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Old 07-03-2013, 03:39   #76
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Re: 440 Sailing with Gib only and no main sail

At the end of the day good seamanship and common sense should prevail, based on the weather conditions at the time and the projected forcast. I started this thread some months ago and it has been very interesting so see the expanse of input. Looking at the film strip of Poco Loco and the recommendations from Lagoon, the rig should already be in a heap around the crews ears. These are all judgment calls based on as I said good seamanship and experience.
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Old 07-03-2013, 03:40   #77
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We used jib only in an urgent situation at 35 to 40 knots for about 45 mins, all worked out so thatbwas a bit of a test
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Old 07-03-2013, 03:43   #78
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Re: 440 Sailing with Gib only and no main sail

All in all yachts are yacht, if a boat of this class cannot hold a headsail up as we've discussed quite frankly the rig isn't worth crap, and i'd be re-rigging it if i judged it as deficient in that way.

Cheers all POCO is doing it easy!
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Old 07-03-2013, 04:12   #79
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Originally Posted by Lagoon4us View Post
All in all yachts are yacht, if a boat of this class cannot hold a headsail up as we've discussed quite frankly the rig isn't worth crap, and i'd be re-rigging it if i judged it as deficient in that way.

Cheers all POCO is doing it easy!
Agree totally, so under strong winds you tear a main and your rig is a chance of coming down? I dont think so.
We blew the main in 35 knot tailwinds kept sailing for 12 hrs with 1/2 of what was left and the jib ,no problems at all.
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Old 07-03-2013, 12:15   #80
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Interesting U-tube clip of POCO LOCO sailing in sloppy conditions during the recent ARC (i believe).

Off the wind there should not be huge loads on the mast, on the wind yes there'll be compression loads.

Watch the clip, see what you think...
Yes, this is from the ARC 2012. We sailed our Lagoon 450 in it too. We ripped out both our Paralsailor halyards attachment from the mast (rigged double halyard for safety ) after 72 hours of continuous flying. After that we used mostly 3rd reef main (to reduce load on the moaning autopilot) and genoa, or just the genoa, often furled at night as that is when the squalls came through with 35+ knots.
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Old 07-03-2013, 12:47   #81
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I was caught by the subject matter under discussion here. Not because I own a cat, 'cause I don't, but because a link was in the right margin of the OpenCPN discussion forum.

The effect of sailing with jib only on rigging is an important consideration, but I believe daddle hit the nail on the head.

"Might be the mast issue. But one of my concerns with jib only sailing is de-powering in an unexpected squall or gust. There can be situations where there are no good quick options. With a main up one has many more options because of the main's better"

Never having sailed a cat, I don't know what measures are available - or how vulnerable a cat is to capsizing in extreme conditions with big waves if forced to lie ahull without a mainsail. A monohull is definitly at risk in such conditions if there is no main up with which to properly heave to. Considering the challenge of raising a main going downwind, and the hazard of a possible broach while turning into the wind in attempt to facilitate getting the main up (even worse if your motor is disabled), it is definitely good seamanship to always be carrying at minimum a double reefed main. If the presence of a main overworks the servopendulum wind steering gear or electric autopilot, then going to a third reef is always an option. The main can also be sheeted nearer to the center line to present a smaller profile to the wind.

Anyone who has ever seen an aerial video of a Coast Guard rescue underway, with the vessel under distress with a bare pole rolling violently ahull to the waves, totally out of control - understands the problem.

armido
This thread is really about genoa with or without main on a Lagoon, but the safety issues came up a few times.

When running with a catamaran, it makes it much more difficult in a unexpected gust with the main up. Catamarans have the spreaders swept back at a deep angle because there is no back stay. Thus the main boom can only go out at max 45 degrees. The last thing you want to do when the wind is coming from the aft quarters, is to head into the wind. As you turn the apparent wind incases (the sail load goes up with the square of the apparent wind) and the momentum puts more heeling load on the downwind hull. The down wind bow may dig in during the turn and the cat capsizes. It is best to turn and run dead down wind. If only the genoa is up, just release the sheet completely if it is that dangerous. You may lose the sail.
With the main up you have to keep running ( see below) as you will have a hard time to reef or take the sail down. I did a main full take down from second reef middle Atlantic one night at 3am. It was not fun and I pulled a batten from a bat car and also ripped one other bat car from the luff. There was no way to turn into 15 waves and reef. It would have been a wild bronco ride at best and a capsize with the extra wind load and the high waves.

Consider this. 30 knots of true wind, sailing at 10 knots dead downwind gives you 20 knots apparent. Wind load equals 1.
Extreme case. You now turn upwind and the cat keeps the speed for a moment. The apparent wind goes from 20 to 40 knots. That is four times the load on the sails. Even if you only turn to 90 degrees apparent angle the wind goes from approximately to 40 knots which gives you 2.25 times the sail load. This does no consider the extra speed from the hull speed increase due to increased wind speed during the turn.
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Old 07-03-2013, 15:53   #82
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I have a great deal of trouble understanding the Lagoon explanation for number of reasons.

