On the wind performance

Fatboyfinn · Post by **Fatboyfinn** » Mon Aug 10, 2009 6:02 am

Any advice would be gratefully received on getting my Mk 2 to go better on the wind. Racing with a F2/3 the other day we were making 5/6 knots but only managing 130 degree
tacking angles. I'm setting the genoa outside the shrouds with sheets brought back to the track by the cockpit, is that normal? Would it be better to roll the the genoa in a bit
so that the leach fits in front of the spreaders so the sheeting angle can be narrower - inside the shrouds? Is the genoa too big? Or maybe I need a concave leach. Also, the genoa needs to be walked through as it gets wrapped around the "baby stay". Apart from that I love the boat, great off wind performance and every thing else that goes with multihull sailing.
We were way ahead at the start of the race with a broad reach - wonderful - then the wind backed so we were hard on the wind and damn it they all slowly caught up. May be the trouble is too much dinghy racing with less than 90 degree tacking angle - spoilt.

Andy
Telstar 127 and Finn 563

trashpad · Post by **trashpad** » Mon Aug 10, 2009 11:46 am

Did you have the main on center line? With the T28 I get the best VMG with a fairly flat main and use the traveler to pull it up to center. After that I haul in the jib tight till just before I start to back wind the main. Depending on the wind, you can also move the crew forward to pull the back of the boat up. From there on out watch the boat speed and sail to the jibs tell-tails

Dan · Post by **Dan** » Tue Aug 11, 2009 4:23 am

Given the age of the boat, I would have to ask what kind of shape are the sails in?

If the sails are blown out, which is often the case with older sails, then your ability to point and sail well upwind will be compromised. Also, furling the sail on a roller furling setup will generally make the sail shape worse, and not improve your ability to point. Most roller furling systems don’t really work well once you’ve furled up about 30% of the sail, though newer furling systems tend to be a bit better. Adding a rope or foam luff to the sail can help improve the shape of the furled sail as well.

Post by **Ron** » Tue Aug 11, 2009 5:00 am

Andy -

There are a number of things that will slow you down and hurt your ability to sail into the wind. As Dan pointed out, the general shape of the sails and furling a head sail are near the top of the list. There's also rig tension, condition of hull, sheet angles, having the center board not all of the way down, motor dragging in the water, gusty and variable winds with a light boat, sea state (chop, etc.), too much weight on the boat, sail plan not balanced, and many others. You probably know all of this already. One other thought (which you probably know as well) - multihulls lose some of their advantages going close into the wind or running from it, and taking his line in either direction may not be the best thing to do if you want to beat him there. I can tack at about 90 degrees, but I'm better off with the 130 (or more) that you mentioned. Since he caught you with your boat at 65 degrees (true) to the wind, I'd look to fine tune everything else.

ajaxpc · Post by **ajaxpc** » Wed Aug 12, 2009 12:29 am

I've got a Mk II - you can see my Blog on it at:

http://telstartrina.blogspot.com/

(1) Tension your rigging properly - this may require attention to the mast support, which can distort.

(2) I've had new sails made, and I got a smaller jib so that I can set it to the inside tracks. I lose a bit of power off wind, but the boat points better and the sail is *much* easier to handle (no more snagging on the baby stay ...). I'll save up for a genniker for off wind sailing.

(3) Going to windward in a chop is sometimes a bit soul destroying - the boat hobby horses a bit a throws wind out of the sails. You can settle the main a bit by rigging preventer in these conditions, but you really just have to bear away ...

(4) You're probably not going to work miracles. I can get the boat tacking through about 110-120 degrees true in good conditions (checking the GPS course over the ground) when I'm sailing with the wind just about on the arms of the masthead indicator, and definitely into the 'close hauled' area of the electronic display. I can pinch a bit higher, but the boat slows down a *lot*.

I think extending the stern (as some owners have done) helps with both the hobby-horsing and the windward ability. I'd like to hear from anyone who has done this.

