Forestay/Backstay Rigging

[Fire99]

Evening folks,

I've been gradually getting my head around the joys of sailing my own boat and have been brushing up on rigging tuning.

One issue I have found is the forestay/backstay tension.

Firstly, the previous owner replaced the standing rigging a couple of years ago so it's in good condition but specs could be open to enterpretation but it does have an adjustable forestay and backstay.

However, after reading up on required tension, I cannot get sufficient tension on the stays even with maximum adjustment on the bottlescrews.

Are there any fairly simple solutions to my problem.

nb- I use hank-on headsails so there is no issue with furling gear.

cheers,

Nik

 

[chriscorr]

How big is your boat? I have a 24ft boat, also open to interpretation on rigging arrangements as I can't find another one to reference to (Foxhound24). Anyway, I had my mast moved a bit and rig adjusted by a rigger on the south coast. I have a forestay with furlex, baby stay and adjustable back stay with almost dead straight spreaders (one set) and two sets of shrouds coming to the same point on deck.

The rigger who did the work told me it's almost impossible to get a small rig like mine with tension everywhere so the shrounds are tight as is the back stay but the forestay is a bit wobbly and the baby stay does very little.

 

[Dan the man]

if the screws go down to their minimum length and the rigging is still too slack (is what I assume when you say you cant get enough tension) it would seem that either the shrouds are too long, ie when loosened right off their is a lot of slack in the wire or that something else might be compressing when you tension the rig. I did see this once on a boat where tension could never be achieved and it was the compression post that had insuuficient support.
I would say that when fully tensioned the turnbuckles want to be half way down the threads.
sorry if I have misunderstood the question.

 

[Fire99]

Thanks for the replies guys. Yeah mine is a 23ft boat so not the biggest little yacht in the world.

I'm able to tension up the Cap shrouds and both the fore and aft lowers without issue.

It's just the forestay and backstay which appear too long. My guess is that the previous owner has gone for slightly too long ones (since it's a DIY job).

What's the route forward? Is the only option to drop the mast and replace the two stays?

 

[VicS]

What's the route forward? Is the only option to drop the mast and replace the two stays?

It may come to that but before you do look at the mast rake and decide if both really need to be shorter or whether is is only one of them that is too long.

You don't have any toggles or, heaven forbid shackles, that can be removed I suppose?

Are the bottle screws permanently fixed to the wires or is there any possibility of fitting shorter ones if you can find them?

A block under the mast foot might be one bodge, if the shrouds will allow it ... you could extend those with toggles. But it could all be just as much hassle and expense as taking it all down and having either the forestay or the backstay ( or both) shortened.

how are the ends of the wires done. If you have Stalock or Norseman or similar terminals maybe possible to remove, shorten the wire(s) and refit.

 

[Fire99]

It may come to that but before you do look at the mast rake and decide if both really need to be shorter or whether is is only one of them that is too long.

You don't have any toggles or, heaven forbid shackles, that can be removed I suppose?

Are the bottle screws permanently fixed to the wires or is there any possibility of fitting shorter ones if you can find them?

A block under the mast foot might be one bodge, if the shrouds will allow it ... you could extend those with toggles. But it could all be just as much hassle and expense as taking it all down and having either the forestay or the backstay ( or both) shortened.

how are the ends of the wires done. If you have Stalock or Norseman or similar terminals maybe possible to remove, shorten the wire(s) and refit.

Many thanks,

I think i'll have to do a little more 'scientific' assessment. At a wild guess, i'd say there is perhaps a touch too much rake in the mast at the moment but i'll take a measure up to be sure. There are no shackles or toggles in the stays nor Sta-lok or Norseman terminals. I think mine are a simple wired eye.

I did wonder if finding shorter bottle screws may help since the two on the forestay and backstay are chunky chaps compared to the cap shrouds etc.

edit to add - They are closed threaded body turnbuckles

 

[chriscorr]

If it's any help in your deliberations, the rigger cut my backstay shorter with the rig up but left it at that with the reasoning above. That said, the last mast (before I owned it) came down of its own accord...

 

[Fire99]

If it's any help in your deliberations, the rigger cut my backstay shorter with the rig up but left it at that with the reasoning above. That said, the last mast (before I owned it) came down of its own accord...

