't evaulate sail shape without actually raising the sail on the boat.

Are you sure that the others that you've talked to are reefing at 17 knots true and not 17 knots apparent?
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Old 01-04-2014
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Re: Evaluating sails in off season

MAINSAIL HALYARD TENSION!!!!!!!!!
Your rig is a hybrid - no jib, no boom, no 'wire stays'/rigging, etc. so the 'normal' methods of analysis of 'heavy helm' will not apply.

However, you probably have a cross-cut (all the sail panels are 'parallel') mainsail made of woven dacron AND you have a mast that is VERY bendy and will 'seriously' bend toward the stern of the boat especially when extreme pressure is put onto the mainsheet.

Several 'problems' here .....
1. the more the rig bends aft, the more the *point at which the maximum draft in the mainsail occurs* moves aft, especially in the top panels of the mainsail - the overall CE of the mainsail moves 'aft'. This should result in increasing 'weather helm'.
2. the more pressure you apply to the mainsheet, the more the rig will bend and the CE will move aft.

I perceive the 'solution' here is: HALYARD TENSION (if this is a cross cut DACRON mainsail --- with a BOLTROPE sewn to the luff of the sail).
Pulling tension on the clew/outhaul will NOT change the point at which the maximum draft occurs ... it may 'flatten' the sail but such wont 'move' the CE forward.

*Moving the CE forward by increased HALYARD TENSION is your probably primary 'solution'*.
Increasing halyard tension will also help to 'trip' or 'open' the leech - the leech will become 'flatter', no longer be 'hooked up to the weather side of the boat' (artificially having the overall draft increased ... like an airplane with its 'flaps' down for a slow speed landing)

Dacron Mainsails with BOLTROPES (a 3 strand dacron 'rope' inside of a dacron sleeve that is sewn onto the luff of a mainsail) should be raised in the following manner, even for sailing in 12-15kts of windstrength .... if not raised in the following manner, the sail will be
draft aft; ..... the boat will be SLOW, will HEEL over 'aggressively', WILL have a LOT of so-called 'weather helm' .... the leech will usually be 'hooked up' (the exit portion of the leech pointing to the windward side of the boat resulting an 'extreme' amount of overall draft). When pointing, the aft end of the leech (near batten #2) should be somewhat / more or less parallel to the boats centerline.

How to properly raise a dacron mainsail that has a BOLTROPE at the luff:
A. Raise the sail to 'just up'.
B. Apply 1" extra halyard strain ..... for each 10-11 FEET of luff length.
C. Go sailing onto a beat, with the boat heeled normally, the leech area near/below #2 batten somewhat parallel to the boat's centerline thus correctly setting mainsheet 'tension' ... and note the helm pressure and then LET GO OF THE HELM !!!!!!
C1. If the boat strongly 'heads up' --- apply MORE halyard pressure.
C2. If the boat 'heads off' --- lessen the halyard pressure.
C3. The goal is to apply the correct amount of 'tension' in the BOLTROPE (via the HALYARD) so that when you let go of the helm the boat S-L-O-W-L-Y heads-up. ... very little 'weather helm' will be felt in the tiller/wheel when the halyard tension is set correctly.
D. In increasing windstength beyond, say, 15++ kts. and with an 'unreefed' sail, you may have to apply MORE halyard tension when the 'weather helm' increases. Again increased halyard tension will move the CE 'forward' and will 'trip'/'open' the leech causing the overall shape to become 'flatter' and more 'draft forward'. With an unstayed mast, increasing bend will help to flatten .... but the CE isnt going to 'move forward'.
NOTE: if you dont add this additional strain via halyard tension to ANY 'bolt-roped' sail you will NEVER attain the SHAPE of the sail as the sailmaker 'designed'.

Note: if this is an 'old' sail, most probably the boltrope has 'shrunken' and it will/may take extreme halyard tension to initially 'stretch out' that luff to the original 'as raised' design dimension that sailmaker intended. Without a boom it will be impossible to assay for a shrunken boltrope ... on the boat; and therefore, you 'should' take this sail to a sailmaker (who actually MAKES/LOFTS sails) and have the boltrope evaluated for shrinkage and have it 'eased'/replaced if necessary if properly applying 'proper' HALYARD TENSION is insufficient to relieve your 'weather helm'.
Like ALL 3-strand ropes, constant repeating cyclical strain will cause the length dimension over time to 'shorten' and the 3-strand boltrope will become 'fatter'.
Boltrope shrinkage is a VERY common problem. On my own sails I usually have to 'ease' the boltropes every 150-200 hrs (every other season) of 'hard'/aggressive sailing.
Boltropes can be 'eased' back to proper length by a sailmaker (or DIYer with a sail needle and waxed sail-twine)

Rx - as a first attempt, Properly RAISE your mainsail with the increased halyard tension (1" for every 10ft. of luff length) as described above to obtain a fairly 'neutral' helm balance. If this doesnt satisfy your 'weather helm' needs, take the sail to an 'actual' sailmaker and get that boltrope 'eased' or 'replaced'.

