Multihull rigging - basic questions and ideas

[fxykty]

Regarding sizing your cap shrouds for Dyneema, you should already have your NA’s load calculations for maximum working load and breaking strength for the wire shrouds. 1/2” sounds about right (that’s what our 54’x23.5’x23000# cat had in 1x19 cap shrouds). But you are adding height and sail area, so hopefully you have the figures for your planned rig, not just the existing rig. Dyneema is sized for creep at a certain load, which would be the calculated maximum working load of the new rig. That will end up heaps (5x or so) stronger for breaking strength. As an example, we went from 12mm 1x19 wire to 18mm Dyneema Dux. Colligo’s web site has tables for this. An experienced synthetic rigger should also be able to tell you how short to make your splices to allow for constructional stretch and the initial tensioning. Our 18m shrouds (whose eye splices were load set to 1/3 breaking strength before putting on the mast) stretched about 150mm as we tensioned them on the boat. Since then 2 years ago, less than 6mm.

Life is hard to estimate but generally 6-8 years, with reports of 10+ years. Could be less than SS wire, but subsequent replacements are less expensive than wire.

Don’t forget to replace the mast fittings and get fittings specific for Dyneema. Colligo is a good resource for ideas and components.

Your mast isn’t rotating, so definitely turnbuckles. You will have around ~4t static tension on your shrouds and twice that when loaded.

Don’t consider synthetic for your diamond wires - too much chafe and much less tolerance for incorrect tensions.

You will want at least two winches for your mast and boom lines - e.g. for slab reefing you’ll want one winch for the halyard and another for the clew line. Juggling loaded lines on one winch is a PITA and slow.

Lines coming out of clutches shouldn’t have much angle at all - that Seawind photo is an awful setup. Add one or two crossover blocks like this https://www.harken.com/en/shop/crossover-blocks/ (for a centrally mounted winch) or deck organiser like this https://www.harken.com.au/en/shop/deck-organizers/ (for two winches to either side) so that every line comes out of its clutch at minimal angle (typically only 4-5 clutches can service one winch).

We have 2x 2:1 mainsheet on a traveller and 54 ratio winches on either side. At full upwind loads we’re maxed out.

Just remember that easing the mainsheet isn’t always the right thing to do to prevent a capsize - turning the boat hard with a tight sheet may be more appropriate at angles greater than 60-70* AWA.

[Benz]

Harken makes an open horizontal sheave that mounts to the deck, designed to be used as a fairlead to a single winch from a clutch bank. You just whip the line in question onto it, put on the winch, and go.
I recommend soft clutches--they're relatively new, but lots easier on your ropes than ordinary clutches and jammers.
I would recommend Dyneema: either Dynice Dux or Marlow's DM20. For absolute top-of-the-line, Maffioli's Ultrawire can't be beat. Use the same BL Dyneema as wire, or go up a size: the weight savings will more than compensate for extra windage.
If you use Colligo terminators, the lashing is as easy as lacing your shoes-you feed the line through a bunch of holes in succession. Having both a lanyard (lashing) AND a turnbuckle is pretty stupid--why have two tensioning methods? Use one or the other; I recommend a lanyard.
Take a look at any Gunboat. How many of them have turnbuckles? You can run the fall of the lanyard to a winch and get all the tension you need.
As for halyard dimensions: you should calculate the load on the sail luff when properly tensioned (a sailmaker can tell you that), then add whatever safety margin you like, and find a dyneema-cored rope that matches. My guess would be not bigger than 9/16" for a one-part, or 7/16" for a 2-part.
A look at the sheave size will tell you what diameter was used before, and serve as a guide.