Well that could be an option. (not the mast self-descending of course. )

 

[William_H]

Forestay

IMHO opinion you don't need a turnscrew in the forestay. The only use for one is to set the mast rake. If you are happy with the rake (and I don't think it very critical) then you can replace the forestay turnscrew with 2 SS plates. I am tempted to say use a couple of shackles. I don't see anything wrong with shackles except they look unprofessional.
Many boats have a split backstay. ie it comes to within 1.5 metres of the transom then splits to 2 wires one each side of the tiller. If you have a split backstay then this type can easily be converted to adjustable backstay. You need a pair of plates with sheave wheels fitted that fit over both bottom wires of the backstay. The plate is pulled downward by a pulley system and in so doing pulls the 2 wires together thus tightening the backstay. It may be that this kind of sytem was intended but removed which would explain the loose forestay/backstay.
Alternatively many boats have the split backstay however the main top backstay has a pulley fitted about 1.5 metres above the transom. A 7X19 wire then runs from one side of the transom through the pulley and down to a tackle which is attached on the other side. The purchase of the tackle multiplioed by 2 gives adjustable backstay.
Backstay is made adjustable so that in strong winds the forestay can be tensioned to reduce forestay sag.
Forestay sag feeds cloth into the middle of the luff so gives more camber to the jib. That is ok maybe good for light winds but it doesn't happen in light winds only in strong when you want a flat jib. All more critical when beating of course.
If you have an inner forestay then this needs to be fairly tight or even adjustable so backstay tension will bend the mast against the inner forestay to induce mast bend.(middle forward) This is desirable to flatten the mainsail.
If you have a fractional rig without inner forestay then tightening the backstay will both tension the forestay and bend the mast. The balance of the 2 being in the mast stiffness. Many racing yachts resort to running backstays to enable more forestay tension without mast bend. One boat at our club has a load cell in the bottom of the forestay and digital readout so you can set a finite forestay tension appropriate to wind stength. good luck olewill

 

[Fire99]

IMHO opinion you don't need a turnscrew in the forestay. The only use for one is to set the mast rake. If you are happy with the rake (and I don't think it very critical) then you can replace the forestay turnscrew with 2 SS plates. I am tempted to say use a couple of shackles. I don't see anything wrong with shackles except they look unprofessional.
Many boats have a split backstay. ie it comes to within 1.5 metres of the transom then splits to 2 wires one each side of the tiller. If you have a split backstay then this type can easily be converted to adjustable backstay. You need a pair of plates with sheave wheels fitted that fit over both bottom wires of the backstay. The plate is pulled downward by a pulley system and in so doing pulls the 2 wires together thus tightening the backstay. It may be that this kind of sytem was intended but removed which would explain the loose forestay/backstay.
Alternatively many boats have the split backstay however the main top backstay has a pulley fitted about 1.5 metres above the transom. A 7X19 wire then runs from one side of the transom through the pulley and down to a tackle which is attached on the other side. The purchase of the tackle multiplioed by 2 gives adjustable backstay.
Backstay is made adjustable so that in strong winds the forestay can be tensioned to reduce forestay sag.
Forestay sag feeds cloth into the middle of the luff so gives more camber to the jib. That is ok maybe good for light winds but it doesn't happen in light winds only in strong when you want a flat jib. All more critical when beating of course.
If you have an inner forestay then this needs to be fairly tight or even adjustable so backstay tension will bend the mast against the inner forestay to induce mast bend.(middle forward) This is desirable to flatten the mainsail.
If you have a fractional rig without inner forestay then tightening the backstay will both tension the forestay and bend the mast. The balance of the 2 being in the mast stiffness. Many racing yachts resort to running backstays to enable more forestay tension without mast bend. One boat at our club has a load cell in the bottom of the forestay and digital readout so you can set a finite forestay tension appropriate to wind stength. good luck olewill

William, you're a legend. Thanks for your input.
Yep mine is a masthead rig and yep I have a split backstay with a single turnbuckle where the two wires meet the backstay.
So with a bit of scientific assessment, (measuring mast angle ) could I potentially lose the turnbuckle off the forestay and replace with something like a shackle and then use an adjuster on the backstay to gain the tension?

Regarding lower forestays, I don't have one of them but I do have two forward lowers which seem to effectively do the same job. I currently have a fair degree of pre-bend in the mast which realistically may be excessive but doesn't seem to upset the mainsail.
But i'm strictly an 'elementary school' student on mast rigging at the mo.

