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Old 06-12-2021, 09:35   #1
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Headsail Furling

We are having a light, performance orientated, semi-custom, cruising catamaran built with a very innovative design.

One of the innovations we're considering is a headsail-only rig. The mast is stepped further aft and raked so that the CoE and CoLR will be balanced. This rig has lots of theoretical advantages:
- much less hardware
- no boom nor mainsail
- less chafing
etc. etc.

The key question is the whether or not we will be able to furl easily. Our designer has a concern that furling will be an issue with a large headsail and I have no experience to offer. The largest furling sail won't be that huge, (compared to a monohull of similar length the cat will be less than 1/4 of the weight with very narrow hulls hence no need for massive sails) and there are lots of much larger yachts that have huge furling headsails so why do they have a concern?

We will obviously be discussion in detail with the sailmaker however before that, does anybody have any thoughts, particularly those with experience on large yachts with big furling headsails?
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Old 06-12-2021, 10:32   #2
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Re: Headsail Furling

What happens to the coe and the colr when the sail area is reduced by 30%. Will you be able to hold the bows up without excessive helm?

Nothing constructive to add, just curiosity.
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Old 06-12-2021, 10:45   #3
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Re: Headsail Furling

Quote:
Originally Posted by markiobe View Post
We are having a light, performance orientated, semi-custom, cruising catamaran built with a very innovative design.

One of the innovations we're considering is a headsail-only rig. The mast is stepped further aft and raked so that the CoE and CoLR will be balanced. This rig has lots of theoretical advantages:
- much less hardware
- no boom nor mainsail
- less chafing
etc. etc.
the chafing is not really less and probably more in some cases. Maybe less hardware, but need larger pieces.

I dont understand how you will maintain balance (weather helm) beating upwind if you just roll away a headsail. So this is really not a very good idea for that reason only.

Further, with fewer control lines, you have a lot less control of your sails. It is not so simple as sheeting at a specific angle, because in different sea states, different sail arrangements, (eg sheet headsail tight and main loose on broad reach with larger waves) to maintain stability etc.
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Old 06-12-2021, 10:49   #4
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Re: Headsail Furling

@sailmonkey there will be at least one inner forestay with a couple of different sized sails for exactly that reason, in order to keep the balance. From a balance perspective it works fine in theory as long as you have an appropriate sail wardrobe with the stays positioned in the right place.
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Old 06-12-2021, 11:03   #5
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Re: Headsail Furling

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Originally Posted by seandepagnier View Post
the chafing is not really less and probably more in some cases. Maybe less hardware, but need larger pieces.
Not sure I agree. Most chafing occurs downwind on stays and mainsail. Yes larger hardware but given the boat is very light and easily driven we're not talking anything ridiculous.

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Originally Posted by seandepagnier View Post
I dont understand how you will maintain balance (weather helm) beating upwind if you just roll away a headsail. So this is really not a very good idea for that reason only.
See answer previously posted. In short it's a question of having the right sized sails on different stays to maintain the balance. I agree that this is critical and needs to be right. Also the whole boat would be built with this in mind so the CoLR of the hull is built to match the rig. It's not about putting this rig on a 'standard' hull, there's no way that would work.

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Originally Posted by seandepagnier View Post
Further, with fewer control lines, you have a lot less control of your sails. It is not so simple as sheeting at a specific angle, because in different sea states, different sail arrangements, (eg sheet headsail tight and main loose on broad reach with larger waves) to maintain stability etc.
In an overall sense I agree that you don't have as much sail shape control in theory as with a mast, however that's less to do with fewer control lines and more to do with the fact that you don't have a fixed thing to attach the sail to. Also that assumes that the mast bend fits the sail and there is knowledge on board in how to use the sail controls... In my experience that is lacking on most cruising boats. Also, unless you have a wing mast, for a given sail area a headsail is more efficient than a mainsail simply because you don't have round section screwing up the aerodynamics. Better efficiency = less sail area required = more safety.

You can still control a headsail very effectively with tracks and barber haulers etc if you know what you're doing.
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Old 06-12-2021, 11:26   #6
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Re: Headsail Furling

An interesting concept. It deals with one of the biggest drawbacks of cruising catamaran rigs on passages-- a large mainsail which is difficult to reef and unreef, and ends up being left at the smallest size expected.

