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Old 18-01-2008, 18:29   #31
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Catamarans' motion

A beamy, light boat will have a quicker motion than a narrow, heavy one. A good catamaran is a very beamy, light boat, indeed. Ted Brewer made an equation to quantify this, and called it the comfort ratio. I doubt whether you could use it to compare a multihull with a monohull, as it was designed to compare monohulls to each other, but it illustrates the concept, at least. See
Ted Brewer Yacht Design .

I would think that a getting a bigger multihull would dampen out some motion, as bigger boats in general dampen motions. To keep the price down, you just make a relatively minimal large multihull with minimal accomodations, like my design on my webpage, http://dunnanddunnrealtors.com/Catamaran.html .
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Old 18-01-2008, 18:40   #32
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Old 18-01-2008, 18:57   #33
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The biggest downside to a cat happens when you have a low bridgedeck. Slamming can be more than an irritation; it can cause structural damage.

In Turkey I met a met a sailor who had a Prout Snowgoose 37 that he started to sail across the Atlantic, and he underwent severe pounding at the start of the passage, and it cracked the foward part of the bridgedeck. He had to turn around and make substantial repairs to the bridgedeck, and he delayed his trip across the Atlantic by one year. He did eventually make the crossing without a problem.

You should do sea trials on a catamaran in rough seas with twenty five knots of wind, and sail her to windward in those conditions to see how the bridge deck fares.

A catamaran with a low bridgedeck unloaded, will have an extremely low bridgedeck when fully loaded.

Some catamarans have only one engine that is placed centrally, and that is a disadvantage as well. Two engines give redundancy as well as better control when maneuvering.

Catamarans make nice shallow water, tradewind, low latitude cruisers. If you are going to be spending a lot of time in the high latitudes, you would probably be better off in a monohull unless you had a very large catamaran with an extremely high bridgedeck.
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Old 18-01-2008, 18:59   #34
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He just missed the www in his URL.... the rest is correct.
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Old 18-01-2008, 19:05   #35
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He just missed the www in his URL.... the rest is correct.
Got it, thanks.

Hey Tim,

That is cool.
Lots like a model I made 20 or so years ago.
When I win the lotto I am going to build a few to see which is the best one. Mast-aft or dual unstayed masts.
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Old 19-01-2008, 06:24   #36
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The biggest downside to a cat happens when you have a low bridgedeck. Slamming can be more than an irritation; it can cause structural damage.

In Turkey I met a met a sailor who had a Prout Snowgoose 37 that he started to sail across the Atlantic, and he underwent severe pounding at the start of the passage, and it cracked the foward part of the bridgedeck. He had to turn around and make substantial repairs to the bridgedeck, and he delayed his trip across the Atlantic by one year. He did eventually make the crossing without a problem.

You should do sea trials on a catamaran in rough seas with twenty five knots of wind, and sail her to windward in those conditions to see how the bridge deck fares.

A catamaran with a low bridgedeck unloaded, will have an extremely low bridgedeck when fully loaded.

Some catamarans have only one engine that is placed centrally, and that is a disadvantage as well. Two engines give redundancy as well as better control when maneuvering.

Catamarans make nice shallow water, tradewind, low latitude cruisers. If you are going to be spending a lot of time in the high latitudes, you would probably be better off in a monohull unless you had a very large catamaran with an extremely high bridgedeck.

Hmmm... this post is some cause for concern. Thanks. I am indeed looking at the very same Prout you describe. Was it that the guy had the thing loaded down like crazy for the trip?

I mean what is the proper bridge deck clearance?

My worry was cats in general in heavy weather too. I've seen plenty of footage of monos in monster storms, but very few of cats. What happens to a boat with a high degree of initial stability in very rough, breaking seas? If you take, say a flat bottom skiff as a model for the cat, it wouldn't fare as well as a rowing dinghy. I woke up thinking about this this morning.

Does anyone have any idea what would happen to a 37' Snowgoose vs a 37' say... Tartan or something in identical storm conditions with breaking waves?

Is this a valid concern?

One thing I liked about our Hirsh Gulfstar 45 was the ability to sit there at anchor outside a harbor in 60mph winds with really steep, huge chop and be somewhat comfortable. It meant I didn't have to run for cover every time bad weather kicked up. I just sat there.

Will a 36' Snowgoose be able to take the seas like that?

