rig tuning with adjustable backstay

[Joetech]

I'm putting on a Roller Furler (CDI) and an adjustable backstay on my 77 C-22.
For the past few years I have used North Sail recommended tuning for this boat. I'll have to look it up to be sure, but you center the mast Port to Starboard and then adjust the lowers to a weight on the main halyard intersects the boom about 4 inches back from the mast.
With an adjustable backstay should it be less?
I read somewhere that in light air they crank on the backstay to tension the forestay to point better and that it give the main more of a pocket and roundness to increase efficiency. OK but do I still use the same settings as above?

 

[OldCat]

Generally the backstay is cranked up as the wind gets stronger*.

A loose forestay makes the head sail fuller - more power for chop or lighter winds.

A tighter forestay is needed as the wind builds to flatten both head and main sails for speed, control and pointing. The mast bends and pulls the main flatter. I think that the various versions of the "North" guide give sag numbers for the headstay - the trick being how to measure it or estimate it.

I did not see in the guides where it mentioned backstay tension for rig tuning - my guess is no tension for "at the dock tuning" - but it is a guess.

OC

*except for very light winds where you need a flatter sail to keep flow attached.

 

[Ken]

You might also want to take a look at the Bartlett sails site and read Pete's recommendations (remember they are starting points)

I ran a 28'1" forestay before I started using a furler and saw no reason to change when I installed the furler. Works just fine for me. (I'd recommend you buy a new forestay with the furler)

Remember more mast rake means more weather-helm, there's a few tricks to help with that if you decide you want a bit more rake. Like OC I don't think your going to find a number for the back-stay...

 

[CaptDon01]

Ditto on the new forestay, and make sure it has a toggle on the top as-per CDI's directions,(very important point that many forget or ignore). To install the new forestay I had to open the masthead casting. If I recall, I probably removed 1/8" from each side. I used my Dremel tool and files to accomplish. It was a pain in the butt, and took longer than I expected, but it had to be done.

Don

 

[sinnettc]

General consensus for the Capri 22 is little/no tension in the backstay when setting the uppers/lowers. Adjustable is very cool when the wind pipes up and weather helm starts to rear its ugly head. Tighten it up and things get much easier. Nice.

 

[watercolors II]

forestay

Check your present forestay, grasp it above your head, see if it will almost move 4 to 6 inches in any direction or about a foot side to side or front to back.

When sailing in moderate winds, tight on the wind and the headsail sheeted in 3 inches from the spreaders, walk forward and sight up the front of the forestay, it should be bowed forward and towards the sail. This looseness of the forestay keeps the head sail from twisting from the bottom to the top.

From the bow look at the slot between both sails and the back end of the head sail from it’s midpoint to the top, it’s much easier to see with the genoa, does it look like its pointing towards the back of the boat from the bottom to the top. If the top looks like it is starting to point out to the side starting at the spreaders and gets worst at the top then the forestay is too tight. Make sure the sheet car is at the forward end of the track, if the car is back on the track this will also cause the top of the sail to twist outward.

If the head sail has a twist in it so that the top is pointing away from the stern of the boat you’re depowering the sail by dumping wind off the top. Air is cleaner with less turbulence the higher you go from the water.

With a back stay adjuster and the forestay loose you’re pulling the top of the mast back, tightening the forestay, thus adding instant twist to the headsail and the mainsail, dumping air off the top and lowering the center of gravity with just one adjustment instead of resetting both sails, on a Catalina 22 that's about 5 degrees less heel.

 

[OldCat]

Check your present forestay, grasp it above your head, see if it will almost move 4 to 6 inches in any direction or about a foot side to side or front to back.

When sailing in moderate winds, tight on the wind and the headsail sheeted in 3 inches from the spreaders, walk forward and sight up the front of the forestay, it should be bowed forward and towards the sail. This looseness of the forestay keeps the head sail from twisting from the bottom to the top.

From the bow look at the slot between both sails and the back end of the head sail from it’s midpoint to the top, it’s much easier to see with the genoa, does it look like its pointing towards the back of the boat from the bottom to the top. If the top looks like it is starting to point out to the side starting at the spreaders and gets worst at the top then the forestay is too tight. Make sure the sheet car is at the forward end of the track, if the car is back on the track this will also cause the top of the sail to twist outward.

If the head sail has a twist in it so that the top is pointing away from the stern of the boat you’re depowering the sail by dumping wind off the top. Air is cleaner with less turbulence the higher you go from the water.

