Benefits of an adjustable backstay on a mast head rig

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BlueSkyNick

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Are there any?

I am no expert (ie know very little) about mast bend, but believe that the top can be pulled back by a back stay tensioner, if the forestay is fixed to the mast lower down, to change the shape of the mainsail.

With a mast head rig, the backstay tension can change the rake to some extent but only as allowed by the forestay - which is a fixed length.

So in practice, what is the benefit of an adjustable backstay on a performance cruising boat?
 
It will really just tension the forestay. So when it is blowing and you are going upwind, crank on the backstay to reduce the forestay sag. You should be able to point higher.
In lighter airs (upwind) ease it off to give a bit more shape to the genoa.
 
Its been on my list for a while.
Only when it is blowing old boots will it help. But thats when I need help.

With a split backstay, I am just havinga couple of blocks with a mainsheet arrangement leading down one side. Cheap and effective (because I got all the bits from a jumble:D).
 
sailorman said:
also with the mast hd pulled aft the main will be flattened mid chord
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That will depend on how the rest of the mast is rigged, and in any event the effect will be negligible if the forestay goes to the masthead.

I would agree with you on a fractionally rigged boat. On mine, the backstay is one of the most important controls upwind.
 
MoodyNick said:
bbg, that makes a lot of sense - thanks for your prompt and succint reply.
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What he said, and if it's been blowing hard and we've had lots of tension on I tend to let it off a few turns when I leave the boat.

SWMBO once took her parents out on our boat when I was away and came back moaning
"She just wouldn't go upwind"
"Did you tighten the backstay adjuster?"
Then it went very quiet at the end of the phone!

Don't forget to tighten the genoa halyard too as the wind strengthens.
 
MoodyNick said:
Are there any?

I am no expert (ie know very little) about mast bend, but believe that the top can be pulled back by a back stay tensioner, if the forestay is fixed to the mast lower down, to change the shape of the mainsail.

With a mast head rig, the backstay tension can change the rake to some extent but only as allowed by the forestay - which is a fixed length.

So in practice, what is the benefit of an adjustable backstay on a performance cruising boat?
Click to expand...

It's more complex than that. Firstly the forestay, and any other part of the rig is not a fixed length, it will stretch as force is applied. Secondly the effect of applying backstay tension will be to bend the mast, yes, even on a masthead rig. The forces applied to the top of the mast will bend the mast by compressing it. Because of the mainsail kicker etc the bend will be forward which will flatten the main.
 
bbg said:
That will depend on how the rest of the mast is rigged, and in any event the effect will be negligible if the forestay goes to the masthead.
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I regularly sail 2 masthead rigged boats and can assure you that backstay tension gives significant mast bend on both of them. One has a babystay, and the other has two forward lowers - both are set up with slight pre-bend.
Yes a fractional rig will show more bend with backstay tension than a masthead rig, but it is not negligible on masthead.
 
Ideally you want a baby stay that is adjustable. A times 4 purchase should be fine. Off the wind you throw it off then when coming on the wind, crank up the baby stay to pull the middle of the mast forward, then crank on the back stay which will allow you almost as much shape adjustment as on a fractional. Also the baby stay can be thrown off when using a spinnaker pole.

All this will give you a huge performance increase over an unadjustable setup.
 
From all the above, all of which is true, one might be wondering why one shouldn't tension the backstay hard and leave it, like the other rigging, but if your boat is anything like my old Mystere, which was a typical early 70s design, if you leave the backstay tight when running off the wind, especially with a spinnaker, steering can be quite challenging and easing the head of the mast forward slightly makes a big difference and in our case made the boat quite docile.
 
Please may I ask a question that is perhaps stupid, but is a serious question as far as I am concerned?

I often read of the adjustments you refer to above, and wonder what effect they really have on a cruising boat.

I have never been on a cruising boat that has any of these adjustments. They have ordinary sails hauled up by hand and swigged up tight enough by hand. Yet they seem to sail perfectly well.

My racing friends go on about it the whole time. But I can't get a sensible quantified answer out of them as to how much difference it all makes. Is it half a knot faster on their racing type boats, or perhaps even one knot?

So, please, how much difference does it make?
Is it something that non-racers should consider?

Please note, this is NOT a TROLL!!!!!

Is there an informed overview of the subject?