Once the boltrope ('pre-load') via halyard tension is correct, be sure not to let a gorilla pull in on that mainsheet ... when pulling in on the mainsheet when pointing, carefully watch that leech area near / below the 'second from the top batten' is parallel to the boat's centerline, ... OK for this area to be sagging off to leeward but NEVER 'hooking up' to weather (unless 'power pinching'). If a gorilla overtightens the mainsheet, expect that leech to 'hook up to weather' ... the boat will significantly heel over and you will get MORE weather helm.

Note: for 'Chesapeake sailing' for recreational purpose, I usually set up boltropes a wee bit 'looser' (less boltrope pre-load or 'more length') which results in a FLATTER and 'faster' sail - good for both the light wind days of midsummer and the 'blammo' days of spring and fall.

Lemme know how this works out for you ..... after the ice melts on the Ches. this spring.

Hope this helps. ;-)

Last edited by RichH; 01-04-2014 at 03:40 PM.
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  #4  
Old 01-04-2014
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Re: Evaluating sails in off season

/\ Nice info, what about sails with slugs?
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  #5  
Old 01-05-2014
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Re: Evaluating sails in off season

Makes no difference if the bolt-roped sail is 'connected' to the mast with slugs or the 'boltrope and its sleeve' fit inside the mast track (no slugs at all).
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Old 01-05-2014
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Re: Evaluating sails in off season

Quote:
Originally Posted by RichH View Post
MAINSAIL HALYARD TENSION!!!!!!!!!
Your rig is a hybrid - no jib, no boom, no 'wire stays'/rigging, etc. so the 'normal' methods of analysis of 'heavy helm' will not apply.

However, you probably have a cross-cut (all the sail panels are 'parallel') mainsail made of woven dacron AND you have a mast that is VERY bendy and will 'seriously' bend toward the stern of the boat especially when extreme pressure is put onto the mainsheet.



Rx - as a first attempt, Properly RAISE your mainsail with the increased halyard tension (1" for every 10ft. of luff length) as described above to obtain a fairly 'neutral' helm balance. If this doesnt satisfy your 'weather helm' needs, take the sail to an 'actual' sailmaker and get that boltrope 'eased' or 'replaced'.

Once the boltrope ('pre-load') via halyard tension is correct, be sure not to let a gorilla pull in on that mainsheet ... when pulling in on the mainsheet when pointing, carefully watch that leech area near / below the 'second from the top batten' is parallel to the boat's centerline, ... OK for this area to be sagging off to leeward but NEVER 'hooking up' to weather (unless 'power pinching'). If a gorilla overtightens the mainsheet, expect that leech to 'hook up to weather' ... the boat will significantly heel over and you will get MORE weather helm.

Note: for 'Chesapeake sailing' for recreational purpose, I usually set up boltropes a wee bit 'looser' (less boltrope pre-load or 'more length') which results in a FLATTER and 'faster' sail - good for both the light wind days of midsummer and the 'blammo' days of spring and fall.

Lemme know how this works out for you ..... after the ice melts on the Ches. this spring.

Hope this helps. ;-)
RichH,

Thanks for the advice. I'm with you on the halyard tension and it's possible I have not cranked that hard enough. That's why I'm still trying to figure out whether the issue is the boat or me or the sail.

I don't think the sail has a bolt rope sewn in under the tabs for the slugs, although I could be mistaken and just not paid attention to that.

I do have a boom, it's just configured as a wishbone boom. I"m not following the comments on avoiding cranking the mainsheet. I do not have a traveler, so the mainsheet positions the boom. Because the sail is set more like a genoa, the boom is generally not brought in over the past the coaming, certainly not to the center line. And the bendy mast is designed to automatically spill gusts, which does work. Still, I get that have have a bit less control over sail shape then some sloops.

I have wondered if the mast could be raked forward just a bit and if that would move the CE enough to affect the weather helm.
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Old 01-05-2014
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Re: Evaluating sails in off season

Quote:
Originally Posted by Alex W View Post

Are you sure that the others that you've talked to are reefing at 17 knots true and not 17 knots apparent?
Good question. I've been having difficulty getting consistent/straight answers. I think because most owners don't pay that much attention to the details...they just sail. Still, I've come across a number of written and oral stories, like the one from a review article in Good Old Boat magazine (July/August 2006), that makes me wonder.

'"However, Jay (the Nonsuch 30 owner) says, "We don't think about tucking in a reef until the wind is blowing 30 knots, because the top of the mast is so bendy that it spills lots of air." Combined with a wide beam and a 40-percent ballast displacement ratio, the bendy mast also makes for a stiff boat.

While traditional catboats are notoriously difficult to handle in high winds owing to weather helm, the Nonsuch 30 is well balanced.'

