Adding a bolt rope to a sail

[Roach1948]

my mainsail vibrates a lot at the luff when going to windward. It seems there is insufficient luff tension to me. The reason for this is that I had my main made in Hong Kong, and although it was remarkably cheap, they did take some short cuts, and a luff/bolt rope was one thing they did not include (I did not know this at the time of ordering)

Now, it is a cheap sail, and I dont really want to spend the same amount of money as I paid for the sail by asking a UK sailmaker to add a luff/bolt rope - so was thinking of doing it myself by sewing on a dyneema rope. The luff has a hem in it so I can feed the rope up the inside of the hem. My question is:

1. How do I get the bolt rope to connect to the tack and head.
2. Was planning to use a speedy Stitcher, and sew through the dyneema with a lock stitch.
3. The slides are currently sewn to cringles on webbing loops. Would they now need to be sewn to the bolt rope instead?

 

[Guest]

Tack ... common to find the rope come round the tack for a short distance onto foot. Short so it doesn't interfere with any boom slot foot sits in ...

Head ... this is harder especially if you have a head board. If you do - then you have to stitch long and hard to the sail for reasonable distance from board down the sail .. on your boat ? maybe 10 - 15 cms or so.

You can do similar at both ends if a turn round tack is not possible.

The stitch I used was a good cross X stitching with locks at every second stitch.

If you can pass the rope up inside the hem ... then that's good enough ... not necessary to stitch other than at ends. BUT make sure sail is stretched hard when you do it ..

You may find that the sail-slides are too tight fitted to allow the rope to feed up ? But being sewn to loops in cringles is in your favour ! They can stay that way with no problem. The bolt-rope is only to provide strength and without slides .. size to fit mast slots.

Back to the vibration .. I would think that it may be due to lack of weight in the luff edge .. if it's just a doubled sail hem without any stiffness it's a bit like a piece of paper edge on when you blow at it ... it vibrates no matter how tight you pull it straight. Another factor is that some cheaper cloths can stretch when in use ... you harden halyard .. after while sailing the cloth is stretching enough to vibrate ...

It may be as simple a solution as stitching a luff tape along the edge to stiffen it up and stop stretch ... or as you say - adding a bolt-rope.

Many think that the bolt-rope has to be sper strong ... not so ... as the sail itself will be part of the vertical strength as well. The bolt-material used by sailmakers ... the solid plastic white core ... I tested some against a repair material I used on a genny luff ... actually white solid plastic washing line - same size .... the bolt-core material broke first. Here on your sail - we are not looking for the bolt-rope to carry the full tension of hoisted sail - just to stiffen luff enough to reduce vibration.

 

[Roach1948]

Many thanks, that has helped a lot.

By putting a bit of weight in the luff hem I think I will reduce the vibration and it is easier than sewing luff tape. Like you say I wont bother sewing the rope on the whole length, just at the top and bottom. I will sew for a foot at the tack and head just to be sure.

 

[KenMcCulloch]

I'm not at all sure about the wisdom of using Dyneema. The point of tensioning the luff of the sail is to draw the draft of the sail (the 'deepest' point of the curve) more forward. I think if you use a rope with very low stretch you may not be able to achieve that. I would use a traditional 3 strand cable-laid rope (but I'm that kind of a guy anyway).

 

[Roach1948]

The reason I mention Dyneema is that a dinghy sailing friend recommended it to do it that way. Surely the sail cut makes the shape and not the tension on the luff - which as I understand it, should be as tight as possible.

To be honest I have no idea. 3 strand would suit me better as I can sew through it easily. Any other opinions?

 

[Guest]

[ QUOTE ]
The reason I mention Dyneema is that a dinghy sailing friend recommended it to do it that way. Surely the sail cut makes the shape and not the tension on the luff - which as I understand it, should be as tight as possible.

To be honest I have no idea. 3 strand would suit me better as I can sew through it easily. Any other opinions?

[/ QUOTE ]

Light braided or 3 strand .. I must admit I kept quiet on the rope front ...

The draw of sail - yes it is true as another says to alter the luff on a sail to change the draw of a sail ... but for average yottie - even some racers I have to add don't bother ... they'll play with foot tension ... they'll play with kicking straps etc. - but usually leave halyards at full hard up tension.

Take another view ... many sails have wire or plastic luff inserts ... how plays game then ?

On a slide sail - I would be less inclined to start palying with luff tension ... as there is no bolt-rope in a slot full length of sail to stop sail becoming too out of shape ... IMHO

 

[Seagreen]

The key point about adding a bolf rope is getting the tension of the new rope equal to that of the cloth.