Thanks, Mike.
 
dmmbruce said:
My racing friends go on about it the whole time. But I can't get a sensible quantified answer out of them as to how much difference it all makes. Is it half a knot faster on their racing type boats, or perhaps even one knot?
QUOTE]

It's not so much speed as pointing ability. A sagging forestay can cost you ten degrees or more. It's all very well thinking that speed doesn't matter when cruising, but if you're trying to beat off a lee shore or round a headland it can become rather important, especially as the penalty gets worse in stronger winds.
Click to expand...
 
dmmbruce said:
Please may I ask a question that is perhaps stupid, but is a serious question as far as I am concerned?

I often read of the adjustments you refer to above, and wonder what effect they really have on a cruising boat.

I have never been on a cruising boat that has any of these adjustments. They have ordinary sails hauled up by hand and swigged up tight enough by hand. Yet they seem to sail perfectly well.

My racing friends go on about it the whole time. But I can't get a sensible quantified answer out of them as to how much difference it all makes. Is it half a knot faster on their racing type boats, or perhaps even one knot?

So, please, how much difference does it make?
Is it something that non-racers should consider?

Please note, this is NOT a TROLL!!!!!

Is there an informed overview of the subject?

Thanks, Mike.
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Its hard to generalize, but I will try.
Most of the sail adjustments that racing sailors would make (carefully adjusting the leads halyard tension etc) will result in less than 0.5K VMG compared to the “casual” sail set up that would be typical in a cruising boat.
However, its not unusual for cruising sailors to have with much less sail area than would be used on a racing boat. For example a few days ago sailing at night with thunderstorms around I was happy to sail with reef in the main. Shaking out the reef would have given me an extra knot of boat speed, putting up a spinnaker (which I would have done if racing) would have given me 2 knots of boat speed. If I didn’t have the provisions like 6 dozen bottles of wine, 60l long life milk, 600l diesel etc etc probably 5% more on the above speeds. Hand steering instead of the autopilot another couple of percent.
The bottom line a cruising sailor the aim is to arrive rested with no drama, or gear breakages. For a racing sailor speed is the overriding consideration.

Even for a cruising sailor it is very helpful to have some racing experience. Some sailing adjustments make a difference to comfort (for example by reducing the healing angle) and occasionally ultimate sailing speed is important even for a cruising boat .When racing sailors go cruising, however, it is important that for most of the time they make an adjustment to the different priorities.
Cruising sailors arrive rested, well fed with noting broken.
Racing sailors arrive say 20% quicker (consisting of typically something like 5% sail adjustment, 5% less gear, 10% more sail area), but tired grubby and with a few near mishaps.
I have done both and it just comes down to the different priorities.
 
In racing advantages are worked at the tenths of knots levels, any adjustments will be worked continuously to gain optimum speed however little gain there might be. The larger rigs prevalent on modern racing yachts have full mains and backstay routinely tight on for "normal" wind speeds as they will be overpowered otherwise. Rigs will be slackened to power the main up for lighter winds possibly tightened again for extremely light winds. The adjustable backstay will substitute for a reef or two of the main (together with other adjustments)
 
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savageseadog said:
In racing advantages are worked at the tenths of knots levels, any adjustments will be worked continuously to gain optimum speed however little gain there might be.
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You've all forgotten the OTHER reason that a racing boat has so many adjustments - it gives the crew something to DO, rather than just sit on the rail and look bored. Tighten this, loosen this, hammer that, change to the #1 kite...ad infinitum. Seriously, a race boat not being sailed hard can be a fairly boring place IMHO. You can't really relax and just enjoy the sail (at least I can't), you can't drink alcohol, you can't work on your tan. Unless you are navigating, cooking, or helming you can get bored pretty quickly if you are not sailing hard...

This thread has been great - coming from fractional rigged J/24s and J/30s that have myriad adjustments, I didn't think it was worth having too many tweaks on my cruising masthead rig. Now I'm going to re-think that, starting with a backstay adjuster and maybe adding a traveller (yes, it is THAT much of a cruiser). She has never pointed very well...maybe it would help.
 
johnalison said:
It's not so much speed as pointing ability. A sagging forestay can cost you ten degrees or more. It's all very well thinking that speed doesn't matter when cruising, but if you're trying to beat off a lee shore or round a headland it can become rather important, especially as the penalty gets worse in stronger winds.
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I mostly cruise, so I usually pull the backstay on firmly to lessen forestay sag. Then when the day's sailing is over I loosen, to take the strain off the hull structure.

I pretty much "set and forget" the mainsail. I adjust luff and foot tension during sailing if conditions change so as to make them evidently wrong. Otherwise I only change mainsail shape with the traveller and sheet.
 
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