Back stay tension 1990 Westerly Merlin 28

[LORDNELSON]

I purchased this Merlin 28 in August 2008. The mast was un-stepped for the first time in my ownership last week. In order to remove the mast it was, of course, necessary to slacken off the rigging, this was done without problem until we reached the split back-stay; the rigging screws were undone to the point where they were almost apart but there was still a lot of tension in the back-stay and it appeared unwise to completely unscrew the rigging screws without precautions. We put a rolling hitch on the back-stay led it through a block to a winch and put tension on the rope and then undid the rigging screw - which parted very suddenly but was kept under control by the tensioned rope. When re-stepping the mast four days later the back stay was, of course, too short to connect with the rigging screw/deck fitting. We attached the main halyard to the back-stay via a block and winch and strained the mast back until it was possible to connect up the rigging screw. Is this normal for the Merlin 28? It seems a bit odd to have so much tension in the back-stay that one has to control it by ropes to undo it, when all rigging screws have been slackened off, but this is the first fractional rigged/bendy mast boat I have owned. When we had finished re-stepping the mast and screwed the rigging screws back to their original settings there was about 1.8% bend in the mast (the Merlin is, of course, a fractional rig with one set of swept spreaders, single aft lower shrouds and deck stepped). I would be most grateful for any comments.

 

[tabernacleman]

I would have thought that there should be sufficient length of backstay so that you could slacken of on a run, you would of course need some device for tensioning/slackening the backstay. I would be inclined to fit a shackle or two onto the backstay, out of interest is there a bottle screw on the forstay, or stainless strap with adjuster holes to alter the rake.
On my Seawolf 30 I had a 16 to 1 tensioner attached to the end of the backstay bridle , quite easy to make up and you could use your existing stay, terminate in a pulley and use flexible 7 x 19 wire for the short length going round the pulley to the tensioner.

 

[William_H]

I agree with Tabernacle man. A fractional rig usually has cap shrouds sufficiently aft of abeam the mast that they will support the mast in the aft direction. Such that in light winds you usually have no tension on the backstay and the mast is straight. (max camber in the mainsail)
You then have a tensioning system so that the backstay can be tensioned to give a decent mast bend middle forward which reduces the mainsail camber for stronger winds.

This is most often achieved by fitting a pulley with bronze sheave at the bottom of the backstay itself and having the bridle fixed on one side and with a 4 purchase to a 2 purchase tackle on the other side. My boat is smaller and has just a 4 purchase onto the bridle.(giving 8 altogether)

I don't know the Merlin so perhaps the owners association can tell you if this is normal or just compare your rig with similar rigs.
The adjustable backstay along with outhaul tension. vang and halyard tension can give a lot of flattening to a mainsail in stronger winnds making it faster and easier to dump the pressure. good luck olewill

 

[Aeolus_IV]

Been looking at some pictures of a friends Merlin 29, not having a picture of '28. Its hard to be confident, but this boats back stay splits at about head height and continues down to the aft quarters. There wouldn't seem to be any means of adjusting the rig whilst sailing.

I would strongly suggest that your back stay is too short. But what to do about it?

The rig should not fall down if you disconnect the back stay while moored up somewhere, the swept back spreaders, being behind the mast exert some aft leverage on the mast. However, judicious use of the main halyard, some lines and an aft cleat or two will provide the assurance that it will not move far anyway.

Having done this you are free to "re-work" the bottom end of the back stay.

I would consider changing the set up to provide the ability to modify the back stay tension under sail. This will work wonders with a fractional rig, and will allow you un-tension the rig when not sailing. Better for the rig and the boat. Obviously, the ability to completely slacken off the back stay will make unstepping the mast much easier in future too.

Regards,
Jeff.

 

[VicS]

[ QUOTE ]
I would be inclined to fit a shackle or two onto the backstay

[/ QUOTE ] Not shackles. Toggles are the correct things to use !

 

[ff_nick]

Just a thought - could it be that the forestay was too short, that somebody had previously shortened it when fitting a new furler, say? Was the mast vertical?

 

[LORDNELSON]

Many thanks to all who replied to my post. Have spoken to the rigger who re-newed the rigging in 2005. He says when releasing the back stay, do this before slackening off the shrouds. The effect of a fractional rig with a bendy mast and aft swept spreaders if you slacken the shrouds first is to allow the top of the mast to move forward and hence place tension on the back stay. He also says that if I want a slightly longer back stay to insert a single toggle with 10mm pin diameter at the top of the split back stay. Sounds reasonable, will check this weekend!

 

[Black_jack]

I agree with your rigger. On a fractional rig the cap shrouds act through swept spreaders to pre- bend the mast aft, so, when removing the mast the backstay will be put under tension if the cap shrouds are released first. Or, when raising the mast, if you try to attatch the backstay before tensioning the cap shrouds the backstay may well appear short.

In my experience, it is not uncommon for the backstay to need persuasion to fit. The most important question is does your rig set up match your sail set up ?