Multihull storm tactics?

[Talbot]

No good reading a monohull sailor's book and expecting to get accurate advice on multihull tactics, they are different. The Pardey's are traditionalists and minimalists, - more power to them, and if that is the way you wish to go, then there is a wealth of advice available in their books.

However, that is not the only way ahead. The best source of data is the "Drag device data base"

A cat needs to be slowed down in a really bad storm. The series drogue is the best way to achieve that, provided that the stern is sufficiently robust to cope with the forces. The parachute can also work. but needs to have an appropriate bridle, and must also be big enough to reduce the movement through the water to almost zero to avoid damage to the rudders. Thus the forces involved with a parachute are several orders of magnitude larger than that experienced with the series drogue. IMHO you also need to reinforce the front windows if using a parachute, as a breaking wave will spillover the boat, whereas with the drogue, the weight at the far end of the drogue stalls at least half of the drogues until the boat is hit by the breaking wave, thus the boat is able to accelerate initially to reduce the shock of the breaking wave, and is then slowed down as more and more drogues come into use, and then the boat is plucked safely through the breaking wave.

[smm]

Originally Posted by Absolute Wind

I thought I was 100% convinced on a multi-hull until I read Lin and Larry Padey's book called Storm Tactics. I know I will be out there sailing in a storm eventually and worry that a big wave crashing on the stern of the boat will break the big door wall windows on a boat like the Lagoon 420 or Fountaine Pajot 60. First...i recommend reading Storm Tactics and concur with author that the para-anchor is critical on any boat of any type size or shape. Second I want to know of people that have heaved-to in cats and what the angle to the wind. 50 degrees seems to be magic number for monohulls using a trisail. Are cat people using a trisail? The reason I am rethinking cat versus monohull is the trade off of the safety you get when heaved to in a monohull with a deep keel. The deep keel of the monohull breaks the wave front pattern far better then the shallow hulls of a cat. Karman effect. In fact the Pardey's imply the cat's Karman effect is so small it is better to lay a cat at 0 degrees to the window and depend on a 28ft diameter para-anchor. What worries me is that was for what I consider to be a small cat. If I get a bigger one like the Lagoon 420 or even a 60ft Fountaine Pajot I have no idea how big of a para-anchor should be used. Pardey's book outlines the futility of running before a major storm and that a-hull isn't a good choice either.
On to the big questions:
1. In a force 10-12 blow, is it possible to get a cat to heave-to and stop sailing?
2. How big of a para-anchor do you need on a big cat?
3. Is that big wide glass door on the back of a cat safe in a storm if the boat is properly hoved?

Well, I would trust the Pardeys a lot wrt to heavy weather techniques for small traditional monohulls. But I would take their advice about catamarans with a grain of salt. Quite a large one, in fact.

In force 10 - 12 (48 - 63+ knots) I doubt that a typical cat or even a modern monohull with a large house would remain safely hove to. At a certain point, windage on the hull will probably overpower the sails and you'll get driven backward and unheave. It will probably be quite exciting. For this reason (and thers) ES doesn't carry a storm trysail. The third reef is very deep and after the wind gets too much for that, we would raise the daggerboards and start quarteing off. In theory.

I'm sure that the para-anchor guys can size a parachute. I'm less sure about their ability to size the rode and bridal and on the ability of boatbuilders to provide suitable attachment points and storage for the same. For examle, "you've deployed a parachute anchor from your 10-ton Lagoon in a steady 40 knots of wind. You get a 30-second gust at 60 knots. What is the steady state load on the rode and what is the shock load?" Until you see detailed answers to questions like that I'd be a bit sceptical. I did see a nice custom boat in Noumea which carried a bridal pre-rigged to large composite chainplates. If you're serious about a parachute, I think that that is the right direction to go.

Now about glass... In force 12 riding to a parachute anchor I think that you would lose all that nice vertical glass in the _front_ of your lagoon in pretty short order. Fishing boats routinely lose stronger windows in less wind. Running with a drogue the impact of boarding seas would be less (because you're moving in the same direction) but I still think that you could lose lots of glass. OTOH, in a force 12 storm, I don't really care about losing windows as long as the boat continues to float.