[smj]

Originally Posted by Benz

Harken makes an open horizontal sheave that mounts to the deck, designed to be used as a fairlead to a single winch from a clutch bank. You just whip the line in question onto it, put on the winch, and go.
I recommend soft clutches--they're relatively new, but lots easier on your ropes than ordinary clutches and jammers.
I would recommend Dyneema: either Dynice Dux or Marlow's DM20. For absolute top-of-the-line, Maffioli's Ultrawire can't be beat. Use the same BL Dyneema as wire, or go up a size: the weight savings will more than compensate for extra windage.
If you use Colligo terminators, the lashing is as easy as lacing your shoes-you feed the line through a bunch of holes in succession. Having both a lanyard (lashing) AND a turnbuckle is pretty stupid--why have two tensioning methods? Use one or the other; I recommend a lanyard.
Take a look at any Gunboat. How many of them have turnbuckles? You can run the fall of the lanyard to a winch and get all the tension you need.
As for halyard dimensions: you should calculate the load on the sail luff when properly tensioned (a sailmaker can tell you that), then add whatever safety margin you like, and find a dyneema-cored rope that matches. My guess would be not bigger than 9/16" for a one-part, or 7/16" for a 2-part.
A look at the sheave size will tell you what diameter was used before, and serve as a guide.

Dyneema is not sized by breaking load it’s sized by the creep in the line, which should give you 2-3 times the strength of 1x19 ss.
Colligo recommends using turnbuckles on all boats over 30’ unless using rotating rigs, Kraken recommends over 40, as they both believe your unable to get the tension needed without the turnbuckle.
We have a rotating rig on a 40’ catamaran and also had a new set of turnbuckles. Kraken determined it would be advantageous to use both lashings and turnbuckles on our rig as the lashings can set the approximate desired tension, then the turnbuckles are there for fine tuning. I’m glad we went this route.

[Chotu]

OK guys. My mind is blown. There is definitely smoke coming out of my ears right now. This is a good conversation. It’s always been a weak spot for me.

I am carefully considering every single post and all of the information here. It’s going to take me a little while to digest and learn this stuff.

I did want to point out, however, and that I am not extending the mast beyond the plans. I am extending the mast TO the plans. So everything is the right size already. The mast was shorter than the plans.

I am extending it to the same size as the mast on Grit‘s boat. that way we can have one design races together. Ha ha ha. gentlemanly races. Just to see how our boats work. We will see if I can talk him into it. I think he’ll definitely win. But it would be fun trying.

so as I was saying in the first post, nobody should be getting hung up on the mast extension. Just ignore that. Just making it the right size.

[GRIT]

Originally Posted by Chotu

OK guys. My mind is blown. There is definitely smoke coming out of my ears right now. This is a good conversation. It’s always been a weak spot for me.

I am carefully considering every single post and all of the information here. It’s going to take me a little while to digest and learn this stuff.

I did want to point out, however, and that I am not extending the mast beyond the plans. I am extending the mast TO the plans. So everything is the right size already. The mast was shorter than the plans.

I am extending it to the same size as the mast on Grit‘s boat. that way we can have one design races together. Ha ha ha. gentlemanly races. Just to see how our boats work. We will see if I can talk him into it. I think he’ll definitely win. But it would be fun trying.

so as I was saying in the first post, nobody should be getting hung up on the mast extension. Just ignore that. Just making it the right size.

Sounds like fun! I'm in!

Cheers.
Paul.

[Cpt Mark]

Been following your journey/sage for several years now. So happy you're coming to the end.

I went with synthetic rigging. On a cat it only makes sense.

My Cat is 35 x 15. A bit smaller than yours lol. I have 2 main winches forward on either side of the companionway. 1 is electric, the other not. I have 2 winches aft for the genoa/spinnaker. All lines are long enough to get to the electric winch.

I'm installing new Garhauer deck organizers and clutches. 4 lines per side. I can take the the lnes from one side and pass them around the non electric winch to the electric winch. Works reasonably well.

As far as deck organizers go. I'm thinking G10 epoxied (I know you can't do this but maybe polyesther resin or hire it out? directly to the cabin top deck and a lot of fiberglass further securing it. No holes in the boat.

