Bayfield 23 Standing Rigging Tensions

[joemccracken]

I am in the process of working to reduce the weather helm on my Bayfield 23 and figured a good place to start is properly tensioning the standing rigging. Unfortunately I haven't been able to come across anyone who knows the proper tensioning levels required for this boat.

Does anyone on here have the standing rigging stay/shroud tensions for this
boat, or at least a guideline on what the correct values to use for a boat of this size?

From what I've read 10% of the displacement value of the boat may be a good value to start with which in my case would work out to about 300lbs. Would this be for inner/outer shrouds and stays?

Thanks in advance

[bljones]

If you want to correct weather helm, get your forestay/backstay tension set, then worry about the shrouds. Someone may come along to correct me, but you probably want some mast rake to reduce weather helm.

[sailingdog]

Joe—

Where ever you got that figure...it's wrong. The rigging tension isn't based on the displacement of the boat...that's idiotic. It is based on the strength of the wire rope that is used in the rigging—to a degree. If the rigging has been upsized, then even that rule of thumb is out the window.

From the Loos website:

Forestay Tension - Fractional Rig: In a fractional rig the forestay does not go all the way to the masthead and forestay tension cannot be directly balanced by tension in the backstay. Therefore, some mast bend is generally accepted and the mainsail is cut to fit the bend. A forestay tension of at least 15% of the cable strength is desirable. However, if this results in excessive mast bend it will be necessary to back off a bit. On some fractional rigs, diamond shrouds are used to reduce mast bend.

Upper and Lower Shroud Tension - Masthead Rig: There is a simple criterion for shroud tension. The initial rigging tension should be high enough that the leeward shrouds do not go slack when sailing close-hauled in a reasonably brisk breeze. The proper value for your boat can be found by a few trial runs under sail. Once the correct tension is known, the gauge can be used to maintain the value. For many boat designs a shroud tension of 10% to 12% of the breaking strength of the cable is adequate. Thus, for 7/32", 302 / 304 1X19 stainless steel cable , the upper and lower shrouds would be set to 600 to 700 lbs. tension. On some rigs it may be desirable to carry more tension in the uppers than in the lowers.


Upper and Lower Shroud Tension - Fractional Rig: For most fractional rigs the correct shroud tension is the same as that for a masthead rig, i.e., a tension setting that will keep the leeward shrouds from going slack. However there is one exception. On certain fractional rigs , the upper and lower shrouds lead to chainplates that are aft of the mast. The spreader is swept back. For such a rig most of the forestay tension is balanced by the upper shrouds. A shroud tension of approximately 20 % of the cable strength may be required to achieve the desired forestay tension. Never exceed 25% of the cable breaking strength. (Refer to the breaking strength chart Table 1.)

Again, this is referencing the wire size and type you're using on your boat based on what the BOAT DESIGNER specified for your boat. If you're boat was originally spec'd with 5/32" rigging and a PO upgraded it to 3/16" rigging, then you will have to tension the rig based on the 5/32" breaking strength, not that of the 3/16" wire.

[CapTim]

I would suppose that the '10% of displacement' rule is some sort of shorthand, which assumes that the rigging is built to ... yeah... no, I just can't make it make sense. I'm sure it somehow does, but I'm not getting it. Certainly, hull strength figures into the max tension on the cables before the hull starts to flex, and a heavier boat [usually] means a stronger hull, so displacement figures in .. sort of.. in a rather cosmic 'everything-is-connected-in-space' sort of way...

Anyway, like that genius SailingDog said, it's really more about your wire than your hull. Mostly. It's all a balancing act, which I realize doesn't really answer your question at all.

So lets start here... what size wire is holding up your mast? I think your boat has a single set of lowers and a single set of uppers, right? If so, they are probably the same wire size, but the lowers may be smaller. Traditionally, the lowers are at a lower tension than the uppers.

Here's another interesting game.. since you have a masthead rig, you might be able to adjust the rake without significantly impacting the shroud tension, since they are mounted athwartships of the boom. Or I'm wrong about that detail, and never mind, you've got to start over with the rig tune.

Either way, tuning a rig is - like everything else on a sailboat - more about getting the right balance than getting the right absolute number.

Here's a usable rule of thumb: if your leeward shrouds don't fall slack when closehauled at the upper end of your non-reefed sailplan, you are not too loose. If the wire isn't more than about 20% of the rated breaking strength, you aren't too tight. Obviously those two things are measured quite differently, but there you go. Everything in between is gravy.

Also, when tuning, another useful 'thing' is to note that if your mast is perfectly straight in terms of side to side (fore-aft it probably won't be straight, especially if you are going to induce more or less rake to affect that weather helm) your shrouds should be at the same tension. Which is to say, if the mast is in column, your port lower should have the same tension as the starboard lower, and the port upper should be the same as the starboard upper. Also, typically, the lowers will be between 45% and 60% of the uppers.

So it's all relative, it's all a balancing act, and if somebody tells you "your shroud should be at 345.74 pounds of tension", slap them and move on. It's really not that scientific. As long as you aren't over that 20% of breaking load, and as long as the leeward shrouds don't go slack when you are close hauled, I wouldn't loose sleep. Once you get a better feel for it, you can get more specific than that... but start there.

