Self righting multihull?

I think that we have the main issue, here, putting aside ballasted keels solution. You cannot rely on the mast of a multihull to be of any help in capsize recovery. Because it simply just break most of the time. For offshore multihull racing sailors, it's a common fact that the mast will always break, that is taken into account in security procedures when capsizing. In the video downbelow, you can hear (in french), crew members shouting to wait until the mast break, before exiting the boat. In order not to get the whole platform on your nose, and to be able to locate the correct safe pathway.



This issue stays also un-solved in the stability calculations of inverted multihulls, according to the ISO12217, which takes into account the volume of the mast to calculate the inverted floating plane. Silly principle...

 

Paul. I have been looking for an article about an approximately 22 x 8 "cruising" cat (tube hulls limited space) that was attempted to be commercialized in the 1980's. I think I am going to have to go through paper mags to find the article. The cat was fiberglass hulls with aluminum tube cross beams. It had a central keel that was long and had a lead bulb at the bottom. The keel could be kicked up (backwards) to allow the cat to be trailed, The cat could recover from 90 plus degrees but if it fully inverted it would not self right, it would have needed outside assistance. Again it did not have sales success. I will search on.

Another solution was a polish guy who built a 20 foot something cat that had "super" large hiking racks. The hiking racks had enough bouyancy to prevent a full capsize and it would recover from 90 degrees. problem was a big amount of windage, ugly and weight in the wrong spot. There are ideas out there but little acceptance of the ideas.

 

A Gougeon 32 is narrower for its length than either an IMOCA or a Mini 650, so with a long enough canting keel, it should be able to recover from a fully inverted position. I guess for casual use, the power requirements of canting that keel in each tack and gybe are too much, but I wish the IMOCA rule allowed such a design, perhaps with a shorter rig to make up for less longitudinal stability. The smaller waterplane area should make the motion easier on the crew.

 

Considering the sail position of a fully inverted cat, and the slim shape of the pontoons, would it not make sense to right a larger cat from end-to-end? If the stern, once the platform was inverted, could somehow retrim to be heavier and the bow, lighter, the mast and sail should begin to move more horizontally to the water surface before deploying some form of above deck airbag, maybe from the end of the boom.

 

Will. Please access http://www.kelsall.com/TechnicalArticles/KCSeaworthinessAndSafety.pdf

This will tell you how Derek Kelsall designed, built and successfully tested a 36 foot catamaran that righted over its ends. The jpeg below is of a 47 foot aluminum cat that was built but the self righting idea was never tested. possible, but in both cases you have a real mess and maybe no rig left in a wave blown situation. As the owner of a 22 foot trimaran (Kliss) found he could self right it in no wind and flat water, it became really hard in any form of a seaway.

May be the real message is sail sensibly and don't capsize in the first place.

 

Jan Gougeon's "Ollie" is the most interesting self-righting multihull that I know of. The ama's are low enough volume that they fully immerse if the boat is laid on its side and the mast keeps the boat from turtling. It has been tested and it works. I'd love to know more about the boat and what it's like to sail, but the only info I have is that the guys who race "Adagio" lust after it. It has more potential to be faster apparently. Ollie did win the Port Huron to Mackinaw race last year.

What get's me about this boat is that it's the only one of its type, yet it's competitive. What if it's actually faster to have very low volume ama's? The boat would require less power because of the reduced weight, so could be lighter, cheaper, etc. It's got a nice interior too.

Why am I the only one that finds this boat completely intriguing?

I did have a very violent capsize in the G-32 once and the mast didn't break. A bit surprising because the stock G-32 masts are not strong.

 

Ollie !

I wonder if part of the problem Ollie had (has?) stems from early tri designs- Crowther, for example, designed low displacement amas, the idea being the lee float submerging would let you know when to throttle back. Some capsizes turned the tide against that, as well as the bleeding edge crowd pushing the speed advantage of sailing a tri on one hull. I’m more interested in a skinny cat I might keep in a mono slip without the hassle of folding/sliding, but I’ve long given in to the conservative culture of sailing being more important than ideas considered too ‘out there’ . Didn’t Julian Bethwaite mess with a tri design that was a BIG takeoff on his dad’s high single hand performance tri? (IIRR, the big tri had a lead keel (?), and in light air, the small floats were out of the water- what design development there was was done with a South American NA- the snide among commentators at the time seemed to go with the ‘training wheel’ sneer.