Roller furling genoa systems are reliable and available for at least 100 m2 sails, so furling should not be a problem.

I used to sail my beneteau between anchorages on my 75 m2 genoa alone. The balance was good, pointing ability was within 5 degrees of the jib and main configuration, and it was easy to tack. However, the big difference was the mono's tendency to develop weather helm when it heeled, which counteracted moving the COE forward with a partially furled sail in heavier air.

I used the mainsail on passages, except for long downwind runs, where I put two genoas on the same furler and dropped the main.

You will probably want a masthead (twin) backstay to maintain forestay tension.

You will have some issues with chafe in light airs and sloppy seas as the sail slats. You might consider a light whisker pole or outriggers to stabilize the genoa under those (or just furl the genoa and turn on a motor.
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Old 06-12-2021, 14:08   #7
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Re: Headsail Furling

We would run this idea by the guys at Boatdesign.net. It will also help if you can provide drawings of the boat.
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Old 06-12-2021, 15:52   #8
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Re: Headsail Furling

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Originally Posted by markiobe View Post
@sailmonkey there will be at least one inner forestay with a couple of different sized sails for exactly that reason, in order to keep the balance. From a balance perspective it works fine in theory as long as you have an appropriate sail wardrobe with the stays positioned in the right place.
Will this not make tacking/gybing the huge genoa a problem? Having to roll it up for such maneuvers is a PITA (as I've learned all too well on our Solent rigged boat).

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Old 06-12-2021, 19:05   #9
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Re: Headsail Furling

@markiobe,

We met a guy (well known in catamaran circles here in Australia), John Hitch, who built a much larger Cat, "X-it", 55 ft., iirc, with such a sail configuration. Upwind, our mono went closer to the wind, and faster, but he wasted us on other points of sail. Some years later, the boat was sold.

I will go over to the multihull thread and put a link to this thread, because I suspect that their community may be able to give you more usable feedback.

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Old 06-12-2021, 19:25   #10
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Re: Headsail Furling

Well, I do know a guy started experimenting with such a concept and ended up using a flying lateen rig. Some of what he's done and learned might be applicable to your rig.
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Old 06-12-2021, 19:30   #11
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Re: Headsail Furling

I think John Hitch's rigs on the Hitchhikers usually had a forestay to each hull originally.
Actually here's his big boat...
https://yachthub.com/list/boats-for-.../custom/268254
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Old 06-12-2021, 20:40   #12
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Re: Headsail Furling

I talked to John about X it. He liked it and it worked well for deep downwind sailing. But I wouldn't want one. It was fast, but it was very big and incredibly thin hulled - you can't point to the rig as the reason it sped along.

After spending over 15 years getting patents and making very innovative catamarans (my hands have paint on them right now because of working on the small cat) I would warn anyone from doing large innovations without huge experience. There is a reason most people don't do something brand new - it is because it probably doesn't work. Small progressions are fine, but massive changes are fraught with bad potential.

The OP mentions that headsails are more efficient - but they are not. If fact large genoas are very inefficient - which is why they are rarely seen on racing boats, and never on fast multis - reachers and screechers for downwind, but when the wind blows up, short overlap headsails and mains are all you see.

The plan form for a genoa is a triangle which is about the worst shape in aerodynamics. Then you have headstay sag, which on this rig will be increased. And with no main to increase foreasty tension the sag will be even greater. Also both rigs require a mast, but the effects on the main are small and the main saiplan can be elliptical or even square top increasing main efficiency and reducing parasitic drag. The mast will not sag to leeward in gusts, like a forestay and the main can even depower itself in gusts, whereas a genoa, especially a large one just gets fuller when you don't want it to.

Mast aft rigs were introduced by Prout decades ago and slowly they morphed into more normal rigs. Problems with reefing mains downwind can be overcome by getting rid of spreaders (use a 3 stay a side rig) and putting nice slides on. Going upwind without a main is pretty hard to do, getting sufficient forestay tension on mast aft rig is hard because of the larger J measurement compared to the aft sweep of the shrouds. So by going large with the genoa you reduce the effectiveness of the genoa itself. I was on board a 40ft cat with an aftish mast rig the other day (it had a main). The forestay was pretty loose but the shrouds were very tight. It is impossible to get high tension on the forestay (without overloading the shrouds) because of simple trigonometry unless you over engineer the mast and shrouds.

