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Old 9th February 2007, 10:12 AM   #1
Del Carpenter
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Default Which sail type for racing narrow longboards

1. My general question is: assuming most current racing sails are designed with formula boards in mind, could a mediocre sailor on a narrow longboard similar to a Mistral One-Design be better off with deeper draft sail instead of a race sail?

I think a sailor using flatter race sails has a smaller movement distance between full-on power and low power. I think a sailor who makes trimming mistakes with a flatter race sail experiences gustier conditions than a sailor making the same mistakes with a deeper draft, more recreational sail (freerace, freestyle). A sailor on a formula board has a more stable platform than a sailor on a narrow longboard so the formula sailor can handle gustier conditions than the longboard sailor.

If the above is generally correct, does the control advantage of a deeper draft more receational sail apply on both the downwind leg of a race course and in the slalom jibing section?

(Of course I could be going in entirely the wrong direction. The quicker on-off nature of a race sail could improve control in some situations.)
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Old 9th February 2007, 09:36 PM   #2
Roger
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Default RE: Which sail type for racing narrow longboards

Hi Del,
I'm not really sure about changes in sheeting angle ("a sailor using flatter race sails has a smaller movement distance between full-on power and low power. I think a sailor who makes trimming mistakes with a flatter race sail experiences gustier conditions than a sailor making the same mistakes with a deeper draft, more recreational sail (freerace, freestyle)."), so I'll have to check this out a bit. Never really thought about this aspect.
But, I've always done a bit better on longboards with deeper draft sails. This I know from years of experience.
Deeper draft gives more power, but does introduce some "control issues" when the wind gets stronger. But most racing is not in really high winds (at least not in the USA besides the Gorge and Maui) so deeper draft sails with more low wind power are normally better for longboards as longboards don't "unwet" to the same degree as a formula race hull will.
Another way to look at this is that the Formula hull has been designed to sail the apparent wind, with the hull pretty much unwet except for a short section at the tail of the board.
So a Formula race sail must also be designed to sail on apparent wind to the greatest degree.
Longboards have more drag, and while apparent wind is obviously very important (at least increasing your apparent wind to the highest degree possible certainly is) the long board does not get the huge "boost" in apparent wind achievable with a formula hull when it full unwets onto a plane.
So, as in almost anything windsurfing, there are more aspects to understanding why things work and were the advantageous "balance points" are than a simple look at them presents.
It's always more complex than it seems as you follow each design criteria along different paths. Change the type of board, and you need something different in the optimum sail. Change the windspeed and sail size, and you need to re-evaluate a whole bunch of other factors to achieve the optimum.
Hope this helps,
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Old 10th February 2007, 08:54 AM   #3
Del Carpenter
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Default RE: Which sail type for racing narrow longboards

Thank you, Roger.
I brought up the issue because I have some really old sails I am going to replace. Simply getting newer sails of either variety is likely to give me better results, so if my racing improves I wouldn't have known if I was helped just by better sails or also by more draft. I'm hoping I will be able to adjust to using an adjustable outhaul to flatten the draft when the wind increases enough to overpower my skill level.

You might not have thought before about what I called the "gustier" conditions created by flatter sails because you probably are faster in your physical reactions than I am. Part of what made me think I may be better off with deeper draft sails is I think flatter sails can much more suddenly turn on power. I'm thinking the number of degrees of sheeting angle from 50% power to 100% power is a smaller number for a flat sail than for a deeper draft sail. If that is correct a sailor with a flat sail would often have less time available to react to the power increase than a sailor with a deeper draft sail. As the wind changes direction slightly or as the sailor changes sheeting angle slightly the deeper draft sail will start feeling the power change sooner and will take longer to get to the full effect. It may be only a half-second difference, but that could be enough of a difference to give me enough time to adjust.

What got me thinking about how that time difference could affect me was remembering that timing is one of the reasons wide boards are more stable than narrow boards. Wide boards give a sailor more time to adjust to changes because it takes longer for them to tip enough to dump the sailor. The time difference may be only a split second, but it really helps.
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