shroud adjusters

[superfluous]

What purchase would i want if i were to fit shroud adjusters? (how many blocks)

Where/how do they attach? (obviously to one end of the shrouds via wire block  )

Where do most folk lead them to? (crew or helm/sigle line or dual line, one each side)

Do they adjust both sides at once or indepndently? (see above)

So many questions i know, probably see you at the dinghy show to find out more but any answers so i can get thinking/drilling/bolting would be much appreciated.

Thanks

Superfluous

[Lukepiewalker]

Indeed, you need a hard point on the deck, then through the block on the shroud. Off hand I think it's a triple cascade under the deck (So that's 16:1 now... I think). The cascade would be anchored either at the mast step or possibly the front of the centreboard case (somewhere strong whichever way you shake it...) and then led back to the centreboard case capping. Usually independent because you want to be able to release the leeward shroud on reaches.
No doubt someone will show up and tell me how wrong I am.....

[John Meadowcroft]

good advice so far...
My suggestion...

I prefer a single line that connects both shrouds.

I would recommend that the end of your shroud is above deck and that you fix a block to it.  From the deck take a wire strop connected to the deck and through the block and then through the deck.  To this then connect a spectra - or low stretch equivalent - purchase arrangement - either cascade or a variant thereof which runs from the mast step to the deck.

The last purchase should then lead from the mast step to a cleat on the centreboard capping.  The further back along the centreboard capping the cleat is the easier it is to share between helm and crew.  Place a block about  six inches behind the cleat so that when you pull from behind the block at any angle it cleats automatically.

Then with the rest of the line repeat the process on the other side of the boat.

We always have the 'right hand' shroud controlled on the 'right hand' side of the boat.  Some people swap them over so that the leeward shroud is controlled from the 'high side'.  I think this makes the knitting more complicated.

We have 16:1 i think.

You could go for a muscle box, but there is a lot of friction.

If you have an older boat, shroud levers should be fine as there is no point trying to get too much rig tension as the old girl will be unable to take the load.

hope this helps
meds

[simon ballantine]

I've just re-rigged mine, so the layout is clear in my mind....
The wire shroud terminates abot 6" above deck level, with a single block fixed to the end of it.
A short wire is fixed to a strongpoint on the side-deck and passes through the above block, down through a hole in the deck and terminates a few inches below the deck with a single block attached to it's end.
A length of rope about 2' long is fixed to a strong point at the foot of the CB case, passes up and through the above block and returns a few inches back in the direction of the CB case.  This rope has a double block attatched to its free end.
So far you have a 4:1 cascade.
A much longer length of rope is tied to a double becket block fixed at the foot of the centreboard case, up through the double and so on to create a 4:1 purchase.  The rope leaves the lower double block, goes vertically upward through the top flange capping of the CB case, round a turning block and through a jammer fitted to the top of the BD case.
The 4:1 cascade acting on the 4:1 purchase gives 16:1.
You have to play around with the various lengths of the ropes and wires to get the maximum possible length of travel out of the system.
Each shroud is rigged independantly.  
A similar arangement for the forestay tension is rigged along the base of the CB case, coming up through the CB case flange to a similar jammer.

[RogerBrisley]

Simon,
My D8 has (and I believe from new) muscle boxes each sde with a similar shroud / block arrangement, control line  going back to the frame at the thwart and out to the side .... works fine for me.

The forestay / jib luff is a x2 x6 which (now I've replaced the cleat) works well also..

Was yours different,  why did you change?

Roger

[simon ballantine]

It was that way when I bought it last year.  

[Jimbo41]

Hi folks!

My Tigress Nuttyshell has muscle boxes, but they do tend to generate quite a lot of friction. One of the main problems was also a crack developed from increased tension in a blow near one of the pulleys. I'll have to replace that bit over Spring. Haven't yet worked out how the shrouds adjust on Passion Pudding yet, since she's in the UK and I'm over here at the moment. Can't wait to get over and pull her strings a little  

Cheers!  

Jim (ITCHY FOR WATER).

[superfluous]

Cheers everyone. It actually makes sense now.

One more question now i can picture it, how much travel do you generally get/want on the shrouds?

[Jimbo41]

Superfluous!

It's not travel that counts, it's tension. The shrouds hold the mast up top. Once you've set up the fore/aft position and got the prebend right, you don't want too much lateral mast movement, so you should only adjust sufficiently to correct for high winds etc, or to allow the leeward shroud to just pant in the wind.  Don't know the actual values, but the muscle boxes on the Tigress N3130 allow for a good 20 -25 cm movement. This is realistic since my Proctor Alu C (?) is not very bendy compared to a carbon superspars compared to an even bendier Angel. Effectively, except in above Bft. 4-5 only the top of the mast moves at the shroud spreader to top level. I've taken off my fixed lowers because of this, since they don't seem to do much.

Cheers!

Jim

[Mikey C]

Travel is important. More allows better boom squaring downwind. Ideally you want so much travel as to be able to get the boom out to near 90degrees....

I only ever had 8:1 on the main shroud bit, witha  single line system as Meds described for both shrouds on 16:1. The reduced purchase allowed a lot of travel.

[Jimbo41]

You mean on the leeward shroud? And you're talking about a carbon mast...

Surely too much travel means the mast bends to leeward, closing the slot and making the boat harder to keep upright, unless your'e on a broad reach?

Jim.

[davidgr (Guest)]

I think that we have 2:1 above deck, another 2:1 cascade below deck, going to a 4:1 to the mast foot, the 4:1 is then on another 2:1 under the centre board case, which I think gives a 32:1 on each shoud, with plenty of throw to square off the boom.

An innovation on our boat (pinched from our previous Crusader) is that the ends of the windward and leeward lines come out at the back of the centreboard case through some cleats and then inddividual blocks before being made off together to a trapeze handle.

The knot to the trapeze handle is such that you can dump both shrouds after you round the windward mark, and grab the handle to pull both shrouds to a preset mark at the leeward mark.

You can also pull some tension on if the run is looking a bit hairy!  Also make sure that you have a pin in the mast step.

Although generally we dump both shrouds on the run, on a reach it might be worth having the windward shroud tensioned enough to keep the mast straight and tighten up the forestay.  While the leeward side is slack, which will power up the main a little and allow the main to be squared off.

Hope that this helps,

David
3461

[John Meadowcroft]

there are two ways to really increase travel

the expensive option is to get tracks which the shroud base is attached to so that you can move the shroud base forward and back

the cheaper option which Tom Stewart has is a 3:1 purchase above deck rather than 2:1.  To get his overall purchase he requires he therefore has less purchases between deck and the mast base than he would if he had a 2:1.  As a result of less purchases he gets a longer 'throw'.

I have the former at the moment.  Next time I invest I will invest less and have the latter.

meds

[janeysailor12]

[quote Surely too much travel means the mast bends to leeward, closing the slot and making the boat harder to keep upright, unless your'e on a broad reach?[/quote]

Jim.....you and your crew hike out like mad to keep the boat upright, we have an ally mast on 3306 and we have enough travel to enable to get the boom out 90 degrees.  AND we have adjustable lowers too.  Why have you taken off the lowers???  sincee we removed the Mast ram and fitted them we've noticed quite a lot of improvement in the boat's performance. Not to mention the jib tacks much better across the foredeck without the mast ram.

Janey

[Jimbo41]