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Fore Stay Sag?

PostPosted: Thu Oct 23, 2008 9:52 am
by Pterobyte
The previous owner suggested a ton of fore stay sag. My sailmaker does not agree however. This is what he says.

I am not sold on this extreme headstay sag idea. Maybe a fair amount in light and lumpy but once you have some power having it straighter will allow you to point better. This is what I would change: a touch of genoa halyard on - just enough to get rid of the horizontal wrinkles, definately some backstay - headstay is way too soft, Then you can move cars forward on the genoa and close up the twist some and sheet in on the main. You would have been higher and flatter(and probably faster) with above adjustments.


He has sailed on the boat and we are discussing the topic. I recently sent him this which prompted the above response.
Image
here

We actually have a fair amount of backstay on in this picture. What are you guys doing with this?

I will be measuring my fore stay this weekend when I take the mast down to move it to Hampton for the Frostbyte series. I was told it should be right at 40'. Step is all the way forward, the plate has an inch or two added to it as well. Mast is blocked all the forward at the deck for prebend. We have no weather helm.

PostPosted: Thu Oct 23, 2008 1:59 pm
by admin
Cant really tell from the shot, but it looks like it's maybe 8-10? In which case I agree with your sailmaker. It looks like you have very little backstay on in the photo and significant headstay sag. I agree with what the PO said, headstag sag is king, BUT only up to about 8...above 8 we'd put on some backstay and the boat was usually powered up enough to go for altitude.

So, as far as the Previous Owner is concerned, I cant believe he wouldn't mention a wind range for the comment about sag...uprange on the #1 (10-12 kn) sag is s-l-o-w....at least in our experience.

PostPosted: Mon Oct 27, 2008 8:33 am
by Motorboat!!
We actually sailed with the sailmaker this weekend, with our new sails, and he really taught me some stuff:
-I never imagined using to much backstay. Even in light air and no chop, we had the backstay on really tight, like what I would expect it to be in 10-15 knots.
-The mainsheet was eased a little to give some twist at the top, much like you would trim a fractional boat.
2 first place finishes, and I guess he was right

Good feedback

PostPosted: Mon Oct 27, 2008 12:43 pm
by Pterobyte
Thanks, this is really good feedback.

Well what I am gather from most, not all, of this is that I should probably fall back on what I know and what has works for me and the boat. This is not really great mystery about these boats.

I live by the 80 20 rule. Right now I think our boat speed and trim is in the 80% zone but our crew work is in the 60% zone. That means focusing on crew work will deliver more bang for the buck then getting worked up over tune.

Thanks!

Re: Fore Stay Sag?

PostPosted: Fri Jan 30, 2009 2:51 pm
by musicman
Head stay sag is a HUGE issue on these boats. In general you want to sail with as straight a headstay as possible (no more than 4-5" of sag) Sails should be designed to fit this...
The ideal headstay length pin to pin is 40.5' This requires toggles to be added. And will also require you to make adjustemnts to the backstay system to allow enough range. I have exact strop lengths for our backstay to work with a 40.5" headstay (this will save you tons of time!!!).
An often overlooked issue that plays a HUGE roll in headstay tension is the strength of the boat itself. We did quite a bit of structural upgrades on "Remedy" to improve this. By stopping movement in the hull (mast step sagging, bulkeads compressing etc.) you will turn more of the backstay tension into headstay tension.
We also have our checkstays led to the transom and up to the cabin top winches. Our mains are designed with VERY little luff curve & require quite a bit of check. The high check tension combined with backstay is key to a straight headstay as well.
Hope that helps.
John Fries

Re: Fore Stay Sag?

PostPosted: Fri Jan 30, 2009 5:57 pm
by Pterobyte
This is huge help. I love having numbers. Check out the pictures of our keel box. I am adding one more rib and taking the reinforcing the forward one to go all the way to the bottom.

Re: Fore Stay Sag?

PostPosted: Thu Oct 18, 2012 11:39 am
by Motorboat!!
John
What line and diameter did you use on your backstay bridle?