Cheers,

Nik

 

[Fire99]

Just to add, I took a quick look at backstay adjusters and they seem amazingly expensive. Certainly far more than I'd want to spend on my boat.

 

[VicS]

I currently have a fair degree of pre-bend in the mast

I am a little puzzled by that statement if you have not been able to tension the forestay and backstay ... ...

Normally you would aim to set the mast at the required rake by adjusting the foresaty and back stay ... in the case of a Snapdragon 23 I'd suggest zero rake, ie upright. ... and then induce the pre-bend by tensioning the forward lower shrouds. It not a hot racing machine so I would not expect very much pre-bend anyway.

( perhaps though your backstay is the correct length and you are pulling the mast head back with that against the forward lowers)

Sort out your forestay and back stay first to get the mast upright or raked backwards only very slightly. The suggestions from William H may be solutions to avoid having to actually shorten either. Then think about inducing a little pre-bend with the forward lowers.

 

[Twister_Ken]

Evening folks,

I've been gradually getting my head around the joys of sailing my own boat and have been brushing up on rigging tuning.

One issue I have found is the forestay/backstay tension.

Firstly, the previous owner replaced the standing rigging a couple of years ago so it's in good condition but specs could be open to enterpretation but it does have an adjustable forestay and backstay.

However, after reading up on required tension, I cannot get sufficient tension on the stays even with maximum adjustment on the bottlescrews.

Are there any fairly simple solutions to my problem.

nb- I use hank-on headsails so there is no issue with furling gear.

cheers,

Nik

Ermmmm - you're not bending the boat are you?

No, I'm not joking - some boats aren't entirely rigid fore and aft, and on others a deck-stepped mast might be compressing the coachroof.

 

[Fire99]

I am a little puzzled by that statement if you have not been able to tension the forestay and backstay ... ...

Normally you would aim to set the mast at the required rake by adjusting the foresaty and back stay ... in the case of a Snapdragon 23 I'd suggest zero rake, ie upright. ... and then induce the pre-bend by tensioning the forward lower shrouds. It not a hot racing machine so I would not expect very much pre-bend anyway.

( perhaps though your backstay is the correct length and you are pulling the mast head back with that against the forward lowers)

Sort out your forestay and back stay first to get the mast upright or raked backwards only very slightly. The suggestions from William H may be solutions to avoid having to actually shorten either. Then think about inducing a little pre-bend with the forward lowers.

It's a good point..

(on a side note the little SD23 won some round britain races in its class back in the 60's.. so it's got a little bit of spirit down below. )

You could be right however soon after getting the boat it was pointed out that all my rigging was far too slack.
I tightened the cap shrouds, forward and aft lowers (all in balance) and then induced a little forward pre-bend with the forward lowers.

However, after reading up on the subject, (Yachting Monthly Sailpower) it appears that the forestay and backstay should be at greater tension than the cap shrouds.
Both are nowhere near the cap shroud tension and there isn't sufficient adjustment to induce any greater tension, hence my current predicament.

I'd have to slacken off the cap shrouds a long way to match the forestay/ backstay and I don't think that would help matters too much.

 

[Bilgediver]

Are the bottle screws permanently fixed to the wires or is there any possibility of fitting shorter ones if you can find them?

I wonder if somehow the boat has been fitted with bottle screws the next size up to required.


I recently changed the lower chainplate ubolts and found I needed to lengthen the cap shrouds about 25mm to get bottle screws mid position with the new ones. Found I had Spare bottle crews ex Boat show and they were longer than those fitted which were due to be retired after 35 years in service

The OP's problem could be overlength bottle screws because they are sized for bigger rigging wire.

 

[Fire99]

The OP's problem could be overlength bottle screws because they are sized for bigger rigging wire.

That could be true too since, and I mean no disrespect to the previous owner, he changed the standing rigging himself and I don't doubt more than a little guesswork going on.

This is quite tricky as a) i'm only a novice on this kinda thing myself and b) the boat must be 40 years old now and there is very little to compare her to.

