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Boom position on a close reach
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People:
I got a few questions regarding balance of Hull 555. I am experiencing a lot of weather helm when it gets above 15 mph. I am thinking the shape of my main is blown out but I am not sure. 1) Is there a procedure out there for checking standing rigging setup that I could follow? By this I mean stays tension and how to measure it, mast rake etc. I can hardly put the boom close to the boat center line when close hauled and I am wondering if this is normal? In summary, on a blow this boat wants to round up and I am fighting it all the time. armando __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around |
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Armando,
I have hull #328 and we experience some weather helm when close hauled as well.? One thing that can help is playing with the centerboard so it is better than half way up (eg., pointing astern) which brings the center of effort (CE) aft a bit.? We have been racing and close hauled and even use the traveler to center the boom on the boat.? There still will be some weather helm which will slow you down; each push on the tiller acts like a brake to the smooth water flow across the keel.? I prefer to use the tiller incrementally, that is to only pull a little in the direction you want her to go and then let off the pressure on the tiller, and continue through a tack, than throwing the tiller hard to lee Our boat will sail itself on a course a bit higher than a beam reach and we can actually modify the course by adjusting the centerboard.? Try this sometime in winds less than 15 as it is pretty cool when your boat will easily sail itself.? Also, as the wind increases you want flatter sails, rather than baggy, so using tightening the outhaul on the main is a good idea as is getting new a new main sail. In terms of rigging and checking the pressure there is a device called a Loos gauge that somehow reads the tension in the wire.? A fairly tight fore stay and back stay will help the leading edge of the jib from sagging and will also add speed and better upwind performance from the sails.? Also to consider is that if it is blowing 18+ when you leave the dock you should put a reef in the main sail, the second reef point if it is really dangerous.? With one reef and a balanced furled jib we have been out in some stinky conditions (< 40) and stayed a lot flatter (with less weather helm) and still had full hull speed more comfortably. Frankly though, a boat with lee helm is a much bigger problem than a boat with a bit of weather helm.? You always need to let out the main in big gusts and you can even adjust the jib accordingly when you see them coming.? But the T27 at roughly 3 1/2 tons can take a good bit of wind before the rail gets in the water. I too have been grappling with the same issues as you and I still think the T27 is a great boat. Odalisque came out of the Hudson River yesterday. Boo hoo. Caleb #328, Odalisque, 1967 Nyack, NY -----Original Message-----
From: Armando Morell To: T27Owners@... Sent: Mon, 5 Nov 2007 12:00 pm Subject: [T27Owners] Boom position on a close reach People: Email and AIM finally together. You've gotta check out free ! |
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Greg Van Pelt
There's a lot you don't tell us Armando, so it's really difficult to
make any observations that might be helpful. OTOH, this is the interweb - any advice you get is worth what you pay, so here goes . . . It could be that your rig isn't properly tuned, but unless you see more problem on one tack than the other, or have lee helm or consistent difficulty going to weather in light air, it's not the first place I'd look. You don't tell us whether you've adjusted the primary controls to flatten the main: are the outhaul and cunningham cranked tight? Particularly with blown out sails, depowering when the wind gets into the upper-moderate range is essential. OTOH, if you have the vang on hard, you're pulling down on the leach, and not letting air spill out of the upper part of the sail, which will induce weather helm. Likewise, you'll want to twist off the top of the main. You can accomplish this by easing the main sheet, and bringing the traveler to weather in order to put the boom near the centerline of the boat. (I'd be careful with this - many people don't actually sight the boom against the backstay, and consequently bring it slightly to weather, which creates huge weather helm.) In the conditions you describe, the top of the sail should twist off to leeward, and the boom should be dropped slightly below the centerline of the boat until the helm balances. |
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Greg and Caleb:
I really appreciate your comments. I have done most of the things I could think of as you are are correctly suggesting to flatten the and de-power the main. This are the things I will like to try next after given some thought to this issue and taking into account your feedback. 1) In an attempt to flatten the main I had the vang tight which as you pointed out is preventing the main from twisting and spilling some air. 2) I should have also tried a first reef. 3) According to some of my readings our boat should be able to carry the 176% Genoa up to 20 MPH so I had the big head sail on. I was talking to a friend and he pointed out that if I was not able to reduce the boat heel I perhaps should have changed to the working jib. He points out and I think he is correct that when the boat is heeling it naturally has a tendency to point higher because of the change in hull shape. My thinking at the time was that the bigger head sail would compensate and bring the bow down 3) As far as the rig tuning I will like to be able to measure the stays tension. I do have some sag on the head stay but I am not sure how much is acceptable. any thoughts here. thanks again for your comments armando --- Greg Van Pelt <greg.vanpelt@...> wrote: There's a lot you don't tell us Armando, so it's __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around |
