headstay vs. staysail stay tension balance

[markxengineerin]

My pacific seacraft 37 has a cutter rig with headstay and inner forestay. They are both tensioned up by the backstay turnbuckle, and the balance between them is adjusted by a turnbuckle on the staysail stay. The headstay has no turnbuckle but can be adjusted in length with toggles.



Due to the furler foils, I have no access to either headstay or staysail stay for measuring tension.

What is the proper procedure to set tensions in this system?

Currently I have the mast sticking straight up with the backstay and uppers properly tensioned, but not sure the best strategy for tensioning the lowers and the staysail stay. I understand the goal is to have a tiny amount of bend (mast top towards the stern, mast mid-point to the bow), and "appropriate" tension on all stays.

While sailing in high wind (30-40 knots), the staysail was previously vibrating quite a bit, making me think that perhaps the staysail stay was too loose. I'm not sure, but that was the result when professionally tuned. The rigger did the balance by shaking the headstay/staysail stay with the sails still wrapped up, didn't seem to have a good idea what he was looking for. The staysail stay turnbuckle was his last step, after having done the lowers, then re-checked the lowers and may have moved them a small amount.

[Bowdrie]

Trying to get the forestay real tight is a lost cause.
You accept that for "normal" sailing.
When the wind picks-up to the point where you want to roll-up the jib and just use a staysail then you add the increased tension with running backstays.
Some boats will have a 4th chainplate aft of the aft lower to use an "intermediate backstay" which attaches to the mast where the forestay is.
This allows greater forestay tension before you need the runners.

[markxengineerin]

Interesting, in that case, maybe I need to get more mechanical advantage on the running backstays. I had the windward one cranked as tight as I could pull it and was still seeing a lot of vibration in the staysail stay, especially in gusts. Am I interpreting that correctly as a symptom of a problem or is that normal for heavy weather sailing?

[Snore]

While I am not an expert on these rigs- It sounds like you had a lot of jib out and it was very loaded. Could this have pulled the mast a smidge forward, thereby unloading the inner?

Next time you see the stay sail’ luff fluttering, try rolling up the jib.

If you reef the main, roll up some jib and leave a full stay sail- it will likely need less rudder and sail faster.

[markxengineerin]

This was staysail only, no jib and no main, with 35-40 knots. I was sailing on a broad reach, 5-7 knots boat speed when not surfing, and the gusts caused a lot of visual vibration in the staysail. The jib is a 130% and would have been severely overpowered. I have 3 reef points in the main but probably need a 4th for conditions this windy and above, based on what I can tell, but I'm learning as I go.

[Snore]

Sounds like too much and unbalanced sail plan.

That wind speed should be 3rd reef and enough stay sail to balance.

[markxengineerin]

Ok thanks, I'll try that out next opportunity and see if it helps, and leave the rest of the rig basically as it was for now.

[Jim Cate]

What part of the stays'l was vibrating? If it was leech flutter, sometimes tightening the leech cord will cure it. Also, additional halyard tension will draw the draft forward and flatten the leech a bit, and that can help.

But it could be that the sail is just blown out and unable to retain shape in stronger winds no matter what you do... and then a trip to the sailmaker is in order ($$).

And BTW, we have a similar problem with our fractional Solent rig: getting both forestays really tight is had to accomplish, even with loaded up runners.

Good luck,

Jim

[GILow]

Originally Posted by markxengineerin

My pacific seacraft 37 has a cutter rig with headstay and inner forestay. They are both tensioned up by the backstay turnbuckle, and the balance between them is adjusted by a turnbuckle on the staysail stay. The headstay has no turnbuckle but can be adjusted in length with toggles.







Due to the furler foils, I have no access to either headstay or staysail stay for measuring tension.



What is the proper procedure to set tensions in this system?



Currently I have the mast sticking straight up with the backstay and uppers properly tensioned, but not sure the best strategy for tensioning the lowers and the staysail stay. I understand the goal is to have a tiny amount of bend (mast top towards the stern, mast mid-point to the bow), and "appropriate" tension on all stays.



While sailing in high wind (30-40 knots), the staysail was previously vibrating quite a bit, making me think that perhaps the staysail stay was too loose. I'm not sure, but that was the result when professionally tuned. The rigger did the balance by shaking the headstay/staysail stay with the sails still wrapped up, didn't seem to have a good idea what he was looking for. The staysail stay turnbuckle was his last step, after having done the lowers, then re-checked the lowers and may have moved them a small amount.