Reefing. I can bring all the lines back to the cockpit. Thinking dyneema line and single line reefing might be nice. The issue as I understand it is friction as you reef down as the single line travels through all the places it needs to go. Dyneema would reduce this a lot and as long as I could get it to the electric winch, that should be fine. Alternatively, installing some patches and blocks on the main sail would go a long way too. Dyneema will be replacing the core in a rope and sized appropriately

[Benz]

Originally Posted by smj

Dyneema is not sized by breaking load it’s sized by the creep in the line, which should give you 2-3 times the strength of 1x19 ss.
Colligo recommends using turnbuckles on all boats over 30’ unless using rotating rigs, Kraken recommends over 40, as they both believe your unable to get the tension needed without the turnbuckle.
We have a rotating rig on a 40’ catamaran and also had a new set of turnbuckles. Kraken determined it would be advantageous to use both lashings and turnbuckles on our rig as the lashings can set the approximate desired tension, then the turnbuckles are there for fine tuning. I’m glad we went this route.

Colligo sizes by creep because they're still using heat-set SK75, which creeps. The DM20 I recommended above does not creep as much, if at all, so to size it to the same BL as wire is fine, and doesn't get you all super-thick. As for not being able to get sufficient tension with a lanyard, well, I guess Colligo and Kraken don't rig Gunboats, but the latter seem to achieve wicked tension with just a lashing--it's just a matter of mechanical advantage, unless there's a hidden mast jack under there I've never seen. I've always just led the fall of the lashing back to a winch and hove it tight.

But to Chotu: you might want to split this thread into several, since it'll get confusing discussing halyard sizes at the same time as standing rigging and clutch banks.

[smj]

Originally Posted by Benz

Colligo sizes by creep because they're still using heat-set SK75, which creeps. The DM20 I recommended above does not creep as much, if at all, so to size it to the same BL as wire is fine, and doesn't get you all super-thick. As for not being able to get sufficient tension with a lanyard, well, I guess Colligo and Kraken don't rig Gunboats, but the latter seem to achieve wicked tension with just a lashing--it's just a matter of mechanical advantage, unless there's a hidden mast jack under there I've never seen. I've always just led the fall of the lashing back to a winch and hove it tight.



But to Chotu: you might want to split this thread into several, since it'll get confusing discussing halyard sizes at the same time as standing rigging and clutch banks.

I haven’t heard of the DM20 but looks interesting.
Gunboats came with both a fixed mast or rotating. Maybe the Gunboats you’ve seen rigged with dyneema shrouds have the rotating mast as it doesn’t require much tension. The Gunboats with the fixed rig appear to use carbon shrouds and turnbuckles.

[fxykty]

Originally Posted by Benz

Colligo sizes by creep because they're still using heat-set SK75, which creeps. The DM20 I recommended above does not creep as much, if at all, so to size it to the same BL as wire is fine, and doesn't get you all super-thick...

https://www.hampidjan.co.nz/product/dynice-yachting/

Dyneema DUX doesn’t creep much but enough that it needs to sized for creep. DM20, which is also sold as Dynice Perma, has much less creep but is considerably less strong, so is sized by breaking strength instead.

Hampidjan’s sizing guide for Dynice Perma: “under 20% load at 20°C the permanent elongation in this new type is below 0,5% over period of 25 years.” Interestingly, the traditional creep recommendations for DUX in standing rigging is working load about 25% (4:1) of breaking strength. So let’s halve the creep factor for Dynice Perma as we don’t need 25 years, to 2:1.

Assuming a 50’ cat (slightly smaller than ours) requires 8t maximum working load for standing rigging (ours is 10t), that yields a spliced breaking strength sized for creep control in the order of Perma 16t and DUX 32t.
- Dynice Perma: 14mm diameter 18.2t spliced breaking strength
- Dynice DUX: 16mm diameter 33.5t spliced breaking strength

It’s not much of a reduction in diameter, but would be slightly less cost. You can of course juggle the safety factors as recommended by experienced synthetic riggers, which I believe Benz is. He recommends same breaking strength as wire (the 50’ cat would typically be rigged with 12mm or 14mm wire with minimum breaking strengths of 10.6t and 13.4t respectively for a 50’ cat), so that produces Dynice Perma 11mm/11.1t or 12mm/13.7t (respective spliced breaking strengths). Definitely a big reduction in diameter now - less than the wire it replaced!

But for cruising purposes I’m not sure if a less than 2:1 safety factor for standing rigging (or even running rigging) is sufficient, as we want to account for chafe and UV damage over time.