 

[William_H]

Rigging

Thanks for the kind comments Nik
The fact that you can get good tension on the cap shrouds indicates that the mast support system is OK. However it is still worth having a look around under the mast in the cabin. If it is a wooden post it can go rotten. There might even be room for a spacer of hardwood or metal on the compression post which will also help the long stays problem.
With some prebend in the mast it would appear that your forestay is too long or the forward intermediate stays are to tight. Shorten the forestay will give less mast rake loosen the forward inners and you will get more mast rake.
Regarding back stay tensioner. You can make one by buying 2 pulleys with metal sheaves appropriate to the wire of the split backstay. The 2 pulleys are shackled together and fitted with the 2 wires of the backstay running throught them. They will sit near the join of the 2 bottom parts. Attach a pulley system which can pull the 2 puleys down so forcing the 2 legs of the backstay together so tightening the backstay.
However it still seems like you need to remove the forestay turnscrew and replace with a spacer or shackles that are shorter.
Some people at our club use a highfield lever in the bottom of the forestay. This is opened each time they leave the boat. This means the total static tension on fractional rig can be quite high but only for actual sailing. The tension is released to avoid distortion to the hull over a long period.
I don't believe you need a lot of tension on stays. The loads when sailing are so much greater than when static that the only concern is what the mast looks like when being driven hard. good luck olewill

 

[Fire99]

Thanks for the kind comments Nik
The fact that you can get good tension on the cap shrouds indicates that the mast support system is OK. However it is still worth having a look around under the mast in the cabin. If it is a wooden post it can go rotten. There might even be room for a spacer of hardwood or metal on the compression post which will also help the long stays problem.
With some prebend in the mast it would appear that your forestay is too long or the forward intermediate stays are to tight. Shorten the forestay will give less mast rake loosen the forward inners and you will get more mast rake.
Regarding back stay tensioner. You can make one by buying 2 pulleys with metal sheaves appropriate to the wire of the split backstay. The 2 pulleys are shackled together and fitted with the 2 wires of the backstay running throught them. They will sit near the join of the 2 bottom parts. Attach a pulley system which can pull the 2 puleys down so forcing the 2 legs of the backstay together so tightening the backstay.
However it still seems like you need to remove the forestay turnscrew and replace with a spacer or shackles that are shorter.
Some people at our club use a highfield lever in the bottom of the forestay. This is opened each time they leave the boat. This means the total static tension on fractional rig can be quite high but only for actual sailing. The tension is released to avoid distortion to the hull over a long period.
I don't believe you need a lot of tension on stays. The loads when sailing are so much greater than when static that the only concern is what the mast looks like when being driven hard. good luck olewill

Well credit where credit is due. You give really good info, and I actually understand what you're saying. (some sailing terminology can get complicated for us novices )

There is no post in the cabin. The support of the mast is absorbed through the roof structure around the 'corridor' to the heads. (it's like a little tunnel with a small door. )

My forward lowers are quite tight (hence the pre-bend) but not ridiculously so but I would say that the pre-bend is probably excessive as it's no carbon-fibre race boat.

She does suffer with excessive weather helm, and yes, that could be caused by a large number of things, but since someone has already commented on its relative lack of forestay/backstay tension, i'm guessing that isn't helping. (Especially when heading towards the wind)

On a side note, she does run a very large mainsail and i've noticed, compared to larger boats (she's only 23ft), that sail balance has a big impact on the direction she wants to sail.

When i'm next down the boat, i'm going to back-off the cap shrouds a little and the forward lowers to get a more neutral mast curve. Then measure everything and start again. Then if necessary, i'll find a suitable device to shorten the forestay length (one of your recommendations sound good) and look at a DIY backstay tensioner.

Then you never know, I may actually go sailing.

Many thanks,


Nik

 

[VicS]

Then you never know, I may actually go sailing

when you do a rough check on the shroud tensions is to sail to windward in a force 3. If the mast stands straight and the lee rigging starts to become slack at about 15° to 20° of heel the shrouds are correctly tensioned.

Check again in stronger winds and if necessary adjust the lowers to obtain a acceptably straight mast ( that's in the athwart-ships plane).

If the lee shrouds do not go slack until after 20° of heel they are too tight.

 

[saltwater_gypsy]

Just a cautionary note.
Keep an eye on the deck as, in small boats, the combined load from the shrouds can put tremendous pressure at the base of the mast and "dish" the deck.
As they used to say about the Mirror Offshore....." If yer loo door jams, yer shrouds are too tight"