Downwind Catamaran Sailing

[Sparohok]

Originally Posted by Dave

No, not quite ... I never had time to release the jib sheet.

Dave, I reread your post and realized that I had misunderstood. "Clew to the wind" meaning strapped (oversheeted) rather than luffing. As a result I deleted my reply as soon as I could. Sorry about that.

Martin

[Southern Star]

44 CC makes a valid point: if the Lagoon has a topping lift, then the topping lift/mainsheet could be used even more effectively than the mainsail to counteract the forestay and keep the mast from toppling forward when sailing downwind. Consequently, mast bending/pumping must be the primary concern - and lets face it, significant pumping will lead to fatigue and could lead to failure of the rig/spar.

If this was something written by 'lawyer' out of an overabundance of precaution, one would expect the manual on all Lagoons to carry the same proviso - do they? Regardless, I would certainly follow the manufacturer's recommendations.

Brad

[impi]

Originally Posted by Southern Star

44 CC makes a valid point: if the Lagoon has a topping lift, then the topping lift/mainsheet could be used even more effectively than the mainsail to counteract the forestay and keep the mast from toppling forward when sailing downwind. Consequently, mast bending/pumping must be the primary concern - and lets face it, significant pumping will lead to fatigue and could lead to failure of the rig/spar.

If this was something written by 'lawyer' out of an overabundance of precaution, one would expect the manual on all Lagoons to carry the same proviso - do they? Regardless, I would certainly follow the manufacturer's recommendations.

Brad

Nowhere to be found in my manual, but this post has made me re think my downwind sailing techniques. Will definitely be observing my mast when sailing down wind.

[Jeannius]

I can't see a problem with genoa-only downwind on a Lagoon 440 or any other cat with a properly supported mast. Lagoon 440 has lower shrouds supporting the centre of the mast as do most cats.

I've done maybe 20000 nm with twin genoas on one furler and no main up and never seen the mast pump even with winds in excess of 40 knots.

Most FPs I've seen don't have lowers and I can see that may cause a problem.

[krafthaus]

Originally Posted by Jeannius

I've done maybe 20000 nm with twin genoas on one furler and no main up and never seen the mast pump even with winds in excess of 40 knots.

That's many miles Jeannius, and supports the general opinion on this thread that jib/genoa only on a catamaran running downwind is not problematic for the rig. And 40+ knots without problems is further endorsement.

Any Lagoon 400 owners out there that can check their owner's manuals and find the same warning that I read? Please post if you do.

[Cruisin Cat]

Originally Posted by Jeannius

I can't see a problem with genoa-only downwind on a Lagoon 440 or any other cat with a properly supported mast. Lagoon 440 has lower shrouds supporting the centre of the mast as do most cats.

I've done maybe 20000 nm with twin genoas on one furler and no main up and never seen the mast pump even with winds in excess of 40 knots.

Most FPs I've seen don't have lowers and I can see that may cause a problem.

Correct, no lower side stays on my FP...but interestingly, there is no mention in the owners manual about keeping the main up when running.

[PaulinOz]

Taken from my L421 Owners book

Between 75 and 130 deg to true wind

from 38 to 45 knots
(3rd reef or Mainsail Lowered and a little more Genoa) 40% Genoa

from 45 to 55 knots
Mainsail lowered and 40 to 30% Genoa

[thinwater]

Originally Posted by webejammin

Our Gemini 105Mc has 2 head sails one a 150% jib and a 200% screacher with a track to move the tack to windward to use for down wind only. We do have a backstay that works really well. Our best speed on just the screecher sail has been 10 kt's in 18 kt's of breeze. We can also fly our main sail and screecher sail wing and wing with no wisker pole and get great speed out of the true wind.

What is the apparent wind limit on the screacher? Often there is a concern on lighter sails that they can be streatched if over used.

[mikereed100]

Originally Posted by Jeannius

Most FPs I've seen don't have lowers and I can see that may cause a problem.

Mike,

I believe FP uses jumpers on the mast in lieu of lowers to keep it in column.

Mike

[Burls]

The Lagoon 380 has the same limitation in the manual (must have main sail up before Genoa). When heading downwind I sometimes run ‘Goose-Wing’, and sometimes on a broad reach, whichever works best for where I’m headed that day. The VMG is a bit better on the broad reach, but if I’m cruising I tend to take the lazy way out and just go Goose-wing.
FYI, I find my Spinnaker is happiest at about 150 degrees off the wind.

[Cruisin Cat]

Originally Posted by Burls

The Lagoon 380 has the same limitation in the manual (must have main sail up before Genoa). When heading downwind I sometimes run ‘Goose-Wing’, and sometimes on a broad reach, whichever works best for where I’m headed that day. The VMG is a bit better on the broad reach, but if I’m cruising I tend to take the lazy way out and just go Goose-wing.
FYI, I find my Spinnaker is happiest at about 150 degrees off the wind.