With a back stay adjuster and the forestay loose you’re pulling the top of the mast back, tightening the forestay, thus adding instant twist to the headsail and the mainsail, dumping air off the top and lowering the center of gravity with just one adjustment instead of resetting both sails, on a Catalina 22 that's about 5 degrees less heel.

Except for the very highest level of professional sailors, getting twist right, as well as all other sail trim, will require a set of well-placed tell tales on both sails. All 'numbers' for sail settings are just a guide and won't mean a thing if the tell tales indicate that the sail is stalling or near luffing. More advanced is to use tell tales to get the right amount of separation bubble along the Genoa luff for acceleration or to punch through chop.

If the OP or anyone else desires, I can give recommendations on tell tale placement and usage for beginners to intermediates. And add references to the debates and discussions for more advanced sailors.

Again - guides are guides - starting points, but actual air flow is power and speed.

OC

 

[caguy]

If the OP or anyone else desires, I can give recommendations on tell tale placement and usage for beginners to intermediates. And add references to the debates and discussions for more advanced sailors.
OC

Please do.
Thanks, Frank

 

[OldCat]

caguy -

On telltales and beginner-intermediate sail trim:

OK, lets do it, but do we put this here at the risk of hijacking the thread - or start a new one? How much info to give a beginner or intermediate could be quite the discussion. I feel the key to helping a newby is to limit information overload. It becomes a discussion of what to leave out, as much as what to put in. I am OK with the controversies that are bound to arise - but where to put the thread?

Start new thread if you wish and pls let me know where you put it if not on the C22 board.

OC

 

[caguy]

caguy -

On telltales and beginner-intermediate sail trim:

OK, lets do it, but do we put this here at the risk of hijacking the thread - or start a new one? How much info to give a beginner or intermediate could be quite the discussion. I feel the key to helping a newby is to limit information overload. It becomes a discussion of what to leave out, as much as what to put in. I am OK with the controversies that are bound to arise - but where to put the thread?

Start new thread if you wish and pls let me know where you put it if not on the C22 board.

OC

http://forums.sbo.sailboatowners.com/showthread.php?p=815177#post815177

Here you go, thanks
Frank

 

[korchinsky]

Is it 4" to 6" or 12" on the forestay? Please CLARIFY.

 

[OldCat]

Is it 4" to 6" or 12" on the forestay? Please CLARIFY.

Yes. If you could pull a straight taught line from the head to the tack of the head sail - then sag is the deepest part of the curve that the forestay makes because of the wind load on the sail.

One of many C22 tuning guides, for reference: http://austinyachtclub.net/fleets/Catalina-22/c22tuning.htm

Watercolors made a very good post - my only addition would be that without a well placed set of tell tales on both sails is that getting this right is almost impossible except for professionals.

OC

 

[rorider]

Is it 4" to 6" or 12" on the forestay? Please CLARIFY.

4" to 6 " in any ONE direction OR 1 foot total movement side-to-side
This amounts to the same thing - think of one as a radius, the other a diameter (if a circle).

 

[OldCat]

Like OC I don't think your going to find a number for the back-stay...

Did we (or I?) miss something? Specifically - the sail maker intended for some pre-bend in the mast. Does that imply that the backstay needs some tension in it when the side stays - especially the forwards - are set up? I think I may have goofed on rig setup by using my marks on the stay tensioners from last year with this year's added adjustable backstay .

OC

 

[Ken]

When I tune I only gently tighten the back stay. Not enough to change either of the lowers. Before I added the furler I too had my backstay marked at the cleat. The marks are gone now and I've not re-marked it nor do I feel it can be used as it was with the hank on sail.

Trade offs....

It's certainly a love/hate relationship I have with the furler.

 

[OldCat]

Thanks folks for the discussion on headstay tension - it confirms what I thought the tuning guides were trying to say.

OC

 

[OldCat]

When I tune I only gently tighten the back stay. Not enough to change either of the lowers. Before I added the furler I too had my backstay marked at the cleat. The marks are gone now and I've not re-marked it nor do I feel it can be used as it was with the hank on sail.

Trade offs....

It's certainly a love/hate relationship I have with the furler.

I checked my rig tune over the weekend - with measurements of forestay sag. As long as the 4-6" of headstay sag at the dock is about right, then I seem to be set up right even though I did not check it when I set up this year. I guess that is the benefit of not messing with the afts and upper shrouds when the mast comes down.

Thanks Ken and Watercolors! for the head stay sag stuff. It is in the tuning guides, but I like to hear that others are apparently doing it that way.

OC