Catamarans and the motion of the ocean

[BlueSkyNick]

Following on from another thread about the effect of extra weight on a catamaran (thanks, Talbot), and never having sailed on one, I have been wondering about how it feels in a bit of sea.

I can imagine that on smooth to slight seas, it must be very appealing to glide along upright at all times. But when the wind picks up to say a F5 and the sea becomes moderate, what's it like then?

On a monohull, its tolerable because the variation in the angle of heel and the motion is usually consistent (unless on a run, which is a bit different). But on a cat, if both hulls are being affected by two different waves at once, doesn't it get uncomfortable quite quickly?

If so what are the benefits of a catamaran, which make them attactive? I've often heard chaps say they might buy a cat because SWMBO doesn't like their current boat heeling over. I'm not sure this is realistic.

No doubt Jools and Talbot will be quick to respond, but it would be good to hear all views.

<hr width=100% size=1>I'm average size, Its just that everybody else is short.

 

[Twister_Ken]

Once heard one wag say the great advantage of a cat was that your mug of tea didn't usually fall off the table.

But the great disadvantage was that when it did fall off the table it landed on the deckhead.

<hr width=100% size=1><A target="_blank" HREF=http://www.writeforweb.com/twister1>Let's Twist Again</A>

 

[jimi]

Twice as much trouble

Two engines, two hulls, two rudders .. potentially double trouble?

<hr width=100% size=1>I Have The Body Of A God... Buddha

 

[tcm]

Not been on one myself but a crew person i met said she had been across the atlantic several times and just once (and never again) on a cat, cos the motion is very different and very weird. She said.

<hr width=100% size=1>

 

[snowleopard]

the important thing to recognise is that the motion of a cat is totally different from a mono. not better, not worse, different.

upwind there is more of a tendency to pitch and the vertical accelerations are higher, they bounce from one wave to the next rather than plough through them.

on a reach the hulls follow the profile of the waves so there is a rolling motion and when the direction of travel is at an angle to the waves that becomes a crkscrewing motion as the boat alternately pitches and rolls. with a short steep sea, the crests of the waves hit the bottom of the bridgedeck - the infamous 'slamming'. as the speed is usually a lot higher than a similar sized mono the motion tends to be pretty lively.

on a run there is no rolling and the motion is a gentle swooping as each wave passes. This is the best motion and doesn't wear you out as a mono can in tradewind conditions.

cookers are not gimballed and plates and cups stay put except when the cabin table is fixed to a flexible bridgedeck floor when they can be projected upwards very rapidly by a wave hitting the underside of the deck.

objects placed on shelves stay put without being tied down and progress around the boat requires hanging on but none of the gymnastics associated with heeling. using the heads is simple and you can sleep in a double berth at sea.

when anyone asks, swmbo always says 'cats don't heel, they bounce'

overloading a cat makes it slow and increases the tendency to bury the bows, it slightly improves motion to windward as long as weight is kept out of the ends

<hr width=100% size=1>

 

[Keith]

the big disadvantage with a cat is 90% of them don't go to windward worth a damn, yes in a beam sea the motion is or can be barbaric, i have been in a beam sea in 35 gusting 40 kts and its not something i would wish to repeat in a hurry, however two engines more trouble? its built in redundancy really i have two engines on mine and have had one stopped for one reason or another but the ability to keep going at reduced power on one engine is pure peace of mind, two rudders again the ability to disconnect the rudders and steer manually on one is a bonus, BUT not all cats will run with one rudder, this is where the case for the skeg hung rudder IMHO is a real benefit as they suffer from a lot less damage the ability to go into a crowded anchorage and anchor where most people can't is great news especially after a long day on the water, and if you dry out, so what it 's not going to fall over. other disadvantages, can't carry weight like a mono, if you do the chances are you will be no faster and quite likely slower than equivalent length mono, some marinas are charging length times breadth for a berth so we get hammered there, there is a tendency for cats to sit in different directions in an anchorage, thereby making ourselves unpopular, getting off a jetty if the wind is blowing you on can also be a problem, where a mono would just spring off and motor out, quite often not so with a cat, the biggest joy of owning a cat is when the wind goes aft of the mast thats the sweet spot and if you like to fly a spinnaker, downwind on a cat its not half the effort as on a mono, most of the gain is because the cat doesn't roll from side to side, and the ability to tack it down to either bow and broad foredeck make for easier spinny handling........at the end of the day its horses for courses, they do take some getting used to after a mono and they are horrendously expensive to purchase compared to a mono...but try it you might be pleasantly suprised.............keith

<hr width=100% size=1>

 

[oldsaltoz]

G'day Bignick,

To sum it all up, you will often hear the words "who pushed me" if you sailed with us, as Snowleapard pointed the deck movement is very fast compared to a mono in heavy or choppy conditions, with the result when walking you put your foot down expecting to find the deck but it's moved 2 inches lower since you took the last step, or worse it's higher and you sort of trip, look around and say "Ok, who pushed me".

