how do cats handle big waves?

Discussion in 'Multihulls' started by Guest1578132542, Jul 15, 2010.

  1. Richard Woods
    Joined: Jun 2006
    Posts: 2,208
    Likes: 165, Points: 63, Legacy Rep: 1244
    Location: Back full time in the UK

    Richard Woods Woods Designs

    I haven't joined this thread for a bit as I am travelling. (I write this in Toronto airport)

    I assume these latest posters have all seen this link I posted earlier in the thread

    So did the boat survive?? and what do you think happened to the crew???

    And also my report on the sinking of my friends Moody

    I don't think it is fair to tar all multihulls with the same "capsizable" brush and then say "ah but only some monohulls sink, usually because of damage".

    You can see an earlier thread on my assessment of the real risks of sailing on this forum. Or if you cannot find it it is on the FAQs page of my website.

    As Mark says, different people like different boats

    The last time I was on a boat like Northern Lights I was in Juneau but sensible headed south, not north. (But at least I have been on a boat like yours)

    However I'll stick to a catamaran.

    An open fishing boat is one of the most dangerous sorts of boat there is (check the CG statistics). Static range of stability is only about 50deg. Whereas a good catamaran will be around 80 deg. The dynamic stability (more relevant in big seas) is way higher for a multihull than for any monohull

    But downflooding (swamping) is more of a concern.

    What happens in big beam breaking/swamping seas?? Don't say you never allow the boat to go in breaking beam seas. Doesn't your cockpit fill with water?? And if not why not?? What about free surface effects???

    And what happens if you have engine failure?? Do you bob up and down head into the waves, or roll your guts out beam on???

    The Wolfson Unit tests pulled sailing boats from a pole positioned to simulate the position of the C of E of the rig. The powerboats were catapulted into/across the breaking seas. So were free floating.

    My flight has just been called

    Richard Woods of Woods Designs
    1 person likes this.
  2. Fanie
    Joined: Oct 2007
    Posts: 4,603
    Likes: 170, Points: 63, Legacy Rep: 2484
    Location: Colonial "Sick Africa"

    Fanie Fanie

    This is cheating if I ever saw it ! So, what's wrong with sailing :D or the mono too slow :D
  3. rayaldridge
    Joined: Jun 2006
    Posts: 581
    Likes: 26, Points: 0, Legacy Rep: 322
    Location: USA

    rayaldridge Senior Member

    Does it sound any better the other way around? "If one is biased, he prefers a cat. If unbiased,monos are safer..." Or, "if one is ignorant, he prefers a cat..."

    One thing I'm pretty certain of: either well-built, well-designed cats are safer than well-built, well-designed monos, or it's the other way around. They can't both be safer than the other.

    In my youth, I liked to ride motorcycles. My teenage sons complain that I won't let them have motorcycles, and that I'm a hypocrite. Probably so, but cars are safer than motorcycles. Period. One could surely construct a special situation where a bike was safer than a car, but as a general proposition, who would seriously argue that bikes are safer than cars on the highway-- except for someone who was biased in favor of bikes? But if you go in any biker bar, you'll hear folks seriously arguing that bikes are safer.

    I'd be happy to hear arguments for the superior safety of monohulls, but "I've been out in a lot of really bad weather in monohulls and I'm still alive" is not very convincing to me.

    Here's an argument that I find convincing, so point out where I'm wrong: Multihulls are safer than monohulls in breaking seas, because in a big breaker, the keelboat will have its keel in solid, relatively motionless water while its topsides are being hit by masses of fast-moving water, making the boat more vulnerable to capsize via the tripping action of the keel. The multihull, with boards up, is safer in breaking seas, because the boat, having no appendages deep in solid water, and being lightweight, will move with the breaking water, and will be much less likely to capsize. I find this all the more convincing, because I've experienced this phenomenon myself. Add in the fact that righting moment and moment of inertia is much greater for the cat, and you have a pretty fair argument, in my view.

