Rigging Question

[sebastiannr]

Hello!

I have a folksong 26, which has a 30.5ft mast and is fractionally rigged. I recently bought a (nearly) new mast for her and have been getting the standing rigging up together.

The boat has three chain plates each side. One heavy duty one in line with the mast step for the upper shrouds, and two fore and aft of the mast step for the two sets of lowers.

The arrangement of the chain plates is that of a mast head rig, where the uppers come down in line with the mast, as opposed to that of a fractional rig, where the uppers (and spreaders) rake back.

Without really thinking about it, I altered the spreaders on the mast so that the uppers would come down in line with the heavy chain plates. My question is: on a fractional rig, how critical is it that the uppers go aft of the mast? I have a horrible feeling that it may be a problem, as the forestay is pulling the mast forward at a point considerably lower down the mast than the backstay, and without the upper shrouds counteracting the fore stay by pulling aft at that point, there will be a potentially dangerous imbalance.

Someone please tell me I don't need to worry about it!

The alternative is to use the chain plates aft of the mast that were originally intended for the aft lower shrouds. I didn't do this in the first place as they are considerably less substantial. I will take a picture of them at the weekend. Although I really do need to get the mast up this weekend.

Many thanks,

Sebastian.

Note: I should say that the fore stay is about 5' from the top of the mast, and it is a Zspars Z145 tapered mast.

 

[Dipper]

I've just bought a new Z Spars fractionally rigged mast because my old mast was showing signs of corrosion. It's a couple of feet longer than yours but the forestay is also around 5 ft from the top. For my rig, the optimal spreader angle is 25°. I wouldn't want to rig it without the swept back spreaders to counteract the pull of the forestay.

I think you will have two options. Either fit properly secured chainplates to allow for the original swept back spreaders or fit new cap shrouds and forestay at the top of the mast. With the latter option you will also need to relocate the genoa and spinnaker halyard upper exit points. I don't know whether leaving the existing holes for the shrouds and forestay empty would compromise the strength of the mast.

I suppose a third option would be to shorten the mast so that the backstay can be attached at the same height as the forestay.

Edit: Your tapered mast may not have the necessary strength in the upper section to allow you to relocate the cap shrouds and forestay.

I'm not an expert so my best advice would be to contact Z Spars or an experienced rigger.

 

[alahol2]

This may be dumb because I'm no rigger but would it be possible to add a couple of 'lowers' from the forestay exit height to the aft lowers chain plate?
Should I get me coat now?

 

[VicS]

A fractional rig need not have swept spreaders.

Some useful and informative reading in the Selden Hints and Advice pdf

I'd suggest though that if the mast was fitted with swept spreaders you should stick to them.

 

[William_H]

Do I need to worry

Yes IMHO you do need to worry.
Firstly the cap shrouds do need to come to chainplates aft of abeam the mast to handle some of the forestay loads. Which can be huge. The backstay can not do this job alone or your will get too much mast bend. And of course some of the forestay pull is sideways anyway.
Secondly the aft sweep of the spreaders is used to effectively push the middle of the mast forward. The spreaders in effect lean on the cap shrouds or the shrouds push the spreader tips forward. This is counteracted by the intermediate sidestays which pull the middle of the mast back. The combined effect gives stability to the middle of the mast. Or you could fit forward intermediate stays although these might foul the jib sheets. Perhaps this is what Vic s says when saying it need not have swept spreaders.

The fractional rig having backstay pulling the top back against a forestay pulling from part way down will induce a curve in the mast pushing the middle forward this is controlled by the intermediate shrouds which pull from a point aft of abeam the mast. So these alone need a robust chain plate attachment.

I think you need to use the aft chain plates for both cap and intermediate shrouds. So they need to be strong.
You may be bale to extend the chain plates down inside the hull. Put in a plywood partial bulkhead to support deck or you can extend the chain plate/shroud down with rigging wire to a solid attachment on the hull.
If you have the spreaders swept aft make sure the base is robust to induce the aft angle. I lost a mast because the spreader base loosened (corroded pop rivets) and the aft swept angle was lost. So push forward to the middle of the mast was lost. Support for the middle of the mast is vital.
Just reading back I am not sure my being adamant is correct. You certainly need to ask questions and consider the support of the mast. There are some huge loads involved.
good luck olewill

 

[stav]

I am no rigger but I would avoid the stresses of a swept spreader rig unless I knew my boat was designed for it. Unless you are racing and need every advantage I would go for a pair of lowers each side to hold the mast in place and keep the traditional spreaders. Doesn't a swept spreader have to be tensioned within 80% of the tensile strength of stainless? It has to be high as the leeward rigging still has to have sufficient tension to hold the mast in place.

