Mono or Multi? New type of ocean racer?

This was on the front page of SA-no details. It's startling how much it resembles Bethwaite's Pterodactyl. Major difference is that this thing has a canting keel along with the buoyancy pods though it may have more of a ballast system than that. Bethwaites boat has a fixed keel and movable water and deck ballast.
Are we seeing the birth of a new form of boat here-between a mono and multi?
Sean Langman's new boat:
http://www.sailinganarchy.com/fringe...ages/LSS_7.jpg

Bethwaites proposed "Skiff Maxi":
http://www.sailinganarchy.com/fringe...billochcut.jpg

[SailDesign]

Doug,
No disrespect to hte designer of that beast, but if those "buoyancy pods" get any higher, they will meet in the middle. Also, why is the hull relatively sleek looking, while the pods look like stretched 1930's sidecars?
Me smells a rat, or a least an SA tease....
Steve

Steve, I hadn't had a chance to post the url for Bethwaites boat(above) by the time you posted and it is definitely "prettier" in my opinion. But what struck me when I saw Langmans creation (or?) this morning was the similarity between the two boats. Now , no one has released any technical detail of Langmans boat other than that it has a canting keel . But Betwaites version uses the beam to move on-deck ballast(including water ballast) across and I wouldn't be surprised that Langman does something similar.
If so then both these boats would be getting gigantic increases in RM compared to a "normal" mono though it is apparent to me that neither is using the "pods" to sail on just as back up buoyancy. At least that's what Bethwaite said about his. Langmans pod's are peculiar shapes but I doubt that the thing would be sailed as a trimaran with a canting keel-but at this point who knows?
I would have gone along with your "tease" theory if the Bethwaite boat hadn't surfaced a few weeks ago-maybe these guys have been drinking together?

[John Perry]

I have doodled various ideas akin to these. A monohull retains at least one major advantage over most multihulls in that it can be made self-righting. Befor anyone rushes to say that monohulls are as likely to sink as multihulls are to capsize I would say that monohulls can also be provided with bouyancy compartments etc. so that they are very unlikely to sink. Hence my interest in trying to retain the self righting ability of a ballasted monohull with righting moment which is considerably more than a comparable conventional monohul design, although it will still be less than that of a multihull of comparable size and overal weight. Performance could be close to that of the multihul, espeicially to windward, since windage and wetted surface could be less. One way to do this is to have a monohul with just enough deep ballast to make it self righting and then add righting moment with water ballast out on pods which may look like small trimaran hulls but actually serve a completely different purpose, although there are options for using them as both ballast and bouyancy. One problem is that in the event of a capsize the bouyancy of these pods and their supports can increase fully inverted stability, defeating one of the main objects of the exercise. I toyed with pods which quickly flood when they immerse and pods which hinge up in a capsise such that they reduce rather than increase the inverted stability. Such hinged pods could possibly be controlled with large gas springs. Altough they are ballast weights during normal sailing it may be worth using them as small hulls when heel angle becomes extreme, that way they exert maximum righting moment at an angle of heel which is such that most of the sail force has been shed by heeling and this may prevent a capsize - prevention is often better than cure. Carrying the pods high, or allowing them to hinge upwards, increases the angle at which they exert maximum righting moment, but once they actually submerge it may still be best to flood them completely. Big problem with high pods or hinged pods is that they tend to interfere with the rig, particularly the boom, at least with conventional rigs. Another possiblity is to forget the pods and have a really small stabilising weight on a really really long folding pole which swings around the transom. The more I sketched all these things the more complicated it all got and in the end I could not come up with anything that looked practical enough or pretty enough to want to build it, so instead I changed tack and built a bifoiler monohul.

As for Chris's question about the crude shaping of the pods, and the height of the pods, as explained above they may be intended to serve as ballast weights rather than as hulls. Also if a small pod hits the sea at speed it may be preferable that it is shaped so that it will plane rather than being a displacement hull.

John

[usa2]

if any of those pods touch the water, its a multi. if i were them, i would get rid of the pods, and just make the keel big enough to generate righting moment. The other super maxis dont need pods, so why should this one? also, someone is going to protest the boat in the Sydney to Hobart if the pods touch water. And the biggest question would be, will it survive the passage to Hobart? it doesnt look very strong.