Assuming that A) you've enough room for a rope in the luff tape and, B) you can sew or whip the track slides round a bolt rope, it can be a relatively simple job, thus:

You have to thread the rope all down the luff, leaving a couple of feet spare at either end. If you have to, cut the stitching by the headboard to take the rope up to the top of the sail with 2 feet to spare. You can re-sew the sail by hand later. If you have a sewing machibe that can cope with the sail, now is the time to sew the rope in, by running the foot of the machine along the rope. Note you are not sewing the rope in, just closing the loose pocket in the luff.

Set the sail up between two strong points at a convenient height. Ie, lash the tack of the sail to a stout ring, or tree at one end of the garden, and lash the head of the sail to another, so that you can tension the sail without wrecking the trees! You may need a couple of tackle set up, one for the sail, one for the rope. A convenient height is one where you can comfortably sew, either standing or sitting on a stool.

Set the luff up first, stretching the sail just enough so that the creasing dissappears but no more. Sew the rope in at the tack just above the tack ring. You'll need to copy the roping stitch which looks like XXXX. take the rope round the bottom of the ring under the foot of the sail, and along the foot by about 6".Sew off, heatsealing the rope, of by gradually thinning out the rope and making a rats tail. use beesway for this, not soap - it goes black and really stains the sail.

The next stage is the tricky one. You have to stretch the rope, adjusting the tension in the rope so that it matches the tension in the sail. This can be done by feel (the usual method) or using a strong spring balance. Once you have the tension right, sew the rope at the head of the sale - more XXXX. Cut and seal. The sail should now set on the luff nice and stiff with no creasing in the sail.

With the tension still on, hand sew the rope into the luff tape at the eyelets for the track. Un-lash the sail, add sliders. cuta nd seal any rope ends not yet taken care of, finish up and voila - job done.

Goes without saying you need needles, a palm, wax and good thread. And two stout trees. Good luck.





Now, set up the luff of the sail so that the creasing of the cloth /forums/images/graemlins/smirk.gif

 

[ex-Gladys]

Dyneema is a definite no no on a main bolt rope, if you can't stretche the luff you can't pull the draft back forward when the increasig wind has pushed it aft.. On a lot of dinghy mainsails the luff rope is pretty stretchy.

 

[Roach1948]

Thanks for that in-depth explanation. I had a look at the old 1940's cotton sail's to see what they did and whether I could copy it; it does not really compare as the rope was sewn along the cotton leading edge - not inside a hem at all.

 

[Guest]

[ QUOTE ]
Thanks for that in-depth explanation. I had a look at the old 1940's cotton sail's to see what they did and whether I could copy it; it does not really compare as the rope was sewn along the cotton leading edge - not inside a hem at all.

[/ QUOTE ]

That's the old way ... common on Lugsails .. old gaffers etc. where it was easier to have it external and able to take fittings etc.

Having threaded and fitted bolt-ropes and wires to sails myself in past .. and as quoted earlier repaired a genny - the work is actually a lot easier than it sounds. I have to say that I didn't need blocks and tackle to stretch sail and rope between trees !! I did it without - just making sure that each were equal. Bear in mind that they are different materials and they stretch different rates .. so over stretching can in fact be wrong.

As to stretchy ropes in sails .... my weekender has bungy cord in luff of the old mainsail ... BUT it also feeds into the mast slot without sliders ... so it works a treat. The new mainsail has braided line .....

Difference in performance ? Haven't noticed any yet !

 

[Seagreen]

[ QUOTE ]
the rope was sewn along the cotton leading edge - not inside a hem at all.

[/ QUOTE ]

The joy of dacron luff tape. Feel free to do it the old way if you want, but luff tape (its just a strip of sailcloth cut along the fabric - nothing special) makes life a lot easier.

BTW should've removed the typos from my posting, but was sent out by the SWMBO for chips!

You don't need tackles- you can loop the rope back through itself like a truck hitch - same effect. You shouldn't need much tension anyway.

 

[Roach1948]

Well this is going to be interesting - tensioning this sail up in a shoe box London flat! I suppose I could do it Hyde Park and get strange looks! I will let you all know how I get on. I have a Palm on order and on Monday I am off to Arthur Beales to choose the bolt rope.

 

[Eastermaid]

The bolt rope definatly needs to be able to stretch. (Being an ex Finn sailor). Finns have shock cord bolt ropes to give the ultimate in sail adjustment /flettening even in the new hi tech material sails.

 

[Roach1948]

OK will get some 3 strand for the bolt rope. But when measuring up I noticed that I dont have a rope at the foot either. Shall I go the whole hog and add a bolt rope to the foot of that sail (there is a hem here too)?