42' Vs 44' Vs 46' Cats for Ocean Crossing

[UFO]

For arguments sake, lets just stick to the length issue rather than different build/manufacturer issues and lets keep the sailing grounds out of the high latitudes.......



Is there a (huge) difference between the above lengths for Safety, Comfort and Stability for Ocean crossing in cats?

[fxykty]

In general more length equals more comfort and speed and possibly more safety and stability, simply because a longer boat will handle a given size of sea easier and will sail faster even with a proportionally larger load. Certainly the space will be greater (assuming same design philosophies).

However, since length is not necessarily positively correlated with more beam nor more displacement, which for catamarans have more effect on stability, you can’t always say that a longer cat will be more stable than its shorter sister.

For monohulls the traditional advice was to buy as much waterline as possible. Not sure that it applies nearly as well to catamarans since they’re not as restricted by hull speed.

[UFO]

Originally Posted by fxykty

In general more length equals more comfort and speed and possibly more safety and stability, simply because a longer boat will handle a given size of sea easier and will sail faster even with a proportionally larger load.

Thanks, but is there a big/noticeable difference between a 42 and a 44? then to a 46?


To put some context, Just trying to decide what is the smallest cat to go for with the above criteria in mind.

[jdazey]

Originally Posted by UFO

Thanks, but is there a big/noticeable difference between a 42 and a 44? then to a 46?


To put some context, Just trying to decide what is the smallest cat to go for with the above criteria in mind.

fxykty gave a good answer. More specifically the difference between 42 and 44 won't be as much as 42 and 46 or 42 and 48. Some may notice a difference in 2 feet, some may not as a lot of other factors come into play. As far as your context goes, there have been a lot of cats crossing oceans safely, quickly, and comfortably that have been well under 42'.


Cheers,

[StuM]

Make sure you differentiate between LWL, LOA and the numbers that the manufacturers stick on their models when doing your comparison

[fxykty]

Originally Posted by UFO

Thanks, but is there a big/noticeable difference between a 42 and a 44? then to a 46?


To put some context, Just trying to decide what is the smallest cat to go for with the above criteria in mind.

Your question is close to asking ‘how long is a piece of string?’ With multihulls you are generally restricted by load carrying capability, which definitely increases with size. So you can pick the smallest boat that meets your needs for space, acknowledging that you will probably be slower and less comfortable (boat motion wise) on a smaller cat. Whether the 2 or 4 feet in length (cubed for volume) makes a difference to you is very personal.

As far as safety and stability is concerned, there will be very little difference if you stick to recognised designs and the middle latitudes as you’ve specified. Cats in the mid 30s have successfully circumnavigated, but not necessarily very quickly, so setting 42 feet as a minimum is very conservative.

[bluenomads]

Much more important are things like: length to beam ratio, prismatic, sail area & mast height & number of masts (assuming sail boat), engine size, amount of fuel and placement, protection of crew in weather, deck safety systems, overall beam, bridgedeck clearance, windage (if sail boat) etc.
You could easily have a 38' that has great of all of these that is much better for some oceans than most 48'ers.
You also need to define your "ocean crossing" a bit: are you talking careful weather windows between Canaries and Caribbean and back to Europe via Azores, or are you talking Cape of Good Hope to Hobart in winter (or actually any time!)?

[Flcracker]

One mistake and big water and you are sideways in the wave I sail smaller cats

[boatman61]

I have just done a W to E delivery of a 2017 Lagoon 450S..
I still think the best size for me is the L380.. everything is so much easier to handle.. the advantages of things like the steering position.. height of boom for working on the main in a seaway if something untoward happens rather than standing 12ft+ above the sea dealing with flailing sail and violently twanging boom and nothing to secure yourself to.. or grab as you fly through the air.
Is that extra ensuite toilet worth it.. Naaw.!!!
Funny enough 380's are also not as noisey below..

[belizesailor]

Originally Posted by boatman61

I have just done a W to E delivery of a 2017 Lagoon 450S..
I still think the best size for me is the L380.. everything is so much easier to handle.. the advantages of things like the steering position.. height of boom for working on the main in a seaway if something untoward happens rather than standing 12ft+ above the sea dealing with flailing sail and violently twanging boom and nothing to secure yourself to.. or grab as you fly through the air.
Is that extra ensuite toilet worth it.. Naaw.!!!
Funny enough 380's are also not as noisey below.. [emoji3]

I like the 380 too.

One of my concerns with typical aging cruisers buying larger cats, particular 50+ LOA, is will they be able to handle the extreme loads big cats generate in heavy conditions. The Lagoons in particular have undersized winches and assume those winches will be powered. If they are not powered for any reason then I dont think they are up to the task in heavy conditions.

A friend's Shuttleworth 65 by contrast has MASSIVE primaries. They are powered also, but clearly up to the task should they lose power.

