written by Matias Collins on November 10 of 2004 and read by 1229
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Roman Koch responds to my commentary: �
Unfortunately we never check the rake; the tension measurement is not possible, because we use forestay and shrouds made from rodrigg.
I also don`t know the rake, because we fixed it the first time sailing our boat with the "Schümann-datas" and have only a second position for very light winds with about 1,5 inches more rake.
The jibstay is a bit sagging (probabely you could see it at Lake Garda, when we were together after the start) but anyway, we are never b2b, eventually I`m too weak to tighten the sheet in stronger winds :-) The blocks are about 4 inches or 10 cm separated.
Stuart Walker Comments:
<I>I conclude from this that Roman has less rake than I do - his boom is much higher off the deck when sailing with a "hard" backstay - and that his mast base is cut at a flatter angle (the mast more upright) so that the jibstay can sag even with a "hard" backstay. This would be, of course, more appropriate to strong winds - in which he does so well. I suspect that most of us have our mast bases cut more steeply for more rake and better light wind performance - and that therefore our mast bases do not fit so firmly on the deck when we reduce the rake in strong winds.
Again from Roman Koch:
We fix the backstay in stronger winds and use the mainsheet to work the puffs; that`s much easier than tighten a very hard backstay and it works pretty good. We also take the under shrouds back first to get some pressure out of the rigg.
Roman is obviously doing the right thing - playing the mainsheet rather than the backstay - in strong winds - like a dinghy sailor! - but it shows how much stronger (not weaker!) he is than we are!
Comments at article: Main Sheet Adjustment by Stu Walker - 10/13/2004 9:29:22 PM
Peter Hewitson asks how I measure jibstay tension underway:
I do not ordinarily measure the jibstay tension while racing (although you can do so). I measure it with the Loos Guage while the boat is on the trailer or at the dock with the jibstay, backstay, etc. set up as I intend to use them. I believe these measures reflect - and measurements while sailing indicate they are little altered - the tensions underway and most importantly are reproducible.
After racing I check the tension that was present when the boat was performing well and by reproducing the settings (jibstay, backstay, shrouds, mainsheet) that created that tension I am able to get the boat to perform effectively on subsequent occasions
Comments at article: Main Sheet Adjustment by Stu Walker - 10/11/2004 10:56:52 PM
From Steve Bobo -
Is it overly simplistic to use TBL as a primary indicator of appropriate rake after applying the mainsheet and backstay tension appropriate for the conditions?
My presentation was intended to imply that the mainsheet was TBL (two-blocked - traveler and boom blocks touching) as a consequence of getting everything else right, i.e., jibstay and backstay tension and shroud position. In this situation I had set the jibstay and backstay to get the jibstay tension and the mainsail flattening I desired and then pulled in the mainsheet til the upper mainsail telltales flicked appropriately and found - surprise! - that the mainsheet was two-blocked. I think that the first consideration is jibstay sag (and jib shape) and the second is mast bend (and mainsail shape) and then you worry about getting the upper leech telltales to flow the way you want. But, of course, this means that you had to start out with approximately the right rake or you couldn"t trim the main leech properly. I don"t think the end plate effect is as important as these factors.
Another point in your article that I found particularly intriguing was the references to Loos tension readings on the forestay. How do you read it while racing, particularly after you have readjusted the rig after the run? Is there a way to permanently install some sort of tension gauge between the forestay pennant and the forestay?
I check the jibstay tension with the Loos guage when the boat is ashore - and although it must change underway - this gives me a baseline that I can reproduce and presumably determines the tension underway. A helpful standard - that applies particularly on Lake Michigan with its waves (and not so well on European lakes!) - is that the jibstay tension should be the amount that just prevents pumping (the "Kostecki Wobble"). In other words you ease the jibstay til it pumps and then tension it just enough to stop the pumping. This means, of course, that you need more jibstay tension in waves than in smooth water (and more in gusty conditions than in steady winds).
Main Sheet Adjustment by Stu Walker - 9/27/2004 12:33:41 PM
When looking over my notes concerning that great regatta at Lake Champlain (I hope that the world doesn't find out about one of its finest venues and begin to crowd out the Solings!) I found - to my surprise - that at 11 knots we were "very fast" with the mainsheet two-blocked (TBL), that at 14 knots we were "fast" with the mainsheet TBL, and that at 18-20 knots we were also "fast" with the mainsheet TBL! Shouldn't the mainsheet/boom end be different in these three dramatically different conditions? (11 knots - the beginning of both crews hiking, when you want maximum power with the sails as full as possible; 14 knots - when you need to reduce power and flatten the sails so as to prevent heeling; 18-20 knots - when you are overpowered.)
At 11 knots I had little more than 1‘ of fore-and-aft mast bend, about 1 1/2" of lateral mast sag, the jibstay sagging (tension at 7 on the Loos Gauge), 30 1/2‘of rake, and needed the mainsheet to be TBL in order to close the leech and just stall the upper telltales.
At 14 knots I had 3‘ of fore and aft mast bend, a straight mast laterally, the jibstay tensioned to 15 (approx.), and 29 3/4‘of rake. A tighter backstay, tighter lowers, and tighter jibstay combined to pull the top and the middle of the mast forward so that the TBL mainsheet - producing the same boom location - was pulling much harder on the leech and resulted in occasional stalling of the upper telltale.
At 18-20 knots I had the shrouds aft to the centerline of the mast, the backstay tensioned so as to provide about 5‘ of fore and aft mast bend, the tip of the mast falling off to leeward, the jibstay tensioned to 35 (approx.), and about 29' of rake. The top and middle of the mast were now pulled even farther forward so that the TBL mainsheet was under even greater tension - presumably counteracting a far greater aerodynamic force - but now the telltales were flowing continuously and the main was twisted into a more open, pitching-rolling-yawing-accomodating shape.
The TBL position of the boom end seemed about right throughout this range, but I wonder if - particularly at 18-20 knots - it should have been tensioned more? - or less?
This article is new series of Technical articles promised by Stu Walker to introduce the "art" of sailing a Soling to all those new sailors worldwide, we are reaching the AMAZING number of 1000. Check for future ones.
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