Sailing advice - mainsail lying on shrouds?

[colemj]

We have both a vang and a boom brake - works a charm for good off-wind performance with good jibe safety. In fact, jibing is so easy and controlled that we do it willingly.

Mark

[2Hulls]

Originally Posted by colemj

No way would I be locking the main to center when going downwind. That is a recipe for disaster - one good gust and wind shift and it could be all over quickly.

I think this is over-generalizing and over-simplifying things, Mark.

I agree that centering the main downwind isn't for every skipper or every boat. But it can have its place and is very useful in the right circumstances. One of those circumstances not to do it would be very gusty and shifty wind conditions. But not because a disaster is imminent but because it would be more trouble than it's worth to "edge" the main in those conditions. The disaster would be no worse - and probably not as significant - than an unintended gybe with the main prevented way over to one side.

What we call edging the main is particularly useful if you want to drop it. Say you reach a waypoint on a broad reach and have been using full main and spinnaker. Next course is dead down wind and the main will blanket the spi. Edge the main to bring it down, or deep reef it if you might want it later, and free up the spi for what it does best.

Dave

[Nicholson58]

Originally Posted by 2Hulls

I think this is over-generalizing and over-simplifying things, Mark.

I agree that centering the main downwind isn't for every skipper or every boat. But it can have its place and is very useful in the right circumstances. One of those circumstances not to do it would be very gusty and shifty wind conditions. But not because a disaster is imminent but because it would be more trouble than it's worth to "edge" the main in those conditions. The disaster would be no worse - and probably not as significant - than an unintended gybe with the main prevented way over to one side.

What we call edging the main is particularly useful if you want to drop it. Say you reach a waypoint on a broad reach and have been using full main and spinnaker. Next course is dead down wind and the main will blanket the spi. Edge the main to bring it down, or deep reef it if you might want it later, and free up the spi for what it does best.

Dave

This is a pretty normal racing technique especially on short legs. We used to call it "scavenging the main" or back-winding. This saved the pounding around on deck especially damaging to speed in light wind and the time to drop & hoist. In those days, we also ran a blooper. The main could be set up for the next leg before the spinnaker drop. I agree its a potential problem even on a monohull if crew is not available on their toes. I would think that if the main is not useful on log legs cruising it is probably best to get rid of it. Easy if you have mast or boom furling.

Photos show some centering of the main on our off-wind runs. If the wind is strong enough you can let the main out a bit but its better to fly the head sails. With a bit of planning, you can deflect wind into the upwind side of the spinnaker. In this way, the main's leech becomes the leading edge. Flattening helps the wind flow around the mast.

[2Hulls]

Originally Posted by Nicholson58

I would think that if the main is not useful on log legs cruising it is probably best to get rid of it. Easy if you have mast or boom furling.

Yes, fully agree. Most of our down wind cruising miles are sans main. Most cats have fully battened mains so the sail is happier with the leech as the leading edge. Good mainsail track hardware seems essential for downwind dropping. Because of the rating penalty and need for more crew, we have never used a spi racing on short courses - but those cats with a lot of crew seem to easily manage centering the main to free up the spi while keeping the main instantly available for the next leg.

Dave

[meirriba]

Originally Posted by Nicholson58

If your main is on the shrouds, you might as well pull out the outhaul & flatten the sail. This & vang will reduce the contact & chafe and let the boom be flown well out. Other than this, good suggestions are noted above. On my Tornado, I flatten the main and reach up a bit. The added speed well compensates for the grater distance.

Two issues with the above advice:
1. The vang advice is fine. However most production cats do not have one. It will help of course on models like Moorings cats that do have vangs.
2. On a Tornado, when you go a little upwind from running before the wind, you gain a large amount of speed and the result is net gain in VMG towards your target. That is not necessarily true for a heavy cruising cat. The small extra speed gained may result in a loss of VMG to a target downwind.
To find out if there is net gain or loss with this strategy it is advisable to prepare a full polar table for the specific vessel.

We usually sail downwind with a spi with the main too close to the center then it theoretically should be. This avoids the chafe on the shrouds and allows free air on the spi.

[2Hulls]

Originally Posted by meirriba

2. On a Tornado, when you go a little upwind from running before the wind, you gain a large amount of speed and the result is net gain in VMG towards your target. That is not necessarily true for a heavy cruising cat. The small extra speed gained may result in a loss of VMG to a target downwind.
To find out if there is net gain or loss with this strategy it is advisable to prepare a full polar table for the specific vessel.

It takes a very light cruising multi to make better VMG jibing downwind like a beach cat. The vast majority of cruising cats simply can't attain the speed necessary to bring the apparent wind far enough forward to make it worthwhile. But you still hear this myth being repeated quite often. My boat, generally considered more performance oriented, won't do it. Some wind instruments include calculators that compute VMG both upwind and downwind - this is the quickest way to verify that dead down wind will be your best VMG.

