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post #4 of Old 04-19-2011
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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 4-5į 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: 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 !!!!!

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 -
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!!!!!!!). 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.

Last edited by RichH; 04-19-2011 at 11:02 PM.
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