    You can say in response, "Well, maybe so, but there are conditions that will capsize any boat, and the monohull will come back up." True, but there's no guarantee it will come back up undamaged. It may lose its rig, it may lose hatches or even cabin tops, as happened to Tzu Hang. A monohull open to sweeping seas will not remain afloat for long, in most cases. Once it loses its rig, it will be capsized many more times, as was demonstrated in the Fastnet disaster. Even if the boat retains its watertioght integrity, crew may be seriously injured by the violence of this motion, and a crew with a broken arm is a lot harder to rescue. In the analysis of the Fastnet tragedy, the commission concluded that losing a rig was a recipe for disaster, because it took away a large amount of moment of inertia. Because a multi has a lot of its mass well distant from its center of rotation, it continues to have a high moment of inertia even when it loses its rig, in contrast to monos.

    Perhaps I am biased, but I've been out in pretty bad weather in both monohull and multihull yachts and I always felt safer and more comfortable in the latter. My first real yacht was a multihull, and then I owned a series of monohulls, and now in my semi-dotage, I've gone back to multis.

    I can cite you a pretty intriguing instance of bias. I'm the book reviewer for Living Aboard magazine, and IM just sent me a copy of Hal Roth's book Handling Storms at Sea for review. It's a terrific book, very well-written and full of good information. But as Roth states upfront, it's written from the viewpoint of a monohull sailor. Now I should say that I admire Roth greatly. He, along with the Pardeys, and the Hiscocks, exemplify the best of small boat seamanship. They took care of their boats, planned their voyages meticulously, and with only a couple of exceptions, traveled around the world's oceans safely and without serious incident. Roth survived a shipwreck near Cape Horn, and so did his boat. He was a great sailor.

    But I think he was probably biased in favor of monohulls. He devotes several pages to the loss of Banjo, the yacht I mentioned upthread. In all that analysis, he neglects to mention that not long before Banjo fell off that 50 foot wave and cracked open, the crew spotted Jones' tiny cat Two Rabbits, happily sailing herself with no one on deck. Don't you think that would have been an interesting fact to add to the description?
  4. Fanie
    Joined: Oct 2007
    Posts: 4,603
    Likes: 170, Points: 63, Legacy Rep: 2484
    Location: Colonial "Sick Africa"

    Fanie Fanie

    I was fishing in the surf a while back, the water was about knee height and the oncoming waves passed under my arms. No big deal, you just hook your toes in the sand (I have big toes ;)) and hope there's not a shark in there also.

    So all went well for a while, then suddenly a somewhat larger wave came up, which was a bit unfair because it was over my head by about 300mm. Now while I was upside down - and most of the thoughts started with 'f' - it occured to me that up to a certain size sea is not a problem for the boat size. Exceed it by some and you need bigger toes :D

    Now if I was ancored by something for added stability, even though I was swamped, the outcome would be much different and I wouln't have lost my veteran fishing hat. Man I was PO. I now have to get a new one and look like a figgin rookie again. Maybe I could put the new hat in the concrete mixer for a while...

    I could wade out of there, some sand got in the reel while I was doing the wagon wheels (4 5 c :() but what if you were stuck on the boat, as Richard pointed out and the motor packs up.
    1 person likes this.
  5. CatBuilder

    CatBuilder Previous Member

    Mark, we had a private talk, so you know I'm not saying this in any mean way. I do want to point out two things in response to this post above:


    If I arrange for you to use my previous catamaran or same model, (my current one is being built) I will wager $10,000 real money you can't flip the boat by sailing it. Really. If you'd like to take me up on this, I'm serious. If you have $10,000 to put up, I'd be happy to take the bet.

    You see, I don't bet on things that aren't certain. (ask my wife)

    I am quite certain you can't flip a cruising catamaran, no matter how hard you try. This is better than Brent's boxing match and smash up derby. This is real, if you'd like to pony up. We could pick a lower amount if you'd like, but I'm happy risking it all on this one.


    I think you are picturing too small of a catamaran if you see people being ejected in bad seas any more than they'd be ejected from a mono.

    That said, I have enjoyed your posts in this thread and your thoughts - especially those where you talk about the steep current/wind generated seas. Those are not often considered when thinking about seamanship or safe design.
    1 person likes this.
  6. Westernman51
    Joined: Jul 2010
    Posts: 10
    Likes: 1, Points: 0, Legacy Rep: 28
    Location: France

    Westernman51 Junior Member

    You don't need waves to capsize a light catamaran

    Just a bit of wind is enough on its own:-

    I have pitchpoled my catamaran myself on many occasions and have never worked out how to avoid it (except by removing sail and slowing down).