Also our boats are not fast enough to do without the beneficial interaction of main and jib upwind or reaching.

As for problems with chafe - I still have my original 21 year old main and altough it needs replacing sometime soon, it is in nice shape and free from chafe. Chafe is not a reason to totally change the rig.

I guess that my words of warning will not be heeded. When I came up with my new cat design 20 years ago, no one could have talked me out of it. I had been around multis for 18 years and had sailed lots of different boats. Same with all the innovations in my larger cat. Most of the major innovations have been removed from the large cat, and if I could go back in time and slap myself in the head and say "Don't build crazy new things, just refine a little" I would jump at the chance. There is so much work in getting something custom built, getting it wrong and redoing it, over and over again.

I had so much eagerness to try something new. It cost me huge amounts of time and lots of money. My advice for the OP is to drop the rig innovation. Or at least try it on a small cat, or talk to John Hitch, he is very approachable, or do lots of sailing on a range of cats. Most new innovations are silly, and waste money. Most working innovations have been done before - my wishbone is old tech, as is the three stay a side rig and the pivoting engine pods. I just refined them slightly to make them work better.

John Hitch drew an amazing new structure for his boat Wired in the 80s. He got an old beach cat and tried it out on this test bed (Flight of Fancy) first. Adrian Rogers wanted to make a fast cat schooner - he made a small version first to prove it (He then built Shotover 2 and it was super fast). These guys really knew their stuff, had built many boats before, were already legends in Oz multis and still they built small test versions before they went full size. To do otherwise is to risk huge amounts of timer and money.
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Old 06-12-2021, 22:35   #13
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Re: Headsail Furling

Markiobe I know of another Hitch Hiker catamaran that changed from a normal sloop rig to a mast in the cockpit and all headsail. A few years later I noticed he had changed back to a sloop rig. I never spoke to him about the change back but I bet it cost a few bucks.
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Old 07-12-2021, 00:16   #14
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Re: Headsail Furling

John Hitch of HIOTCHIKER catamarans fame tried this with EXit, had three headsails and no main.
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Old 07-12-2021, 02:45   #15
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Thumbs up Re: Headsail Furling

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Originally Posted by donradcliffe View Post
An interesting concept. It deals with one of the biggest drawbacks of cruising catamaran rigs on passages-- a large mainsail which is difficult to reef and unreef, and ends up being left at the smallest size expected.
This is one of the biggest reasons for the idea

Quote:
Originally Posted by donradcliffe View Post
Roller furling genoa systems are reliable and available for at least 100 m2 sails, so furling should not be a problem.

I used to sail my beneteau between anchorages on my 75 m2 genoa alone. The balance was good, pointing ability was within 5 degrees of the jib and main configuration, and it was easy to tack. However, the big difference was the mono's tendency to develop weather helm when it heeled, which counteracted moving the COE forward with a partially furled sail in heavier air.
Makes sense, and obviously the effect would need to be studied on a cat that heels very little. This again talks to the idea of reducing sail by changing to an inner forestay rigged sail as on the cat you wouldn't have the heeling counteracting the potential lee helm.

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I used the mainsail on passages, except for long downwind runs, where I put two genoas on the same furler and dropped the main.
We were discussing the idea of a 2-skinned headsail which, in addition to being used in the normal way, you could attach a sheet to both skins and then sheet both sides of the centreline like butterfly wings for deep downwind sailing. I think this exists already by a few sailmakers.

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You will probably want a masthead (twin) backstay to maintain forestay tension.
Yes, I think so too. otherwise with no main you'd struggle to maintain forestay tension in a breeze

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Originally Posted by donradcliffe View Post
You will have some issues with chafe in light airs and sloppy seas as the sail slats. You might consider a light whisker pole or outriggers to stabilize the genoa under those (or just furl the genoa and turn on a motor.
Makes sense
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