You seem oddly resigned to sailing in a storm. If you look through cruising reports I don't think you'll find many where the skipper did everything right wrt the weather forecast and still got clobbered. Storms with force 10 - 12 winds are pretty keenly monitored by the weather bureaus of the world, and while strong winds may show up 100 miles from where they were expected, the chances of sailing into an F10 storm that didn't show up in any forecasts are pretty small.

-Scott

[cat man do]

Originally Posted by smm

"you've deployed a parachute anchor from your 10-ton Lagoon in a steady 40 knots of wind. You get a 30-second gust at 60 knots. What is the steady state load on the rode and what is the shock load?" Until you see detailed answers to questions like that I'd be a bit sceptical. I did see a nice custom boat in Noumea which carried a bridal pre-rigged to large composite chainplates. If you're serious about a parachute, I think that that is the right direction to go.

Now about glass... In force 12 riding to a parachute anchor I think that you would lose all that nice vertical glass in the _front_ of your lagoon in pretty short order. Fishing boats routinely lose stronger windows in less wind. Running with a drogue the impact of boarding seas would be less (because you're moving in the same direction) but I still think that you could lose lots of glass. OTOH, in a force 12 storm, I don't really care about losing windows as long as the boat continues to float.

-Scott

On the newie we have built our Anchor bridle/parachute bridle from the black stuff.

When speaking to some composite engineers they asked if I could pull any slack out of the anchor rope in 60 knot's and i said that I would have thought that 2 or 3 guy's surely would, 'cause I pulled the pick up in 50 knots on my last boat by hand by myself.

They then suggested that maybe no more than 500 kg load would apply which sounds light, but how much can you pull up? Thay also thought just a few layers of 600gsm Carbon extending back 300 mm would be enough.

SO, as I had a heap left over from a couple of jobs ago, and it owed me nothing we went back 1000mm and used 15 layers of 600gsm carbon and fanned it out over a big area. Should be right.

I agree on those window's on the Laggoon, very vulnerable, but hopfully the 10 mm Lexan or Shinkolite ones at an angle will be ok on ours plus the deck is 1900mm above the water so that will help.



Dave

[maxingout]

Originally Posted by cat man do

On the newie we have built our Anchor bridle/parachute bridle from the black stuff.

When speaking to some composite engineers they asked if I could pull any slack out of the anchor rope in 60 knot's and i said that I would have thought that 2 or 3 guy's surely would, 'cause I pulled the pick up in 50 knots on my last boat by hand by myself.

They then suggested that maybe no more than 500 kg load would apply which sounds light, but how much can you pull up? Thay also thought just a few layers of 600gsm Carbon extending back 300 mm would be enough.

SO, as I had a heap left over from a couple of jobs ago, and it owed me nothing we went back 1000mm and used 15 layers of 600gsm carbon and fanned it out over a big area. Should be right.

I agree on those window's on the Laggoon, very vulnerable, but hopfully the 10 mm Lexan or Shinkolite ones at an angle will be ok on ours plus the deck is 1900mm above the water so that will help.

Dave

I finally got around to posting a picture of my parachute sea anchor chainplates that I installed in new Zealand. I use these chainplates when I deploy the parachute sea anchor off the bow. As you can see, they have a bail out in front of the bow so that they are chafe free when I am using the sea anchor bridle.

I also use the sea anchor chainplate bridle system when anchored near shore in major storms.

So if anyone is not happy with the strength of the cleats on their bows, they can always put deck chainplates in as back up or primary attachment points of anchor bridles.

Dave
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[Absolute Wind]

Originally Posted by smm

You seem oddly resigned to sailing in a storm.

-Scott

I confess to being an engineer with a view colored by personal observations of very high seas. I am resigned to the fact that based upon my experiences I will eventually be in the same type of seas depending on my boat to keep me alive. I think preparing for that time by selecting the right boat and equipment is a good investment.

Richard Woods's report in my opinion should become required reading for those that can learn from his mistakes.
#1 Based on literature I have read, the device that could best save his boat was drastically undersized. Hence it is prudent to provision your boat with the correctly sized para-anchor.
#2 He admits that he only used it once and stowed it for years. Hence it is prudent to test and inspect equipment that lives depend upon.
#3 Richard Wood conclusion "I don't think I would recommend a sea-anchor again." Should be taken with a grain of salt. Of course his anchor failed, it was undersized, not maintained and tested on a regular basis, and he did not have his bows ready to spread the load between them as others have suggested here.

