Forums > Land Yacht Sailing General

width to length ratios

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Created by kennatt > 9 months ago, 12 Nov 2017
Bynorthsea
89 posts
26 Nov 2017 5:04AM
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Your absolutely correct, not a windsurfer and certainly not offended the advise is great and I'm sailing tomorrow so I will have new look at what I am doing. What I do know is the discussion has helped me decide to set up a bottom boom arrangement, it will go on the new yacht I'm building, I'll get some pic of that soon.

Chook2
WA, 1203 posts
26 Nov 2017 9:11AM
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Thanks Ken, I'm not up to speed with windsurfing so that has explained it to me as well. Cheers for that.

Greg has found a great trick to get the cambers onto the mast really simply and easilly.
We rig the mast, fit the sail, then attach the boom and thread the sheet rope normally.
We then DONT downhaul, but only use sheet rope pressure to get the mast to curve right to the front of the mast pocket/luff.
It is then a very simple process to clip the cambers on, as and very easy to get some room to get your hand into position them.
Because the mast pocket is still fairly loose, practically no tension in it at all, there's plenty of room to adjust them into there correct positions and do up the zips without any struggles.
Then downhaul tight while the sheet is still tied off. The bottom camber sometimes needs a bit of a wriggle to align the rollers to the mast after downhaul (as it's been pulled the furthest down the mast and doesn't always align squarely being the smallest camber) and then zip it closed.
Doing this there is "No stress" and they simply click on every time.
Then when we jump in to go sailing we add more downhaul to set the sail draft as needed.

Note; If the top camber is difficult to get on it means that you haven't adjusted your sheet rope correctly for a start. Do this first ("more usually" or less sheet rope tension) and when the top cam clicks on easilly, the others below will be a doddle. With time you will gauge the amount the mast needs to push forward into the luff when tying off the sheet first up.

When we pull up for a spell out of the yacht, we back off the downhaul slightly and have a fairly loose sheet to take some strain off the mast during the heat of day. Not necessary but feel it helps.

De-rigging is the reverse. Keep your sail sheeted quite tightly and only then drop your down-haul completely and pop the cams off. "Never ever completely dump the downhaul without good sheet rope tension", or just ease up the downhaul to slacken it off slightly to make removing the cams easy. Otherwise you stand a chance of saying goodbye to the tips of your battens, as the cambers jump off the mast with incredible force.

Hope this helps, Chook

Bynorthsea
89 posts
3 Dec 2017 11:43PM
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Another question Chook. The fork you have on your boom am I right in presuming it is locked into the boom end to stop it rotating or pulling out as you put on the downhaul? Cheers

Chook2
WA, 1203 posts
4 Dec 2017 10:38PM
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Select to expand quote
Bynorthsea said..
Another question Chook. The fork you have on your boom am I right in presuming it is locked into the boom end to stop it rotating or pulling out as you put on the downhaul? Cheers






Yes my boom is constructed from 2 old carbon mast tips.
I found just one was too flexible with big sails.
One slides inside the other. The inner mast tip is around 300mm back from the very front of the boom. Larger diameters to the rear. A 60mm long wooden plug in the front takes the shaft of the steel fork. It is drilled into the plug at an angle to allow the straight section of shaft behind the fork to sit fairly level/at right angles to the mast when the boom is sheeted pretty tight. The wood and fork shaft are first glued in with epoxy after first roughing up the carbon and steel and then finally (when the whole thing has completely set) keyed into place with a self tapping screw (in a hole that's predrilled up from the bottom and some epoxy glue added before screwing it in.

Each pulley block along the boom is held in place with a stainless saddle and 2x 4mm stainless steel pop rivets. These rivets through the saddle and 2 layers of "mast tip" sandwich it all together along the bottom as well. I give the holes a squirt of super glue and insert and quickly pop the rivets.
I drill and de-burr an oversize 8mmm hole from top to bottom at the rear of the boom and a racing cleat is screwed on underneath for the sails rear clew attachment using 5mm dyneema cord.
My smaller 5.7 storm sail clew cord, attaches through one of these blocks stainless saddles and the excess boom simply sticks out to the rear of the sail.

When rigging the sail onto the booms fork "straight bit of the shaft out of the wooden plug" , the downhaul triple block is positioned behind the sails clew downhaul attachment point (we use a stainless hook now to make it quicker than the shackles "as used in the photos on the previous page" to setup), so the downhaul tensions the sail forward towards the mast as the downhaul pressure is applied.

This is the hook we now use. It attaches/is laced, to the sails original downhaul point by the hole and goes over the fork shaft, in front of our booms triple block downhaul system.
It's a "Ronstan RF533" with the pin ground off to discard the retaining clip/arm bit. This allows quick assembly of a previously fiddly job of working with small shackles to get it attached to the fork shaft when rigging the sail. It slips over the 10mm shaft really nicely.