    The interesting thing about this video is you see the catamaran perfectly balanced, no waves and then for no apparent reason it flips. :eek:

    Monohulls don't do that, they just broach and fall over sideways. ;)
  7. Richard Woods
    Joined: Jun 2006
    Posts: 2,208
    Likes: 165, Points: 63, Legacy Rep: 1244
    Location: Back full time in the UK

    Richard Woods Woods Designs

    Nothing goes to windward like a 747 except, it seems, my flight. It's been delayed.

    I like this USD10,000 bet idea. I bet USD10,000 I can capsize and sink Northern Lights easier than Mark can capsize my Eclipse. Only snag is, I'll probably die in the attempt, whereas Mark will probably live, if he can capsize it that is.

    BTW I see over 200 people have drowned in Canada so far this year. On average 34 people drown in their CARS each year in the UK. Many more in their baths of course.

    I don't think we can compare monohull accidents with multihulls. We do need to know the risks and how to deal with them though.

    As flying is fresh in my mind right now. Train travel is safer than flying, so why don't more people take trains instead of planes??

    I had several friends at school who had motorbikes. One was killed, another is paralysed from the neck down after an accident. Why do you not need to wear a helmet riding a motorbike in Florida (yes I know, crazy but true) but must wear a lifejacket, or at least get fined heavily if they are not on board?? Surely that is equally an infringement in civil liberties??

    Google Canadian boating accident to see the most recent deaths on board a fishing boat

    Sorry, becoming incoherent, but I have been awake 24hrs so far and still not home

    Richard Woods of Woods Designs
  8. Gary Baigent
    Joined: Jul 2005
    Posts: 3,006
    Likes: 121, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    hey Westy
    That is a bit more than just a little wind in the cartwheel - they have way too much sail up - but where's the fun in reducing sail if you want to really blast?
  9. cavalier mk2
    Joined: Mar 2010
    Posts: 2,123
    Likes: 55, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    I don't think this boat design forum betting thing works. I offered my boat for high speed, high wind planing tests for the price of a suit of sails and here I am modifying and stitching together used ones.....
  10. rayaldridge
    Joined: Jun 2006
    Posts: 581
    Likes: 26, Points: 0, Legacy Rep: 322
    Location: USA

    rayaldridge Senior Member

    That's a spectacular crash, but I guess all in a day's fun for a beach cat.

    If I recall correctly, Chris White talks about how beach cats have affected the perceptions of sailors in regards to cruising cats, even though they are far different, more different than a planing dinghy is from a Tahiti ketch. The vast majority of catamarans in the world are beach cats, and somehow people have gotten it stuck in their heads that a cruising cat is as vulnerable to capsize as a Hobie.

    I really saw this in action when I was designing Slider. Because Slider is only 16 feet LOA, people could for some reason not get their heads around the notion that she was not a beach cat. One guy made fun of me for trying to reinvent the Hobie 16.

    Of course, if I ever find myself out in mountainous seas in Slider, I'll certainly die. Stability goes up very rapidly with size, so that a cruising cat twice as long as Slider is many times as stable. But it probably won't have a much higher sail area/displacement ratio. It would be tough to capsize Slider in strong winds, but a lot tougher to capsize a bigger cruising cat.
  11. Boston

    Boston Previous Member

    interesting reading but not quite what I need to help me understand the historical performance of both in bad weather

    I am partial to mono's myself
    but then again the mono's I like are not the most seaworthy things that were ever designed ( I like large windows )

    multi's kinda scare me cause its a one shot deal as near as I can see, which isn't exactly 20/20 cause I've really not been around big ocean cruising cats. Which is why I asked in the first place.

    I know there is a lot of animosity between one side of the coin and the other but I say lets just set that aside and keep it to events and circumstances. I agree that a good sailor well prepared in a bad situation can generally survive but thats not often the folks who get themselves in trouble. Bad decisions can screw up the best preparations or an idiot can gum up the works just as fast no telling what led to the circumstances of stuck in bad weather .