[UFO]

Originally Posted by bluenomads

Much more important are things like: length to beam ratio, prismatic, sail area & mast height & number of masts (assuming sail boat), engine size, amount of fuel and placement, protection of crew in weather, deck safety systems, overall beam, bridgedeck clearance, windage (if sail boat) etc.
You could easily have a 38' that has great of all of these that is much better for some oceans than most 48'ers.
You also need to define your "ocean crossing" a bit: are you talking careful weather windows between Canaries and Caribbean and back to Europe via Azores, or are you talking Cape of Good Hope to Hobart in winter (or actually any time!)?

So what is a good Length to Beam Ratio - Over 2:1 or Under?


I am a warm weather person, so the thought of Hobart in Winter sends a chill down my spine

[zboss]

Have you found this site yet?

Multihull Dynamics, Inc. - Home

[Steve_C]

Originally Posted by boatman61

I have just done a W to E delivery of a 2017 Lagoon 450S..
I still think the best size for me is the L380.. everything is so much easier to handle.. the advantages of things like the steering position.. height of boom for working on the main in a seaway if something untoward happens rather than standing 12ft+ above the sea dealing with flailing sail and violently twanging boom and nothing to secure yourself to.. or grab as you fly through the air.
Is that extra ensuite toilet worth it.. Naaw.!!!
Funny enough 380's are also not as noisey below..

I would be very interested in your impressions of the 450S. I would have thought the boom height would not be an issue since its the "S" model.

One thing I do NOT like about the 450S is the Helm Seat. Its very upright and close and since its built in it would be a major issue to do anything about it. At least on the 380 and 400 it would be very simple to upgrade to a much better aftermarket seat.

I have been conflicted for a long while about the benefits of the 450S vs the 400 and the 380. I love the thought of all the extra storage and room but I also can REALLY appreciate keeping everything smaller and more manageable. Its not very often that I can find true unbiased direct comparisons.

I am especially interested in hearing more about the noise issue. I have noticed when chartering a 450F that they can be noisy below when underway.

I would really appreciate hearing your thoughts.

Thanks!

[Mike Banks]

The larger your vessel, the more expensive to buy and maintain, and the more complex its equipment. The more complex its equipment, the more likely are breakdowns.

Two people need no more than a forty foot cat properly designed for ocean passages. Once one gets big enough to need more crew and powered sheet-handling equipment, the more one needs auxiliary power.

My plump would be for about fortyifive foot, down to thirty-eight. I would also use a non-standard bi-pod rig with wishbones and furlers. Two bi-pod masts, maybe three if the vessel was longer. Easily handled, self-tacking, and one can run any damn rig one likes from them. I like wishbone booms, but even a crab-claw sail or two if the ethnic designs and their largest area of sail in relatively undisturbed air get you excited.

The whole idea of ocean crossing or coastal passage is to get there safely. With safety as a first priority, getting you there as quickly as safety will permit. That means efficient and easily handled sails, and I think that tghe efficient sail means it can be a smaller sail, or one better positioned to catch the wind--and the best wind is high on the mast, not close to the deck. Wharram with his comparatively narrow rectangular wing-sails illustrates this very well. Most boats carry far more canvas than they need--most of it in the wrong place hugging the deck where the waves and the ocean troughs have disturbed the laminar flow of the wind. The reason the small crab-claw sails work so well is the fact that the business end of the sail, the one generating the power, is in the cleaner less turbulent air well above the decks. A small-ish crab-claw sail will out perform a much larger conventional sail. If the mast is a bipod type, it will put far less stress on the rig and vessel itself.

To get back to your original question--smaller and more easily managed can be the safest option. My advice, for what little it may be worth, is to stay close to forty feet or so--anything larger needs crew and lotsa dough to keep it sailing safely. In a severe storm, the bigger the vessel the more seas will impact it. The heavier it has to be,. The larger and more expensive its anchor tackle and the handling of it, the taller its conventional masts, the more absurd the tension required to brace them against the power of larger sails etc etc.

Stating the obvious, really.

[fxykty]

Originally Posted by UFO

So what is a good Length to Beam Ratio - Over 2:1 or Under?


I am a warm weather person, so the thought of Hobart in Winter sends a chill down my spine

Many current boats are under 2:1, with smaller boats having lower ratios due to still having reasonable beams while for larger boats beams max out in the low 8’s (e.g. Leopard 40 is 1.78 and Leopard 45 is 1.86 and Leopard 50 is 1.91). Older designs tend to have higher ratios as they were generally built narrower.

Cold weather sailing is more comfortable in a catamaran as the helm station is generally more protected than with a monohulls, but having originally come from cold water all year round Pacific Northwest I am loving year round shirtsleaves in Auckland. Our boat has central diesel hydronic heating and it’s a treat.

Back to your original point, don’t worry too much about the ratios and all the rest of the technical specifications unless that’s really your thing. Most every production boat in the last 20 years (and including many great independent designs, of which Australia has a plethora) has been well designed for safety and comfort in non-extreme sea conditions. So pick the boat that emotionally speaks to you (and your partner if applicable). In our case a gorgeous sheerline and comforting cabin ergonomics meant a whole lot more to us than the 2.26 length/beam ratio.