I know with a mono it's relative to the displacement, since that's what keeps you steady when the conditions get rough at anchor. With a cat, you are puposefully building a boat with a light displacement, so will I get creamed every time the waters get rough and winds kick up to 60mph?

I do plan to be in multiple lattitudes. High lattitudes at first (North Atlantic, Bay of Fundy, etc... for several years. Later, we plan to head through the Caribbean and across the Pacific... eventually.
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Old 19-01-2008, 06:56   #37
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The book "sailing promise" is about a young couple who do a circumnavigation in a Prout (37?) It was a good read (my wife really liked it as the author talks a lot about her feelings) and it might give you some info on what it is like to cruise in one.

Brian
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Old 19-01-2008, 07:10   #38
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Originally Posted by ssullivan View Post
My worry was cats in general in heavy weather too. I've seen plenty of footage of monos in monster storms, but very few of cats. What happens to a boat with a high degree of initial stability in very rough, breaking seas? If you take, say a flat bottom skiff as a model for the cat, it wouldn't fare as well as a rowing dinghy. I woke up thinking about this this morning.
Sean

As to weathering a storm in a cat. Take a few minutes and read this account. The grand daddy of storms was documented.

[PUP] Multihulls in the deep blue

This is the same storm from a different perspective. Written by the Captain of the rescue ship

Queens Birthday Storm 1994 - HMNZS MONOWAI
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Old 19-01-2008, 07:17   #39
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can you tell us what will happen to the 37 tarten in those conditions? (as a curious cat sailor)
and under what surcomstances you would be in such conditions. how ofterndo you plan to sit at ancor in 60mph winds?
are you looking for a boat that can delibratly go sailing in storm conditions.?
friends of ours have recently returned for a 30,000mile
and 10 years crusing. they have been right round in a 37ft cat they have averaged if my maths is right 8.2miles a day.
so that probbley took two hours at at conservative 4.1kn, so perhaps you should also consider the best type of boat for the other 22 hours a day. and get some decent wether forcasts.
but plenty of these prouts have been round the world.
every boat is hopefully owned by someone who found it to be the best for there pocket and there needs.
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Old 19-01-2008, 07:18   #40
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Bridgedeck clearance IS important, but it is not a question of a specific height. There are many formulas, but currently many naval architects are suggesting that 10% + of maximum beam is appropriate. Other factors come into play, however: the bridgedeck profile should be curved for and aft, without the blunt leading edge seen in many boats with forward doubles located in the bridgeck. Further, bouyancy in the bows is a critical factor and one which is antithetical to the currently popular plumb bows, seen on so many cats: front overhang creates an increase in volume in three dimensions upon being depressed. Other design features such as 'knuckles' in the forward topsides also operate so as to increase volume as the bows depress.

Can cruising cats capsize? Of course, but it is an EXTREMELY rare occurence in a properly designed and sailed boat. Even when taking seas beam on (generally bad seamanship in a cat), most will sideslip, and many have rigs designed to fail before the wind forces are sufficient to raise a hull past the point of no return. Pitchpoling is more likely, and this is why it is critical to have good bouyancy in the bows and a means of slowing the boat in extreme conditions. There is some serious debate as to whether that is best accomplished by deploying a para-anchor off the bow, or by trailing a series drogue astern. Both have their proponents, but either should only be required in EXTREME conditions. Many delivery skippers merely go below and run with the storm while crossing the Atlantic in conditions up to force 7!

So yes, you can sail a properly designed cat anywhere and in any conditions that a monhull will survive. Just don't try lying ahull when the going gets really bad (in fact, generally a bad strategy for modern monos as well). You must also understand that the design and construction of a cat intended for offshore voyaging is as different from those intended for Caribbean/med chartering as it is in monohulls. Bridgedeck clearance and shape, access to the mast in a seaway, a lower center of gravity (forget the Lagoon 440 'flying bridge'), protected helm station(s) and solid construction, even if at the expense of some increased displacement, are all important factors.

Will the Prout work for you? Maybe, and a number have circumnavigated successfully. I am actually surprised to hear of bridgedeck failure on an older Prout as they were built to Llloyd's offshore standards and have notoriously solid (and heavy) bridgedecks. That being said, the older Prouts are relatively slow, have limited accomodation for a cat of the size and the solid foredeck adds weight precisely where it is NOt required.