This is not, again not at all the problem 'some' would have you believe, and the best thing anyone can do is step aboard and go for a sail, even better if you can arrange an overnight stop, you will not believe how comfortable a cat is at anchor.

The primary difference between a cat and a mono is the cat runs ON the water and a mono runs IN the water, so wind and wave cause very different effects at very different speeds.

I hope this helps.

Avagoodweekend on a cat......



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[doris]

Run up to the beach and...

just ask the chap to bring over the rum-puch/beers or whatever is your fancy. There is a happiness in shallow waters that monos will never know!!

<hr width=100% size=1>Real men do it 2handed.

 

[Talbot]

I dont think there is really very much more to add to what has already been written. The point about progress to windward is valid for the older generation of Cats, but not so much for the new designs that are available now - but that can also be said for a lot of monohulls. Mine particularly does not like the solent chop, but longer waves are not such a problem. If you are cruising then you really try to plan tradewind style passages - and it is here that the real advantages of a cat are revealed. The monohull pendulum effect when sailing downwind in biggish seas can be accepted for a day or two, but after a couple of weeks it sends some people totally cranky. You do not have that with a cat!

Best advice is to try it

<hr width=100% size=1>

 

[Boathook]

Re: Twice as much trouble re jimi

The advantage is that when one half starts to sink you move into the other half. If you are in partnership it is always the partners half that causes the problems ..

<hr width=100% size=1>

 

[Jools_of_Top_Cat]

I believe and could get shot down here that in moderate weather there is a coming together of life on board a cat to life on board a mono albiet different but the same affects on crew tiredness and fatigue.

A mono rolling through the sea has a similar affect on crew as a cat pitchpoling along, although getting around the cat is still easier as your mean (average) position is upright, where the mono could be rolling at a mean angle of 20°. Holding on and waiting a few seconds means you can carry on your journey to the heads unhindered for example, yet on the mono you still have to cope with the heel.

As a nice helmsman I will always turn off the wind if someone has gone below, if I can of course, in a central cockpit such as the twins the pitching action is much reduced. I once nearly fell asleep in a F7-8 running back to Fishguard, the motion when running was so comforting even though popping my head up above the dodgers showed all hell letting rip outside.

I will state fr the record though, my first trip on Top Cat bringing her up from Salcombe in 1989 I hated her, I hated the movement, it wasn't right this was not a good way to be on the water. Now I would have trouble going back to half a boat.

<hr width=100% size=1>J

<A target="_blank" HREF=http://www.topcatsail.co.uk>

</A>

 

[BlueSkyNick]

Thanks for all the comments. It seems to me that cats are no different to any other boats in a way - people make a particular choice for their own specific reasons.

Some are very happy with their 25yr old long keeler, others with their 3yr old AWB, and then there are catamaran owners too. None of us are wrong, in fact we are generally all right if we've got the boat we want.

With regard to the motion, I am sure that it is one of those things you get used to - ie your sea legs and brain become familiar with it, and hence second nature.

Would love to try it - let me know if you need a crew sometime, Talbot!! I'm less than an hour from you, and would be happy to reciprocate.

<hr width=100% size=1>I'm average size, Its just that everybody else is short.

 

[Jeannius]

I did ARC2002 in a Privilege 435 cat having previously been almost exclusively a monohull man. By the end of the trip I was totally converted to cats as we had a very comfortable ride in contrast to the crews of many monos who were complaining about the constant rolling. When we stepped ashore in St Lucia we were quite capable of leaving the same day to head for the BVI.

This ARC was considered to have had relatively heavy conditions with regular 30-35 knot squalls and confused seas so the fact that we arrived so fresh is a good indication of the suitability of a cat for long offshore passages

<hr width=100% size=1>Mike

<A target="_blank" HREF=http://www.sailbvi.net>www.sailbvi.net</A>

 

[grafozz]

"cats don,t go to windward" -90% even !Isail a cat a pretty ordinary cruising cat ,with two inboard deisels, and passed several 35-45 ft cruising monohulls in 30-37 knots westerly "breeze" heading for yarmouth recently from the east and can report that they all had nice clean bottoms, and in one particular boat,keel! its wrong to generalise about any type of boat, no doubt there are some monohulls that don,t go to windward too . I have taken many sailors out and all have been surprised at how peacful life is aboard a cat, (whilst doing breakfast in 25 knots of wind ) don,t pass judgement until you have experienced it.

<hr width=100% size=1>grafozz