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-   -   Curing weather helm on my cutter (http://www.sailnet.com/forums/seamanship-navigation/73758-curing-weather-helm-my-cutter.html)

Bazzer 04-19-2011 12:28 PM

Curing weather helm on my cutter
 
I have a True North 34, it's actually about 42 with the bowsprit and pulpit. I have just purchased a new mainsail and sailed her for the first time. Initially I hoisted just the main in a freshening wind in San Pablo Bay, the amount of weather helm was horrible, being single handed with a crappy old autopilot it was hard to hoist a number 1 Yankee, but I did get it up, but still weather helm, with several degrees of rudder needed even down wind. Do you think I should have put a reef in? Or maybe a larger Yankee or a jib? There is some growth on the hull, but not a lot, I do have a large genny type Yankee.
What are your thoughts??
I would love to here from other cutter owners.
I should add that a True North has a full length keel with a stern hung rudder.
Thanks

Bazzer

Boasun 04-19-2011 01:02 PM

By weather helm; you mean the equivolent of pulling your tiller to windward in order to keep your boat from rounding up into the wind.
you can reverse the order of raising your sails.
Under main alone you may want a reef or two taken in. With a cutter you may want your stay sail hoisted, then the main and finally the yankee. Play around with the hoisting sequence to see how your boat responds.
Check the rake of your mast. If it raked to far aft you can straighten it up some what.
And I'm sure that others here will have their worthy advise given also.

SVPrairieRose 04-19-2011 01:05 PM

More headsail or less main.

Put simply a main sail drives your bow up to weather and a headsail pushes it back down again. To attain no weather or lee helm your sails must be balanced. So if you have a full main up you want a matched amount of headsail to keep things happy, if the wind is strong enough to warrant less sail forward then you should also be shortening your main.

Not the most scientific answer your going to get, but I hope it helps. Enjoy the new sail, I am very jealous.

RichH 04-19-2011 02:26 PM

There is an inherent problem with 'cutter rigged' boats: the headstay and forestay (where the little FOREstaysail flies) both share a single backstay.

FIRST PROBLEM backstay reacting with TWO forward stays.
The result of a sloppy headstay is that when windloaded the bigger of the two sails (the headsail) stretches the headstay disproportionately more than the staysail stretches out the forestay .... and as a result the forestay increases tension as the headstay simultaneously unloads. The sail shape result is that the headsail luff curve (luff hollow) no longer matches the expected 'sag' of the headstay.... and the headsail becomes draft aft, the leech hooks up to weather and the draft radically 'deepens'. All this increases the boats tendancy to SKID OFF TO LEEWARD (a common trait of cutters - they cant point unless set up 'differently' than a 'sloop') and aggressively 'heel over' while going SLOW. The skid to leeward adds undue side pressure to the rudder (and keel) .... and the helmsman usually erroneously blames 'weather helm'. So, the first thing to do in a cutter rigged boat when you 'think' you have 'weather helm' is to look at the stern wake to be SURE that its is coming off at NO MORE than 4-5 from the center line when close hauled. If so, there are two solutions:
1. release tension in the FORESTAY so the BACKSTAY reacts primarily with the HEADSTAY, ..... tensions 'mostly' the headstay and prevents undue 'sag to leeward' of the headstay AND the headsail.
2. Apply additional tension to the headstay/forestay combo via RUNNING BACKSTAYS .... or backstay tensioner (but dont 'bust' the rig by over-tension).
3. HOW MUCH TENSION IS NEEDED? .... go to: http://i1086.photobucket.com/albums/...LuffHollow.gif and check the 'match' between the 'luff hollow' of the headsail and the SAG in the headstay.... and adjust backstay or running backstay tension so that the 'luff hollow' curve closely MATCHES the 'sagging headstay' geometry ... and adjust backstay/runner tension (and unload the forestay) so the two shapes/geometries of sagging headstay and the 'luff hollow curve' are EQUAL !!!!!
http://i1086.photobucket.com/albums/...LuffHollow.gif

Note: depending on the mast position (true cutter will be with the mast at 40-50% back from the bow, sprit., etc.), when youre running correct headstay tension the boat will typically sail quite well at all points with just the headsail and staysail, & NO main and with just a slight 'helm change'. Most of Bob Perry's (true) cutter rigs can do this .... all depends on that headstay tension !!!!!!
Note2: All the applied force from a jibsheet winch, will equilibrate to the headstay ... if you have gorillas as winch grinders, then plan on increased backstay tension .... or the sag of the headstay will greatly increase due to the 'sheeting loads'. Dont 'overdo' the winch grinding !!!!!!!

SECOND PROBLEM is probably 99% of non-racing sailors (sloops, cutters, etc. etc. etc.) have no idea of how to properly raise/shape a woven dacron mainsail !!!!!!!!! go to: How to properly RAISE a woven dacron mainsail - SailboatOwners.com
Once you have the luff shape correct for the headsail/forestay (I usually run my forestay as low as ~5% when 'beating', backstay @~20%, therefore headstay @15+%) .... and on a hard beat in 10-15kts: then apply ADDITIONAL mainsail halyard (or cunningham) strain/tension ...... to move the mainsails *position of maximum draft* FORWARD ... which also 'opens' the leech (leech exit should be parallel with the boat's centerline), ...... until the 'helm' goes 'dead fish' neutral, then back off until you get a 'slight' weather helm. ....

Weather Helm is usually a result of improper *position/location of maximum draft* in setting/shaping/raising the mainsail (all boats!!!!!!!). :eek: A cutter has the additional problem of usually a 'NON CONSTANT TENSIONED or loose headstay' that promotes leeward skids (erroneously 'felt' as 'weather helm').

If you do BOTH of these Suggestions, your cutter will point like a banshee (sometimes better than a sloop rig) and with an almost 'neutral' helm. However, the rig has to be properly tuned first, including the needed mast 'prebend'.

If this works and makes your cutter point like a banshee and with a 'light' helm, Id appreciate to know. :rolleyes:

Waltthesalt 04-19-2011 03:22 PM

Agree with everything heretofore said. Also easing of on the main in heavier winde, let it backwind a bit will also ease the weather helm.

Minnewaska 04-19-2011 06:43 PM

Quote:

Originally Posted by Waltthesalt (Post 721889)
Agree with everything heretofore said. Also easing of on the main in heavier winde, let it backwind a bit will also ease the weather helm.

This is what I would do, until the foresail was up. A use for poor sail trim!

Unless, you are saying the weather helm is still bad (there should be a little) once your foresail is up too.

tomperanteau 04-20-2011 07:31 PM

Quote:

Originally Posted by Waltthesalt (Post 721889)
Agree with everything heretofore said. Also easing of on the main in heavier winde, let it backwind a bit will also ease the weather helm.

Well-put. I had to do this a few times this past weekend on the way to Catalina. Weather helm and too much listing can make for an exhausting sail.

Barquito 04-21-2011 01:00 PM

Also, being a keel mounted rudder, there is no counter balancing as with a spade rudder. Therefore, for the same degree of weather helm you will have to pull on the tiller/wheel harder.

There is a good review of modifications done on boats to decrease wx helm in the latest Good Old Boat.

RichH 04-21-2011 11:28 PM

Guys, the original poster referred to weather helm 'probs' on CUTTERS ..... much different than 'sloops'.

tomperanteau 04-21-2011 11:30 PM

Quote:

Originally Posted by RichH (Post 722827)
Guys, the original poster referred to weather helm 'probs' on CUTTERS ..... much different than 'sloops'.

So do yo have anything to ad perhaps?


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