I would suggest that before buying any cat read, read some more, speak to owners, test-sail and then make a decision.
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Old 19-01-2008, 07:53   #41
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how ofterndo you plan to sit at ancor in 60mph winds?
Probably 3-4 times a season. It's a fact of life when you live at anchor and a tropical depression offshore creates a gradient offshore. Other times it's from a straight line thunderstorm front. Fact is, I sit at anchor in 60MPH storms a few times a season in hard chop that is on the order of 6-8ft.

I understand your point, though. It's best to think of what the boat is used for. It will be used as a permanent liveaboard and cruiser.
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Old 19-01-2008, 07:55   #42
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Have a look at you tube, search for catamaran and storm. I saw one of a cat in, if memory serves, a 50 knt storm and the wife was happily typing away on the computer without anything to steady her elbows. Can't have been too bad to do that.

You just may have to build a Schionning Wildermess as I am. It addresses Southern Stars points admirably

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Old 19-01-2008, 08:13   #43
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Cat

I have been sailing/living on board now for quit some time on my own Cat and previously on another cat. I currently am on a simple little 30 Gem.
I have been through hurricane dean and every tropical storm that came across this year.
Through out each storm I came out ahead.

My wish list for a cat is simple... If it does not have twin screws then I would not be interested in the boat. When the wind is screaming and you need to tuck the vessel into tight quarters a single screw on a cat just does not cut it, it really does not matter how great you think you are at the helm the boat simply will walk and walk where it wants unless you keep the power on.
The other item you need to look at is to ensure all of the deck ware has backing plates, ensure there is mid ship cleats, and ensure your cleats are over sized.
I will not even get into storm stories as this is a long winded opinion and non factual discussion.
I loved my mono, but it simply was not practical for sailing the Yuccatan and bahamas.
When it comes to speed and handling it is very important to understand how to load the cat. I can shift around 100-150 lbs and gain an easy two knts.
Marinas are different around the world, some places nail me for the "Cat Charge" but most do not.. I would say after your beam is larger than 15 you will have to understand that this lowers your chances of pulling up to a marina and just grabbing a slip.
Have a great time looking for a boat and be sure to check out the web groups for each boat, they always list the boats down sides and upsides..
Just my 2 bits..
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Old 19-01-2008, 08:21   #44
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Thanks for posting this. This is good first hand info from a small cat live aboard.

I will not be seeing marinas much... it's just not my style. So... it does not have the twin screws. I know it won't steer into a tight slip area properly with rudders and an outboard. Definitely not.

However, I can just tie the dinghy up to it and push it in like every marina worker does when they move a boat. That's the plan.

Thanks for this input. I think I'm still going for this Prout. I just want to make sure I'm aware of all the downsides... because I'm far too in love with the "up sides!!"


Quote:
Originally Posted by Ativa View Post
I have been sailing/living on board now for quit some time on my own Cat and previously on another cat. I currently am on a simple little 30 Gem.
I have been through hurricane dean and every tropical storm that came across this year.
Through out each storm I came out ahead.

My wish list for a cat is simple... If it does not have twin screws then I would not be interested in the boat. When the wind is screaming and you need to tuck the vessel into tight quarters a single screw on a cat just does not cut it, it really does not matter how great you think you are at the helm the boat simply will walk and walk where it wants unless you keep the power on.
The other item you need to look at is to ensure all of the deck ware has backing plates, ensure there is mid ship cleats, and ensure your cleats are over sized.
I will not even get into storm stories as this is a long winded opinion and non factual discussion.
I loved my mono, but it simply was not practical for sailing the Yuccatan and bahamas.
When it comes to speed and handling it is very important to understand how to load the cat. I can shift around 100-150 lbs and gain an easy two knts.
Marinas are different around the world, some places nail me for the "Cat Charge" but most do not.. I would say after your beam is larger than 15 you will have to understand that this lowers your chances of pulling up to a marina and just grabbing a slip.
Have a great time looking for a boat and be sure to check out the web groups for each boat, they always list the boats down sides and upsides..
Just my 2 bits..
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Old 19-01-2008, 09:32   #45
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Whimsical,

I think this is the video you are referring to:

Warp Speed

My wife, Donna, is doing emails as we run south to the Canaries before winds of 40 knots with higher gusts. It was a bouncy ride, but you can also see that the captain got his sleep lying on cushions in the salon.
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