Rigging based on specification

[ulfp]

With the assumption that you are rigging your sail using the same mast/extension/boom, it is easy to assess the relative changes to downhaul and outhaul using the mast/extension/boom as reference, but how do you know “where you are” in the relation to the recommendations/specifications for the sail?

Do you measure your mast+extension and mark the “recommended spec” or can you trust the specifications. How accurate is the specified measurements of sails, mast and extension? (+/- ?mm)

I’m also puzzled on how/when to use the upper and lower downhaul point on the sail, and if changing the downhaul point normally should be combined with changing boom height and/or mast foot position on the board?
 
I have been using the lower outhaul point on my YES Freestyle 6.7 on my 260x60 board, and when I one day tried the upper downhaul point, the feeling of the rig changed a lot, so I moved it back down again. Should I have made some other adjustment at the same time?

[sukhdev]

Ulf,

re specs: I always use this just as a guide. Real world use may vary tremendously. In cases the specs can even be wrong..I know of at least 2 notable examples. The specs are a starting point, immediately on the 1st rigging I look at the top battens (as per my article on Retro tuning) and this gives me a quick feel for whether the extension is too much/too little.

The retro is a good example. Rig it to specs and its a powerhouse, tremendous pull, but for speed you would need to go above the specs, anywhere from 2 to 4cm . Ultimately one has to rely on feel, other variations such as mast type, carbon content all come into play. When I am in the initial stages of tuning a sail, especially a race sail, I'll set the extension about 2 to 4cm over spec so that I can get a feel for what the sail behaves like when over downhauled...the biggest problem with race sails still today is convincing sailors to crank on the downhaul.

As the sail ages, sometimes there is stretch and rerigging/tuning is required. Its worse here as most singapore sailors tend to leave their gear rigged up, in some cases not even de-tensioned. Its actually easiest to mark the rope if you want precise reproduction, extremely critical on race sails (assuming you use light colored rope).

Re your point about downhaul point, I assume you mean increasing/decreasing the amount of downhaul? Increasing the downhaul flattens the entry into the foil and loosens the leech, better control and speed, decreasing does the reverse.

My own preference is to use alot of downhaul, keep the foil fairly flat but use a high boom to handle more power. This way when I get to the limit lowering the boom & lenghtening the lines gives me another parameter for staying in control. Re mast foot, I'd find a position where the board just stops pitching up and down and that would be a good flat water position. I'd vary 2cm forward from that point for choppy conditions.

On some sails the clew has 2 or 3 holes for the outhaul. This can make a big difference, use lower clew hole for control and increasing the leech twist and upper for power.

[ulfp]

Outhaul:
Sorry about the mix-up in the last two paragraphs of the topic. Should have written upper/lower “outhaul” point and not “downhaul” point. Anyhow, your answer covered that aspect pretty well...

Follow up questions:
As you explained, upper/lower outhaul provides power/control adjustment. For a particular sail (I’m talking B&J and not racing), would experienced sailors find a preference in terms of using either the upper or lower outhaul all the time, or do they vary selection dependent on the conditions?

I also noticed that in your various rigging guides/posts that you prefer a leaner foil even for light wind conditions. Personally, I prefer a deeper foil for light wind since that gives me the feel of more power, but apart from making me feel more power, I have no “evidence” that it makes me go faster (even though I have a hunch that it sometimes can keep me on plane better than a flat foil).
Is you opinion that the deeper foil is more of an illusion than of true benefit (i.e. it only makes you feel more power, but it doesn’t give you more speed and lower planning threshold) or is this more of a personal characteristics where you are looking for top speed and don’t care about the performance in the “borderline” planning wind (or is it that I got it all wrong by trying to apply formula/large-sail theories on my B&J sailing)?

[sukhdev]

lets say you are planing comfortably, gliding smoothly along and suddenly you hit a small plastic bag on your fin, not enough to bring you to a stop, but enough for your legs to start feeling the strain and the board to slow down. Would this feeling be considered "power"? Obviously not, yet alot of sailors rig their sails so that their arms feel precisely this kind of pull and they end up thinking the rig is "powerful". This is stretching the analogy a little but i think it communicates what I'm thinking.

To me a powerful sail is one that you can pump and get a strong good boost and then when planing will keep accelarating and yet feel light and smooth in the hands. It should have no instability, draft should not wander. At the edge when it starts to get too much it should be possible to trim the sheeting angle and still keep going, right at the very edge it should "communcate" before it gets totally too much. The sail should have totally predictable handling across its entire wind range.

Flat would be a wrong word to describe my preference, I'd prefer to say I like sails with lean foils. The angle of entry at the mast should be smooth, without a thick blunt edge. This curve is set by downhaul. Outhaul then determines the depth of the rest of the foil with batten tension helping keep the entire foil taut.

Lets take a silly extreme, bag out a sail (any kind) with very little downhaul and outhaul. Try pumping it and it will be like pumping a loose bag. Now add downhaul till the mast is nicely tensioned, the foil is lean and clean and there is some leech looseness at the top. Pumping a sail well rigged this way will give you a lively feel since the mast has sufficent tension in it to "spring" with your pumping.

Setting a foil too deep and thick ends up with lots of low end that quickly builds to become drag while planing (ie drag increases faster than lift). I'd prefer to pump a little to overcome the initial hump and then rely on apparent wind, this goes whether its a wave sail or race sail. Once this smooth feeling is experienced you don't want to rig sails any other way, everything becomes alot easier and less tiring to handle, even gybing becomes easier as the foil handles better.

[ulfp]

Thanks for the excellent description.

I like the comparison with the plastic bag (I always feel like I have a plastic bag stuck on my fin), and when I rig my sail deep, it is very unstable if the wind gets stronger, so I will try a "leaner foil" next time the wind is light (or perhaps drop-by at pasta fresca so you can show me)...

[sukhdev]

Ulf, ok no problem, drop by sometime. We do get many good light days during the southwest; perhaps you should consider something slightly larger but still loose and fun to sail.

[ulfp]

Went to PA quite a few times last SE season with my 6.7, but I noticed that the wind often was around 8knt and not the 10-11knt that I need for my 6.7. Assuming that I get a wide board (formula or HS), what kind of sail size would I need to get going at 8knt (I'm about 64kg).

My 10y old son is also starting to learn. Got any board to recommend that could serve both as a "learner" for him and as a "wide" board for me, or would that be too much of a compromise (i.e. perhaps better to rent a Start for him at Pasta Fresca. I’v heard stories that kids learn very fast on the modern equipment).

How is ManaMana during SE season. Is there enough wind for beginners to learn. I find East Coast not so beginner friendly (always rollers and deep water with "rocks" waiting on the sides).

[sukhdev]

Ulf, the START would be perfect, entire deck is rubber and at his size it would feel very very stable.

We just set up a Sailworks Retro Ripper last weekend. This is a proper kids sail, designed to be used for children under 12, if you come down you can take a look. The boom etc are all made for very small hands.

At later stages the following 2 Starboards would be an option:
http://www.star-board.com/products/kiddy.asp
http://www.star-board.com/products/play.asp