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Old 13-07-2015, 17:51   #16
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

I think you mean by "dumping the main" releasing the main sheets to let it flap. Can't you just round up into the wind? Then you could drop the main if necessary. I use a 4 or 5 mm spectra line as a downhaul on the main. It goes from the top sail slide i.e. below the headboard ( to prevent twisting the head board ) then down and back to the cockpit and a jammer. I also have a small slack loop at the top with a sail hank onto the halyard eye to retain the halyard in case the shackle comes undone. I can pull the main down into the stack pack without leaving the cockpit. It's not a new idea Joshua Slocum had down hauls when he sailed singlehanded around the world in 1896/7 in Spray. You also need to pay out the line as you hoist, and then tighten it to stop it blowing back. It just sits there alongside the mast as you sail not flapping or doing any harm. You don't need a stack pack for it to work. Slocum didn't have one.
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Old 14-07-2015, 08:13   #17
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

Rounding up into the wind is a big no no for multihulls because it introduces a overturning moment.
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Old 14-07-2015, 11:28   #18
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

Thanks to all.
Good thaughts.

Will use the attached on Pt & Stb & add a downhaul as well.
Allows for faster reaction in a rush.

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Old 14-07-2015, 15:33   #19
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

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Rounding up into the wind is a big no no for multihulls because it introduces a overturning moment.
Right I get that about multihulls from having sailed small ones. I didn't read carefully enough to see that we are talking about a multihull. A friend capsized his Great Barrier Express cat in Auckland harbour because he couldn't release his boom vang quickly enough due to a gust from between hills. My suggestion about having a main sail downhaul still applies, though after coping with the surprise gust. Also more importantly reefing early in anticipation. A few years ago I was wandering a marina on the lakefront in Toronto. There was not much wind and a monohull was trying to sail out between the island with the airport. Suddenly out of a clear blue sky and within 5 minutes it was blowing a recorded 55 knots from the west for a couple of hours damaging the Skydome roof. The yacht had dropped their main a couple of minutes earlier and turned back. They either saw it coming or received a radio warning. Anticipation if possible.
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Old 15-07-2015, 09:16   #20
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

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Originally Posted by GrahamHO View Post
Right I get that about multihulls from having sailed small ones. I didn't read carefully enough to see that we are talking about a multihull. A friend capsized his Great Barrier Express cat in Auckland harbour because he couldn't release his boom vang quickly enough due to a gust from between hills. My suggestion about having a main sail downhaul still applies, though after coping with the surprise gust. Also more importantly reefing early in anticipation. A few years ago I was wandering a marina on the lakefront in Toronto. There was not much wind and a monohull was trying to sail out between the island with the airport. Suddenly out of a clear blue sky and within 5 minutes it was blowing a recorded 55 knots from the west for a couple of hours damaging the Skydome roof. The yacht had dropped their main a couple of minutes earlier and turned back. They either saw it coming or received a radio warning. Anticipation if possible.
Reef for the gusts....

The old style pivot vang that attached to or near the mast base does keep the boom down when the mainsheet is let go. Both the center mainsheet system with the beam vang/preventers and the double mainsheet system allow the boom to kick up when released getting rid of power more quickly. I'm attaching a sketch to demonstrate.

Interestingly I found both systems use about the same amount of line, the continuous vang preventer run to the outer beam came out to be the length of the 4 part centerline mainsheet. It only needed 2 inexpensive single blocks though, making it a bit more economical. I tell people I'm inexpensive, not cheap but there has been some debate. I found that setting the vang then using the mainsheet tackle to take the twist out meant not needing secondaries for the vang. There are many ways to rig both systems.

One advantage of the centerline mainsheet is its easy and quick to center the boom for windward work or short tacking. Vangs off, pull in one line. Same with light air jibing. Last weekend I was in a narrow channel rounding an island and the land contours made the wind shift every 20 seconds. I kept the vangs off and jibed with the changes keeping in the center of the channel with the mainsheet not needing to be changed for each side. The same could be done on a double mainsheet system by careful setting of each side.

Both the systems do give more power to the main with better twist control than the old pivot vang. I was surprised at the difference.

For safety in a big gust after dumping the main you should be releasing the jib. If you only have time to do 2 things those are the ones. Remember not to have the windward vang/preventer cleated for safety.
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Old 15-07-2015, 09:57   #21
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

The concern seems to be capsize, and you are concerned about the one-time cost of a traveler? Seems more important to basic safety than rafts, PFDs, EPIRBs, and anchors. Monos are different, and I can see the utility of the system.



