Bavaria 36 Backstay Adjuster

[Guest]

Having read the review of the new Bavaria 36 in YM I was startled to see the reference to the backstay adjuster. The article said the test boat had been upgraded to 48:1 and the standard boat had 24:1.

I think my Bavaria 34 has a 12:1 and I have never pulled it more than hand tight - even so this has a significant effect on sail shape.

So my question is how much can you safely bend a mast? - would I be safe to winch my backstay adjuster in when the wind gets up?!

Steve

 

[Chris_Stannard]

It sounds as though you have a pulley system, since you refer to 12 to 1. My own thought would be that under no circumstances should you winch it as this would multipy the effect of your tensioner to much greater than 48 to 1. The effect of pulling to much pressure on your mast in manifold, you do not only bend the mast backwards, you try to pull the stern towards the top of the mast. Overpressured this can make the boat banana shaped, witness some Sigma 33s that have raced extensively. It also increases the pressure on the heel fitting of your mast.

In my boat, which has a tensioner wound on by a winch handle, there is a procedure to follow which sets the maximum the rig can be tensioned, and the amount it must be let off, to relax everything when not sailing. This procedure should be set out in the builders handbook that came with the boat. In your case this should consist of a reading of either how much rope you can take in from slack to maximum working tension, so you can mark the working part of your tackle, or a reading of how far you can pull the block at the upper end of the tackle down. This also will allow you to mark the working part of the tackle.

If you do not have the builders handbook, or it does not give this figure,ask Bavaria, they designed the boat and should be able to provide it.

Incidentally to much tension and bend in your mast can make the luff of the main baggy and inefficient. The principal reason for bending the mast is to reduce the fall off in the forestay to enable you to sail closer to the wind. However, and particularly offshore if you cruise, pulling the forestay tight reduces the power from the sail, so that you tend to lose more speed when you hit a wave. This is why offshore genoas tend to be cut less flat than round the cans equivalents. In my view most people tend to sail with their forestay far too tight and lose speed in tryintg to point higher. I think you should not be winding full tension on until you are almost at the point of reefing the main. The cruising alternative is to set a mid point and leave it at that, but this will not do for racing.

When you come on to a reach you should not need a lot of tension on the backstay though a little helps, and downwind you want to let the mast go forward as much as possible for best performance.

Hope this helps



Chris Stannard

 

[Guest]

Nope nothing in the manual - and to be honest I've never considered using a winch until I read the review

I presume the Sigmas must be masthead rigged as the effect of tightening the backstay would be as you describe.

The Bavarias have 7/8 fractional rigs with swept back spreaders, so tightening the
backstay actually pushes the lower mast forward flattening the main but has
little effect on the forestay tension. (Swings and roundabouts really!)

In the article the new Bav 36 is praised for having a powerful backstay adjuster
and a bendy mast. In the full page picture the rope adjuster can be seen tightened
almost to its limit, so I was curious as to whether I was being too timid in my use of my own adjuster.

Steve

 

[Chris_Stannard]

Sigmas are fractionally rigged with the exception of the Sigma 362. I had thought the Bavaria was mast head rigged so excuse my ignorance. Having a bendy mast is not necessarily the whole story. Firstly, even with a fractional rig tensioning the backstay will move the mast head backwards as well as bowing it. This will have the effect of tightening the forestay, although it will not be so pronounced as a masthead rig.
There are other ways to flatten the main, and genoa. Most people have their halyard to tight and this flattens the sail in light winds. Similarly the foot tension has a pronounced affect on the lower third of the main. Lastly of course as the the wind force increases the traveller needs to move to leeward thereby increasing the leech tension. It really is a question of altering things to see what works best, but it might be worth reading a book on tuning to find out how to get the best out of your rig.
As a general rule start with tensions lower than you would normally use, for example the genoa halyard whould be tightened until the creases just disappear and then slacked back an inch. I also find that on the whole the boat goes best if the genoa is sheeted in until it just touches the guard wires, but you will have to find your own measure.
If you are worried about your backstay tension do ask Bavaaria, they ought to know and should give you an anwer.

Have a good season.

Chris

Chris Stannard

 

[Jeremy_W]

If the backstay is set up as adjustable you should be able to pull it until the two blocks are touching. Certainly that's how the Sigma 33 is built. Whether you will want to is another matter and Chris Stannard's observations are pertinent.

I'm not in the business of drumming up business for sailing schools, but in this situation you could probably learn a lot very fast from a weekend's "own-boat" tuition from a race trainer.

 

[Guest]

Thanks for all for the comments, and I will try and ask Bavaria. To be honest I thought I had a reasonable grasp of sail shaping - I use the adjuster a lot, but the comment in the review makes me question whether I am even in the right ballpark in terms of maximum backstay tension - if so it will be nice to be able to delay reefing a little longer.

Perhaps I should have titled the post how much can I bend a mast before it snaps?!

Steve

 

[Twister_Ken]

Used to sail on a Swan 411 which had a hydraulic b/s adjuster. We'd often pump it up to 5000 lbs pressure without doing any apparent harm. When you let it off, after turning the uphill corner, the rig would relax like an junkie taking the first hit of the day.

 

[Guest]

masts and junkies

I love the imagery