Dave

[pbr]

Originally Posted by colemj

I think this is over-generalizing and over-simplifying things. For example, our boat has soft PVC shroud covers and chafe patches on the battens. We regularly run downwind with the main pinned against the shrouds and have never experienced one small bit of chafe in 12 years.

It all depends on the boat and sail design and setup.

Many catamarans have proportionally small headsails, so there is a large range of wind and sea conditions between safely running a spinnaker and wallowing along under just a headsail. Much better to use both sails in this range, and setting up the boat to allow the main to operate fine is a good thing - not something to be avoided.

No way would I be locking the main to center when going downwind. That is a recipe for disaster - one good gust and wind shift and it could be all over quickly.

Mark

Correcto

[Nicholson58]

Originally Posted by meirriba

Two issues with the above advice:
1. The vang advice is fine. However most production cats do not have one. It will help of course on models like Moorings cats that do have vangs.
2. On a Tornado, when you go a little upwind from running before the wind, you gain a large amount of speed and the result is net gain in VMG towards your target. That is not necessarily true for a heavy cruising cat. The small extra speed gained may result in a loss of VMG to a target downwind.
To find out if there is net gain or loss with this strategy it is advisable to prepare a full polar table for the specific vessel.

We usually sail downwind with a spi with the main too close to the center then it theoretically should be. This avoids the chafe on the shrouds and allows free air on the spi.

You are sure right about the Tornado & VMG. The thing is so mast its always going into the wind.

[senormechanico]

Originally Posted by meirriba

We usually sail downwind with a spi with the main too close to the center then it theoretically should be. This avoids the chafe on the shrouds and allows free air on the spi.

We do the same with our Dragonfly trimaran.
Best downwind CMG is attained with a beam reach and gybing as necessary.

[beiland]

Originally Posted by doublewide

That said, the after shrouds do limit a cat's ability to trim for a most-efficient broad reach or run. Running, we douse the main and we sail under genoa or twin headsails, "wing-on-wing." Now that's a pretty sight!

Originally Posted by spiv

That's what I do when broad reaching.
When going downwind, I drop the main and use two headsails.
After 5y living aboard and crossing two oceans downwind, no wear on the main.

Roger both of those

[beiland]

Originally Posted by 2Hulls

The best response, so far, IMHO.

If your main is on the shrouds or spreaders you're unnecessarily chafing the sail. On a cat this is a signal to switch your downwind strategy and drop the main - or center it to the wind - and go with a sym spi or genoa/reacher/screecher. If you're cruising, why risk the wear and tear on the mainsail and aggravation of sailing downwind on the main with the risk of an accidental gybe?? A symmetrical spinnaker flown alone is a terrific sail for deep angles on a cat. No pole is needed and the thing essentially gybes itself. Child's play. In wind too high for cruising chutes, simply using a genoa or reacher with no main is very easy on the boat and crew. Several years ago on an 8 day passage from the Ches Bay to Tortola we didn't even raise the main for the first 6 days. It was a downhill sleigh ride with genos or sym spi. Very easy bluewater cruising.

Dave

And roger that.

There are those times that if the wind continues to rise steeply while sailing downwind, you may have waited until its too late to get that mainsail down easily that is pinned against the shrouds and the spreaders. Then you fight it down rather than risk turning back up wind, or gybing by accident.

[meirriba]

Originally Posted by beiland

And roger that.

There are those times that if the wind continues to rise steeply while sailing downwind, you may have waited until its too late to get that mainsail down easily that is pinned against the shrouds and the spreaders. Then you fight it down rather than risk turning back up wind, or gybing by accident.

I found it possible to turn directly downwind, center the traveler, and then by stages, ease the halyard a little and take in the reefing line until the reef is fully taken in. We have good battcars.
I have done it single handed (crew was asleep) from full mainsail to the second reef.

[colemj]

Originally Posted by meirriba

I found it possible to turn directly downwind, center the traveler, and then by stages, ease the halyard a little and take in the reefing line until the reef is fully taken in. We have good battcars.
I have done it single handed (crew was asleep) from full mainsail to the second reef.

Yes, we reef our main downwind single handed the same way. Center the main after turning down deep if necessary, ease halyard a bit, pull reef line, repeat until reefed and let main back out and resume course.

Mark

[beiland]

Didn't say reefing was impossible, just a slow, deliberate process that gets more difficult as the wind strength builds very quickly on some concerning times.

And its often not a single-handed operation unless you have some auto-pilot device to do the steering while you are reefing that main in step-by-step operations.

On the cruising rig (single-masted ketch) I have designed, there is no mainsail to worry about, and all 3 sails roller furl,....truly a one man rig
Sail Propulsion - Revisiting a Mast-Aft Sailing Rig

[paxfish]

The trick is just to go faster! Turn up wind a bit, get your speed up with sail trimmed for a reach and then fall off downwind as your boat speed comes up.

Notice around the 20 second mark, the sails are trimmed well off the shrouds, but the waves reveal we are heading nearly downwind....

https://www.youtube.com/watch?v=7vBKJrrUD8w