Ok guys Im coming to you for any information you can give me on this. This past weekend I sat aboard Legacy in an inland body of water (at anchor /love my Rocna) to ride out tropical storm Cristobal. I live on the Mississippi coast and we had quite a bit of wind. Highest gust measurements on my instruments read at 55kts. During the larger gusts my mast (both main and mizzen) would start vibrating pretty violently. Enough to where I started get pretty concerned about losing the rig if a stay failed.
Now Ive noticed what I thought was minor pumping of the mast in around 20-25 kts at the marina. I didn't think much of it at the time, but this really has me concerned now. All of my standing rigging seems reasonably snug and somewhat equal, from just feeling from hand. I know this isn't the best way to judge it (LOL). Im not completely sure it was the mast pumping and not the forestay vibrating in the wind.
A couple of other boats that were anchored with me (2 slightly larger Island Packets) didn't get this vibration. I have access to a Loos gauge now and would like to set the stays to the proper tension and see if this stops my issue. One other item I need to throw in with this, is that my boat is set up with an adjustable backstay. I have no idea what I need to have this set as. I want to get rid of the adjuster as Im not a racer and really dont want another failure point. So If i can set the fore /aft stay to the correct tension, i will leave it set.
Please can anyone tell me what my tension settings should be for the main and mizzen mast stays. Also any more insight you can give me on this issue would be greatly appreciated!
I should add that is wasn't a high frequency vibration but a lower, more like a pump (3-4 cycles per second). Hard enough to shake the whole boat...
The gauge is a great start. You will need to measure your rigging to determine the setting. For instance, I went up a size when replacing standard rigging. Or it could be metric or...
Forestay is impossible to measure if you have a furler. Add a split backstay and it makes it tough to determine backstay tension. Look at the bow in the foil while sailing to see if the head is tight enough?
I never paid to have anyone do anything on my boat. A rigger is the exception. A good one rigged for my weather helm complaint and went a long way in reducing it.
A bad one left the cotter pins out of the triatic and it backed off and separated while on passage to the Tuamotus. Damn near lost the mizzen mast. If we hadn't been on a downwind we would have.
Finding that good rigger in my area is the tough part. We have one, but ive heard numerous complaints about him.
How much bow should I have in the forestay when sailing? I understand that is kind of a tough one to answer as its dependent on how much weather helm you re getting. From what I understand I should tighten the forestay for upwind sailing, and loosen it for downwind. What im looking for is a happy medium where I dont have to make that adjustment.
SV Journey is right on correct. To correctly tension the standing rigging you must know the wire diameters to the 1/32nd of an inch. You must know the diameters to aquire the correct Loos gauge. One rule of thumb is to set the tension to 25% of the wires breaking strength. You will have to consult wire table to determine the breaking strength and go from there. That would offer you a good baseline.
Another factor could be the tension on the rod between your mast base and your mast collar. Is that under tension? If not your deck could be moving up and your hull side moving in allowing reduced tension in the shrouds.
Also keep in mind there is a big difference between a tensioned rig and a properly tuned rig. A tuned rig means the mast shape is proper under load and your headstay tension is correct for your furler to operate properly.
Is your backstay adjuster hydraulic? If not there should be no concern of a failure point. Even a hydraulic adjuster reaches a positive stop.
Dale
Obersheimers
Maruska
The backstay tensioner is one item I plan on removing when I replace the standing rigging in the future. At the moment it uses two fiddle blocks with a cam cleat on one. This pulls two blocks down the split backstay that are joined via a ring between the two. So when you tighten the fiddle blocks it pulls the split backstay together and tightens the back stay. I really dont like this setup as it seems like a failure point.
Im starting to also get the feeling from talking to others, that what I may have thought was the mast pumping was possibly due to the forestay with roller furling getting vibration from the wind. If it wasnt tightened enough, I can see where the wind might cause the vibration. I really wish I had went outside when this was happening, but was a bit concerned about the rig coming down on me. Let me tell you it was shaking enough to really spook me. I could SEE the mizzen mast out the hatch vibrate due to this.
The rod between my mast base and the collar isnt overly tight, but its not loose either. Compared to the tension of that rod ive felt on other boats, it seems about tthe same.
I will measure my rigging and get a loos guage, and at least make sure I have equal tension and the correct amount.