Bynorthsea
89 posts
5 Dec 2017 4:32PM
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Thanks again I'm currently working on a boom made from and old carbon mast tip as a rig for my new yacht, it will be sewing machine out next. When I've got a sail done I'll get some pictures up.

Bynorthsea
89 posts
6 Dec 2017 9:11PM
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Here is the downhaul arrangement I've come up with does concern me a little that the boom and the swivel makes the sheeting very tight but we will see





Hiko
1181 posts
6 Dec 2017 9:49PM
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I take it the whole caboodle sits over a stalk upright a la Chook,s arrangement? Should work fine.
Might be a good idea to have some way of holding the mast down in the yacht though
like a short piece of rope or something.

Sylk
WA, 209 posts
7 Dec 2017 3:03PM
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Some good ideas there Bynorthsea well done.

Hiko I doubt there is any need to "tie the mast down" I have been sailing with a similar arrangement for almost 2 years and never had a problem.

Hiko
1181 posts
7 Dec 2017 4:30PM
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Sylk said..
Some good ideas there Bynorthsea well done.

Hiko I doubt there is any need to "tie the mast down" I have been sailing with a similar arrangement for almost 2 years and never had a problem.


I have to admit the only time I have heard of a mast coming out was a case where the yacht sailed into the surf
mast came out when yacht turned upside down injuring the pilot who was very fortunate that help was close at hand
to get him out I have been into the waves at speed two or three times but fortunately no drama other than a good dunking. Class fives can be a bit reluctant to steer at times in certain conditions!

Bynorthsea
89 posts
15 Dec 2017 1:19AM
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Well 6.2 sail modified and boom made, this is the first rigging for the new yacht. With a bit of negative rake booms a bit higher than I would prefer but probably ok. There is no way I could alter the downhaul on the move with the angle of he cam cleat but I think I can bend the mounting plate. One question I have is now that I have quite a lot of back and forward mast adjustment as well as adjustable mast rake the simple adage of more rake for high winds, les for light becomes more complex, how do I get the best from my sails?


Hiko
1181 posts
15 Dec 2017 5:31AM
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Wow that looks nice Good job!
The answer to your question is probably best answered by yourself
You have the tools with all those adjustments to be able to tell us.
As Chook has said before looking at your track on the beach especially in the turns can give you some clues as to trim etc

Bynorthsea
89 posts
26 Dec 2017 4:17AM
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Hi guys Christmas dinner over but I'm not allowed in the workshop today so with time to think and to avoid Christmas TV I've some more questions.
I've modified two sails and set up a bottom boom, I didn't think much about it when I rigged and took the pic in the previous post but now I have sailed the rig I just need some advice.
Different to setting up a wishbone rig attaching the outhaul on the bottom boom has no impact on the sail or battens until you take in the main sheet, without that the boom just lifts and the clew extension remains slack. When sailing whilst the rig with the wishbone stayed tight and quiet, easing the sail on the straight boom was a bit flappy like a normal sail, now I was using a sail probably too large for the wind strength so that could have made it worse. So if my basic set up is ok what is the best way to set up?
Full downhaul to set the battens, then outhaul, then sheet in tight and recheck batten positions on the mast?
Or partial downhaul, then outhaul, then sheet in tight, check the battens, add more downhaul f needed to position the battens?
Or?
I appreciate once I have the settings it won't be trial and error but if you can I would appreciate the benefit of your experience to get there.
Seasons greetings.



kennatt
25 posts
26 Dec 2017 5:45PM
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hi btnsea, to answer your question simply.....downhaul, downhaul, downhaul, in winds where the sail is a bit more powerful than you need.Downhaul is the controlling factor. If you look at the F2 sail in the photo,in strong winds,the cloth between the top two battons should have a crease running from the leach towards the mast, If still overpowered,more downhaul until this crease shows in between the next two battons down. and so on down the sail. Some windsurf sails ( ezzy sails) had markers on the sail indicating the point where you should get these creases to develop to,ie light,medium and strong. The theory being that if you get the leach loose between the clew and the tip of the sail as a gust hits the mast flexes downwind ,thus tightening up the leach,and also allowing the flow of air to slip up and over the sail reducing the force on it.
When these loose leached sails came on the market,a long time ago now, we downhauled as per the instruction and all said these look all wrong when looked at on the beach,but as soon as we were sailing and looked up at the shape you could see the theory working, tight as a drum and the tip flicking and flexing in the gusts. One other advantage was that instead of five or six sails to cover a wide wind range,we needed less. In theory you can downhaul almost a meter out of a given sail size by downhaul till its loose all the way down to the clew.

Try it, give it some stick with the downhaul,if you get the chance to watch a decent windsurfer rig up you will see him just about busting a gut,with both feet on the base of the sail,using all of his strength on the downhaul rope. There is even a downhaul tool that fits into the mast base with a handle to wind the rope to make it easier to get enough on.
good luck and fair winds force 4 to 5 bf would be nice ken.



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"width to length ratios" started by kennatt