Fractional rig, swept shrouds... backstay function...

[agprice22]

This is a swept rig, cap shrouds, uppers, lowers, and forward shrouds. 9/32 forestay and cap shrouds. 3 different shroud sizes. Masthead has a 14" or so crane to move the backstay aft to make room for a bigger mainsail. This 28 ft boat carries over 540 sq ft of sail. With a 150 genoa.. closer to 600 sq ft. My 272... carried about 1/2 that with a 150!
Ok. Something went wrong last Saturday. After sailing in high winds Tuesday, and moving along around 13 knots(!), we determined we needed to tighten the standing rig. The leeward shrouds were sagging. I had not used a gauge, instead using feel and experience. Unfortunately, my experience is with a masthead rig with standard shrouds.
I tensioned the shrouds, equally, but again by feel. I tensioned the backstay which has a big Wichard tensioning wheel on it.
We went sailing, and after just one tack in high winds, going fast enough to scare my friend, we decided to reduce the genoa and flatten the main. I did both, but as I returned to the cockpit, I noticed my backstay... you guessed it, flailing around wildly!
I jumped to the tensioner on the stern, but I quickly realized the tensioner was not the problem. I followed the backstay up the mast, and I found the crane collapsed.
Ok... the design saved us from a dropped mast. The mast didn't move. We lowered the sails, tied off a temporary backstay, and returned to the marina.

So, talk to me about the backstay function in a swept rig... I am on a rather steep learning curve!
Luckily, I had the original masthead welded, and I purchased a new masthead from Rig-Rite. I return to the boat, on the trailer, with the mast unstepped, to install the new masthead.
I would like to know that my backstay is really only for sail shape, so it does not need much tensioning. I would like to confirm that the shrouds in this swept rig support the mast to the rear.

Thanks,
Andrew

 

[Jackdaw]

What boat?

ideally on a fractional about you set the rig tension based on wind speed, normally in four different bands.

The backstay will indeed bend the mast and create flatness to the middle of the main sale, and also tighten the forestry, reducing Sag. It also has the undesirable fact of loosening the shrouds

In big breeze down when going down wind you put the backstay back on to keep the mast stable. It's unlikely to invert but it certainly helps, and to keep the stable

 

[agprice22]

What boat?

In big breeze down when going down wind you put the backstay back on to keep the mast stable. It's unlikely to invert but it certainly helps, and to keep the stable

Hi Jackdaw.
This is a Telstar 28.
In this one sentence, you say, "put the backstay back on..." Do you mean tension it?
Also, if I am tensioning while sailing, how do I know the limits? How loose is too loose? How tight is tight enough? I sure as heck think I found out what happens when it is too tight! Or did I rip the masthead some other way? Perhaps it started by not tensioning the shrouds enough?
I am relieved I could get a new masthead. But I do not want to break another one.
Thanks!

 

[seadaddler]

In the early days Hunter used a back stay but all new B& G no longer have a backstay but I think
Selden beefed up the mast and more important they have more cross support rigging.
I think add the backstay but I think you should not adjust it like a normal rig and it is just there as backup support and not really needed or not meant to be adjustable and I am not a expert and only my 2 cents.

 

[shemandr]

When the mast crane breaks, there's too much backstay. Kidding aside, there probably was a crack or fault in it anyway. I can't see what happened from the pics.
My H356 had no backstay. The mast stayed up - albeit I would have liked a way to increase forestay tension in a breeze. My Mark 25 was fractional and had a backstay. It was a beautiful thing. But you have to adjust your idea of that backstay. It was there as running rigging. In other words it was a sail control and not standing rigging to hold the mast up. I don't know the Telstar but my guess is you could have sailed the rest of the day without that backstay, but you would have been hampered in terms of sail control. It's never a bad idea to return to the marina when gear breaks or you are unsure of the mechanics of the boat.

 

[agprice22]

Thanks, guys. I agree. I realized after attaching a temp backstay that the rig was meant to stand with shrouds. The crane has too much leverage on the masthead fitting to be meant for standing rigging. I could certainly add some support, but then I would be attempting to set it up for something for which it was not intended.

Thanks,
Andrew

 

[Jackdaw]

A boat with swept spreaders does NOT need a back-stay to stabilize that mast in normal-light conditions. We sail with ours totally off (loose) in less than 8 knots.

A wheel adjuster can really load up a backstay, maybe too much. A crane should be able to take a lot of load, so maybe your was flawed. But I would get advice from other T27 owners.

Having lowers too tight (in static mode) prohibits the mast from bending and helps the backstay load up too fast. They NEED to be slightly loose statically to allow the mast to bend. They really are designed to tighten up when the backstay some on.

 

[agprice22]

Ah. Ok. I get it. Thanks ALL! This is a different rig, and the fact that she is light and fast makes the learning curve steeper. She was going about 13 knots and flying one hull when we decided to reef the genoa and flatten the main. Waves were breaking inside the leeward outrigger. The lake can get a vicious 3 ft chop with breakers when the wind is out of the north. It has lots of fetch.