You could always add some runners at a later date.

This picture seems to show a similar rig to yours?
http://members.optusnet.com.au/coastalcruising/images/StripplankedtimberFolkboat.jpg

 

[Seajet]

There is a lot of Folksong info' available on this forum or Scuttlebutt next door, Zagato is another owner who has the contacts, or try searching 'Folksong' ?

I take it the Folksong doesn't have the jumper struts & stays on the upper forward part of the mast that the original Folkboat has ?

 

[Dipper]

This may be dumb because I'm no rigger but would it be possible to add a couple of 'lowers' from the forestay exit height to the aft lowers chain plate?
Should I get me coat now?

Not dumb. That would work but the aft lower chain plates need to be very strongly attached and in the correct orientation for the spreader angle. They will need attachments for both the cap shrouds and the aft lowers. Cap shrouds on fractional rigs are tensioned significantly more than those on a masthead rig because they take over some of the function of the backstay (counteracting the forestay). The aft lowers will add even more forces to the plate. As William_H says, there are huge loads involved.

Edit: the OP needs to discuss this with a professional rigger or yacht designer.

 

[Dipper]

A fractional rig need not have swept spreaders

I was stuck in a traffic jam by the marina this morning and saw a fractional rigged yacht that did not have swept back spreaders. The solution in this case was to have, in addition to the normal backstay, twin backstays secured at the level of the forestay and leading down to the corners of the transom. It also looked like a tapered mast but I can't be sure of that.

 

[gardenshed]

I was stuck in a traffic jam by the marina this morning and saw a fractional rigged yacht that did not have swept back spreaders. The solution in this case was to have, in addition to the normal backstay, twin backstays secured at the level of the forestay and leading down to the corners of the transom. It also looked like a tapered mast but I can't be sure of that.

........commonly known as runners or running backstays. On very bendy rigs, supplemented with checkstays. 80's IOR race boats at their best, great fun gybing in heavy airs scrambling to get the new ones on and release the old ones without losing the rig, tearing the main or broaching.

All reasons why the original poster should stick to the Folksong's original rig design or get in touch with a competent rigger, surveyor or designer.

Can you imagine the insurance company's reaction when it clatters down around your ears and you are filling in the claim form:

modifications: yes

under whose supervision/design responsibility: some people on a forum

 

[30boat]

One thing I don't think was mentioned is that if you move the forestay to the mast top then the foretriangle will be altered.Mast head rigs have their masts further aft than their fractional counterparts.
As said only keep the fractional arrangement if the boat was designed with that in mind as the stresses will be substantially higher,(20/25% of the breaking of the wire in tension as opposed to 15% for the masthead version).A masthead rig is easier to tune and more reliable.

 

[Seajet]

I'm afraid I have to disagree about masthead rig being easier to tune; why are almost all racing boats fractional rig then ?!

Tweaking the backstay on a fractional rig will bend the mast and adjust the fullness of the main, for a start.

Not any safer either; once reefed, a fractional rig is close to masthead rig, and if running backstays ( which I personally don't like ) are fitted it could be said to be more secure in a blow.

This is a Folksong we're talking about, even if it balanced with regard to centre of effort ( which is unlikely ) a masthead rig would look dreadful and halve the boat's value !

The answer to the OP's problems is to chat with other Folksong owners - they are on these forums - and re-rig her as intended by her designer- bearing in mind that as almost certainly a kit boat, there is no guarantee at all that she was right before the OP's changes - this may explain a lot.

If he has not done so already, the OP should contact the experienced Folksong owners; a search for 'Folksong Info' here should reap dividends.

 

[Seajet]

Sebastiannr,

try the people on this link...

http://www.ybw.com/forums/showthread.php?t=252769&highlight=folksong

 

[alahol2]

There's a sail plan here... http://billwhateley.wordpress.com/2009/08/12/on-sailing-a-folksong-interview-with-eric-bergqvist-continued/
which seems to show inline uppers and twin lowers on the fractional rig.

 

[alan_d]

I'm afraid I have to disagree about masthead rig being easier to tune; why are almost all racing boats fractional rig then ?!

