open 20 footer

[usa2]

"likely to work"....
Even you dont sound 100% sure about this anymore....

[Andy P]

There are many different and equally relevant ( but in different ways ) methods of defining length

overall length
from end to end - eg Orange 2 is 120' ( ish ), 18 skiff is 30 foot( ish) inc fixed bowsprit , i14 is 17foot (ish ) with retractable bowsprit, moth is 13 foot (ish) inc rudder extensions.

Hull length eg 18 skiff is 18 foot, i14 is 14 foot, moth is 11 foot, J class 80 foot ( ish), Etchells 30 foot, flying fifteen 20 foot, Hobie rave 21 foot, hydroptere 60 foot

Waterline length at rest
in development classes this is usually the same as hull length eg 18 skiff is 18 foot, i14 is 14 foot, moth is 11 foot., but J class 60 foot, etchells 22', flying fifteen 15'

For foilers the important measurement is the wheelbase or footstep
int moth 8 foot, hobie rave 16 footish , hydroptere 40 foot.

And also rated length - eg 12 metre, the old IOR quarter tonner in range 16-18 foot.

[usa2]

Andy P-
J Class were between 76 and 90 feet on the water. Unless you are referring to a different J class...

2, "likely" means I'm not sure?? Wrong......

[usa2]

Lorsail-
For ocean racing monohull foilers, what good is retracting the main foil going to be if the boat actually foils mainly on the rudder foil? The rudder foil will get smashed up too, unless you can take it completely out of the water. Is it possible to have the rudder foils feather or be retracted somehow as to prevent damage? Also, most sailing foilers right now(except for the moth and the R/C skiff you're working on) are multi hulls, because they are much more stable. A boat like a moth can be controlled by one person, who can like "tune in" to the boats balance and keep it flying and moving quickly. But any offshore foiler will need to have a crew and be stable. I dont think any monohull sailing foilers have been made except some experimental ones and the Moths. If you know of any others, we might gain some more insight on how they could be a reality. Based on what we know right now, the negatives outweigh the positives...

2, where in the world did you get the idea that any foiler foils mainly on the rear foil?? Not true.Most foilers sail with something like 80% of the weight on the main foils....
Again, the only boats I know of that have used lifting foils at sea for long periods over several years -including rudder t-foils in a couple of instances- are the Orma 60's. Thats not necessarily a recommendation because the type of foil they use seems to be able to get them in a lot of trouble(not fully submerged all the time, no altitude control system and no foil on the daggerboard). Your apparent fixation on the foils getting smashed is valid from the standpoint of junk in the water-not from a structural engineering standpoint once the bugs are worked out.

[usa2]

Lorsail-
You yourself said that foilers use the rudder foil, when you were talking about the moths rudder foil being included in "sailing length". If this is a monohull foiler, like a moth, than it will have the same general sailing characteristics as a moth. If a Moth does not foil mainly off its rudder-which i believe you said it does-than why bother to worry about the rudder being included in "sailing length? I know mulitfoilers dont use the rudder foil to provide the lift. But we are talking about a theoretical monohull foiler. My "fixation on the foils getting smashed" as you put it(thats probably a reasonably true statement) is based on the assumption that the foils will be made out of carbon fibre and the fact that carbon fibre doesnt like shock loading, which will lead it to disintegration. Now, if you have a different material you're making the foils out of, than maybe the shock loading wont affect it. But exposed carbon foils in the shape of an upside down "T" as in the rudder foil are vulnerable to the ocean, which may quickly reduce that upside down "T" shape to something more of an "l" shape.

I repeatedly mentioned the Moth "sailing" on the rudder foil which it does as do all multi foilers as well. The load on the rudder foil changes but nevertheless the rudder foil is part of the sailing length of any foiler as is the hull(and bow) in non foiling conditions hence the suggestion of a practical "new" convention for foilers of overall length(bow to trailing edge of the aft foil)
The loads I mentioned earlier are relatively correct for most successfull foilers-at least those with a main foil and a trailing rudder foil. The boat would not sail properly if the rudder foil
carried most of the load. The Rave , my F3 and 16 footer are designed with this kind of loading-which is a "design loading" since the rudder foil loading changes after takeoff as speed increases.

[CT 249]

Doug, do you think that Andy P's enormous impact in foilers and Moths gives credibility to his idea that the footstep is the vital measurement?