So, even allowing for some (maybe a lot) of hyperbole, it still makes me wonder....
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Old 01-05-2014
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Re: Evaluating sails in off season

Quote:
Originally Posted by Jiminri View Post
I don't think the sail has a bolt rope sewn in under the tabs for the slugs, although I could be mistaken and just not paid attention to that.
If your mainsail is cross cut, woven dacron, 99.9% of the time there will be a boltrope to control the luff stretch and to make the luff 'stable' in varying wind strengths.

Quote:
Originally Posted by Jiminri View Post
I do have a boom, it's just configured as a wishbone boom.
In the context of 'sail shape analysis', your (wishbone) boom configuration doesnt help.
When evaluating a sail on a conventional boom, all one has to do is look at the tack angle in the data book, the listed tack angle is from the OEM boat designer. ... the tack angle, the 'designed' angle that the top of the boom makes with the mast, sailmakers are VERY careful to have this angle very precise when making sails. In such analysis a (good) sailmaker will usually always 'start' the analysis by properly raising/loading a boltroped mainsail to see if the tack angle is correct when the luff is 'loaded'. If the databook tack angle is not observed, then the sailmaker KNOWS that the dacron sail will have serious faults in sail shape.
Most mainsail 'tack angles' (luff to foot angle) when the sail is properly raised allowing the sail to be 'stretched out' to its intended dimensions will be in the range of 87° to 89° for 99% of all boats. You cant do this with a 'wishbone rig'.


Quote:
Originally Posted by Jiminri View Post
I"m not following the comments on avoiding cranking the mainsheet. I do not have a traveler, so the mainsheet positions the boom. Because the sail is set more like a genoa, the boom is generally not brought in over the past the coaming, certainly not to the center line. And the bendy mast is designed to automatically spill gusts, which does work. Still, I get that have have a bit less control over sail shape then some sloops.
Your mast is freestanding, there are no wire stays to resist your mast from 'bending'. When there is little to no wind the mast will be essentially straight up; when the sail is fully loaded or overloaded the mast will bend, significantly and especially towards the stern; the top of the mast and the top portion of the mainsail will now be 'relocated' towards the stern. The overall CE of the mainsail when the mast is 'really' bent is now much further back than when the mast is 'straight up' or unbent. Shifting the CE rearwards will increase 'weather helm'. When the mast bends back the leech will become 'more loose' (tripped); but, if you now tighten up on the mainsheet, you will remove the the flattish shape of the leech that the mast bending caused ... Tightening up on the mainsheet with a very bended mast will cause the leech to 'close' become 'rounded' and which will increase the overall amount of draft if you get too carried away with mainsheet tension.
The only way on your boat to 'rebalance' the CE is to apply 'luff tension' which causes the point at which the maximum amount of draft occurs to 'move forward' with increased luff tension; moving aft when you release luff tension. Also increased luff tension will also cause the leech to become 'flatter' which will also reduce the 'amount' of overall draft in the sail.
Overtensioning the mainsheet, will cause the leech to again become more 'rounded' (less 'flattish'), and will cause the 'overall' sail shape to increase the amount of draft. Most sailors radically overtension their sails - leads to 'sail shape' problems and causes permanent 'stretch' in the fibers and films. Overtensioning the mainsheet adds to even more mast bend ... and more of the CE going 'aft'.


Quote:
Originally Posted by Jiminri View Post
I have wondered if the mast could be raked forward just a bit and if that would move the CE enough to affect the weather helm.
Simple rule here w/r 'weather helm': ... rake the mast ONLY after you have absolutely concluded that the sail SHAPE is perfect and is taking the shape that the sailmaker designed into the sail. Most 'weather helm' problems in well designed boats (yours is) are usually sail SHAPE problems, and usually because of insufficient luff tension that allows the 'point of MAXIMUM draft' to occur too far aft in a sail.
I make the claim that on 99% of ALL 'cruising boats' that folks simply dont correctly raise their boltroped sails .... you can SEE this by the position of their booms when 'beating' - the aft end of the boom is usually ALWAYS lower than the gooseneck. (If I see this on a competitor on a racecourse, I KNOW that this boat will NEVER catch me during a tacking duel to weather and I look for the 'next' competitor that I have to 'conquer'. )


The info I offered here about correctly 'raising' woven dacron sails is also found (different wording, etc.): How to properly RAISE a woven dacron mainsail - SailboatOwners.com post #1
Lastly, you'll never have good 'trim' if your sails are incorrectly 'shaped'.

I keep my boat at Worton Cr. on the Ches. directly across from Middle River. Ill be returning from sailing 'de islans, mon' in late spring or early summer. If you wish and Im available, perhaps we can get together and 'evaluate'. You can send me a PM to remind me.
;-)

Last edited by RichH; 01-05-2014 at 01:49 PM.
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Old 01-05-2014
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Re: Evaluating sails in off season

I really appreciate the time you spent to explain with such details. Helps a lot. Very clear. Many, many thanks!
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