Interestingly, the 14mm 1x19mm wire cap shrouds that we replaced with DUX had a minimum breaking load of less than a safety factor of 2. Our 18mm DUX cap shrouds have a spliced breaking strength of 40.6t with a safety factor of 5. That’s comforting.

[Benz]

Originally Posted by smj

I haven’t heard of the DM20 but looks interesting.
Gunboats came with both a fixed mast or rotating. Maybe the Gunboats you’ve seen rigged with dyneema shrouds have the rotating mast as it doesn’t require much tension. The Gunboats with the fixed rig appear to use carbon shrouds and turnbuckles.
Attachment 264957

The Gunboats I've seen have carbon (ECsix) shrouds and lashings: both the fixed and rotating. I've tensioned some of the standing rigging on a Gunboat or two; I simply led the fall of the lanyard to a winch. No doubt some have turnbuckles--there's lots of Gunboats out there now, and every owner modifies his to make it "his." Not always an improvement.
Thing about catamarans is you don't need that bowstring-tight tension a marconi-rigged monohull does: the jumper stays keep the mast in shape, and the shrouds only have to keep the mast upright with a generous, wide staying angle.

[smj]

[QUOTE=Benz;3684544]The Gunboats I've seen have carbon (ECsix) shrouds and lashings: both the fixed and rotating. I've tensioned some of the standing rigging on a Gunboat or two; I simply led the fall of the lanyard to a winch. No doubt some have turnbuckles--there's lots of Gunboats out there now, and every owner modifies his to make it "his." Not always an improvement.

Thing about catamarans is you don't need that bowstring-tight tension a marconi-rigged monohull does: the jumper stays keep the mast in shape, and the shrouds only have to keep the mast upright with a generous, wide staying angle.[/

Which is pretty much what my previous post stated? Correct?

[fxykty]

Originally Posted by Benz

…

Thing about catamarans is you don't need that bowstring-tight tension a marconi-rigged monohull does: the jumper stays keep the mast in shape, and the shrouds only have to keep the mast upright with a generous, wide staying angle.

The mast not only has to stay upright with no sail loads, but has to stay upright with dynamic sail loads. You want the cap shrouds tensioned enough so that the leeward cap shroud goes soft but doesn’t flap around when the rig is fully loaded (basically at the reefing wind speed), and when the rig loads spike such as punching though or falling off a wave.

Turnbuckles handle this tension and can easily be precisely adjusted. Lashings not so much for higher loads, but YMMV.

This has nothing to with keeping the mast in column, which is what the diamond and/or jumper stays do, or if it’s a spreader-less carbon rig that holds itself in column.

[Benz]

[QUOTE=smj;3684566]

Originally Posted by Benz

The Gunboats I've seen have carbon (ECsix) shrouds and lashings: both the fixed and rotating. I've tensioned some of the standing rigging on a Gunboat or two; I simply led the fall of the lanyard to a winch. No doubt some have turnbuckles--there's lots of Gunboats out there now, and every owner modifies his to make it "his." Not always an improvement.

Thing about catamarans is you don't need that bowstring-tight tension a marconi-rigged monohull does: the jumper stays keep the mast in shape, and the shrouds only have to keep the mast upright with a generous, wide staying angle.[/

Which is pretty much what my previous post stated? Correct?

It seemed you were saying that only the rotating rigs required less tension. Apologies if I misunderstood.
I believe that even on a non-rotating catamaran rig, sufficient shroud tension can be achieved with a lanyard.

[tomtriad]

You might benefit from joining the FB group Sails & Rigging. It's populated by experienced pros and amateurs. Lots of good info there, also sources for materials:
https://www.facebook.com/groups/sail...ing/?ref=share

[blubaju]

42' Schionning Wilderness Catamaran, 2010, all 10mm Dyneema (German brand), for safety outer shrouds changed 2 years ago, could not break at 8000kg test, safe load is (was?) 10000kg. All chainplates formed into hull carbon fiber. No turnbuckles. Here is a great site to learn soft shackles and dyneema rigging: https://l-36.com/soft_shackles.php