Our Imoca foiling boats actually still monohulls?

[billgewater]

Very interesting indeed. Let's hope the technology trickles down or opens new doors.

BUT "mono" means "1" . "Multi" means an integer greater than "1" .

The boats shown have one "hull". Not "multi".

The Webster Dictionary definition of a hull ..... "the main body of a ship or other vessel, including the bottom, sides, and deck but not the masts, superstructure, rigging, engines, and other fittings."
Foils would seem to come under "other fittings".

Foils have been used now for generations. Aircraft have them. Birds have them. (Oh please don't mention sport of fencing!)
We don't call a 747 a multi fuselage do we?
I think Dave S has got it right as have others, so we all wait to see how this affects the cruising world.

[Seawolfflo]

This is what I feel also.

Originally Posted by Dave_S

As far as I am concerned.

It is a catamaran in function hidden in a mono's appearance. I expect NZ design team realised the hull was almost irrelevant when they were designing last season's cats. The hull is almost just mechanism for supporting the foils and the midship foils are points of righting moment which are substantially offline to the centre line of the boat and seperate to each other.

The rear foil on the rudder can now be a single because of the single hull and this will save drag. I expect there are also significant gains in drag reduction made by adjusting the angle of the arms to more closely match the righting moment with less losses and helpful when setting up for turns and tacks.

[DDabs]

Originally Posted by Dave_S

By that definition then catamarans are also monohulls as they are one piece construction that contacts the water in two planes.

They still have two hulls, even if the coachroof that connects them is one piece...

[Dave_S]

Originally Posted by DDabs

They still have two hulls, even if the coachroof that connects them is one piece...

I get what your saying but to me it's definitely a grey area. If you define hulls as the supporting body you get a catamaran when it's foiling and a trimaran when it's not.

There are power boats that sit in the water in full contact from Port to starboard when not moving but sit on two planes with a clear bridge inbetween when moving and they are described as cats.

I think it's a case of technology has out paced definition.

[DDabs]

Originally Posted by Dave_S

I get what your saying but to me it's definitely a grey area. If you define hulls as the supporting body you get a catamaran when it's foiling and a trimaran when it's not.

There are power boats that sit in the water in full contact from Port to starboard when not moving but sit on two planes with a clear bridge inbetween when moving and they are described as cats.

I think it's a case of technology has out paced definition.

A foil is not a "hull" though...

[fxykty]

Originally Posted by Dave_S

I get what your saying but to me it's definitely a grey area. If you define hulls as the supporting body you get a catamaran when it's foiling and a trimaran when it's not.



There are power boats that sit in the water in full contact from Port to starboard when not moving but sit on two planes with a clear bridge inbetween when moving and they are described as cats.



I think it's a case of technology has out paced definition.

??????

Hydrofoils are not hulls, by basic definition. They are foils. Just as rudders, keels, daggerboards, centreboards, etc. are not hulls, they are foils. Just because a foil has lifting surfaces that does not change the fact that it is still a foil.

You could argue that a hydrofoil (that is, a boat of any number of hulls that uses foils to lift its hull(s) out of the water) is a boat type of its own. Just as monohulls, catamarans and trimarans are boat types.

Or, as is common usage right now, you can call AC75s foiling monohulls, Hydroptere a foiling trimaran, and the UFO foiling catamarans.

But to change the type of boat based number of foiling surfaces is totally ridiculous.

And IMOCA 60s cannot yet be called hydrofoils as they still use keel weight for stability and are not stable on their foils in fully lifted state.

[Factor]

Juan Kouyoumdjian is the mind behind many of the higher tech advances in IMOCA and many other classes, in his words

"It depends on acceptance. I could argue that a canting-keel monohull
is a very inefficient multihull. Imagine canting a keel to leeward
and instead of ballast you have air. You would achieve the same
increase in righting moment in a lighter solution, and in fact you get a
multihull. Our sailing community is divided, and choices are made on
style or fashion; otherwise we'd all be sailing multihulls"

[barnakiel]

"...Could we not say that, the foils, are actually kind of turning these monohulls into a type of catamaran? ..."


Yes, we could. But doing so would show our ignorance.


I say this with all due respect, not to offend you.


Catamarans have TWO HULLS.
Trimarans HAVE THREE.
Monomarans have one.
etc.

;-)
b.

[barnakiel]

Could we not sail that a catamaran, once it lifts the windward hull off the water, is a type of monohull?


I mean it!



barnakiel

[fxykty]

Originally Posted by barnakiel

Could we not sail that a catamaran, once it lifts the windward hull off the water, is a type of monohull?


I mean it!



barnakiel

No, it still has two hulls.

[jmh2002]

Originally Posted by fxykty

??????

Hydrofoils are not hulls, by basic definition. They are foils. Just as rudders, keels, daggerboards, centreboards, etc. are not hulls, they are foils. Just because a foil has lifting surfaces that does not change the fact that it is still a foil.

You could argue that a hydrofoil (that is, a boat of any number of hulls that uses foils to lift its hull(s) out of the water) is a boat type of its own. Just as monohulls, catamarans and trimarans are boat types.

Or, as is common usage right now, you can call AC75s foiling monohulls, Hydroptere a foiling trimaran, and the UFO foiling catamarans.

But to change the type of boat based number of foiling surfaces is totally ridiculous.

And IMOCA 60s cannot yet be called hydrofoils as they still use keel weight for stability and are not stable on their foils in fully lifted state.

^^^ This

[Dave_S]

Originally Posted by barnakiel

"...Could we not say that, the foils, are actually kind of turning these monohulls into a type of catamaran? ..."


Yes, we could. But doing so would show our ignorance.


I say this with all due respect, not to offend you.


Catamarans have TWO HULLS.
Trimarans HAVE THREE.
Monomarans have one.
etc.

;-)
b.

Hahahaha

[ggray]

I raised this sort of issue with my sons a month or so ago.

That for foiling sailboats, the issue of one or two hulls became irrelevant once the hull(s) raised out of the water. The hull(s) were there to support the boat when stopped.

So the foils are the thing, and which "structure" was best for housing those foils?

Perhaps someone could design a foiling boat with inflatable hull(s). Having only structure to support the foils and rig; and the hull(s) deflated and collapsed once up to speed.

I didn't get a response from them about my brilliant idea.

[Pegu Club]

Originally Posted by Dave_S

By that definition then catamarans are also monohulls as they are one piece construction that contacts the water in two planes.

Hence multi hull

[MicHughV]

a rose by any other name remains a rose....

you can shove a V-12 engine in a car or an inline 4...but it remains a car..

we have monohulls that go by the names sloop, cutter, ketch, schooner, yawl, cat, etc....and even those can be sub-divided into planing or displacement hulls, but they remain a monohull..the Vendee boats are just another breed of monohull....

Cats and tri's are correctly termed multi-hulls, as they sport more than one hull...whether one hull is flying in the air is moot..