[Bergalia]

Originally Posted by Lorsail

Bethwaites proposed "Skiff Maxi":
http://www.sailinganarchy.com/fringe...billochcut.jpg

So that's where my third dart went... I've been looking everywhere

2, I don't think you can say it's a multi if the pods "touch the water". Modern tri's that length are designed to have the weight of the boat supported partially by the outside hull and partially by the banana boards in the ama. These two boats-at least the Bethwaite version-are designed to NOT have the pods support the boat in any way in normal sailing; not even as Bethwaite senior said of the HSP:" .."tip floats for static stability only". Of course, he also described his HSP's as trimarans but I think I disagree with that especially on these boats where the pods don't even provide static stability: they're just there for back up from gusts especailly when tacking and to provide a place to put ballast.
Both these boats have the potential to have far greater RM than a "normal" monohull by using ballast as far out as the pods and both have ballasted keels. But they don't compare to the RM available to the same size square tri flying the main hull where most of the weight of the boat is developing righting moment.
So if defined as a monohull these are potentially very powerfull but if defined as a tri not so powerfull.
But with the ballasted keels chances of a 180° capsize are reduced as is the chance of a non- recoverable pitchpole.
Both these boats appear to me to be excellent candidates for the use of a bi-foil hydrofoil arrangement which would bring speed into a range heretofore reserved for multihulls.
Lots of potential with the concept: a (mostly) self righting speed machine. John Perry's suggestions might further improve the self rigting advantages.

[stewi]

I guess, the designer had the concept of a pacific proa in mind, with the modification that each outrigger could serve as a pod and vice versa.
The pacific proa (speed record of the Crossbow proa) flies the outrigger high above the water, keeping the wind force on the sails and the ballasted outrigger in balance.

[usa2]

Why use the pods in the first place. The other 100' supermaxis dont need them, and skandia is narrower than the thing in the picture on SA, and she doesnt need "pods". I know they provide more stability in the event of a knockdown, and added righting moment, but its just going to cause a huge controversy and it wont rate under IRC.

Whats wrong with a little controversy?! We're not just talking about a little "added righting moment" we're talking about huge gains in power to carry sail compared to any normal leadbelly.
And along with all the power the likely retention of the "good" qualites of a keel boat. Sounds pretty cool to me.
edit: But the most interesting part of this concept to me is that it would allow(by virtue of so much power and an upright sailing attitude) the use of a two foil hydrofoil arrangement similar to that on a Moth and recognized as a MONOHULL hydrofoil configuration. The power of this type boat could make just two foils practical on large boats whether they were all lifting with an altitude control system or just partially lifting like the foils on the big tri's.And the ability to effectvely use just two hydrofoils sets this type apart from most other large boats.

[stewi]

I agree. The difference between this design and a trimaran is the purpose of the outriggers. In a racing trimaran, the center hull may be lifted and sailed on an outrigger hull. The risk of capsizing is relative high.
In the proposed design, the center hull supposed to stay in the water and the outrigger balance the sail forces.
Talking the language of proa fans, who refer to aka and ama, on a pacific proa the outrigger is aimed windwards and the safety pod leewards. However, changing the sailing direction on a proa requires sail and rudder re-arrangements.
Not that I would ever be daring to sail such a thing, I like the concept.

[cyclops]

Why is it, this modern concept keeps saying, "Popular Mechanics" , " Popular Science "? I am old enough to recall most of the creative, do it yourself ideas and projects after WWII. This is not new. Resurrected, yes. Logical, yes. Why do modern designs go back in time to improve? It is happening in other fields.

[Tactic]

Cyclops,
The ideas themselves arn't new..but the materials and technology of today makes it possible to acheive them (maybe)

[cyclops]

Best answer today!

Well, I won't buy in to this 100%. The use of two hydrofoils on a large monohull is new; in fact two hydrofoils have only been used on any sailboat since around 1999 and have only won races recently-prior to then those sailboats that used hydrofoils had three or four.
And I for one have never seen a large monohull designed to take such advantage of on-deck movable ballast as does Bethwaites Pterodactyl-probably for the reasons mentioned by Tactic but the design is new-not a rehash as best as I can tell- because it simply wouldn't have been feasible some years ago.The use of on-deck movable ballast on a large seagoing boat is a new idea ,based on my experience, even though one of Hereshoff's favorite boats apparently was a small boat that moved a brass ingot or two from side to side.
I think these guys have come up with a radically new form of ocean racer but I would be very interested in any historical examples of anything remotely close in length to either of these boats.The concept fascinates me...