There is no doubt that the footstep is a vital measurement.But what I was talkng about is a new convention to recognize the sailing length of a foiler that must, in my opinion, include overall length since a foiler sails in two different ways: on foils and off foils.

[Andy P]

My lengths ( eg J class ) were mostly approx, and off the top of my head, so i stand corrected!

For comparison purposes, maybe overall length inc all extensions would be more easily understandable for the ' man in white van -ie the general public' ( but of course all us here are 'experts'! ).

eg moth is ~13 foot, hobie trifoiler with it's fwd sensing float thingies is ~25 foot, hydoptere is ~6o foot.

but the imost mportant dimension for foilers when flying is the wheelbase.

[NiklasL]

Some thought:
Here is some interesting read about a 26.2ft serious design concept.
http://www.1720sportsboat.com/designer.htm

Common sense:
Almost anyone can make a good boat but earning a living on it is very difficult!



As a designer you can start from several diffrent boat concepts (keelboat, foiler, skiff), and develop (r&d) a desired concept.

But mother nature always sets the limit. If you want a fast boat on the ocean then you are always compromising with safety of the crew one way or another.

At the southern ocean the limit of what a human can take comes alot closer. Bruce Schwab (Vendee Globe) mentioned for example that sometimes it was like beeing in a car crash over and over again in the waves. So speed is probably not number one priority there.


What I have learned is that high aspect ratio keel/centerboard/rudder/hyrdofoil and lightweight boat with maximum sized and optimally shaped sails for the design conditions with as little stability as possible is a key to go fast. It also is a way to make a boat very expensive.

[Paul B]

Originally Posted by Lorsail

One more time: a canting keel monofoiler is likely to work well especially if the foils are used off the wind. In addition, a flap on the canting keel strut can be used to develop RM reducing the required ballast even more. The main foil could retract into the hull in non foiling conditions.
Still plenty of problems but probably doable in the not too distant future....

Not too distant future? On what scale?

On your flap idea, please provide us with a sketch showing the lift of a normal keel, even when canted. Now show us the size and angle of the flap, with the calculations showing how much RM you will get.

After you've done that you'll surely provide us with the dimensions required for the foil that will lift a 20+ foot Offshore Foiler, and show us how something this size can retract inside a hull. Of course it will need to retain the required strength to survive the conitions it might encounter.

Oooh, wait. You've never produced any drawings for any of the ideas you claim expertise in, have you? I'll bet this one will keep your record intact.

I think we better not hold our collective breaths waiting for actual info on the 18 foot canter you claimed was "under development", nor the 12 foot, 14 foot, or 18 foot foilers you are "developing", or the Offshore Monohull Super Secret Foiler, or anything else...

"Paul B"- If you were interested in this kind of technology you would have done enough research to know that developing RM using a flap on a canting keel is not my idea; you might have also found a US patent or two that covers the technology.
As far as what I'm working on you have no idea whatsoever: you deliberately distort what I've said and again fall victim to your own apparent inability to do research.

[Paul B]

Originally Posted by Lorsail

"Paul B"- If you were interested in this kind of technology you would have done enough research to know that developing RM using a flap on a canting keel is not my idea; you might have also found a US patent or two that covers the technology.
As far as what I'm working on you have no idea whatsoever: you deliberately distort what I've said and again fall victim to your own apparent inability to do research.

Imagine my surprise! No attempt to provide ANY information. Post after post of, "..blah blah..offshore foiler..blah blah..retractable foil..blah blah..canting foiler..blah blah blah...", yet no apparent understanding of the mechanics of any of these technologies.

Yo Chumley, you don't have to be the "inventor" to describe to us your solution for the problem. So please tell us, Mr. Insider, how do YOU calculate this flap RM while the boat is sailing upwind. You ARE the expert, or are you the guy who simply reads magazine articles and websites and gloms on with little or no understanding?

So please, tell us how you plan to have this main foil retract into the hull. Maybe it will be similar to your solution for having a canting keel without the hull bump (which you have never been able to show any drawings of either).

Maybe first you should tell us why you keep referring to YOUR 16 foot FOILER if it has never actually foiled? Has it? When? Are we to believe some designer with a super-secret offshore foiling design confided top secret information to YOU, who can't seem to get a 16 footer to work?