Frank Bethwaite’s HPS.

 

Minis use tackle to cant keels…. It would make the ‘insane thing’ more interesting

 

That was a view around when I was sailing Sol Cat 18’s & 15’s. It doesn’t work. And given what righting athwartships was like, that’s saying something….

 

I use to sail a Hobie 18 with wings, but I never had the experience of knocking her over. Went out in thirty knot winds once, but the ring wouldn't catch because of the wind, so I never got the main up. Had to make it back to the ramp by jib alone. The next day, in twenty knots and six foot seas, I put on a scuba mask to see, as we were under water a lot, but it calmed down once we got out to the reef to snorkel.

If we had turtled, and the main was set, caught on that ring at the masthead, it would have been hard to right, but since the sheets were usually in my hand, the boom would have been free to swing. On a large cat, where standing on the dagger boards and heaving my weight to start the righting, wouldn't make a wit of difference, I see it as a different story. Underneath, are a close hauled boom, caught on a cam lock and winch, same with the jib.

Imagine the catamaran designed with weights on swinging arms under the bridge deck, between the hulls. The boat is engineered to trim well with the arms forward against the inside of the hulls.
1. In a turtle, position, the weights can be unlocked, maybe even automatically, based on upside down attitude.
2. The weighted arms then get swung aft, such that the transom sinks while the bow becomes lighter. This would cause the mast to move toward the surface trailing the sails underwater.
3. Maybe an air bag on the boom or the spreaders could bring the mast all the way to the surface.
4. Once the mast was near horizontal, the main could be dropped, the jib furled and/or the sheets freed. You don't want your boat sailing off, as soon as she's righted. With a little boost from the air bags, you could more easily over balance the hull to drop them right side up while winching the weights back forward into their locked position.

A bit complex, especially for a small cat, but maybe, with the right engineering from the start.

 

Capsize durability and recovery are a couple of reasons why Lasers (and her ilk) changed sailing. Callaghan’s Hadron has changed the game a bit more, as far as capsize recovery, as well as Handley’s K1. Both are more complex to set up though. I’ll see if I can find some videos. The Fox and Bongo also come to mind.

A design consideration for a ballasted self righting catamaran would be something to grab or stand on during if a capsize exceeded 90 degrees- Russell, when your G32 went over, did you stand on the side of the cockpit, grab something and stay in the boat?

 

K1- ballasted dinghy race ( along with Flying Fifteens) in puffy, clocking conditions: forward to ~ minus 18:40 minutes on for 5 minutes or so shows sails near to & in the water & recovering while the skippers stay in the boat- & this on a planing sailboat. (The whole YouTube is very good, very beguiling, um, even the beginning, if you like skippper’s meetings…) there’s another that shows the sail flat on the water if I can find it, the skipper stays in the boat and it comes up.

 

Hadron Dinghy youtube: Safety Section of the vid ~ minus 2:30 (-2:30) in-

 

~ 3:30 in G 32 capsize & recovery (Ollie recovery is just before it)

 

A few ideas

1. a symmetrical boat. Most boats are symmetrical either fore and aft or port/starboard. This boat would be symmetrical above and below. This also saves anti fouling as you would perform intentional "flips" regularly.
2. automatic air/water pumps controlled by inertial unit that understands how to right the vessel.
3. electric or human powered oars could also help prevent capsize by applying a force to prevent it. Similar to a kayak roll, they could help right the vessel in conjunction with #1 provided there is also a mast float.
4. rockets on top of the mast triggered by accelerometers
5. articulating daggerboards/rudders that rotate and twist and are also similarly controlled by imu (help prevent capsize)
6. winch/hydraulic amas that fold up that in conjunction with #2 can always right the boat automatically. This system would also allow trimming the angle of the hulls for at anchor, vs sailing in different conditions and even make it possible to lift the center hull using the outer ones for more safety.

This is very interesting. Would it work in rough sea? I am also concerned the waves would break the mast or even the boat itself if any of the hulls are flooded.

If the amas are fully submerged, it would also avoid wave drag similarly to a submarine, so a very short ama could be used as well? Small hulls have more wetted surface area for the righting moment.

I think ultimately < 100% bouyancy will have less righting moment and less power unless they also used hydrofoils. So even if slightly slower, since you can push it harder and not be afraid of capsizing, a boat like this could be sailed faster.