Hi Burls,

Just to be clear on what your manual is actually saying, does it mention downwind in relation to the need to have the main up before genoa, ie is the statement intended to prevent rig damage?

Or is it just making a genaral statement to inform a potentioally inexperience skipper that under certain wind/sea conditions it may be difficult to turn into the wind to raise the main if he already has the genoa fully out?

Agree with your cruising comment....for me it's much more about ease and comfort than having a sail plan that gives you an extra 0.5kt but is difficult to manage particularly when a squall comes by.

[Burls]

Originally Posted by Cruisin Cat

Hi Burls,

Just to be clear on what your manual is actually saying, does it mention downwind in relation to the need to have the main up before genoa, ie is the statement intended to prevent rig damage?

Or is it just making a genaral statement to inform a potentioally inexperience skipper that under certain wind/sea conditions it may be difficult to turn into the wind to raise the main if he already has the genoa fully out?

Agree with your cruising comment....for me it's much more about ease and comfort than having a sail plan that gives you an extra 0.5kt but is difficult to manage particularly when a squall comes by.

I'm not near my boat manual right now, so can’t remember the exact wording, but it definitely says do not to sail with the jib/genoa, without the mainsail being up. I was under the impression this was prevent rig damage, but who knows. As far as ‘don’t sail directly downwind’ that’s got me thinking, and I’ll have to re-check the book!

[krafthaus]

I finally found a PDF copy of the Lagoon 400 Operating Manual online today in the Yahoo Lagoon Owners Forum. The information here is same as I remember from the manual I mentioned in the Original Post.

Some excerpts from the section titled - Navigation Under Sail:

There is a caution that catamarans don't heel like monohulls so sailors beware to "constantly monitor real wind speed and trim sail surface areas as a priority in accordance with speed". Essentially, trim early to avoid being over powered with too much sail up and especially if wind could build. Time to reef on a cat is when you start to think about it is an item I’ve often seen mentioned.

There is a section for Close Hauled Trimming (between 75 and 50 degrees to True Wind).

Also a section for Close Reached Trimming (between 75 and 130 degrees to True Wind).

Guidelines are provided for 0 to over 55 knots of wind.

At conclusion of the trimming guidelines there is a note:
DANGER – Any different setting of these recommendations may result in breakage of the mast. In particular, the 100% genoa with 2 reef in the mainsail is prohibited absolutely.

Further on there is a section:
Navigation Wind Astern
-Do not fall off more than 150 degrees to the apparent wind.
-Put the traveller out as far as possible and slacken the sheet slightly.
-Make sure the mainsail does not touch the shrouds; the rubbing of the battens will wear the material and cable very rapidly.
-Keep mainsail + solent up to 15 knots speed and put in one reef or more if the accelerations are sudden and strong or if the sea conditions deteriorate.

My take on this from the manual and all the excellent posts made on this thread are there is an element of cover your a$$ on the part of the manufacturer (but I rather doubt Lagoon would be the only builder to include these sorts of comments in their operating manuals). Also these guidelines provide a prudent level of caution to ensure the vessel and crew are not at risk and to remind sailors to use an appropriate level of caution, good seamanship and judgement.

Thanks all for your insight and comments on this topic. I’ve found it very informative and instructive.

Krafthaus.

[s/v Jedi]

Originally Posted by krafthaus

DANGER – Any different setting of these recommendations may result in breakage of the mast. In particular, the 100% genoa with 2 reef in the mainsail is prohibited absolutely.

Exactly. This is what I always try to explain but gets ignored by most. Because a cat doesn't heel, you get shock loads in the rig. On a mono, these get absorbed by the boot "giving" by heeling. If you double reef while maintaining 100% genoa, you try the ultimate breaking test of the mast too. That's where that cutter stay pop up.

Now, here's the thing: on a mono, you can calculate and test the required strength of the rigging. Simplified: from shore you winch the masthead down all the way to the water (hull at 90+ degree angle) and measure the maximum force on the cable used for this. Next add a safety factor and there is your number.

For a cat you obviously can't do this. To add to the difficulty, there is a linear relation between the forces on the rigging at one side, and the combination of sail area and wind speed at the other side. This makes wind the unknown factor, hence the importance of reefing early to always stay within the design limits. There is no automatic fail-safe as with a mono.

You will also find that cats have a more substantial rigging than mono's. I believe they use much wider safety factors as well as the warnings in the manuals.

In short: reef early, balance sails and also inspect rigging often.

ciao!
Nick.

[colemj]

I think the warning about a deeply reefed main and a full headsail is to prevent mast inversion. Without the full main, you lose the prebend in the mast that the cut of the luff provides, plus you lower the aft force of the headboard down to the middle of the mast section and well below the countering forward force of the headsail. This is also a problem on monos - particularly racing ones with thin mast sections - except many of them have forward lower shrouds to help keep the mast in column.

Unless one is sailing deep off the wind, a deeply reefed main and a full headsail is always a bad combination for all types of boats, unless there is specific rigging to compensate.

Mark