Rig Tune

[RobbieB]

Through trial and error I was able to confirm the Boston tuning guide IS done using the black Pro loos guage. If you are using the loos C guage your rig is WAY too loose!

Still hoping to hear if adding the extra 2" to the headstay to get to 31' 10" gets the upwind performance as advertised. Anyone????

We sailed our first two races this past Saturday in a fleet of J24's, (very competitive fleet in Charleston SC). There were 7 boats total. It blew between 15 and gusts close to 20. We were tuned 29 on uppers and 24 lowers, (could have stood to be a little tighter). Not much backstay. Had to play the main hard on the traveler in gusts. 95% of the time a good traveler dump, (often all the way to the leeward side) kept us on our feet. We sailed using the #3 headsail and with 5 crew on the rail were more overpowered than the 24's, but could hold our own. Were 30 seconds late on the first start and got a 5th. Had a nice start on race 2 and got a 3rd.

There's also "wiggle" in the new rudder we'll need to find a way to work out. I believe our vertical position is good. The wiggle is side to side in the rudder head. Would appreciate any fix ideas.....

[SHNOOL]

Wiggle might be cheek plates? Check with Stef.

[Tac Boston]

just sail with the class headstay length. that is a good length. We have played with the longer lengths in the past and all it does is create weather helm.

You should have been a few turns harder on the rig and that would have helped. Can't help you with being late for the start

The wiggle in the rudder could be two things. 1) you need a second bolt through the aft lower part of the rudder head case/rudder area. 2) if you have that and they are all snug, take a plastic bag and tear a bit off and put it on the pintles, creating a supper thin shim.
Tac

[RobbieB]

Wiggle might be cheek plates? Check with Stef.

We have the original cheek plates in there and it was all we could do to get them in while installing the new rudder, (broke the original rudder last fall).

Guess things could have loosened up while sailing.

Tac, if we go with the second bolt that will not allow the rudder to swing up correct? Just wanted to check to make sure I'm following the suggestion correctly.

[Stef]

With the rudder it can only be a couple of things, assuming the pintles are tight on the stern.
1. Worn rudder head bearing or pivot bolt.
2. Worn gudgeon bushings.
3. Worn cheekplates at the pivot hole.

If you had a tough time installing the rudder, you may need to split the plates from the spacers and add some shim. When my head is assembled the rudder slides in snug, but I don't have to force it. I also have 6" diameter .010" thick Teflon washers to help it pivot.

[AJ Oliver]

Be aware that the rig tune also depends on whether or not you have an "old" or "new" mast.

As the Boston tuning guide says, "As mentioned previously the old mast is much softer and therefore bends much easier and . ."

I have an old mast, and another 7.9 across the dock from me has a new one. The new one seems to sail very well with little mast rake, and more rig tension.

Does that make sense?

[normbue]

Hey....Throughout this forum, I see the use of the Loos gauge to tune the rig. On both my 6.7 and the 7.9, I have always used the method in S2's set up guide, where you crank the backstay down, and tighten the uppers to it. How does this compare what the guage will do?

[RobbieB]

Hey....Throughout this forum, I see the use of the Loos gauge to tune the rig. On both my 6.7 and the 7.9, I have always used the method in S2's set up guide, where you crank the backstay down, and tighten the uppers to it. How does this compare what the guage will do?

My $ .02 is if your cranking on the backstay and then tightening the shrouds to match you'll always be tuned for heavy air. With the rig properly tuned for the wind conditions you'll find you rarely use the backstay, (just in puffs or when it's blowing 15+ and you have the #1 up or close to 20 with the #3) while going upwind as it depowers the rig.

Also easing the backstay DW allows the rig to move forward a little which is a good thing for power when the chute is up.

Lastly, with this backstay method how are you checking the mast tip to make sure it's centered in the boat and how do you check the mast to make sure it is straight and in column?

[normbue]

Sorry this response took s long, I just saw it. I usually check it side to side using the main Halyard. Then visually up the main sail track with the tight Halyard. Then I adjust the backstay just tight enough to get the adjuster to almost come to the top by it self.
I am on a lake that is 1/2 to 3/4 miles wide with hills and lots of variable gusts. My main competition is 4-5 Capri 25s. Last year it could out sail them, this year its not so good. Almost every event this year has started with winds about 10kt, and by the third race its blowing 18 to 25. And I just can't find the right setup.

[RobbieB]

Sorry this response took s long, I just saw it. I usually check it side to side using the main Halyard. Then visually up the main sail track with the tight Halyard. Then I adjust the backstay just tight enough to get the adjuster to almost come to the top by it self.
I am on a lake that is 1/2 to 3/4 miles wide with hills and lots of variable gusts. My main competition is 4-5 Capri 25s. Last year it could out sail them, this year its not so good. Almost every event this year has started with winds about 10kt, and by the third race its blowing 18 to 25. And I just can't find the right setup.

The more it blows the tighter the rig should be. It depowers the boat and helps you stay in control, flatter and faster.

[Bruce Baker]

I have a few questions about rig tuning:

1. The Doyle Boston guide has a tuning guide for an "old" mast and a "new" mast. How do I know which I have? My serial number is 430.

2. I assumed that I have an old mast, and I've used the published numbers for my Loos "B" gauge. (I bought this when I owned a Catalina 25). But I looks pretty clear that Doyle was using a different gauge. Loos C, I think. How does that translate into B?

3. There is no mention of forestay tension. With a masthead rig boat, forestay can be adjusted with the backstay. However, with fractional rigs, the backstay only bends the mast. It doesn't affect the forestay. I set my forestay to about 25 on the Loos B. Does that sound right?

Thanks,
Bruce Baker
GIT-R-DONE 430
Falls Church, VA

[USA007]

Hi Bruce,

I can't speak to your first two questions, but I can speak to the third. The headstay should be set to a dimension and not a tension. The forestay should be set to 31'8'' pin to pin, which is also the class maximum. From their you can set the tensions on the caps shrounds, once you have the rig straight of course. The cap shrouds and backstay will have a dramatic impact on the forestay tension. The backstay will impact the forestay tension on any fractional rig boat, but with the rounded mast step on the S2 7.9 the impact is quite dramatic. When you are going upwind and apply backstay tension it is very easy to see some of your headstay sag go away.

I don't know of a way to measure the headstay length without going aloft. I know in other classes they mark the headstay against the band on the mast, making the dimension much easier to check. Has anyone done this on the 7.9?

Hope this helps.
Drew - Bond Girl #007

[SailingUphill]

Prior owner to my boat left me with a 50ft tape measure... the halyards exit above the pin for the stay (on either side) that being spin, and genoa halyards.

Anyway, they added a 1.5" ring to the tape measure tape end (I guess to copmensate for that distance)... and also to allow you to use the halyard to hoist it up, and measure the pin to pin length. If I dig it out later, I'll see if I still have the EYE they made from it, so I can take a picture and measure it. Found a pict to show what I mean of the mast...

[RobbieB]

Yes. Playing the backstay does have a dramatic effect on forestay sag and is a big depower tool. However, if you put too much on it will stop the boat.

My upwind depower plan goes like this. Puff on, back stay on first then drop traveler. Puff eases pull traveler back up and let backstay off.

I play these constantly in puffy/breezy conditions to keep the boat flat as possible.