Thank you Scott for agreeing that I am not crazy about being concerned over the potential of blown in windows in high winds. I am resigned to replace or reinforce all the factory supplied glass. I have in mind some laminates I have seen designed to make windows bomb proof. I may never need windows this strong, however, it will let me sleep better. I guess I will have to depend on the structural engineers that the wind load on the superstructure itself can be withstood.

I am rather surprised how little I can find on this subject in Chapman. I did find this bit about creating an oil slick to alter the surface tension of the water. Now this one I am really doubtful of. Why a breaking wave wouldn't break based upon a thin film of oil on its surface is beyond me. I will research that a little more before dumping olive oil over the side.. Geezzzz. You think I was going to try some bunker C?

Phil

[44'cruisingcat]

Originally Posted by Absolute Wind

Richard Woods's report in my opinion should become required reading for those that can learn from his mistakes.
#1 Based on literature I have read, the device that could best save his boat was drastically undersized. Hence it is prudent to provision your boat with the correctly sized para-anchor.

Phil

Remember though, that Wood's boat survived the storm fine, with no sea anchor, and no crew.

[Octopus]

I'd agree that the vertical windows on Lagoon cats seem vulnerable and gave the matter some thought before placing an order for a 420.

How many commercial fishing boats do you see with small sloping windows? Not many. And why not? Answer: because vertical windows are safer. Perhaps?

Let's start with the better all round visibility. There must be more chance of spotting other shipping and avoiding collisions, more chance of spotting the uncharted reef, the surfacing whale, the rogue wave or the half-submerged shipping container with such superb visibility. Lookout duties lie with those on watch and on deck, but eight sets of eyes are better than one and if those in the saloon have a chance of seeing what's coming then everyone's a bit safer.

Then there's the option to steer from a sheltered position using the autopilot joystick. Not generally recommended, but there might be occasions when it's a good idea. With vertical windows and nearly 360 visibility, why not? Better than being on the helm and being half-drowned every so often.

But, vertical glass must be more vulnerable mustn't it? Certainly, commercial fishing vessels occasionally get windows blown in, but they are generally big pieces of glass. The bigger the pane the bigger the distortion the more likely they are to pop out. The Lagoon windows are fairly short in comparison - long yes, but short.

Structurally, it must be a lot easier to engineer strong rebates and buttresses where horizontal structures support vertical glazing. Much more tricky to achieve the same strength in-plane in an inclined structure.

The biggest danger of imploding windows must come from water not wind. Take a big wave badly and you've got several tons of water knocking on your windows. I'm no expert on fluid dynamics, but I suspect that gravity takes a hand and most of the force of that water is heading downwards, So perhaps in such cases vertical glazing is good and semi-horizontal is bad.

It's all a bit theoretical, but I reckon the Lagoon windows are just fine and if not then we will still have the answer on board our boat. We are taking with us on our travels two transparent acrylic glazing reinforcements - otherwise known as the Molokini Kayak - to strap across the windows in severe storms and take the worst of the punishment.

As far as storm tactics are concerned, I did the research and the first piece of safety equipment we bought was a generously sized good-quality parachute anchor. The tips on bridle reinforcement and anti-chafing techniques on this forum are excellent.

I'm not yet convinced about series drogues.

Chris

[smm]

Originally Posted by Absolute Wind

Richard Woods's report in my opinion should become required reading for those that can learn from his mistakes.
#1 Based on literature I have read, the device that could best save his boat was drastically undersized. Hence it is prudent to provision your boat with the correctly sized para-anchor.
#2 He admits that he only used it once and stowed it for years. Hence it is prudent to test and inspect equipment that lives depend upon.
#3 Richard Wood conclusion "I don't think I would recommend a sea-anchor again." Should be taken with a grain of salt. Of course his anchor failed, it was undersized, not maintained and tested on a regular basis, and he did not have his bows ready to spread the load between them as others have suggested here.

And you have missed mistake number 1: he knew a storm was coming:

"There was a time onstraint as we knew there would be a bad gale coming through the Gulf of Tehuantepec on Wednesday afternoon, and we had wanted to get past that area by then."

