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Old 08-11-2005, 20:25   #16
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Waves

What Alan said about the graph.
Simply put any boat can be rolled by a wave, it is simply a matter of degree. Other factors may be boat size, wave shape, whether it is breaking or not, and a bunch of other stuff. The graph is not much use in my opinion. All boats should be aiming straight at them or away from them, when the waves get nasty. If you do not think this has some truth then you need to go out in bigger waves, especially ones that are breaking.
The graph shows the motion of the energy, which is a lot different to the motion of real water moving. When the top of a wave is breaking you have water moving. I want to be going with the wave at a controlled speed if I am ever in that stuff.
My theory and opinion only.
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Old 09-11-2005, 01:27   #17
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There is no One type of Wave. Scott has already alluded to that. I have not seen them all either, and am definitly sure I don't want to. It's one aspect I would like to remaina compleate novice on.
I have however been on forty ft stuff twice. I am most happy to say, both occasions were on someone elses boat and one was built specially to take on this stuff and we were out testing it and the other was a ship and coped quite well. Although many passengers were greener than the carpet on the ship. But here is an interesting point. These huge waves were giant roller coasters. Nothing was breaking and the distances apart were just as enormouse. I actually was having fun. (Hmmm, OK maybe not if I was in my little boat.) But I have also been in much much smaller stuff that scared the living daylights out of me. I have been in 8-10ft stuff that rose almost verticle and each an every one looked like it was going to curl right over our little 18fter. You simply couldn't slow the boat down enough as you had to go up the face of them, but once you reached the top, you launched out off the top and slammed in to the trough below which made your heart leap into your mouth.
Another time was wrong place wrong time with 35knt wind and tide against swell. This time I ws in the 45ft yacht and these waves were breaking and rolling down their faces. Now maybe we had a touch of that "how big was my fish" syndrome, but I swear these monsters looked enormouse in through my little Pilot house window. I do think they were around the 15ft mark, hard to say. But these things would break over us and on down the boat and over the Pilot house and out the back.
A close friend who has sailed many Sydney Hobart races has been in stuff that dwarfed his mast in hight. The main point he made to me that I will never forget, was that it was not just a big wave face, but big waves that sat on bigger waves that sat on the really big wave all moving in differing directions. Sounds exactly like what Scott has mentioned.
Scott, I hope your adventure was enough for many of us here. I'll believe ya, I don't want to go out and see stuff like that for myself
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Old 16-11-2005, 10:45   #18
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I've only sailed monohulls and have no axe to grind over multihulls. The space / cruising / anchoring stability etc they provide is surely a cruisers dream.

But I confess to still having worries about managing a cat in a real blow.

Two years ago we crossed Biscay and had 24 hours of F9 behind us as part of Rally Portugal. Whilst all the 20 + monohulls came through wet but fine (and including smaller Hunters and Bavarias with relatively inexperienced crew), the skipper of the solitary 37' multihull taking part confessed afterwards of more than a few 'brown trouser' moments.

Whilst all others sailed on before the gale, he found it neccessary to heave to and sit out some of the night. It was rough that night - 5 Spanish fishermen were lost when their vessel was swamped in the same area.

I've no doubt heaving to was a sensible choice, and I've no recollection if he deployed a drogue or sea anchor, and after all he then made it in OK and actually not very far behind the slower monos.

But it did reinforce for me the need for solid practical experience in sailing cats so as to minimise risks in heavier weather. IMHO with stronger conditions they appear to need more thought - more work effort - than same length monos.

BUT. This is an opinion NOT based on personal practical experience. Maybe someone who sailed both hull forms in lots of similar conditions is best placed to comment?

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Old 16-11-2005, 11:49   #19
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Voyage 380 aqnd Strong gales

Makai as it was being delivered from SA came around Hatteras in a Strong Gale force winds 47-54. The delivery captain said he had been in winds like this on many multis. He gave no warnings that they were any safer or more dangerous than monos.

One of the biggest points he made was the experince of the crew rather as much as the quality of design and construction of the boat makes the difference.

We have spent some time in 40 plus not winds while passagemaking. I would not recommend it, but have not had an issue with the boat. Even though we have high wind experince I still get some brown moments. High winds and big waves can be nerve racking.
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Old 16-11-2005, 11:59   #20
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The conditions that tend to settle the argument are something more like 80knts of wind and 40ft and bigger Sea's.
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Old 16-11-2005, 14:59   #21
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Quote:
swagman once whispered in the wind:

Two years ago we crossed Biscay and had 24 hours of F9 behind us as part of Rally Portugal. Whilst all the 20 + monohulls came through wet but fine (and including smaller Hunters and Bavarias with relatively inexperienced crew), the skipper of the solitary 37' multihull taking part confessed afterwards of more than a few 'brown trouser' moments.