I think you have missed the point: easier to tune equals simpler, and more forgiving if you get it slightly wrong. It's like saying a sound system is easier to adjust with a single tone-control knob compared to a graphic equaliser. With your fractional rig or your graphic equaliser you can get better results in the end, but they are not as easy to use. Which is why almost all racing boats have fractional rigs, and many cruisers prefer the simplicity and robustness of the masthead rig.

 

[Rigger Mortice]

My boat has in-line spreaders and shrouds and is fractionally rigged.
A little unusual, but it works fine.
Two set of lowers. The aft ones are tightened pretty firmly. The forward lowers are only tightened a little (to the point of doing nothing!)
I do yank the backstay up hard when underway.

But, if you are worried professional advice is needed.

(Despite my name I'm not a rigger; sorry!)

 

[gardenshed]

Rigger Mortice:
I've also got twin lowers on my rig but do the opposite: Tension the forward ones to ensure that
a) there is some pre-bend
b) that the mast won't invert if slamming into waves going up wind
Then tighten the aft lowers to the same tension (twin spreader, mast head rig)

Inverting the mast (midsection bending backwards / behind a line from the masthead to the mast foot) is often the cause of mast failure.

 

[William_H]

A couple of misconceptions about fractional rigs

The use of, or need for running backstays ie temporary stays from the top of the forestay to the transom,
is a function of the degree of fractionality. ie the distance between the top of the mast (backstay) and the forestay attachment and the stiffness of the upper mast in fore and aft direction. Also dictated by the tension desired on the forestay in stronger winds. This latter usually dictated by demand for performance over operational simplicity.
A fractional rig of 80% fractional or more with a reasonably robust mast should not need running back stays for normal racing/ cruising. As you crank on the backstay you get adequate forestay tension with the right amount of mast bend.
An alternative as mentioned is to use jumper struts. ie small spreaders that extend forward from the mast at 30 degrees to centre line mounted just above the forestay. Stay wires go from the point where intermediate stays attach, to the mini spreader ends then to top of the mast. They are tensioned to reduce mast bend backwards which then applies more tension to the forestay when back stay is cranked on.

The other misconception and many will disagree is that static tension on rigging does not have to be greater than a mast head rig. Sure it is important to take up the slack as far as possible. However the applied tension under sailing load can be higher under some conditions. Especially running with backstay loose. When on the wind the load of the mainsail will take the place of backstay in pulling mast back.
The distance the chain plates are from centre line and distance aft of abeam the mast will affect the tension on cap shrouds the smaller the distance the greater the tension while sailing. (but you don't need a lot of static tension to start with) (IMHO)

The strength of the aft swept spreaders and the rigidity of the cap shrouds under tension providing this push forward of the middle of the mast is the critical part.

When I bought my boat of the builder/designer 30 years ago I was in love with mast head rig 5 stays traditional. I asked if he would sell me the boat without rig so I could rig it myself. He declined and I bought it anyway. I was quickly converted to love fractional rig. Ease of flattening the mainsail, small jib and ease of tacking along with performance are the reasons. olewill

 

[Signed Out]

I can't answer the question, just here out of curiousity and interest in Folksongs.

Will say though that Folksongs are almost all fractional, as I think Sebastian is aware. I only know of one masthead version, Matilda, which has been for sale for some time if I am not mistaken. In a blog the owner referred to trying to sort out the weather helm, and little else regarding the rig.

The boats, being home completed have quite a variety of rigs; besides this one masthead there was at least one junk (that ended up wrecked of Argentina) and various degrees of fractional. Zagato's has what looks to be a quite high main to fore ratio, and runners, while others not far off masthead.

As for chainstays and rig strength I wouldn't like to say anything but what others have- find a professional for this if nothing else. I've seen some scary set-ups. Close to home.

 

[sebastiannr]

Thank you everyone for all the (as always) incredibly informative advice.

I should mention that the original mast did not have swept spreaders, and the height of the mast and position of forestay and upper / lower shrouds were the same as on the new mast.

I have attached a picture of the boat with the old mast up, this is essentially exactly how she would be rigged with the new mast. The alterations I have made to the new mast are:

1) add two additional tangs to allow for an extra pair of lower shrouds
2) alter spreaders to allow the upper shrouds to come down in line with the mast and heavy chain plates
3) replace 4mm backstay with the original 5mm backstay.

As can be seen from the photo, the rig is not heavily fractional, but I think the general consensus of having a professional rigger look over it is the wise thing to do.

Thanks again,

Sebastian.