And, he had no excuse not to know that such storms were common, reliably forcast, and very dangerous. Any cruising guide covering the gulf will explain this. If you google "gulf of tehuantepec" the very first result,

Isthmus of Tehuantepec - Wikipedia, the free encyclopedia

notes that the gulf is dangerous and why.

-Scott

[cat man do]

Absolute Wind, welcome to the forum and wash your mouth out with soap.

Signed
Future monohull or cat-owner. Still not sure.



Alby Mckraken at Para-Anchors Australia will be able to advise.

I used one of his on a delivery to New-Cal and was very impressed with the quility of build and how it performed.

Sea Surface Anchors. Para-Anchors Australia Pty. Ltd.

Have you heard of a wave coming into the back of a cat ??

Are Lin and larry multihull expert's ??

And unbusted 67, do a bit of research into parachute anchors and you might change your tune.

I'd reckon if the mono's in either of those book's had a parachute on board they would have used one and have been better off for it.

Less stress on the boat and a rested crew has got to be better than fatigued crew and stressed and broken boat.

Dave

[cat man do]

But of coarse if using a drogue is going to put you towards a lee shore the parachute is the go.

From anything I have read by the time people get around to deciding that they need to do something fatigue has started to set in. For my money i'll be using a parachute and ensuring i'll be rested for if the $hit really hit's.

When we used the parachute, and fair enough it was only blowing at around 50 for a few hours, but we did have 35 to 40 for about 5 hours, the waves were around 4 to 5 metres and we never had one break over the bow's.

Not saying that it doesnt happen though.

After beating into 20 to 25 for about 20 hours we were getting a bit stressed, and the boat wasn't her usual happy self so we put it out early and were amazed that it was like being on anchor in a rough anchorage.

We had hot meals, did some maintenance had a few rumbo's and watched the waves roll by And then continued on fully rested .


Did I mention that I like Parachute anchor's ?




Dave

[Intentional Drifter]

Dave, thanks for the link to Para-Anchors Australia -- lots of good information, there. I'm interested in more details of your experience with it. This was a cat, I assume. How did you secure it to the bows? Deal with chafe? When on the anchor, do you center and lock the rudders? Any concern about spade vs skeg-hung rudders (since we're buying a production boat, we're stuck with the spade even though it is not my preference).

Thanks!

ID

[44'cruisingcat]

Chris, what kind of glass are the Lagoon windows made of? If they are automotive type laminated glass there is absolutely no way wind alone could hurt them - you get cars travelling at 300 odd km/h without windscreens caving in. If they aren't laminated, (although I expect they would be), then changing them wouldn't be all that hard or expensive would it?

But really, getting caught in that kind of weather these days is getting very close to poor seamanship - he knew the storm was coming, but decided to travel anyway.

[Intentional Drifter]

RE: The vertical windows, Lagoon has been building boats with these windows since 1997. Their supposed vulnerability has also been a point of criticism since the same time. Yet, there are now well over 500 of them out there in the world (380's, 410's, 440's, 470's, 500's) and I have yet to hear of a single incident involving their failure. Although a somewhat different design, Fountaine Pajot has been doing the same, since about the same time, also with over 500 boats out there. That's about 1000 boats, many of them cruising far aflung. Can anyone point to one incident of catastrophic failure of the vertical windows? (Not talking about leaks, here.)

ID

[DtM]

I love aflung !!!

Sorry, couldn't resist.

[smm]

Originally Posted by Intentional Drifter

RE: The vertical windows, Lagoon has been building boats with these windows since 1997. Their supposed vulnerability has also been a point of criticism since the same time. Yet, there are now well over 500 of them out there in the world (380's, 410's, 440's, 470's, 500's) and I have yet to hear of a single incident involving their failure.

I would take this as being more indicative of the owners of these boats avoiding F12 conditions than of their suitability for the same.

The problem is not wind, it is 3 meters of breaking wave smacking into a para-anchored boat at 30 knots. If you get a meter of water actually hitting the house, across a 3 meter front that's, oh, 3 tons. So, about like being hit by a
truck.

FWIW, Unless you're planning a trip to Antartica, I don't think that the Lagoon windows are a real liability. However, we were having a discussion about a hytothetical Lagoon with a hypothetical skipper para anchoring in F12 conditions, the forcast for which he ignored. At the end of this admittedly tenuous chain of hypothesis, I do believe that vertical Lagoon-style windows are a liability.

-Scott