Anyone know where to look for possible rig problem?

[jb2006]

We have a fractional rig - 2 sets of back swept spreaders - adjustable backstay- cap shrouds with inners from the chain plates to the mast at the lower speader and from the lower spreader to the mast at the upper spreader.

The rig was recently inspected and tensioned and seemed great. When we were out in the strong wind on Sunday the forestay appeared to be sagging to leeward excessively so we couldnt flatten the jib properly and I now notice that the lower inners don't appear to be as tight as they were.

The cap shroud tension still seems fine.

Any ideas ?

Also, we were recommended not to use the backstay with a reefed main (backstay improves forestay tension a little on our rig as well as adding mast bend) - any thoughts on this?.

 

[Twister_Ken]

Hate to say this, but if the rig set up has been lost, odds are the mast, rather than the rigging, is the problem. Has the heel shifted in the step or has it lost some pre-bend?

 

[Lakesailor]

You don't say what the boat is. Is the mast deck stepped? Is the deckhead flexing? Are the cap shrouds dominant, overcoming the balance between the rest?

 

[jb2006]

Mast is keel stepped and I didnt notice anything wrong when putting the log spinner in the other day. As I said, the cap shrouds seem fine it is the inner lowers and the forestay that seem a bit slack. Possibly with Sunday being the first time out in strong winds since the inners were tightened (always a bit slack from new I thought), they might have stretched a little.

 

[William_H]

From the description of your rig it seems like the upper spreaders with stays from the mast out to the spreader and back to the mast can only give stiffness in the sideways direction. Presumably the lower spreaders are about half way from deck to cap shroud top. Presumably also what you call cap shrouds don't actually go the the top of the mast but rather to the top of the forestay.
You have not mentioned how far aft of abeam the mast that the chain plates are situated. Presumably some distance aft.
So I am guessing this is really a pretty standard fractional rig in essence.

The tension on the backstay will both increase tension on the forestay and bend the mast. Both are desirable. But it does mean that you can't choose how much tension you have on the forestay compared to the amount of bend.

It is a bit inevitable that the lower stays wil go slack as you haul back the top of the mast. The windward lower will usually take some support of the mast from sideways load. You could tighten the lowers a bit but excess tightness will force the mast to bend only in the top half which is undesirable. You might get a little improvement in forestay tension by tensioning the forestay itself but this is iteractive to all the other stays so not too much.

So unless you have a new and unusual sagging forestay problem I would say all is normal. This is why some fractional rigs have running backstays to get backstay tension right at the top of the forestay.

The situation should not be significantly different with a reef in the main. The mast still needs to be bent but some of the bend becomes irrelevant as the main is not in that area of the mast. If the top of the main is low enough and you are really keen you could attach another backstay from just above the top of the main sail to improve forestay tension but then you probably don't sail reefed often anyway. good luck olewill

 

[Richard10002]

If this was the first time out in strong winds since the inspection and tensioning, then it is possible that nothing is wrong, and nothing has changed.

If the leeward shrouds are really slack, then perhaps they werent tensioned enough.

As far as I can tell, correct tensioning needs time on the water in reasonable winds, as well as setting up alonside or ashore.... this means that tensioning without going sailing is only half of the job..... which is normally what is done.

I think I had the same experience, but thought that slack leeward shrouds were normal. Slightly less tight is probably more normal.

There might be a set up guide produced by your mast maker?

 

[VicS]

[ QUOTE ]
There might be a set up guide produced by your mast maker?

[/ QUOTE ] But if not the Hints and Advice pdf from Selden masts might be worth studying.

It's the third item on This page

 

[oldsaltoz]

If the rig was set when out of the water it will need re setting to fine tune it.

 

[Twister_Ken]

If the problem is only visible under a press of sail, then the lower tensions just need to be taken up a bit more, symmetrically. But if the problem is now visible when parked, then something has changed. If the mast is keel stepped have any of the chocks at deck level shifted? These are often under a gaiter, so hard to see. Unlikely to be a spreader problem, or the cap shroud tension would have gone too. I don't buy the idea that the lowers may have stretched - unless they were either totally new, or grossly underspecced in the first place. Take a good look at the chain plates where the lowers are attached - any sign of movement?

 

[savageseadog]

I have a similar rig to yours, it can be difficult to get and keep forestay tension. One fairly horrible thing that can happen is that you find that the boat's structure is not strong enough. You keep tensioning the rig and the hull keeps distorting and slackening it. Hope it's not that.

 

[Lakesailor]

That's what I was hinting at, but thought that a keel stepped mast would overcome that. I suppose it's possible in any circumstances, as long as there is some give somewhere in the structure.