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Tuning

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Created by Bynorthsea 7 months ago, 20 Apr 2017
Bynorthsea
78 posts
20 Apr 2017 8:13PM
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Hi guys I have just set up my yacht with uncut windsurf sails and I have been experimenting trying to get the set up right, yesterday we were sailing in light winds on concrete and at times I was struggling to get going and certainly not doing as well as conventionally rigged yachts, I was left with a couple of issues that I would appreciate some advice on.
With previous set ups on the beach balancing the yacht has always been straight forward skittish steering more mast rake, loosing the back end less, on concrete with the terrific grip has made me question what I thought I knew. What ever I was doing yesterday I was scrubbing rear tyres but without breaking away so my question is this is, is the break away either front or rear a result of higher lateral forces or is it as a result of lift from the sail making it easier to drift the back or front end, if the latter I would need to alter the set up I had yesterday with much more rake to ease the load on the rear tyres and make more efficient use of the power. The mast step on the yacht is well forward compared with a lot of minis where it is on the pilot's side of the steering bar.
The second is about getting the sail right, the sail is a 6.1 and not cammed, in the light winds it was a struggle to get the battens to pop around the mast but if I put more downhaul on the sail lost the shape and was depowered, do I have to give it more outhaul also am I simply relying on tightening up the battens, inducing camber for initial power? When the wind picked up a little it did sail reasonably well. Any advice would be appreciated.

Hiko
1161 posts
21 Apr 2017 9:52AM
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Is the wheel alignment and tyre pressure OK ?

BenBoulder
WA, 243 posts
21 Apr 2017 6:31PM
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More rake on mast.
Add tell-tales to sails ( so you dont oversheet)
Grab the foot of your sail and "pop/flick" your battens ehen changing tack.
Lots of downhaul the leech should be loose.

dirkski
24 posts
21 Apr 2017 8:17PM
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When you apply the masttype and hight, the luff- and boomlength as mentioned on the sail, your sail will be rigged perfect. And as Ben stated: you must have loose leech. Windsurfers rig their sails this way. When done right, the top has to lift by putting little pressure on the mastfoot when the sail lies on the ground.

mineral1
WA, 4348 posts
23 Apr 2017 12:51PM
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Hope I get this right, but from a windsurfer prospective this is the set up.
Downhaul the sail as per the specs on the sail sheet.
I know its not what is expected, and you will wonder if its too much. But the biggest problem with windsurfing set ups sail wise is the user hasn't set enough down haul. When you get it right, look at the top and second baton. These should be pointing mid section of mast, and not off to one side. The top leach will be floppy down to near on the boom height.
The intent is:
The center of effort on a windsurfing sail is right at the boom level as in your photo. We swing off the harness lines set at 1/3 back from the mast for the front line with about a good hand span to the back harness line. If we experience spin out (fin cavitation) we
we move the rear harness line back a tad. You cant with yours, but you get the idea.
When tracking 'upwind' we pull the leach on so the sail is flatter, and we are not getting pushed sideways down wind.
When running with the wind, we let the leach off, to give bigger billow for want of a better word.
Hope this helps.
But downhaul it to spec, plus or minus 10mm max.
If unsure, just google say NP sail set ups, or Ezzy sail set ups and you will see how they set them up.
.

Sylk
WA, 202 posts
23 Apr 2017 3:02PM
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Like Ben said more rake.
To my eye it looks like your centre of efort would be someware around your thighs/knees with that setup.
You want it around your bum.

Also what Ben said about down haul and lose leach.
I find with my bigger camed sails 6.5 & 7.2 in light wind I have to grab the foot and give it a flick as I tack.

Grip levels on concreat are very similar to good salt.
Have a look at the rake on Bens yacht rigged with a 5.5m sail. (The one in the middle with the V8 sail


Try and ignore the fact that the front wheel's missing. Only a minor inconvienience when your 10km from the car.


PS: Dont be put off, it takes a bit of work to get this system working right for you. Remember the tec (mast and sail design) is quite different to standard im still improving my tuning a year after building it.

Bynorthsea
78 posts
24 Apr 2017 2:12AM
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Thanks guys I'm checking alignment and hoping to sail again in a couple of days. Wind predicted should give me a chance to try my middle sail, 5.4 with two cams. I had set up the rake on the principle of large sail crank it forward but It had thought that it looked wrong so experimentation will follow. With uncammed sails how much camber should I be inducing with the batten adjusters and should I camber all the battens? I've no intention of giving up with the set up because on each sail so far there have been glimpses of good performance all I need is get it more consistent and to know the impact of what I am doing.

Sylk
WA, 202 posts
24 Apr 2017 3:54AM
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Sorry I dont have any experience with uncamed sails in this type of setup.
Perhaps somone else can jump in?

kennatt
19 posts
24 Apr 2017 2:50PM
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I've got mixed feelings about uncut w/s sails,I have a blowkart,and being a long practitioner of windsurfing have w/s sails ranging from 4 meter to 10 meter,Ive tried w/s sails on the kart and would like to put my views. I prefer the standard kart sails.
I think with w/s sails the kart points higher but needs slightly higher winds,I believe this is because the windsurf rig is designed to have the center of effort at boom height. ,with that force being held in the centre of the boom by the rider who forms a triangle with the board sail and mast thereby driving the board forwards.With the rig on a kart the end of the boom is held, which I believe allows the front of the rig to tip forwards,thereby forcing the centre of effort to move away from where it was designed to be,forwards and upwards. I base this on the fact ,that every windsurfer knows,if youj set the harness lines on the boom too far back the sail becomes unmanageable and simply throws you over the front of the board. They need to be in the centre in line with the C of E. I used the w/s sails both unsupported and by setting with a second support up to the front of the boom and with the mast base on a U/J on the spine of the kart.The second being better than unsupported. I also found that in tight gybes at speed the extra weight of the boom caused too much sudden change of power which caused the kart to tip,unless I controlled the sheeting hard in and controlled out as I turned. True they are better upwind and don't flog about like normal kart sails,and because of the basic design when set with enough downhaul and outhaul, will always be more usable as wind increases because they form a better solid foil. But at the moment I am firmly on the fence still unsure which in better,still use my large w/s sails in light winds,but only because the biggest kart sail I have is a 4m. The testing is ongoing... Just my view cheers .

Sylk
WA, 202 posts
25 Apr 2017 7:41PM
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Finaly had the right conditions to rig my largest sail today. This is a 7.2m 4 cam race sail.
My bum rests about 8"-10" forward of the rear axle line.
This rake and mast position was perfect for the very light winds we started out in 7-9 knots then as the wind picked up to about 10knots with 12 knot gusts it would have been good to straighten the mast a couple of degrees as the back wheels were breaking away 1st.

Top speed for the afternoon was 61.8kmh Max wind speed was 12 knots.


kennatt:

Im not surprised you had mixed results on a Blokart since your mast position and rake are fixed it would be very unlikley you would get the rig properly balanced. The main reason these sails are working so well for us is because we can adjust the mast position and rake to suit the sail and the conditions.

kennatt
19 posts
27 Apr 2017 2:34PM
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yes ,having read the posts on this,You are probably right,and not much I can do about it.Might have to start a new build

gofaster
74 posts
29 Apr 2017 6:24AM
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kennatt
I'm interested in what you did mounting the ws sail behind the mast foot on your blowkart. Did you reinforce the mast? How did you attach the mast to the blokart? - using the blowkart mastbase to mount a stub mast? Depending on how you did that you could alter the sail rake.



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"Tuning" started by Bynorthsea