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The P303 is quite sensitive vs. weather helm to sail SHAPE.
The P303 will quite adequately sail to weather with genoa alone ... and still have some weather helm IF you 'really' know how to 'set' and 'shape' the sails. Sailing a Bill Shaw designed Pearson - its easier to sail on just a genoa than reef the mainsail !!!!!!!!!!
Bill Shaw really knew how to design a boat and a P303 will sail along nicely and without much perceptible adverse helm ... but you need to 'balance' the sailplan (actually - correctly 'set' the position/location of maximum draft - which is positioned by applying the ***correct halyard tension***).
The CE of a designers sailplan is only a 'concept' and is **only** valid if the boat is sailing perpendicular to the wind. The 'actual' CE is a *dynamic* balance of the interaction of the two sails and is more dependent on where the position of maximum draft is located by the sailor who properly 'stretched-out' the 'preload' in the boltrope(s) by correct halyard tension. If THAT fails to get you proper helm, then and ONLY then does one begin to think about raking the mast, etc. MOST sailors simply 'raise' their (boltroped) sails and never correctly 'stretch out' the luff boltropes ( ........ and then complain of 'weather helm').
A too loose forestay (adjusted by tensioning the backstay) will give a set of symptoms similar to 'weather helm' ... actually, too loose a forestay sets the boat skidding off to leeward, gives a LOT of 'side-pressure' on the rudder/helm which you THINK is weather helm .... makes the boat HEEL and additionally gives difficulty when trying to 'point' or come through the eye of the wind when tacking. Make sure that the rigging especially the forestay/backstay is *tight* .... 18-20% of tension if you are using a tension guage.
Another way to *match* the forestay sag with what the sailmaker 'designed' into the jib/genoa sail: take the genoa and lay on FLAT ground; make a double accordian pleat fold about 2ft. back from the luff ... this will allow the sail luff section to lay unwrinkled and FLAT on the ground with NO wrinkles within 3 ft. of the luff section. Then take a string and stretch it between the head of the sail and the tack .... then measure / remember the maximum distance of the 'curve' that the sailmaker put into the luff of the jib/genoa at the luff (called 'luff hollow' - to *match* normal forestay sag) ..... and when sailing at 15-18kts on a beat that maximum 'curve' you measured/remembered in the shape of the genoa luff should ***MATCH*** the sag that you get in the forestay !!!!!!!!!!!!!!! If the forestay sag is greater than the hollow-curve (that you measured) that the sailmaker put in ... you get the symptoms of WEATHERHELM as the boat skids-off to leeward as it aggressively heels over!!!!!!!
Do the following:
1. If the mainsail is original, the luff boltrope is probably 'shrunken' (shorter due to age than when originally installed). This is probably the CHIEF cause of weather helm when using a dacron sail (with a boltrope in a sleeve) at the luff.
1a. Remove the mainsail and lay it on FLAT ground with the luff straight, then accurately measure the luff length. For a P303 the luff should be 34 ft. 8 inches EXACTLY. Then measure the angle that the luff makes with the foot of the sail ... should be 88 degrees, exactly.
if the luff length is much less than 34.ft, 8 inches or the angle between the luff and the foot is much GREATER than 88 degrees, then the three-strand luff boltrope is shrunken and should be 'eased' by a sailmaker.
A shrunken boltrope will cause the point of maximum draft to be located too far aft (giving weather helm), the leech will be 'hooked to weather' (giving weather helm) and the sail will be radically 'too full' (giving lots of heel but no 'go').
1b. If the luff dimension is 'close' to 34ft. 8 inches then you are probably not raising the sail properly!!!!! ... and you will get the 'shape' as outlined in 1a. above. A sail with a three-strand bolt rope is constructed with the bolt rope purposely shortened by 1 inch for every 10-11 ft. of luff length and is done so that when a dacron sail is wind-loaded at approx 18 knots you dont 'overstretch' the sail cloth. Therefore, once you 'raise' the sail, and intend to sail in ~15kts of wind you must: additionally 'stretch' the halyard (luff) another 3.5 to 4 inches ... after 'raising' the sail .... this will remove the boltrope 'preload' (shortening) that the sailmaker subtracts from a dacron boltroped sail targeted for 18kts. max. wind. ... The sail luff should be 35ft. 0 inches when raised AND the luff boltrope is 'properly' and additionally 'stretched'.
A 'good' sailmaker will also additioinally adjust the boltrope so the sail is maximized for venues with FLAT water (1-2ft. waves) or for venues with lots of 'steep chop', etc. (you dont get this from a 'mail order' sail loft).
Setting the mainsail (with proper boltrope dimension) for proper 'helm balance':
In 12-15kts of wind with the genoa flying, raise the mainsail, add ~3.5 inches of additional luff 'stretch' .... and then notice the helm balance when on a beat. If you still have weather helm .... keep adding halyard tension until the helm becomes totally ***neutral*** when beating; then reduce halyard tension by 1/2 inch increments until you properly affect a 'very slight' bit of weather helm. Your P303 will begin to 'fly' at this point (rudder angled just a 'degree or two to leeward' ... and you will probably note that the boat is 'climbing' towards the wind as the keel is now 'lifting' towards windward and the boat is now 'pointing' like a banshee!!!
If the mainsail luff and tack angle dimensions are out of whack ... simply get a sailmaker to 'ease' the boltrope. A mainsail with a shrunken boltrope when raised and 'improperly' stretched (or not stretched at all) at the luff boltrope ..... will have the aft end of the boom LOWER in the horizontal plane than the gooseneck !!!!!
Raise the sail, then stretch that boltrope/halyard an additional 3.5+ inches ... then get OFF the boat and 'see' if the aft end of the boom is lower than the gooseneck. If the aft end of the boom is LOWER than the gooseneck then you probably have a severely shrunken boltrope, ... take it to a sailmaker to have that boltrope 'eased' .... a fairly 'simple' and fairly inexpensive 'fix'.
I design and make my own sails, sail hard ... and have to 'ease' the boltropes after every season of hard sailing. A P303 is a 'very sweet' sailing boat and should have an ever so slight (almost imperceptible) weather helm ... IF and ONLY IF you have the sails correctly set with correct halyard tension (and dont have (very common) shrunken boltrope in the mainsail).
The SAME applies to virtually all boats with woven dacron sails with dacron three-strand boltropes at the luff .... and are complaining of 'weather helm'.
Hope this helps. ;-)