conditions: not quite enough wind, planing 80% of the time with sail bellied. You should really go up a sail size but you left it at home.

How should you rig the sail?

If you belly it out, it will get you on the plane but does it increase the aerodynamic drag? Will you be more likely to come off the plane earlier? Does it reduce upwind ability which is crucial in these conditions.

If you rig flatter then pump up onto the plane, is your sail's efficiency increased? Will you plane more? Will your upwind ability be improved?

i always go for option 2.

and agree with your comments on option 1.

rig for the apparent wind speed and then make love to the rig as was suggested in another thread.

I hate those conditions.

C'mon Haircut. Time to finally spill the beans.

I reckon half of Haircut's 2 knot wind planing ability comes from those r/c helicopters, being able to balance the rig riiight on the edge without going over (much), gradually and smoothly building up apparent wind. He doesn't pump often either, mostly flutters the sail a bit, possibly with the front hand more than the back.

More belly will get you planing earlier, but don't go beyond the max, whatever that my be for your sail. More outhaul will improve upwind ability, and tighten the leach for more early planing power, but less will give you more belly and power.

So I guess for the most power to get planing you simply want a tight leach and full belly. Move mast foot back a bit too and boom up high so more weight is over mastfoot. Bearing away during a gust helps.

It's all about MastFootPressure.

...Meh, I've gone off-topic a bit.

My 2c.

dave, where were you sailing ? didn't think there was wind at scarbs so I went home, then ended up sailing up there. I tend not to bag my sails out too much, maybe just a tiny bit at most. I find I virtually just rig them the same, and always go for a fair bit of downhaul no matter what. I find if you keep the leech loose, even in marginal wind, you can pump the sail better. When its bagged out and less downhaul, I personally then find the sail doesn't feel as nice so I don't work it as hard. thats just what I find.

I'm not sure that the flatter sail = more upwind really applies in marginal conditions...

A couple of times I've had the situation occur where I was having trouble getting upwind, bellied the sail out more and got upwind easily.

I think it's to do with having to go broad to keep planing in a lull -- a more bellied out sail will pull you through the lull a lot more easily than a flat one, so you lose less ground with a full sail.

$0.02

I'm with Nebbian... if I can get planing then I can get upwind. Otherwise the option is to spend my time dogging and railing upwind, which I hate.

Less downhaul, less outhaul than normal and away I go. Mind you, I sail Naish Force - powerful sail even normally rigged. I find it much easier to pump on to the plane with the sail rigged like that as well.

Just use an adjustable out haul system and your problem is solved. Bag your sail out to get going and flatten it once your up to speed. I use them all the time even wave sailing.

They are great on the inside of a break where the wind is light and flukey. It gives you better power to get out of the impact zone so much easier/quicker.

My 2cents

You should remove the outhaul and downhaul, take boom off the mast put rig into your car and go home...

i only change downhaul by 2-3cm if very strong or light wind .. in light wind i run nuetral out haul .. sail lays on some part of boom .. as wind gets stronger dump sail in water and trim outhaul while im floating ...

hehe that's windsurfing

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P.C_simpson said...

You should remove the outhaul and downhaul, take boom off the mast put rig into your car and go home...

Touché

in marginal planing conditions definately less outhaul/downhaul.

in 5/10 knot conditions less outhaul will get you upwind higher and planing quicker.

less downhaul almost always equals higher pointing angles no matter if light/strong wind. exception being holding too big a sail size for wind then more outhaul may get you higher into wind.

less downhaul usually makes sail feel less nice and slower topend though esp in gusts.

trick for planing in marginal wind,use ultra light large board no heavier than 8kg.

every 1kg of extra board weight to my experience makes monolithic difference to planing threshold.

here is an interesting link.

although this is written about yachts it is the same theory for all sail craft and is exactly what you will see guys on the race course doing.

http://www.sailtheory.com/tuning.html

Great link. But my tell tales all fell off at Gnaraloo

lol, fair call, but i does have pictures.

in laymens terms.

having a leech that is too tight (no pun intended) ie. "no twist" will make the sail drag when going to windward.

too tight is dependant on apparent wind. apparent wind is dependant on, apart from other things, boat speed and sailing angle etc.

so you need to guess what speed you are likely to achieve and tune your sail for that. ie. planning speed, hence the need for pumping to achieve planing speed.

the rule of thumb is flatter sail upwind, fuller sail downwind.

this is also why sails don't perform when under downhauled for their design.

edit* manufacturers have allowed us not to use tell tales by specifing downhaul and outhaul setting.

reading/understanding this link makes me realise why i failed somewhat at school.

to tight a leech will make sail drag going to windward/gestalt.

for max pointing angle i dont think so.

maybe for topspeed upwind a tighter leech will slow you down a little but for max pointing angle upwind the tightest leech is nearly always best.

only with really large sails 8.0m plus if sailing overpowered will increasing downhaul get you higher into the wind.

the sideways push of strong wind on large full sail maybe the reason for this.

