40' Required for Circumnavigation

[Jimbo485]

Thanks for the link, Evans. I remember a long time ago that Beth and your plans for your second boat were to have an aluminium cat. That coincided with our ideal as well. For reasons based on time and $$, we took a compromise. What changed you from your original idea to Hawk?

[44'cruisingcat]

It really does come down to personal preference. Which is more important to you, being afloat, or being right side up?

[catty]

Originally Posted by Paul L

44,
Do you have any links or can you post some polars for these Cats? I'd like to see some hard data on how close to weather they sail at design weights.

I have no dog in this fight, so 'you guys' doesn't really apply. Just interested in what some of the better cruising cats can these days.

The only polars for performance cruiser cats I have been able to locate are the gunboat ones. To my knowledge Schionning (Craig and Geoff) and Oram don't publish polars.

There is however a lot of windward race data now available on the net however, I have personally participated in races with Orams , schionnings, and monos involved with the monos generally having the edge to windward and on the square legs in lighter conditions. There is still a huge performance gap between racing and cruising catamarans.

Hope this helps
Regards.

[Paul L]

Originally Posted by estarzinger

This by shuttleworth is worthwhile reading.

That's an interesting writeup. I like the comment
'It is interesting to note that this development, resulting in a dramatic increase in seaworthiness and speed, has taken place over virtually the same time period as the monohulls have been deteriorating in seaworthiness. '
I would have liked to see specific reference to some cruising boat models that matched the type 1 to type 7 multihulls. It is hard for non-multihull person to know where the popular models fit into his classification.

Not sure I understood the explanation that a cat goes to weather significantly better with full sail, than reduced, and that ' modern multihulls will sail upwind in a gale long after the monohulls have had to heave to'

[44'cruisingcat]

Originally Posted by catty

The only polars for performance cruiser cats I have been able to locate are the gunboat ones. To my knowledge Schionning (Craig and Geoff) and Oram don't publish polars.

There is however a lot of windward race data now available on the net however, I have personally participated in races with Orams , schionnings, and monos involved with the monos generally having the edge to windward and on the square legs in lighter conditions. There is still a huge performance gap between racing and cruising catamarans.

Hope this helps
Regards.

Which race would that have been?

[Cheechako]

Originally Posted by Jimbo485

Check out Chris White´s book. It is an excellent read for the OP.

He states that capsize resistance (roll moment of inertia) is proportional to the cube of size. So doubling your length from 25´ to 50´ results in 8 times the capsize resistance. There are a few assumptions in there, so read it yourself and then come back here.

I guess this is what I was trying (poorly!) to explain in my earlier post.
also:
I'm not sure beam on capsize tests are a good gauge here.... (who is going to present their boat beam on to large breaking waves?? Mono, power or cat.) Thus I used running down the wave face at 45 degrees, but not sure if that is better or worse than dead down wind in a cat.

As usual, it's probably more about the people than the boat....

[colemj]

Originally Posted by hoppy

[IMG]

I'm not sure of your point. Those are three pictures of the same boat - one that was flipped at anchor when hit by a recorded tornado. A monohull was holed and sunk by the same storm system in the same anchorage.

BTW, it wasn't so easily recoverable

Mark

[colemj]

Boy, I was just looking at hoppy's photos again and had the thought that while the ultimate stability in a perfect storm can be debated ad nauseum, there can be no debate on the ultimate safety when everything does go wrong. I mean, look how high that boat is floating and keep in mind it is an older and heavier design (really, by decades).

You can play the odds against the boat capsizing, or play the odds against continuing to live if you do capsize.

That would probably be a whole 'nother thread completely. Maybe a poll: would you rather have a statistically small chance of not capsizing or statistically large chance of surviving a capsize?

Mark

[colemj]

Originally Posted by catty

The only polars for performance cruiser cats I have been able to locate are the gunboat ones. To my knowledge Schionning (Craig and Geoff) and Oram don't publish polars.

There is however a lot of windward race data now available on the net however, I have personally participated in races with Orams , schionnings, and monos involved with the monos generally having the edge to windward and on the square legs in lighter conditions. There is still a huge performance gap between racing and cruising catamarans.

Hope this helps
Regards.

Both Lagoon and FP used to publish polars on their boats. They may still - I haven't looked. However, these were calculated polars by the designers and I have sailed some of these boats and seriously doubt the accuracy of those polars.

Mark

[catty]

Originally Posted by colemj

Both Lagoon and FP used to publish polars on their boats. They may still - I haven't looked. However, these were calculated polars by the designers and I have sailed some of these boats and seriously doubt the accuracy of those polars.

Mark

Very true. The gunboat polars have been pretty much discredited as being extremely optimistic to say the least with all the race data now available.

Regards.

[Factor]

And yet a gunboat is quicker than the maltese falcon. Who would have thought!

Discredited by whom? Reference please. If its just your opinion, thats fine but please say so.

[dennisail]

And yet a gunboat is quicker than the maltese falcon.

Wasn't the hull of this thing purchased cheap after some rich guy could not afford to complete it as a powered ship, then the sailing rig added as an after thought?

[colemj]

Originally Posted by dennisail

Wasn't the hull of this thing purchased cheap after some rich guy could not afford to complete it as a powered ship, then the sailing rig added as an after thought?

I believe Tom Perkins commissioned the design and build from the start (I think it was his "starter" boat to get into sailing with). And that rig is no after thought! The uniqueness and complexity show a lot of thought going into it, and the boat had to be designed specifically for it.

Mark

[hoppy]

Originally Posted by colemj

Boy, I was just looking at hoppy's photos again and had the thought that while the ultimate stability in a perfect storm can be debated ad nauseum, there can be no debate on the ultimate safety when everything does go wrong. I mean, look how high that boat is floating and keep in mind it is an older and heavier design (really, by decades).

You can play the odds against the boat capsizing, or play the odds against continuing to live if you do capsize.

That would probably be a whole 'nother thread completely. Maybe a poll: would you rather have a statistically small chance of not capsizing or statistically large chance of surviving a capsize?

Mark

Or you can buy the type of yacht that you will enjoy sailing the most and let the "fear the worst case scenario" for the paranoid sailors who would probably be sitting at home except more people die from accidents at home, so they venture out

[Sand crab]

Owengg, you probably want to buy Gregor Tarjans book.
REFERENCE BOOK: “CATAMARANS, The Complete Guide for Cruising Sailors” - Aeroyacht
It's really well done and without being too technical like the Shuttleworth paper (no offense meant). The book is 40 bucks and usually in stock at Barnes and Noble. Without starting another war I suggest that some of the mono contingent give it a read as well. He gives some very compelling reasons for cats. BTW he is a naval architect and a broker so he knows more than most of us about this subject. He certainly knows more than me. BOB