Measuring backstay movement

[letlmt]

I want to be able to measure how much backstay I have on. I would like to mount some kind of "ruler" on the backstay with fully relaxed at 1 and then numbers coming down for a couple of feet.

The problem is that it is a split backstay and I am not sure how to mount it.

Have any of you done this? If so, can you send me a picture? If not, any thoughts on how to do this (I know some of you are pretty handy)?

 

[jssailem]

Backstay adjusters might work. They are expensive as they need to manage a lot of force. Here are a couple of images. A marker moves up and down giving you a scale of the tension on the backstay.


Or if you are using a cleat and line perhaps you could mark the line, indicating how much to pull in for different conditions.

 

[letlmt]

These are for single backstay's. The Capri 22 has a split backstay. Two legs forming an inverted V up to a block with the single backstay going up to the mast head.

The problem is that I have controls on both legs of the split. If I only had controls on one side I would put measurements on like a vang, but I can't because the pull is a combination of the 2 block and tackles and each one may be different depending on what was done with the other.

That leaves me to measure the actual movement of the backstay above the connection point.

 

[jssailem]

Have you seen this from Ulman Sail regarding backstay adjustment. (It is why I suggested the marks.)

Sailing Guide
Mainsail Trim
Backstay
The Capri 22 has a large mainsail with six different adjustments including the outhaul, cunningham, mainsheet, traveler, backstay, and boom vang. The backstay is a very critical adjustment because it affects headstay sag and the shape of the headsail. When the wind builds, the backstay needs to be tightened to flatten the mainsail and reduces the amount of headstay sag. This will also flatten the headsail. As the wind gets lighter, ease the backstay to make the mainsail more powerful and induces headstay sag, making the headsail more powerful as well. When you adjust the backstay, the mainsheet and genoa sheet will need to be adjusted at the same time.
To determine your maximum backstay adjustment, pull the backstay on until the main develops wrinkles from the middle of the mast to the clew. Place a couple of marks on the backstay for a quick visual reference. This will be your maximum backstay adjustment.
​

You have the upside down Y connector. Some sailors have upgraded this connector to put a block system in so they only pull on one side. Easier to gauge the function but it adds a bit of friction to the adjustment and weight in the rig.

 

[jssailem]

From Catalina direct.

 

[letlmt]

Correct. However, I have decided to put a block system on both sides of the Y so the part that goes through the block at the end of the backstay portion going to the mast head will move around from side to side and not always be in the same spot (depending on how much I have pulled or released from either side) like it would be if I only had a block system on one leg. If I had a block system on one leg then marking the movement would be the same as marking a boom vang.

I wanted to be able to play the backstay from either side without coming off of my spot on the rail.

 

[letlmt]

Your picture is what came standard on my boat ad I am changing it out.

I am getting a large roach main so I need a backstay kicker to get the stay around the roach and I will have a Spectra backstay so that it is more flexible. I will have block systems on both the port and starboard legs of the inverted V portion.

 

[jssailem]

My bad. I had forgotten we are not in Kansas any more. You are tricking out this Capri22.

Just thinking about your modifications. The purpose of backstay control is to pull back on the mast head and mast to tighten the forestay and induce “more” bend in the mast rig when going upwind. Pressures on the back stay are intended to be inline with the center of the boat. That is why on most split backstays configuration the connector (the inverted Y) has a single shroud to the mast head and the lower part slides on a pair of sheaves that adjust to keep the point of pull along the center line of the boat. With your setup you will be adding mast twist as well as bend when you pull in on one side of the backstay controls from the rail. At some point you will need to let go of the pressure as in downwind sailing condition and this will require you to leave the rail and adjust both controls to releive the induced twist in the mast.

Are you really getting improvements from this rig setup or just adding confusion to the process?

 

[letlmt]

Why would it twist the mast? The inverted V goes through a block at the end of the portion that goes to the mast, it will slide through the block just like it does with the block system on one side only.

My system is the same as the standard configuration but both legs are adjustable instead of one, the portion that goes to the mast is the same configuration.

