when to tighten/loosen adjustible backstay

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benlui

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I do some light club racing but have began to wonder if i have been getting this wrong!

When should I tighten, and loosen my adjustable backstay?
I have a sloop rig with a harken furler head sail and an adjustable backstay.
Also, how do i know when tightening it that im not tightening it too much?
Thanks in advance.........
 
benlui said:
I do some light club racing but have began to wonder if i have been getting this wrong!

When should I tighten, and loosen my adjustable backstay?
I have a sloop rig with a harken furler head sail and an adjustable backstay.
Also, how do i know when tightening it that im not tightening it too much?
Thanks in advance.........
Click to expand...

If it's masthead rigging, the backstay serves to bend the centre of the mast forward which flattens the mainsail when heading into the breeze - depowers it somewhat. About 5 degrees of bend is a general rule. Looking around marinas you see folks who have almost turned their masts into bows, and left the mast under tension when not in use. Poor practice.

If yours is a fractional rig, you can still get some bend in the mast but it's very easy to put the top section above the forestay point under intolerable strain for no gain.

But whizzing the mast in and out of tension is a lot of fun, along with fiddling with the leach lines...

Personally, I prefer sailing....

PWG
 
As well as helping to flatten the main tightening the backstay tightens up the forestay which is essential for upwind performance. The general rulle is: tighten up upwind, let it off downwind.
 
The amount of pre-bend you will apply all depends on the cut of your mainsail. If it´s a good mainsail you have onboard then you shouldn´t need so much pre-bend when going to windward - the sail should be flat enough with a small amount of pre-bend. Agree above that this pre-bend will de-power the mast for beating. Then when your running off release the backstay - power up the mast, give the mainsail some depth and hoist the party pennant ! Last to the bar buys the round ?
 
Sorry to disagree, but IMHO, the backstay adjuster has little effect on mast bend and mainsail shape on a masthead rig, which is what I think the OP has, ( Shipman 28 ). What it does do is tighten the forestay to improve genoa luff shape and hence pointing ability when beating.
The situation is quite different with a fractional rig
 
earlybird said:
Sorry to disagree, but IMHO, the backstay adjuster has little effect on mast bend and mainsail shape on a masthead rig, which is what I think the OP has, ( Shipman 28 ). What it does do is tighten the forestay to improve genoa luff shape and hence pointing ability when beating.
The situation is quite different with a fractional rig
Click to expand...

Seconded.

Tim
 
Backstay tension

The function of the backstay is to hold the skipper upright while he is supervising the crew from the back of the cockpit in a tiller steered boat. If the backstay gets too saggy the skipper will not be upright so its the job of the observant crew to tighten the backstay so the skipper stays back where he should be - that's why its called a backstay.

Don't let people fool you with their bending the mast tales - that's what the forward and rear lowers are for - those and a little steel mainsail leechline and a tight kicking strap will bend most masts sufficiently then you can very the twist in the sail by winching in the topping lift to suit.
 
earlybird said:
Sorry to disagree, but IMHO, the backstay adjuster has little effect on mast bend and mainsail shape on a masthead rig, which is what I think the OP has, ( Shipman 28 ). What it does do is tighten the forestay to improve genoa luff shape and hence pointing ability when beating.
The situation is quite different with a fractional rig
Click to expand...

Thirded

On a fractional rig it flattens the mainsail and depowers it.

Tightening the forestay on a fractional rig is done by tightening the cap shrouds which is what - on a deck-stepped mast - prevents the heads door from closing.

A tight backstay is also better for the skipper to hang on to.!!!

BTW - so I am told - downwind let the backstay off and tighten any spare jib or genoa halyards to bend/move the mast forward - if nothing else it adds another thing to tweak!!!!!!!!!!!
 
Ok, some good advice there i think. From what I am reading so, tighten for upwind performance, and let looser for down wind.
I’m gona give it a shot to see if i notice if she will point higher or not. But, i wonder would you really ever be able to tell the difference on a boat such as mine.........Am i just nit-picking or looking for other things to blame when we don’t get a good result. Of course its never the skippers fault :-) haw haw

Thanks
 
Racing

Sorry but IMHO you will never do any good until you stop trying to sail with partially rolled jib.
Get some smaller jibs and change the jibs according to the wind expected. You can keep the furler for furling and reefing if necessary but a jib sized and cut for the job is what you want. Each jib should have marked the correct sheeting position on the jib car track.
As said back stay on tight for strong winds loose for light winds.
In light winds you may find that your furling genoa jib is made too heavy /flat and a light wind jib would do much better. olewill
 
If yours is a fractional rig, you can still get some bend in the mast but it's very easy to put the top section above the forestay point under intolerable strain for no gain.

But whizzing the mast in and out of tension is a lot of fun, along with fiddling with the leach lines...

Personally, I prefer sailing....

PWG[/QUOTE]

Hi Pete I think you give a wrong impression here. On a fractional rig the mast above the spreaders should be a suitable stiffness that in bending the top you put a gentle bend in the whole mast at the same time putting an appropriate tension on the forestay. In other words backstay tension should give a very convenient and correct amount of mast bend to flatten the mainsail.
If it doesn't then you have to resort to running backstays to tension forestay without bending the mast or jumper struts on the top of the mast to stiffen the mast and limit bend at the top.
However I appreciate OP has a mast head rig. He perhaps thinks sloop rig means mast head when to me sloop means a main and a jib. it is difficut to get much mast bend in a mast head rig although more tension on the baby forestay will help. olewill
 
Agree with olewill and most of the others. If masthead, the biggest effect of backstay tension will be to tension the forestay, not bend the mast.
Tension on upwind, tension off downwind.
Less backstay in light air, more in heavy air.

Next time you are beating, don't put any backstay on. Go to the bow and look up the forestay. See how it sags a lot to leeward. Maybe 12 inches or more. Crank on the backstay (or better yet have someone do it while you are on the bow) and watch the forestay sag reduce (it will never disappear).

You'll be helping the performance of the jib.

PS - hold on.
 
backstay -v - pre bend

pre bend is a condition the mast is subjected to depending upon the cut of the mainsail, intended to allow the mainsail to obtain its designed shape (built in be sailmaker)
pre bend is obtained either by 1. forward baby stay. 2. forward lowers 3. backswept spreaders (some boats fitted with all three systems)
Rule of thumb I believe is same amount of prebend at spreaders as the thickness of mast. Easy to check by pulling main halyard down to gooseneck and looking up mast.

When the wind gets up, and of course we are talking apparent wind, so it gets up when we beat and goes down when we run, the power developed by the mainsail pulls the mailsail luff back bringing draft too far back as the mast straightens.

As the mast straightens this tightens the forestay, a bonus on masthead rig. When the wind is enough to move the draft too far back and or danger of mast bend inverting, tension up the backstay. Draft to far back in strong wind equals excessive heel and leeway.
Any boat IMHO benefits by having the mast properly tuned, fractional rig tuning is (again IMHO) a black art.
Doors not fitting is usually due to cap shrouds being overtightened.
 
I would just add to what others have said by stating (if it's a fractional rig) that the time to put some on is when you notice lots of weather helm. Tightening up at this stage (on the wind) will remove a good portion of weather helm allowing the boat to come under more control.
If that does not do it , either back off the mainsheet or think about reefing.
 
To follow jakeroyd's post - my sequence when I am starting to feel overpowered is
- flatten the sail. Outhaul, cunningham, backstay (fractional rig). Then more backstay. And yet more backstay.
- drop the traveller
- ease the main to twist off the head (got to remember to ease the vang)
- reef
 
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