I've sailed nothing but cats for 30 years and I don't get it.
  • Reef early. Basic flattening is also obvious.
  • Round head up when that makes sense (close hauled only).
  • Play the traveler in the gusts. MUCH easier that playing the main sheet in most conditions, though not as dramatic. And now reef.
  • Have ready access to dump main and traveler if needed, but you really should have anticipated better than that. In other words, you goofed up.
  • Vang is not needed. It can be helpful if running very deep, but is better served by an adjustable preventer that is attached only when the apparent wind is well aft (rare on most multis). And a wide traveler that is locked down at the end is already a pretty effective preventer, BTW.
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Old 15-07-2015, 10:10   #22
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

Horses for courses, a full width traveler wouldn't work on my boat without heavy, expensive reconstruction. And the system described works great, very easy to use. The traveller is really a unnecessary expense for the cruiser as you shouldn't have enough sail up to need to play the traveler. If you do play the mainsheet it works fine as small releases are all that is needed for most depowering because the boom kicks up. Hmmm, less clutter, expense,weight and similar performance...
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Old 15-07-2015, 10:53   #23
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

Regarding my opening post.

I fully agree.

On a cat:

  • Reef early enough is surely best.
  • Round up if sailing upwind.
  • Bear away if true wind is aft in a sudden squall.
  • Roller furling jib is helpful, but optional.

Apart from that.
By keeping the double mainsheet system I can control the boom position almost as good as with a traveller but at a fraction of the cost to refit one.
Leading the mainsheet to the steering position allows the required quick dump, if in a squeeze.
See post #18

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Old 15-07-2015, 11:15   #24
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

The double mainsheet system is a good one. Your setup looks good. I think you have better sail control than with a traveller due to being able to apply force in 3 directions rather than 2. Dumping the main is just as easy unless the boom is way out but I doubt it would be able to go past where the leeward sheet is vertical without the main hitting the shrouds anyway.
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Old 15-07-2015, 11:44   #25
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

Your diagram looks perfect. I like the twinsheet system and have converted a few boats, all owners are very happy, and some can lie down in the cockpit now...

Only change I would make is to have the line continuous, meaning less line, as one gives, the other takes away. Also have snap-shackles on the lower ones, so you can move them around for different reasons, like Sailing Downwind (move one forward as preventer) Parties (Clip onto drunk friend and pull out of canal) Get it out of the way at anchor...etc.
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Old 15-07-2015, 14:17   #26
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

Not sure if endless is achievable in terms of one side gives and one takes.
After all you need to be able to play both sheets to control sail twist.

Basically you have two lines to control here two sheets. Similar as you would have with a single mainsheet and a traveller control.

If you have enough forward momentum you can center the main and leave it mostly untouched when tight tacking.
Keeping the jib/genoa on the old bow until she really completed the tack helps of course too.
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Old 18-07-2015, 14:09   #27
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

We have a double mainsheet system and like it. When both sheets are tensioned against the topping lift the boom is locked in place, like having a boom crutch. We have a pendant attached to a mid-ships cleat on each side with snap shackles on the lower fiddle blocks on each sheet. This allows us to move the sheets outboard when running. Not only does this work as a preventer, but it also helps keep the mainsail off the shrouds. We have never had to release the sheets in a hurry, but the plan is to release the windward sheet, then the leeward sheet, then the outhaul, then the halyard if it should ever come to that.
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Old 18-07-2015, 18:02   #28
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

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We have a double mainsheet system and like it. When both sheets are tensioned against the topping lift the boom is locked in place, like having a boom crutch. We have a pendant attached to a mid-ships cleat on each side with snap shackles on the lower fiddle blocks on each sheet. This allows us to move the sheets outboard when running. Not only does this work as a preventer, but it also helps keep the mainsail off the shrouds. We have never had to release the sheets in a hurry, but the plan is to release the windward sheet, then the leeward sheet, then the outhaul, then the halyard if it should ever come to that.
Another option is to have a central main sheet (not necessarily on a track) and use a another removable purchase with snap shackles to set out on the rail on either side depending on the conditions. It can be used to windward or leeward or taken forward on the deck as a preventer when running. My main sheet is on a track but I also have a removable "handy billy" purchase similar to a main sheet. It's also useful when at anchor to keep the boom from rocking around.

It's just another option which may suit some sailors. When doing short tacks it's not used so the main sheet doesn't need adjusting.
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Old 18-07-2015, 18:20   #29
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

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Horses for courses, a full width traveler wouldn't work on my boat without heavy, expensive reconstruction. ....
Fair enough, just not my taste.

The suggestion to move the cleats to an accessible location seems most practical.

Something missing on many cats with self-tailing winched mains is a cam cleat to park the tail when it is breezy. It takes too long to fool with the self tailer.
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Old 18-07-2015, 21:26   #30
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Re: Does anyone know of a good quick system to dump the main with a double mainsheet

I was wondering if anyone would remember travelers were once called horses.
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