Least, that's my thought. Rig tuning is fun!

[joemccracken]

After taking a measurement of standing rigging wire diameter (5/32"), I came up with the following values as a starting point from the Loos website. Values they suggest as a starting point based on this diameter of standing rigging is as follows:

500 lbs for the Forestay tension
350 lbs for the Shrouds tension

I'll try these values initially once my tension gauge arrives in the mail. The
upper shrouds will be set at 350 and I'll try about 200 for the lowers. After this, I'll see how she sails and keep this thread alive with the results/adjustments.

Thanks for the help guys, it's given me the confidence to tune this rig up properly, and hopefully I won't end up tightening the rig too much (or leave it too loose as I suspect it is now).

[paulk]

Weather helm is caused by having the center of effort of the sails too far aft. To cure weather helm you want to try to move the center of effort of the sails forward. There are several ways to do this. All involve adjusting the sails. As sails age, they stretch, and their bellies tend to move aft. This tends to move the center of effort aft too. Flattening the sail by pulling the downhaul, outhaul, and perhaps even the boom vang can help compensate for this. You have probably already done this. You can buy new sails, with their bellies forward, but that can get expensive.

The cheaper route is to adjust the mast to REDUCE rake. If the mast is moved forward, the whole sail is moved forward, and the center of effort HAS to move forward too. To do this, you need to shorten the forestay, regardless of the forestay tension. Unless you're racing one-design in a 40-boat National Championships, using tension gauges on a Bayfield 23 is probably overkill. From the photos I could find, it looks like the mast is stepped on deck. You can move the center of effort forward by shortening (tightening) the forestay . Try about 4 or 6 inches to start, and see what happens to your weather helm. If the mast is stepped on the keel you can also try moving the foot of the mast back (and then taking up the slack in the forestay). Let us know how it goes.

[SEMIJim]

There's a very good rig tuning guide that's a sticky right at the top of the gear and maintenance forum. You might also consider obtaining a copy of Ivar Dedekam's Sail and Rig Tuning.

Jim

[RichH]

Here's a VERY good simple method of rig tension by using only a steel tape measure and the human brain: xwww.anything-sailing.com/showthread.php/101-Rig-tuning-instructions-adjust-your-rig ..... just *remove the x* before the www and paste it into your browser

[joemccracken]

My Loos Gauge finally arrived today. Glad I picked up the pro version in which adjustments can be made with the tool hooked onto the stay. It made adjusting much quicker.

I followed the instructions that came with the tool and tensioned the forestay up to about 14% breaking strength. Rake seems minimal to nonexistent to my eyes. I was expecting the rear stay to balance out to about the same tension as the forestay but surprisingly it was quite a bit lower. Probably because of the weight of the boom, and the longer length. I'm sure I'll find the reason why as my quest to tune this rig seems to be in it's infancy.

On to the Shrouds. Definitely a balancing act with trying to get left and right lowers to equal out. The only way I actually got close to having these balanced was with a slight bend in the mast left to right. I imagine this isn't exactly a desired shape one wants in their mast so I went back to adjusting the upper shrouds a little more and then back to the lowers. All in all, all four of the shrouds are sitting around 9-10% of breaking strength.

So the biggest change in tension was in the headstay tension in which I brought the tension up to 14% from a rather loose 8%. I figure this should help with headsail shape quite a bit and hopefully will help with pointing and the weatherhelm.

Looking forward to going out and testing the old girl to see how she performs.

[CapTim]

If your mast is bent athwartships with equal tension on the shrouds, I would take a hard look at the spreaders.

It's quite important that the spreaders bisect the angle of the shrouds. which is to say that if you look at the two angles they form, one angle with the shroud that goes from the spreader to the hull, and the other angle formed between the spreader and the upper half of the shroud, both of those angles should be the same. That's a pretty cumbersome sentence, but hopefully you were able to muddle through it.

At any rate, lots of bad things happen if those angles aren't equal. And one sign that they may not be is what you've described: with the mast vertical (as viewed when laying down at the base of the mast and sighting up the sail/slug track) the port and starboard shrouds measure different tensions. If they are very slightly different, I wouldn't worry.. there is a certain amount of +/- error associated with any measuring device.

So, goal #1: get that mast perfectly straight. You'll be amazed how accurate you can get by laying right at the bottom and looking up. You'll be able to see even tiny deflections as you make adjustments, especially if you are watching the mast while a partner turns the turnbuckles. Goal #2: Spreaders bisecting the shroud angles. _then_ goal #3: equal tension on the congruent shrouds (obviously the upper and lower shrouds won't be equal.. the lowers will have much less tension).

Also, as to your backstay not having the same tension as the forestay.. that's largely because it's at a lower angle. Since the angle isn't as accute, the tension drops. That's partly why some folks like looser lifelines.. they aren't under as much tension, and so they don't fatigue or fail under a given stress.

The big rigging test, of course, is how she performs under sail. As long as those lee shrouds stay taunt and you don't have too much headstay sag, you are golden.

well done!