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Forestay tension in a blow

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ray.gall
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Forestay tension in a blow

Post by ray.gall »

No frozen lake at Carsington, boat packed and on the trailer, hoping to put the skids underneath DWSC pre victory role.

Clearly Draycote Water are confident of their anticipated success in the inter club challenge, not sure yet that the result is a foregone conclusion!

We are handicapped slightly by the absence of George Love but Robert, Robin & I are well up for the challenge.

Hope you have organised some wind, apart from the rhetoric :lol:
Charles
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Post by Charles »

Just after the start of Race 2 Robin N was following me up the beat in 6-10 knots of breeze. I asked him if my leach was hooked, he said it looked OK.

My blocks were my hand width apart (3 1/2" or 9cm).

Obvoiusly in more wind the leach will open & so I need to shorten this distance, but block to block is either a F8 or stretched sail.

Perhaps Robin can comment as he also has the old blocks.
Charles
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God does not deduct from our allotted life span the time spent sailing (or talking, texting, reading, posting to websites & emailing about it)
Robin Newbold
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Post by Robin Newbold »

Charles' leech did look ok with ~9cm gap. I had pretty much the same gap, any more and the sail stalls. When the breeze picked up a little at the end of the second race, I was able to sheet in more, so maybe ~6cm gap, but no more in that wind. Like Charles said, I only go block to block when the wind picks up (force6-ish). I haven't thought that there may be difference in height between the new/old blocks. (Charles, wasn't not too sure what I was meant to be commenting on, but I tried)
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Robert
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Post by Robert »

From what you've both said here, I can't think that my mast does rake forward that much, then. In fact I think it's likely to be about spot on for most conditions. All three boats (1237, 991 and 1351) seemed to go OK on Saturday, anyway. I guess that some people's sailing styles suit the block-to-block setup well and others get on with a bit of a gap. I would probably go down a hole on the shrouds and put a shorter shackle on the mainsheet if I was a bit concerned about wind strength.
I didn't look too closely at Chris Black's rig as he thought about luffing me on the reach on Sat but I wonder if he would still go block to block if he tightened up his rig. If not then there's no essential difference.
I have some interesting measurements provided by Steve Willis and when the season warms up a bit I intend to do some checking. Thanks again Steve. In the meantime, it's provided some chat at least.
Robert England
Georgecart
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Re: Forestay tension in a blow

Post by Georgecart »

Jim Coleman wrote:Hello Everyone and a Happy New Year.

During my 1st year sailing the Sprint I have got on well sailing it with the loose set up as it was when I bought it from a very good Sprint 15 sailor; ie, 3rd hole down, a loose forestay, and mainsheet blocks going block to block in the middle with a strong pull when on shore. When I sailed with this set up in a few strong winds I was well on the pace in a straight line, although dreadful through the tacks, which I will work on.
But it seemed to make sense to use the rig tensions for stronger winds in the “Tips” articles "Sailing in a Blow" by George Carter and "Stay Tooned" by Paul Smith. So in the last two F5/F6 outings sailing Unarig I set the shrouds (not quite) to the tension recommended by them, ie “…to the point where it is difficult to deflect the shrouds inwards by pushing with your finger ends….” However with that set up I found on the beat that it was very difficult to get the boat to accelerate. If I set traveller well low and bore away to get speed it took me miles off the point, and velocity made good (Vmg) was poor. The alternative was to keep the traveller in a bit, accept the lower speed and point up, as that seemed to give reasonable Vmg. Is that the way to go? On the reaches and runs I found the stiff set up was very good.
I must admit I liked the loose set up on the beat and will go back to it if necessary. But do the articles by George and Paul refer to Unarig and/orSport mode or both? No particular mode is mentioned in the articles. And can someone please enlighten me about sailing on the beat with the stiffer rig. I should add that weight is not the problem as I’m about 86 kilos in the kit and I know a few lightweights who go very fast using the stiff set up.
Hi Jim, just thought I would reply to this. My setting of the rig tension is very straightforward. My shrouds are standard length from Steve Sawford. My forestay was shortened to allow a rope to be used to adjust the tension at the bottom. I tighten the forestay rope to have the maximum tension while still allowing the mast to rotate by the wind. In light winds this means that it should be easy to rotate until 90 deg, only then do the shrouds get tight. It is very important that the wind can fully rotate the mast (almost to 90 deg) upwind. In medium winds, then the rig should get tight just before 90 deg and in strong winds then the rig gets tight quite a bit before 90 deg (but with a fair bit of effort I still can rotate the mast 90 deg by hand). In strong winds the rig will feel quite tight when you push and pull the bridle wires.