Regards,

Fatboyfinn · Post by **Fatboyfinn** » Thu Sep 10, 2009 9:56 am

Thank you all for your advice and comments. I recently managed to get hold of a secondhand Jib/Genoa - in good nick - that will set on the inner tracks.
Took her out in a good F3 and seem to be getting 100 degree angles and also an ease of tacking that was a problem before.
I also managed to pull up the standing rigging - taking the slack out of the leeward shrouds. On getting back to my mooring,
checked the tension and mast straightness and found 200kg load on the cap shrouds
- does that seem ok. Bye the way - made my own gauge, if a little cumbesome, its a board with two bolts 40" apart and an arrangement to pull
the wire over by 0.5" thereby multipling the force needed to displace it by 20. ie 10kg = 200kg.

Good sailing

Andy

luigisante · Post by **luigisante** » Thu Sep 10, 2009 11:30 am

My experience on multihulls is that rig tuning can have a significant effect on up-wind performance. Glad to see you're coming to grips with your issues.

Lou Giansante

ajaxpc · Post by **ajaxpc** » Thu Sep 10, 2009 12:27 pm

I bought a book on rig tuning - it's on the boat, so I can't remember what it's called ...

Anyhow: following the instructions in the book, I ended up with cap shroud loads of nearer 500 than 200, and a backstay tension in the order of 800. The forestay is meant to be about 1000, I think, which sounds downright scary. I can't check it directly, though, because of the roller furling gear.

Before trying these sorts of loads, though, you should reinforce the mast step - I had to do this.

One the wind in a blow, the leeward shrouds go just slack, and no more, which is about right I think?

Post by **Ron** » Thu Sep 10, 2009 2:19 pm

I've always tuned rigs based on the breaking point of the individual wires, what sort of loads you want on them, and what you want to do with the inclination and shape of the mast. Breaking strength is based on the wires composition and diameter. When tuning a rig, you normally adjust the loads to be around 10 to 18 percent of the wires failure. Going any higher on this static measurement will only cause you trouble when the rig is fully loaded in high winds. The difference between, say 14% and 100% is your insurance that it can take the higher load. 18% is a little on the high side for a cruising boat, so I'd want to be a little lower than that.

I'm not sure, and am curious about, what you mean by cap shroud loads of 500, 200 and 1,000. What is the measurement over there? Is it pounds of force? Assuming that you've got 1/4 inch stays or shrouds, 15% of the breaking strength would be around 1200 pounds. 200 pounds on a 1/4 inch wire would be extremely low - maybe 2 or 3 percent of breaking strength. Incidentally, Performance Cruising recommends about 600 pounds of tension on the "cap" ("upper" in Americanese) shrouds on the Telstar 28's 1/4 inch cap shround, which in theory would be about 7 percent of the wires breaking strength. But this boat has solid tube lower shrouds which are used to rotate the mast when bringing it up or down. Pulling the mast down towards the cabin top may cause some trouble in the folding process.

If you're talking pounds of force, 500 on the cap shrouds is reasonable and 1,000 on the head stay sounds about right (assuming it's at least 1/4 inch wire). I'd probably want to go a little higher. As far as the cabin top being able to take that load, you're the expert. If it doesn't have a compression post now, it will probably need it.

As you mentioned, the final test is that the leeward shrouds should go slightly slack in medium air (say 12 to 15 knots). Very slack means that you've got more work to do.

ajaxpc · Post by **ajaxpc** » Sat Sep 12, 2009 9:24 am

Ron -

These are useful statistics. 1/4 inch must be about 6mm, or slightly more. And now you have me worried:

My shrouds are 5mm and the backstay and forestay are 6mm, from memory.

The loads I gave are in kgs, which makes 800 on the backstay come out as about 1750 lbs, which is high based on your numbers. I'll check this the next time I'm up (next weekend). And my unknown forestay tension must be higher, since the angle between the forestay and the mast is less than the angle between the backstay and the mast. Is that right?

I also haven't retensioned the rig since the start of the season, and the last time I was out I noticed that the lee shrouds were a bit slacker than I remember them being in May. Either something has stretched (unlikely?) or my memory is a bit unreliable...

The Mk11 rig is very traditional: forestay, inner forestay (baby stay), two pairs of lower shrouds, cap shrouds, backstay.

The compression post in the MkII is offset to port (it's on the forward end of the CB case), and this gave me some problems two years or so ago. I had to reinforce it.

See http://telstartrina.blogspot.com/search?q=mast+step for details.

International Telstar Owners Association