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owengg · 29-09-2011, 20:04

What size catamaran is needed for a circumnavigation? I've read of the dangers of pitch polling in catamarans. From what I've read a circumnavigation shouldn't even be attempted in a boat under 40 ft.

Why are monohulls under 40 feet considered safer? The physics don't make much sense to me.

Factor · 29-09-2011, 22:50

Mythology mainly.

Talbot · 30-09-2011, 01:54

A lot of heavenly twins have circumnavigated and they are 27ft

The Prout range, particularly the 31 and 37 ft have a lot of circumnavigations.

I have a Privilege 37 which I have built for this sort of cruising.

The woods eclipse is less than 40ft and the original managed to sail over 1000 miles without even anyone onboard!

44'cruisingcat · 30-09-2011, 01:55

Quote:

Originally Posted by Factor

Mythology mainly.

Not quite right. Mythology ENTIRELY.

Lots of circumnavigations have been made on cats less than 40 feet. The "Bumfuzzles" did it on a 35 foot cat with zero experience when they set out.

S/V Alchemy · 30-09-2011, 07:33

Perhaps not the best example...

The only reason I would think one would want a 40 foot cat is because you start to have more tankage and stowage options a smaller cat would limit. Throw in the possibility of more generous area for ground tackle and solar panels, etc. and you have a cat that is capable of great independence from the shore, which is what a lot of monohullers prefer.

But in terms of the actual sailing, no. Loads of smaller cats can and do make these voyages...they just have to go to shore more often!

barnakiel · 30-09-2011, 08:55

I have seen people circumnavigating in a 9 meter (about 30') cat.

All the matter of your skills, where you sail, how much luck you get.

The bigger boat gives you better safety margins and way more living space.

36-42 seems like a nice size - many nice cats in this range.

b.

**David M** · 30-09-2011, 09:04

Size does not have much to do with seaworthiness. Size does help with comforts though.

The skippers knowledge and how they apply that knowledge has the most to do with safety.

Jesse · 30-09-2011, 09:36

Much smaller boats have done it and continue to do it.

Cheechako · 30-09-2011, 09:52

I believe the original reasoning had to do with wave size and dipping one bow in when planing down the face of a wave.... If memory serves. If you are running down the face of a huge wave at say a 45 degree angle, the windward ama may be lifting at the bow and the leeward ama may be dipping in at the bow. The would be the perfect situation to do a diagonal roll. If you think it through, it does seem like a cat would be more prone to roll than a mono in this situation. However, each boat is different and the key is to know your craft and avoid it's pit falls! Short wheelbase cars like a Jeep roll much easier that a longer wheel base with the same width. Think about driving a car that had a square wheelbase! That thing would roll super easy in a tight turn (remember the suzuki samarai?) Cats are generally built with a beam about half the length., does this change with length? I'm not sure....

Factor · 30-09-2011, 14:18

With all due respect, I am not sure what Suzuki samurais have to do with the hydrodynamic operation of my boat?

Quote:

If you think it through, it does seem like a cat would be more prone to roll than a mono in this situation

Thought it through and couldn't quite agree with you.

owengg · 30-09-2011, 17:44

I think the pitch polling of a cat would have more to do with the hulls not having the ballast weight of a mono.

Victory49 · 30-09-2011, 19:02

It has to do with ultimate stability. A cats most stable position is upside down. A monohulls is right-side up...
When it gets real nasty!

That's why cats have escape hatches and monohulls have to be prepared to ditch the rigging and limp to port under jury rig...

Any boat can be flipped. He longer the boat the nastier the waves can be and you'll still be ok.

colemj · 30-09-2011, 20:13

Apparently, not just a multi characteristic...

dennisail · 30-09-2011, 21:42

Quote:

Originally Posted by colemj

Apparently, not just a multi characteristic...

Great! So now I can argue that my upturned mono will make a great life raft like a cat if the keel falls off.

Have you found any pics of inverted cruising yachts yet to add to your collection? Those upturned boats are pure racers with broken canting keels and an oversized inshore racing dingy with vestigial ballast (the kiwi 35 wingnuts).

....Anyhow, I think cats are just as safe as monos. Asking these questions on the net will get a lot of rubbish from both sides. Just because I own a mono does not mean I am on the "side" of monos either. One day I will own a cruising multi and I still love my beach cat. However posting a pic of it upside down will provide about as much evidence against the seaworthiness of cats as the pics above do for monos.