This is all very important to get right as the trick to going fast upwind in a blow is to let the traveller off, sometimes all the way, but have the sheet very tight. Most people have the traveller in too tight and the sheet too loose. If your rig is too loose you can't get the sheet tight enough before the main goes block to block. This is the reason I never move my mast back as some do in strong winds. You simply cannot get the main in tight enough. I never change the position of my shrouds ) 3rd hole from top.

When sprinting with the jib and trapeze I use tighter rig settings to avoid excessive jib luff sag offwind (although I don't think this affects speed very much - in fact in the Albacore you let the rig tension off on the reach and runs specifically to achieve sag), and as in medium winds the rig can sometimes flop towards you when the wind dies upwind and you are on the wire. So I use more rig tension when sprinting.

When buying new shrouds always always compare the length of the old ones against the new ones using two screwdrivers. Then you are confident that there are no differences.

Hope this helps

George
robinl

Post by robinl »

Hi,

Really good post George.

I have to admit, apart from batten tensions, I rarely changed rig setup race by race for the conditions. I ended up going for a setup that works well in most conditions, but especially if its choppy in moderate winds. This helps if you tend to be rushing a lot when rigging the boat...... May not be the fastest approach but does get you alfoat.

Regardless, rig tension was as loose as I could get away with while still being able to get a tight leach in a blow. Simply don't sheet in so tight when its not.

It varied more depending on which mainsail I was going to use.

Cheers

Robin Leather
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Martin Searle
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Forestay Chat ariticle on FAQ page

Post by Martin Searle »

Hi George,

I found that chat post very informative and tells me a lot about where to look for tweaks in upwind speed. Got to beat that pesky 'F'ing Dutchman' :lol: at least once or twice this year. oops :roll: may have abbreviated that wrongly oh well...

I have added it to the TIPS part of the site.

Martin S.
Ex Sprint 15 Webmaster
Ex Seasalter SC Webmaster
RYA Regional Race Officer (South East Region) (Expired)
RYA Club Race Coach (Expired)
RYA Dinghy Sailing Instructor (Expired)
Jim Coleman
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Post by Jim Coleman »

Thanks George. I will try your forestay settings through the wind range. .I have already loosened the setting for strong winds from that described in my original post (it was much tighter than your tightest setting) to pretty close to what you describe, and found that I can now make good speed upwind in a straight line, although I still need lots more practice to become efficient at tacking in a blow.
A question for you re Sport sailing when trapezing. Do you pull the mainsheet and jib as tight as possible and adjust the traveller out until not overpowered, or do you set the traveller to midpoint and loosen the main and/or jib?
And stemming from my other life as an RS600 dinghy sailor I find that loosening rig tension to ‘spring the rig’ downwind is fast when sailing direct on a run in the RS 600 and I think it is too in the unarig Sprint. The greatest exponents of springing the rig in two sail boats are sailors in the Star, who do it to allow the boat to sail deeper and faster. The rig rakes so far forward that the (large) jib is used like a spinnaker. I might try a toned down version of that in Sport mode in non-trapezing winds with a loose rig tension. Has anyone tried it?
Jim Coleman
Georgecart
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Jib & Main Tension

Post by Georgecart »

Hi Jim,

To answer your questions..... Firstly when sailing upwind in good wind with both sails I set the jib, not necessarily as tight as possible, but in strong winds it is very tight. I then set the traveller so that I am not overpowered. In strong winds the traveller may be all the way to the end of the track. As always you need to let the traveller out to reduce power not the sheet except in a gust. Following on from Robin's comment about having a looser rig (he sails sprint), you will find that the jib luffs before the main when sailing upwind and that you may get the outer tell-tales fluttering at the top of the main. That is because the main can sail closer to the wind than the jib, so you will always need the main sheet slightly looser when sailing with the jib, typically by 1-3 inches, depending on the wind strength to avoid oversheeting the main.

I agree with you that you will sail faster with a looser rig offwind. Many classes have adjustments to release the rig tension to do this. The trouble is the rig tension is fixed for the whole race and the compromise on the main sheet tension upwind is just too great as it goes block to block if the rig is too loose. So I always ignored that and adjusted the tension just to allow the mast to rotate in light winds and to get the mainsheet tension tight enough in strong winds.

The other limitation is that loosening the rig tension offwind is great to get a curve in the jib luff and a fuller jib with a wider slot, all of which can help off-wind speed. We do this in the Albacore with 6-8" of jib luff sag on a broad reach and run, and the Stars that sail here lean their mast forward at least 10 deg if not more offwind. However having a jib with hanks rather than a forestay built into the jib luff means you do not get these benefits and just get an untidy-looking loose jib luff between the hanks without the smooth curve.

Hope this helps

George
Jim Coleman
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Post by Jim Coleman »

Hi George,

Thanks for the very interesting and helpful comments. There aren't many fleets where a top gun gives away his secrets! You have cleared away the doubts I had about how I need to set things and sail the boat when trapezing in Sport mode.

Cheers

Jim Coleman
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