Edit, ignore my initial post, just found the later post with references to the running backstays.

Sounds like not enough tension on the running backstays to me.

Mine are dyneema with 4:1 blocks that lead to winches when things get nasty.

[neilpride]

Are you sure there wasn't a pair of running backstays before?

[GILow]

Regarding getting the correct initial or “resting” tension on the staysail. The approach I used, which I read somewhere, not sure where, is as follows:

Release both running backstays. Set foresail tension in the usual way. Wind on staysail tension until a very slight forward deflection is noted in the mast. (I used a laser for this, at night, worked really well.). Wind on one running backstay, moderately hard, to see if the mast pulls back into column. Adjust staysail tension until a moderately hard running backstay balances the staysail perfectly.

I have found this setting to be just right for my Swanson 42 for a couple of thousand miles now, including more damn gale force passages than I want to remember. The dyneema running backstays have very little stretch, which helps a lot. I usually don’t bother with winches on the running backstays unless apparent wind speed is over about 20 knots, but I am a heavy bloke and I can get a lot of tension with a 4:1 block.

[markxengineerin]

There are still running backs, they were just not shown in the original picture I posted, sorry for the confusion. I have never brought them to a winch, so I will be able to try that and see if it makes any difference.

The vibration I noticed was the luff as much as the leech, that's why I started thinking about the forestay tension.

The sail is brand new and pretty heavy duty, so hopefully it's me and not the sail


GILow's procedure is about what I was thinking, but, what to do about the lowers during this procedure? They also seem to influence the movement of the middle of the mast. Do you set them first? Any adjustment to them needed after the forestay/running back procedure?

[neilpride]

To me, this is the procedure if you have a turnbuckle in the staysail and forestay.
set the mast straight , no rake at all, backstay tight and forestay tight, staysail furler a bit loose, FWD and AFT lowers a bit loose to, turn the staysail screw until you see a bit of rake in the mast, just a little bit ,, tighten both lowers but don't let the tension in the lowers correct the shape of the mast, usually if you turn to much the aft lower,, now ,next time you set sail again use your runners and take notes or make marks in the screws and set accordingly.. Probably after this procedure you need to check backstay tension again, in any case , forestay proper tension its number 1, staysail proper tension nº2.

[GILow]

Originally Posted by markxengineerin

There are still running backs, they were just not shown in the original picture I posted, sorry for the confusion. I have never brought them to a winch, so I will be able to try that and see if it makes any difference.

The vibration I noticed was the luff as much as the leech, that's why I started thinking about the forestay tension.

The sail is brand new and pretty heavy duty, so hopefully it's me and not the sail


GILow's procedure is about what I was thinking, but, what to do about the lowers during this procedure? They also seem to influence the movement of the middle of the mast. Do you set them first? Any adjustment to them needed after the forestay/running back procedure?

A question about your runners: what is your current setup for tensioning them. Blocks, winch?

Some boats around our size seem to be happy to run them straight to a winch without any blocks. I looked at that but figured it was nice to be able to crank them on by hand-only in lighter air. I rarely need the winch with the 4:1 purchase.

Also, what are your running backstays made from? I’ve seen a few that were made from ropes that had more stretch than I think is ideal. Really, I think they should be either wire or dyneema if you want to keep things straight.

As for tensioning the lowers…

In my case I rigged the entire mast first as though it were not a cutter at all. I just ignored the staysail as my logic was the staysail luff tension should be perfectly balanced by the running backstays. Certainly nothing I do with the staysail appears to have any effect on the lower stay tension. But the mast on my boat is a bit of an old tree trunk.

For the record, the staysail on my boat is the most frequently used sail of all. It is the first to deploy in any wind state and the very last to be put away as the wind speed increases. The next step for me is bare polls. In strong winds, say 30 knots or more, I run only the staysail and set both running backstays to improve sail shape.

[markxengineerin]

I believe it's a 4:1, not sure about the material of the rope. The crappy looking white span between blocks is about 5' (x4=20') and the rest looks like a good quality core. Both came with the boat.


I could lead the 4:1 to a winch and make it tighter, will try at next opportunity to see if I can make a difference in staysail stability. I have not yet developed the ability to sight the mast or sail shape from the cockpit and like to avoid going up on deck in those conditions because I am alone.

The staysail is my most used (and favorite) sail as well, and I have been using it with no main in >30 knots. The boat seems overpowered w/ 3rd reef in main, but I might be erring on some other adjustments (vang? traveller?).