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Greg Van Pelt
3) As far as the rig tuning I will like to be able toAs Caleb mentioned, rig tune is achieved by use of a No. 90 or PT 2 Loos gauge. My recollection is that base rig tuning specs are in the Tartan 27 Owner's Manual published by the Chesapeake Bay Tartan Sailing Club. I don't have access to my copy at present, but I'll be glad to check and post the recommended rig tuning. I am somewhat curious regarding your statement about headstay sag. Do you have a backstay adjuster, and have you tried tightening the backstay tension, which would also flatten the main? |
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By head stay sag I mean that while sailing I have gone
forward and looked up the head stay to asses how much it sags or deviates from a line. I estimate that it deviates about 12 inches at its max. I do have a turnbuckle on both stays so I could change the tension if I wanted to, however I do not want to over do it. Which is why I wanted to measure it. As far as the specs I have the manual and one of the alternate methods suggested, involves tightening by hand and then putting 5 more turns on the turnbuckles. I also need to check the mast rake, if it is to far back I assume I could also have the excess weather helm problem. Can somebody estimate the maximum weather helm force force on the tiller. 10 lb, 30lb, 50 lb. what is your best guess at max tiller force when is blowing hard say 20 mph. I have gone home after a long session with sore arms and I am questioning if this is normal. armando hull 555 Magothy river/Chesapeake bay --- Greg Van Pelt <greg.vanpelt@...> wrote: 3) As far as the rig tuning I will like to be abletomeasure the stays tension. I do have some sag onthehead stay but I am not sure how much isacceptable.any thoughts here.As Caleb mentioned, rig tune is achieved by use of a __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around |
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We do not have a boom vang set up (yet) which is why we tend to reef in winds 18+ kts.? Our main is quite old but full battened and with a decently set reef we are much more comfortable.? You can keep the genny full or furl it in to match the reefed main, which I prefer.? We only have a turnbuckle on the aft stay as when we replaced our roller furling the Furlex unit was installed without any adjustment to the fore stay tension.? We probably have about a foot or so of sag at the leading edge of the jib when under load and will be replacing the aft turnbuckle so we can tighten it up a bit more. In terms of mast rake (aft mast rake that is) I do not think that you want any for a T27.? I also own a 19' Lightning which is currently set up with a lot of aft mast rake (presumably for light air sailing).? The mast on the Lightning also has an aft stay tensioning system which will induce some bend and therefore twist into the sail for higher winds.? The mast on our T27 will not bend much, if at all.? Since the Lightning is a pure bred racing boat it has all kinds of sail trim adjustments that are not always available on the T27.? The Lightning can go a bit faster than the T27 if tuned correctly in the right wind. I would guess that the weather helm force on our T27 is in the 30 - 50# range when at its worst.? When this is the case we always first play with the centerboard.? On downwind tacks when racing we usually bring the board up to reduce drag but if it is too far up the boat will tend to yaw and pitch more, causing the helmsman to have to over compensate.? In this case more (lower) board is called for.? On upwind legs we generally like the board at about a 45+ degree angle that helps move the center of effort astern which helps to reduce the weather helm. Another control to consider with all of this is the jib fairleads.? In high winds the blocks should be moved as far aft as possible to help pull the entire sail flatter yet allow for the maximum 'slot' between the jib and main.? This allows for some twist in the upper part of the jib as well.? In lighter winds the blocks should be moved forward to help create more belly in the jib and tension on the leech.? I am still learning about all this stuff so your mileage may vary.? There have also been many books written on sail trim but only you know how you sail your own boat. All the best. Caleb #328, Odalisque, 1967 From: Armando Morell
To: T27Owners@... Sent: Tue, 6 Nov 2007 4:45 pm Subject: Re: [T27Owners] Re: Boom position on a close reach By head stay sag I mean that while sailing I have gone Email and AIM finally together. You've gotta check out free ! |
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Thanks to all who are contributing with their
experiences and thoughts. It is great to have this type of discussions. Others who are listening (reading) please join in, I could use all the help I can get. I agree with you that we can not bend our mast much, our standing rigging is not setup for that. As far as rake I read in the handbook that the boat was nominally designed with about 11 inches of rake for most wind conditions to a minimum of 0" for about 20 mph. If it warms up in the next few days I am going out to try a few things like not using the vang upwind and pulling a little harder on the outhaul and the halyards to flatten the main and move the draft forward. thangs again armando --- calebjess@... wrote: ________________________________________________________________________ Email and AIM finally together. You've gotta check __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around |
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