Whilst all others sailed on before the gale, he found it neccessary to heave to and sit out some of the night.
I've no doubt heaving to was a sensible choice, and I've no recollection if he deployed a drogue or sea anchor, and after all he then made it in OK and actually not very far behind the slower monos.

But it did reinforce for me the need for solid practical experience in sailing cats so as to minimise risks in heavier weather. IMHO with stronger conditions they appear to need more thought - more work effort - than same length monos.
Cheers
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I dont know of any experienced catamaran sailer who seriously considers heaving to - its not something you should do as it actually puts the boat in danger.
A catamaran sailing downwind in a blow is definitely at its most vulnerable, as a pitchpole is a serious threat if travelling too fast. Therefore a cat going off-shore needs some method of slowing down in these circumstances e.g. drougue, warps etc. My personal preference is for a series drogue.

In bad weather a cat does need a bit more TLC than a mono, but the crew are normally in much better condition to be able to do so
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Old 16-11-2005, 15:58   #22
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Heave

Most cats don't heave to as the low aspect keels will slide sideways through the water fairly easliy. This is great when a large wave is rolling under you on the beam as we slide down the wave front rather than being rolled over.

We use a parachute type drogue that goes off the bow on a bridle. It keeps the bow to the wind and slows the boat down. Makes the ride comfortable.
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Old 16-11-2005, 19:31   #23
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Cap'n Bil

I'm not sure I understand your last post. You say
Quote:
We use a parachute type drogue that goes off the bow on a bridle. It keeps the bow to the wind and slows the boat down.
.

But in the previous sentence you say
Quote:
This is great when a large wave is rolling under you on the beam as we slide down the wave front rather than being rolled over
So, are you sliding backwards? And if so, isn't that a big NO NO? Or are your sliding forward over your drogue?

I'm not a big Cat sailer (just up to 19'ers) but wouldn't you want the drogue off the back. From what I've read that is the way to go, so as not to submarine into the next wave........_/)
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Old 16-11-2005, 19:37   #24
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I'm just impressed that Bil could say the ride was comfortable. The best I have hoped for in those conditions is tolerable
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Old 17-11-2005, 03:26   #25
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I would be seriously concerned if I was sitting on a drogue secured from the bow. A drogue allows the boat to still move through the water, and a big sea would put intolerable strain on the rudders.

A parachute is the only viable item from the bow, as it stops movement completely, and a drogue from the stern - provided stern design can take the occasional mega goffer, and cockpit drains are god (and directly overboard, not into the bilge!)
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Old 17-11-2005, 04:42   #26
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Clarify

The parachute is 24 foot ParaTech and is designed to stop the boat. We do not move backward. I couldn't think of a descriptive word for drogue as a device that is dragged through the water. A better term is sea anchor.

Off the bow allows the boat to point and ride over the waves. Comfortable is a relative term. Sailing downwind or off the wind or even beating into high winds is very uncomfortable, even dangerous while sitting is more relaxing. Relatively.
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Old 17-11-2005, 07:04   #27
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24 ft para-anchor good grief, thought that the 18 ft one was correct size for your boat.

Have you done a recovery yet of this beast? I dont understand how a half boat would find the space to re-pack it, but not so much of a problem on a proper boat.
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Old 17-11-2005, 13:28   #28
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Sizing

We got one size larger as as a recommendation because we met only one of the criteria for size and wieght.

We are a cat and sail a whole boat so we have a large foredeck. We also have a lofrans horizontal windlass and it is easy to access the rope gypsy to retrieve. It still is a lot of pulling and back labor.

It packs into a bag and is best packed opposite of deployment. Also make sure lines are not twisted or knotted because bouncing around is the last time you want to work out kinks.
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Old 18-11-2005, 11:41   #29
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Question

I haven't been out in big seas on a Cat yet. But I do know they can surf fairly quick down the crests.
So, with that parachute up forward, what keeps you from surfing down the back side of a large roller and then snapping tight again on the sea anchor line, going up the next crest? Or does the line stay tought?

From what I've read, the procedure is the keep the parachute 3-4 swells ahead. Does that help?
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Old 18-11-2005, 12:15   #30
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combination of two things - the stretchiness of the 100+metres of main rope to the parachute will expand as the boat goes up the slope and contract on the otherside to take up a large percentage of the slack, and this is aided by the windage helping to prevent acceleration on the back side of the wave.

Incidently, this elasticity puts a lot of strain on the rope and 3 strand is not really suitable for two reasons - it tries to unwind under strain, which means a swivel is essential. Also when the strain goes off, it can be very quick, which means that sometimes a 3 strand will knuckle instead of going back into shape. These knuckles seriously weaken the rope. Octoplait is a much better material for this.
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