No twist.

 

[jssailem]

Ok ... I have not seen that setup.
Here is a link to a discussion on backstay adjustment... https://www.sailingworld.com/getting-most-from-your-backstay

During my racing days, and they are 20 years past, I drove to manage the sailshapes with the rigging needed, yet minimize the amount of control change I had to do to get the results. This kept my head on the sails, the boat and the changing conditions. Having one backstay adjustment and a longer line if needed was my trick. The types of changes backstay adjustment impacted was in the moderate breeze conditions and a single line served the purpose as I did not need to be on the rail in moderate conditions.

In addition to the backstay I had traveller, mainsheet and helm. All were designed to be tweaked while on the rail.

 

[Scott T-Bird]

Why not use the block system on one leg only, except use a double ended line, each end leading to the respective rails with fairleads? Then you can simply mark the standing leg for the end block position.

 

[letlmt]

Good article. Thanks

 

[Scott T-Bird]

It seems like a block system on both legs might be over-complicated, but perhaps you've seen it done and it looks good to you. One way I might think about it is to mark the control lines where they exit the cleats. That way, you might set the lines at predetermined positions, but always have an idea about where the lines are respective to the relaxed position on both sides. You might have to do math in your head, but it should be simple enough.

 

[delling3]

I had this set up on my Pearson Flyer. The Flyer is very beamy, and it was a big help to be able to adjust the backstay from the rail. I had mine run forward to the middle of the cockpit, giving the main trimmer and helmsman equal access to the backstay, although it primarily was adjusted by the helmsman.

On the Capri, I have not yet felt the need for this. The Capri rig is designed in such a way that the boat does not need the backstay to support the mast, only to fine tune the mast bend and headstay sag. I also have a spectra backstay and kicker installed. My rig is tuned such that there is no backstay tension in light air, and I simply increase to balance the rig/helm as the weather builds.

 

[Davidasailor26]

I believe what you're describing is a setup like this -

You pull one of the green lines which tightens the red line, tightening the backstay, correct?

I've been on boats that used this arrangement but we always just estimated the tension. I suppose you could probably mark the tails od both green lines with numbers, basically as Scott suggests, and then your total tension is the sum of the two numbers.

 

[letlmt]

Yes, that is exactly the set up.

I was thinking of taking 2 sticks(battens) attached at the bottom where the legs attach to the transom and forming an inverted V with a yardstick attached to the point and going over the portion of the backstay going to the mast head, forming an inverted Y, with a ring. The yardstick would be positioned so that when the backstay is fully relaxed the 1 on the yardstick would be at the block and as I pull the backstay I would be able to see how far it has moved.

My fear is that this will be flimsy

 

[Scott T-Bird]

Does "Rube Goldberg" ring a bell?

 

[Davidasailor26]

I was thinking of taking 2 sticks(battens) attached at the bottom where the legs attach to the transom and forming an inverted V with a yardstick attached to the point and going over the portion of the backstay going to the mast head, forming an inverted Y, with a ring. The yardstick would be positioned so that when the backstay is fully relaxed the 1 on the yardstick would be at the block and as I pull the backstay I would be able to see how far it has moved.

That might work, although you'd be measuring the output side of the blocks rather than the input, so it would be much harder to perceive the changes you're making. For example, you pull on 12" of stay line, but because of the blocks and added tension/stretch you may only move the point of the split down 1". Now you're driving in a race trying to look up at your bouncing yardstick and perceive whether the split is at inch 18 or 19. Could be a challenge. Then if you can't tell and think it's at inch 19, when it's really 18, you pull on another 12" of stay, and repeat.

 

[letlmt]

I agree it is Rube Goldberg which is why I am asking for suggestions on a better way.

I would be measuring actual backstay movement because the inverted Y would be fixed and the backstay, the vertical portion of the backstay system would move relative to my measuring device.

 

[Will Gilmore]

if you flip the tackle around, the cam at the top, you can bring the adjustment line with you when changing tacks. Then you could mount the other block on either side of your transom.

-Will (Dragonfly)