60'+ or - 20' Ocean Racing Monofoiler Design Discussion

A bit off topic... but I don't recall Brett's Windrush ever racing against one of the early Fastacraft foilers, though perhaps they did some testing in Perth in the early days.

Brett's development was killed off when the Moths banned wing mounted foils. Although it suffered control problems, it's hard to say where it would have progressed to given another five years of development.

 

why so heavy?

Current WOR 60's displace about 9 tons, and so do the Volvo Open 70's.

The latter already have raised the 24 hour mark to 563 nm in 24 hours (23.5kn average, top speed above 30kn). The record for the WOR 60 is just 470 but this was single-handed.

Compares with record for ORMA 60 tri at 610nm (25.7kn) - but again, single-handed.

Bottom-line is that there is less difference than one might think, in the current state of affairs.

Now can one make a WOR 60, or a Volvo Open 70, fly? In their current incarnations I doubt it - total displacement is 9 tons to be compared to the 5-6 tons of Hydroptère (and the 6 tons of an ORMA 60). Of course if you had a central daggerboard with an inverted T (like on the Moths) you'd have more, and more efficient, wing surface than on Hydroptere where the foils are slanted. But still.

My take is that it will be easier to fly an ORMA 60 on three inverted T shaped foils (one each hull, one rudder), than to fly a WOR 60 or Open 70. And it will be more stable. And the development work needed will be less (actually I'm quite surprised that no one seems to have even tried yet - beyond the curved centerboards that have some foil effect, used on current ORMA 60's).


To fly one of those big monohulls you'd need to give up on a lot of the ballast - which would change them into super-dinghies, much less safe and probably impossible to sail single-handed. Or you'd need to add wings with small hulls at the end, for safety / stability check, in which case they'd start looking like trimarans.

I believe that we'll definitely see flying 60' monohulls - just maybe not the ocean-going type, more boats to be used in extreme, near-shore regattas.

 

60' monofoiler

Antoine, the 60' monofoiler described in the first post has a displacement 6.69 tons(2200lb tons) unballasted and 8.4 tons ballasted. That compares to Hydroptere at 6.5 tons light and 7+ tons ballasted.
If you scaled up the 60' monofoiler to 70' the weight would be just about the same as a VOR 70
which range in weight from approx. 11.18 tons to 12.54 tons.
The monofoiler concept relies on wide wings with the capability of moving ballast out all the way and also on a canting keel strut capable of at least a 90° cant. The canting keel strut is only there to make the boat selfrighting from a pitchpole.
As I mentioned earlier, if you ditched the canting keel, widened the beam and used small amas a la Hydroptere BUT used only two foils with a 100% water movable ballast system you would have a boat just about the same weight as Hydroptere with 1/3 fewer foils. Both boats use movable ballast.
However, the monofoiler is intriguing because it offers a speed potential close to or better than ORMA 60's with a selfrighting capability-unmatched by any multihull(so far-except possibly for Rob Denney's selfrighting proa). Orma 60's use foil assist and routinely fly about 60% of the all up displacement of the boat.
I think a bi-foil monofoiler offers the potential of an extremely fast ocean going boat as well as the same for a coastal sport boat.

 

thanks Doug

as far as I know Hydropère is closer to 5-5.5 tons unballasted, add 0.8 ton of side ballast plus I don't know how much main hull ballast, total maybe 6-6.5 tons ballasted. Which seems about right given the 6 tons of Orma 60s.

on the VOR 70s I thought they displaced about 9 tons like the IMOCA 60s but after checking the Rule I saw that displacement was fixed in a narow band around 14 tons. Which would be very close to purely and simply scaling up the 9 tons of an IMOCA 60.

the monofoiler concept described, if can be achieved at 6.7 tons, looks like it could potentially fly indeed (after all most of the displacement of an IMOCA 60 is the bulb down below so it's easy to build a lighter boat)! Clearly there would be compromises in terms of stability making it potentially more suited to crew and not single-handed but that's fine by me.

thanks for the data on the Orma 60's. I know of course that they use what you call foil assist (the curved centerboards of the side hulls), and it's pretty clear that this helps keep the side hull largely out of the water even when the boat flies two hulls. So it was always clear to me that the foil was carrying a lot of weight. Now thanks to you I have a data point: up to 60% if displacement you say? Is this per foil, or for both foils? I guess for both foil, so about 30% per foil?

That would already give 1.8-2 tons per foil, i.e. comparable to what each of the Hydroptère's front foils are carrying. So maybe the figure is less. I guess those things are tough / impossible to measure.