As a former structural engineer it's difficult to give credit to the argument that the mainsail, which places load on the mast, also serves to stiffen the mast. I would like to hear from an experienced designer engineer experienced in yacht structures. The mainsail might provide stiffness when sailing to windward and the sail is more or less in line with the mast, but downwind with the sail out to one side? I doubt it.

Secondly, it is common practice on yachts, and particularly cats to sail without the main. On a cat, the inability to set the main out far enough to be very useful due to the side stays and the blanketing of the headsail makes downwind sailing with the main unpopular. Given the likelihood that Lagoons will be sailed in this configuration, and the general awareness in the sailing community that this is a common practice, I cannot believe a designer would consider NOT allowing for this load condition. There is a duty of care and a vague statement in the owners manual is unlikely to absolve the manufacturer of the responsibility.

Lastly, where is the failure history? If this is indeed a design limitation on the 440, and it's clear that many are sailed downwind under headsail alone, of the hundreds built how many have failed? Maybe someone knows of a case, but if 440s were failing then I'm sure we would all hear about it pretty quick.

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Old 07-03-2013, 16:27   #83
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I agree with you, Bob. It all sounds too strange. Sailing downwind with your main up and the likelihood of squalls is crazy, especially in a cat. And it adds more strain and work to the autopilot, the opposite of a previous posters claim.

If it really is a concern to go downwind with no main, then add a couple of running backstays! Then you can feel really comfortable with a couple of large foresails or a huge spinnaker when you come down a wave and bury both bows. Leave the boom firm with a preventer, no main and a tightened topping lift and there should be no worries.
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Old 07-03-2013, 23:20   #84
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I agree with you, Bob. It all sounds too strange. Sailing downwind with your main up and the likelihood of squalls is crazy, especially in a cat. And it adds more strain and work to the autopilot, the opposite of a previous posters claim.

If it really is a concern to go downwind with no main, then add a couple of running backstays! Then you can feel really comfortable with a couple of large foresails or a huge spinnaker when you come down a wave and bury both bows. Leave the boom firm with a preventer, no main and a tightened topping lift and there should be no worries.
I believe what comes into play here is the following:

The tension of the shrouds and the forestay puts a lot of compression load on the mast. This is like placing a several ton piece of concrete on the mast. The swept back spreaders pretend the middle of the mast forward. Hoisting the main sail will pull some of the prebend back aft, as the luff of the main is cut with a little less curve in it. This prevents the mast from buckling forward under the compression load. As the main can never swing out more than about 45 degrees, there is always significant pull aft in the mid section with the main up.

Without the main up the mast is wanting to buckle forward under the compression of the forestry and the shrouds. However, the cross sections is still stiff enough to prevent this. With a large wind load in the genoa the forestry wants to sag, increasing the compression pressure on the mast. The higher load in the forestry also wants to pull the top of the mast forward. This must be compensated by higher loads in the shrouds, further increasing the compression pressure. The large piece of concrete on top of the mast just got a lot bigger. Imaging pushing down on a straw, now push gently in the middle to curve it slightly. It will buckle pretty quickly.

So the failure mode of the mast is most likely buckling forward in the mid section under the compression loads. Keeping the topping lift tight and pulling down hard on the main sheet will help, but only to a certain extend.

I still use the genoa only running down wind and hope that the really large section on the mast will by strong enough to prevent the buckling.

Would be nice to hear from a rig,designer if temporary running backstays to the midpoint on the mast between forestay attachment and foot of the mast will help here significantly.
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Old 07-03-2013, 23:44   #85
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Re: 440 Sailing with Jib only and no Main Sail

I've built many masts for mono's to the designers drawings,. i appreciate that high compression loads build most when hard on the wind and thumping through waves. The mast suffers immensely and is trying it's best to drive itself downward through the compression post/beam whatever.

But i agree totally with Bob, when off the wind the sail itself gives little strength unless maybe reefed in hard (3rd reef) and centred, then it would give some lateral strength via the mainsheet up through the leech to the third reef point.

Always when sailing one of the walk around checks is to sight up the mast looking for bend or pumping, BUT you are not going to get it sailing at this angle. The load is taken aft by the two stays each side one at7/8th and the other at 50%, a tightened topping lift/mainsheet would give strength at mast head.

I really do not see the loads off wind being capable of bringing the stick down before the sail blew.

Much rather de-power by easing the sheet and reefing furiously than turn and accept the full force, albeit deafening, it's amazing how quickly these winches get rid of a Genoa. FFR is different again but i'd likely unfurl the Genoa in front of it to gat a chance to blanket it and furl. The weight in my mainsail furling boom would tear the stick out in short order if the main got free in such conditions. hence i just don't want to off wind with it on long ocean runs.....

As Bob said 'Show me the money'.
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