You should remove the outhaul and downhaul, take boom off the mast put rig into your car and go home...

If I did this more often i wouldn't whinge as much..

hi peter,

we are not talking about longboards in sub planing conditions. are you?

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petermac33 said...

reading/understanding this link makes me realise why i failed somewhat at school.

to tight a leech will make sail drag going to windward/gestalt.

for max pointing angle i dont think so.

maybe for topspeed upwind a tighter leech will slow you down a little but for max pointing angle upwind the tightest leech is nearly always best.

only with really large sails 8.0m plus if sailing overpowered will increasing downhaul get you higher into the wind.

the sideways push of strong wind on large full sail maybe the reason for this.

no. on my 5m and 6m always found it considerably easier to get back to starting point with less downhaul [tight leech]. a looser leech i was faster but ended up more downwind.

a few years ago got caught out using 9.0m in 20/25 knots, i applied heaps more outhaul and was able to sail way higher into wind. i am guessing more downhaul in these conditions will do the same.

a general rule however[for normal sailing conditions] is less downhaul equals higher pointing angles and better bottom end.

more downhaul equals higher topspeed[esp in gusts] and a better feeling sail.

Hi peter,

i see where you are coming from now and agree. less downhaul will give you more power.

however i still don't agree that less downhaul (tight leech) will make you go upwind better on a short board. i've tried it numerous times. living in qld really forces you to sort out marginal wind sailing.

look at the guys on the race course. when they go upwind they tighten the outhaul (open the leech and move the draft back) and when they go downwind they loosen the outhaul (deepen the draft and move it forward)

with my sails i just set the downhaul and leave it. then adjust outhaul to suit conditions. if i find i can't get the feeling of being sucked to windward i tighten the outhaul and that does the trick. not enough drive and i let the outhaul off a little. to much power (only when overpowered) and i increase downhaul.

in my experience just letting the downhaul off won't help getting upwind. yes you will plane earlier and have more power but that's about it.

the key to sailing upwind on shortboards is speed. contemporary sails are designed to open up to work, if under downhauled to tighten the leech they just don't work as well and aren't as fast.

obviously it's all far more complicated than this and there are 101 ways to skin a cat. less downhaul/more outhaul, more downhaul/less outhaul they all adjust the leech as you've pointed out.

*edit* this is another interesting article which really validates why we both see things slightly differently. seems we are not the only ones.
www.onemetre.net/Design/Draft/draft.htm

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petermac33 said...

no. on my 5m and 6m always found it considerably easier to get back to starting point with less downhaul [tight leech]. a looser leech i was faster but ended up more downwind.

a few years ago got caught out using 9.0m in 20/25 knots, i applied heaps more outhaul and was able to sail way higher into wind. i am guessing more downhaul in these conditions will do the same.

a general rule however[for normal sailing conditions] is less downhaul equals higher pointing angles and better bottom end.

more downhaul equals higher topspeed[esp in gusts] and a better feeling sail.

i still disagree,although i probably use smaller sails than you.

when racing/reaching on my 5.8m in moderate but planing conditions with too much downhaul applied [3rd batten down] i usually finish downwind of opponents.

with less applied to [2nd batten down] i find in lulls esp that i can maintain my same pointing angle where as with more downhaul i have to bear off to maintain planing and speed.

this is where real advantage of sailing with tighter leech for me anyway is most apparent.

testing many different combos recently i have found in moderate wind that a wider chord fin of same length points higher. also my 64 wide board points higher than my 58 wide board.

best combo for me reaching/upwind in moderate winds is 64 wide board with 36 fin and 5.8m set to no more than 2nd batten down.

^no worries.....

it does sound like you are using less downhaul than me. my sail sizes are 6.4 - 5.3 these days. but busting out the 8.5 again as the wind has been crap.

with my wave sails i downhaul so to 2nd panel falls away (2nd batten if you ignore the very top batten at the head) and use the outhaul to tune it. to liitle outhaul and the sail doesn't go upwind.

slalom sails i downhaul so 3rd panel falls way and run zero to +1cm outhaul, more outhaul if i need to do a lot of upwind.

edit** i was thinking the difference is porbably in the fins. on wave kit i run a 30cm wave fin with the 6.4 so to much power in the sail sends me sideways.