I continue to believe that Orma 60's flying on inverted T foils on the side hulls are not far in the future. Challenge is wet surface and the way to fight this would be to have a T where the top bar could fold together for light air sailing - but this would massively increase the engineering complexity, not so good for a boat that wants to go far. Also if one had to inverted T foils and one broke (hitting an unidentified floating object - ufo), then what, one would be sailing with one hull flying and the other not? Pretty dangerous. Still i continue to hope / look forward to.

in the meantime I've see videos of a 18-footer flying on foils on lake Geneva last fall. Doing "only" 20-22 knots but doing them in 13 knots of wind so not bad, not bad.

 

Hadn't realised Macquarie Innovation had achieved 45.2...

...in just 18 knots of wind last fall (2006)

and by the way, their top speed (instant) was said to have reached 48.4 knots.

apparently their Sandy Point base does only rarely offer 20-plus knot winds these days so the team is looking for other sites (and even considering having a speed trench dug for them!). So we may not hear from them before several months?

it's not clear to me what the potential of the boat may be. it clearly seems a very efficient boat (2.5x faster than the wind) but it does not strike me as having many / any design advantages over Yellow Pages (same team as we know) apart from optimisation everywhere. so I guess I'd be surprised if it did massively better than Yellow Pages in its day? Of course just 2 knots better would be enough.

in any case these guys continue to show pretty clearly that, for flat water surfaces at least, planing hulls are at least as good as foils, and possibly better because lighter. But on choppy seas that would be another story of course.

There is a good new video of Hydroptere at see in choppy waters (2-3.5 meter = 7-11ft waves), there:

http://www.hydroptere.com/accueil/images/videos/var/lang/FR/rub/19.html (click on the 31 Jan 07 video)

 

60'monofoiler

Antoine, its great to see your enthusiasm for these fast boats! The ORMA 60's use the ama for pitch control instead of a rudder t-foil at least on most of the boats-two have small t-foils. And its only the leeward foil that is loaded and at max safe load when the main hull is flying and the leeward ama supports around 30% of the load. This foil assist scheme does have problems: the boat can go so fast that the ama is lifted clear of the water(main hull and windward ama already flying) and even with a rudder t-foil the boat immediately becomes unstable around the diagonal mainfoil/rudder foil axis and many times a crash has resulted. For those w/o a rudder foil when this happens the boat suddenly has zero pitch stability.
A t-foil arrangement with an altitude control system (like the RAVE or SKAT) is not possible under the ORMA rules which have a cap on beam: thats why they use curved foils. With a straight foil, running diagonally thru the ama at an angle that would allow vertical lift when the main hull is flying, the beam restriction would be exceeded
when the foil was retracted in non-foiling conditions. With the beam restriction removed you would probably see a configuration like a scaled up Rave or even Hydroptere(80'wide). An 80' wide 60'LOA fully submerged(foils) foiler using the foils to generate RM would be interesting,very interesting. But so would an 80' wide 60' bi-foiler(multi or mono) with movable
ballast. Lots of potential for very fast, "seaworthy" multies and monos using foils... But, once again, the monofoiler may have an edge in being selfrighting and would certainly be the fastest monohull over 20' LOA for a while.
==================
Antoine, you might find this interesting. To the best of my knowledge it is the first monohull keelboat to be designed to use some degree of"foil assist"(not full flying). Doug Schickler uses two unique curved keels:
First Use of Foil Assist on Mono Keelboat - Boat Design Forums
Address:http://www.boatdesign.net/forums/showthread.php?t=15470

 

thanks Doug

dumbly I had forgotten about the cap on max beam in the ORMA 60 Class Rules.

also taking another look I realised that there was a cap of maximum 1.8 sq.metre on the horizontal projection of any lifting surfaces...

I don't have the Hydroptère book here w me, but the foils are 6.5m long and form a roughly 45 degrees angle. And by the looks of it they're easily between 1 and 2 meters wide, roughly. So the total are of each foil would very roughly be (1+2)*6.5/2=9.75 sq.metres.

take a 45 deg angle so the projection on a horizontal plane would be sqrt(2)/2 times that, i.e. 6.9 sq.metres.

double it for 2 foils, you get 13.8 sq.metres

so clearly with a cap of 1.8 sq.metre on the projection of any lifting surfaces onto a horizontal plane, that's far from enough to ever lift an ORMA 60.


And in any case, the inverted T's maybe be a better design concept-wise, but for everyday life they wouldn't work, would get caught in things, would hit jettys and break. Maybe it's because of those practical limitations that Hydroptère team decided to go for the foils they have. This, and the ability to lift them out of the water for non-flying times, probably determined the design.