    So Im left with the question

    in which type is a complete idiot most likely to survive

    can you just throw out a sea anchor and hunker down just as well in both or are there more special needs in a cat than in a mono

  12. mark775

    mark775 Guest

    First, that Hobie sailing looks a hoot! I want one! Second, let me think about flipping your cat - I'm trying to figure how to make it survivable. I have plenty of surf experience and know I can flip it (I used to do the rough weather beaching of 17' Achilles inflatables with 35 Johnsons for USFW Aleutian Islands reserve. Try Buldir Island surf for a rush! I know it is not the same as a cat but I AM well familiar with waves, wave patterns, and feel that steerage and manueverability are deciding factors in stability. I have flipped backwards, pitchpoled, been absolutely landed upon...and am still here) The money ($10,000) is steeper than the waves but I like the cut of your jib! I hate to be a wuss but I seriously don't know how to survive a bigger boat flipping in surf (plus the damage will be more than the bet)...let me see a pic of the boat, first?
    I know that you could roll my boat - I could, too. There have been many instances were a loss of power alone cud have meant capsize and sinking. In a powerboat, mechanical aspects are a critical concern (that not enuf pay attention to). In nearshore situations, drogues and such don't have the same meaning as at sea. Anchors can tie you down in a way you don't want to be.
    As far as my not having cat experience, and I do not have ANY cruising sail cat experience, please entertain that someone might garner experience thru watching, comparing how boats react in like seas from another boat. I spend a lot of time with 30 to 45 ft cats, swaths, Stolkraft, etc. and do pay attention. Heres an example of one that I don't want to cause a ruckus about but let's just say...they leave it parked and use a different boat;


    Perhaps I am thinking of too small of a cat, but just a little, deep in your heart, don't you feel that catamarans are an alternative that are just a, alternative? "You know that I am not saying this in any mean way..."
    Seriously, a fun thread, overall, I appreciate every comment. I'm learning from you guys and I will buy the book mentioned...Amazon?
  13. rayaldridge
    Joined: Jun 2006
    Posts: 581
    Likes: 26, Points: 0, Legacy Rep: 322
    Location: USA

    rayaldridge Senior Member

    Here's a video clip that I saw on another forum (I think).

    Conditions are not awful, but if you've been out in similar conditions on a monohull, the interior of the boat will be a revelation to you. In those conditions, going downwind, you wouldn't leave your laptop sitting on the table.

    Mark, I'm not sure what you mean by "alternative."

    It's good to remember that the Polynesians were colonizing vast stretches of the Pacific in double canoes, back when Europeans were afraid to sail around the tip of Africa. As deep sea boats, cats probably have a lengthier history than monohulls.

    In any case, I'll hotlink this pic from Chris White's site, and hope he won't mind:

    This is his Alantic 46. The beam is over 20 feet.
  14. magwas
    Joined: Oct 2009
    Posts: 287
    Likes: 8, Points: 18, Legacy Rep: 47
    Location: Hungary

    magwas Senior Member

    I think it is a mistake to state for any boat that it cannot be flipped/rolled over/sunk. See Titanic for an example. The sea is mighty.

    If I knew how to survive it, I would take your bet and would head to the nearest tropical storm. I would look for a spot where the current is against the wind, put the keels down, get the waves and wind abeam, and put up canvas.
    It maybe harder than finding a suitable surf ashore, but safer, and makes less damage.

    Is strengthening the standing rigging with some elements of running rigging okay by the rules?
    Any survival tips? I guess first thing is not to get hit too hard by the flip, then not to float away from the boat, then get inside safely. Maybe carrying lots of PET bottles as cargo would be a good idea:)

  15. mark775

    mark775 Guest

    It is a revelation. It does nicely in that following sea, to be sure. So nice that it piqued my interest and I looked at their site. They may not be proud of their engine space on these things as I cannot find any pics of, and not much mention. Do they make one of these that can travel at say eight or ten knots under power? How thick/well set do they make those forward windows? Can they well take a thrashing/pounding going into some stuff? I have to admit - pretty dang nice but how do they do when it gets a bit meaner - say those waves start to coam and the bow wants to dig in?
    I looked at many of these things and listened to the tiresome pitches. If you get a little smaller, the spaces get tight, a little bigger, seems like a good direction to go. Who wud you recommend for something like this but a little less motorhome-like and a little more robust, say workboat tuff, lots of attention to the construction, less to foof? Wud it make sense to mostly motor one of these but sail when the conditions are perfect for it? I think engines and diesel are often cheaper than sails and certainly open horizons in fickle winds.
    Take no offence to the "alternative" comment - I don't swing that way but like multi vs mono, to each their own!
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.