Sailing Performance

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John2411

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Could someone advise me why my Moody 336 sails better and faster on port tack than she does on starboard. I have checked the shroud tension and can find little difference. Could it be the fact that most heavy gear and fuel tank are to port and may be keeping her more upright? I would welcome more experienced advice. Thanks.
 
Same on my boat, although the weight trim is opposite to yours. I have never managed to find out exactly why, but the boat balances slightly better close-hauled on stb, so I can usually keep the wheel lashed and the boat tracking almost indefinitely on that tack, but not so well on the other.
 
Sorry. The initial post on MOA was
I sail a moody 336 II and I have noticed she is approximately one knot faster when she sails on a starboard tack.
This year I decided to fit a new main sail and the same difference in speed keeps happening.
Has any other owner of this type of boat noticed the same?

Answers were the same - log position being main suspect. Also rigging and keel not dead straight.
 
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Could someone advise me why my Moody 336 sails better and faster on port tack than she does on starboard. I have checked the shroud tension and can find little difference. Could it be the fact that most heavy gear and fuel tank are to port and may be keeping her more upright? I would welcome more experienced advice. Thanks.

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The other aspect that you might consider is sail trim. If you trim sails in exactly the same way on both tacks (genoa car position and mainsheet/kicker settings the same) you will set the sails with the same amount of twist on either tack. The effect of wind shear means that generally you need more twist on starboard, so a little less mainsheet and genoa sheeting further aft, than on port. These are quite subtle effects but combined with differential ballast distribution the effect can be quite noticeable. You should also be thinking about the effects of wind and tide; waves are often coming from a somewhat different direction on one tack than the other and even modest little waves can have an effect on boatspeed.
 
All good advice but I would also suggest that it could also be due to assymtery of the hull, keel and rudder alignment.
Most production boats are assymetric.
 
My B&G log fitting has adjustment screws that allow the impeller to be rotated to avoid exactly this problem. Unfortunately, in our case the unit is more than 20 years old and the screws are made of brass, in a brass housing, so are corroded solid. We constantly see 1 knot or so faster on one tack than the other, but GPS confirms that there is actually no difference.
 
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Am I right in thinking that wind shear differences wouldn't apply if the wind was steady?

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I don't think so. Wind shear is to do with the drag between the lower layers of air and the surface (sea or land) they are blowing over.
 
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