 

fully submerged foils

Antoine, the area of the submerged part of a Hydroptere foil* at speed is approximately 2' X 6'= 12sq' or 1.12 square meter per foil( 24sq.ft. total/ 2.24 sq.m total) but, of course, both main foils aren't always in the water-just most of the time. That is at close to max speed and is one of the advantages of fully submerged foils since the nominal 1st run area of the monofoiler main foil is 30sq.ft.( 2.79 sqm); Hydroptere at speed has only 80% of the main foil area of the monofoiler.
But the monofoiler has one less surface penetration...
-----
If you read the first post there is a comparison
of SA/ wetted surface between the monofoiler and an ORMA 60 tri-quite revealing.
==================
* This is an updated correction to my estimate of Hydropteres wetted area at speed in the first post.
==================
You might be interested in these foil loading comparisons: (based on main foils supporting 80% of the load)
----Monofoiler: Light: 393 lb. per sq. ft. Ballasted:493 lb.per sq.ft.
----ORMA( main foil supporting 70% of the load):
450 lb. per sq.ft.+ (estimated)
---- Hydroptere: light @ takeoff: 171 lb. per sq.ft. / Ballasted,at speed estimated:684 lb. per sq.ft.
---------------
An interesting correlation to the puzzle is that while Hydroptere has much lower foil loading at takeoff its est. SA/sq.ft. main foil area is 66 vs the Monofoilers 83.(Moth about 84)

 

yes Doug, I know that the immerged foil area is that small on the Hydroptère at speed (and if I didn't, it would be pretty clear from the photos).

What I was referring to, was the ORMA Class Rule, which sets a 1.8 sq.metre limit not on the (projected on a horizontal plane) submerged foil area WHILE FLYING, but rather on the submerged foil area below the waterline, when not flying. And clearly on Hydroptère that area is larger (at least once the foils are down).

Now these rules generally like for designers to respect the SPIRIT rather than the letter. At the limit one could imagine to have a Hydroptère-like design (folding foils) which would be within ORMA 60 class rules, and then "promise" to never exceed the total foil wetted surface limitation, by smart management of the foil's inclination...

 

Explorius

This imaginative concept was first brought up on foils.org and now there is a thread on SA about it.
Here is one guys version of a large monofoiler:
ARNOLD FREIDLING
Address:http://www.freidling.com/explorius.html Changed:8:12 PM on Saturday, February 10, 2007

 

Very interesting. Please note that it is part of a design school project. It is quite obvious that the student has no idea of what might work at 12" to 1' scale. I call your attention to the frame where the upward force from the foil is acting through the CG and the large green arrow that shows righting moment. for the foils to produce righting moment the lift must be offset to leeward of the CG or there must be moving ballast.

Also note the forward angle of the surface piercing foils. Anyone with experience knows forward sweep is a problem both for design of the structure and for keeping the foils debris free. Since it has two forward foils and a t-foil it is not a "monofoiler" or bi-foiler, but a tri-foiler.

 

Imagination

Yeah, the devil is in the details; he may figure it out given time and more study.
One thing though: a single hull boat with foils is a MONOFOILER.
======================
A copy of my e-mail inviting Mr. Friedling to participate of this forum:

Sent e-mail message

From: lorsail@webtv.net(Doug*Lord) Date: Sat, Feb 24, 2007, 8:51am To: website@freidling.com Subject: Explorius
Mr. Friedling, congratulations on what appears to be a very exciting concept! There has been a thread posted on www.boatdesign.net under "Sailboats" entitled "Designers dream or reality" and I'd like to invite you to participate either in that thread or under the "60' monofoiler" thread where your concept is also posted. I and others would love to hear more about the technical apects of your design particularly in regard to righting moment.
Sail Fast, Doug Lord
------X18T - www.monofoiler.com (soon)
------F100 - www.microsail.com

 

That definition makes much more sense.

 

Maxi Skiff / Sean Langman

Close, very close-just add foils ,50% more beam and change the buoyancy pod shapes:
LSS_7.jpg

 

but if you add 50pc more beam, and foils...

...and then, say, lower the pods so they have less air drag and offer more potential stability, what do you get?

it's called a trimaran, yes

surely the idea here is to build a fast monohull that IS a monohull, isn't it?

as the trimaran concept has already been quite well optimised in the ORMA class, I was thinking that this forum was going to be more about how to build a fast, ocean-going REAL monohull?

don't mean to offend anyone and so sorry if I do / did. But really, the trimaran design has been explored a lot, so developing a monohull that would be a trimaran in disguise, why?