Are wing masts feasible for use on small cats? During all this recent controversy about the Little America's Cup being revived, some people have talked about putting wing masts on the F-18HT's and others have mentioned that C-Class technology, including wing masts, could be adapted to smaller cats, as well.

But first of all, I am not clear on whether people are all talking about the same thing when they refer to wing masts. There are wing masts that are just normal masts with a fabric sail but the mast is deeper from front to back. And then there are very deep wing masts with a relatively small section of soft sail, and then there are wing masts that are totally hard wing. So what is the correct terminology for these various types of wing masts?

And, also, I vaguely remember that in the early days of the Tornado, they were experimenting with a wing mast (deep wing with some soft sail??) and, although it was faster than the soft sail, it was rejected as not being practical because the mast had to be lowered whenever the boat was on shore -- too unstable and blew over too easily.

Hi Mary, All three types of masts you described are all considered wing-masts. The reason, I believe, that smaller beach cats don't use wing mast's are because (1) you cannot reduce or remove the sail area if the weather turns ugly
(2) They are complicated to raise and lower the "mast" and you would have to arrange a place on your trailer to put it where it would'nt take control of your trailer at 65 mph!

Don C.

Right, they are all considered wing masts, but that is why we need terminology to distinguish between the different types and degrees of "wing." Lilke mini-wing, half-wing, full wing?

As far as I know Fully riggid sails are called wingsails while long cord masts (often with a much flatter profile) are called wingmasts. In literature wingmasts with soft sails behind it are often refered to as so and so % wingmasts. For example a soft sail rig with a wingmast that has a cord of 30 % of the overall average cord of the compet rig is refered to as a 30 % wingmast rig.

Of course wingsails come in different shapes. You can have a wing out of one section or have a wingsail that is made up from several vertical section that are spaced a little apart. These wingsail are often described by the number of slots that are between the segments. A two part wingsail is than refered to as a single slotted wingsail. Three part wingsail as as a double slotted wingsail and so on.

In the case of miss nylex which had three segments but where the rear panel was split into two (almost) vertical alligned flaps the wigsail is still refered to as a single slotted wingsail despite the fact that it was made up out of three segments. The reason for it is that from a aerodynamic point of view it behaves as a single slotted wingsail.

Hope this helps although I'm often told that I don't know my rear end from sailing technology. So I could be completely of the mark here.

Wouter

with respect to being practical ?

well no not really but if your hot enough on spending money and effort to buy yourself a considerable advantage both upwind and downwind than, yes, there is nothing technical stopping you from putting one of these on your platform.

I mean people also disassemble and drive around glider with more than 25 mtr. oerall wingspan planes in enclosed trailors why chouldn't the same be done with the seperate panels of say a doubleslotted wingsail ?

wouter

Wouter

I read somewhere that in the early days of the Tornado, they did some A/B testing of inflatable sails. I think one boat had the soft sloop rig and the other had a unarig with an inflatable sail. The unarig kicked butt.

I think wing masts haven't really caught on with smaller boats because the weight of a wing rig is too much for that size of platform. The masts tended to act as pile drivers and even some of the early C-class boats suffered broken main beams etc.

Maybe a wing mast could be made using a conventional metal spar surrounded by styrofoam or an inflatable set up. This would keep most of the benefits of a simple wing rig while keeping weight aloft down and reducing the pile driver effect.

David Ho
TheMightyHobie18 1067

Mary,

Wouter explained it all. I just want to summarize:

-A rigid sail (with or without a separate mast) is a wingSAIL.
-A rigid streamlined rotating mast with a soft sail behind it is a wingMAST.
-Combinations of both exist, so these definitions are not final.

-WingSAILS use airplane wings terminology, slots, flaps, etc.
-WingMASTS with soft sails use normal terminology - except for the mast chord/rig chord % ratio.

-The chord of the rig in its foot is the foot length plus the mast chord. The mast chord is the length of its section.

PS - I don't know for sure is if the correct spelling is "Chord" or "Cord"...

PS2 - Bill Roberts worked in the development of wingsails and is certainly on of the best references, if not the best, on the subject.

PS3 - In my opinbion, unless new technical solutions to reef and fold rigid wingsails are developed, they are not practical for small cats. Wingmasts with bigger chords seem to be the best choice today, because very light masts can be built in carbon - weight was one of the main restrictions preventing wingmasts to have longer chord.

So how long does the chord of a mast have to be before it is considered a "wing mast," rather than just a tear-drop-shaped mast section that is common to most cats, designed to facilitate air flow over the soft sail?

it is more a question of the ratio between the cord and the thickness of the mast section that determines wether it is refered to as a wingmast rather than a "normal" mast. Although general shape of the crossection comes into play too.

Yes, I didn't invent this way of calling things too.

Mary / Wouter

I think that this is a grey area, mainly because I can not think of any strict or final definition.

A reasonable definition would be:

"A wingmast is a mast that adds (more lift then drag) to the rig's performance".

The problem is that the same mast could qualify or not according to wind speed and angle.

I can not think of a definition that does not include "averages" or "initial conditions" that necessarily make them less general, those conditions and averages being grey areas themselves...

By the way - I thought all streamlined rotating masts commonly found in beach cats were wingmasts.

Most of the sailing world calls the masts on current beachcats wingmasts. By my definitions the masts on new A-class boats are wingsmasts. For most other cats, they are in a grey area. However, they can produce a surprising about of lift. If you want to see, wait till it's really blowing, turn the boat beam to wind, and then play with the rotator. I did that years ago while trying to hold the boat down in a storm.

I recall an 18 sq having a wing.. If Im mistaken I appologise but also recall this combination winning the US 18 sq titles.. Now if I recall correctly then a wing is viable on an 18 foot cat.. How this wing would interact with a genacker I dont know..

...wait till it's really blowing, turn the boat beam to wind, and then play with the rotator...

Yeah, but one could argue that under bare poles it's not a wingMAST anymore - it's a wingSAIL A tall and thin one, but still a wingsail...

Tight definitions are slippery.
Grey is beautiful!

I am going to reply to my own question here.

I just talked to Ben Hall of Hall Spars. He makes masts for a living, so I asked him what a wing mast is. He said there is no real definition anywhere, but he would consider any of the conventional, air-foil-shaped, rotating masts that are on most modern catamarans to be wing masts. As far as he is concerned there is no particular chord length and no magical ratio between chord and mast thickness that determines what a wing mast is.

He said an A-Class mast is about 5 3/4 inches by 2 1/4 inches, which is not substantially different than the masts on Hobies, Nacras, etc.

He said the deeper the chord of the mast, the less practical it is for small cats, and a full, solid wing mast (wingsail) is totally impractical, because:

#1 They are very fragile and usually get wrecked if the boat capsizes.
#2 You have to take them down every time you are on shore, because the boat can blow over so easily.
#3 You need a team of three or four people to raise and take down the mast, because of its fragility.
#4 You need some sort of box ("violin case" was the term he used) to cover and protect the mast because if somebody just trips over it while walking past, it can damage the fragile surface of the mast.

"The full wing mast is esoteric and beautiful," Hall said, "and I would love to have one on my A-cat, but it is just not practical."

Ah, now I see...Wing masts are soooo like women!

OUCH....run dave....RUN!

Why should he run? There aren't any women on this forum, are there? And besides, that was a compliment; wasn't it?

Miss Nylex went over a few times but never wreaked her rig in the capsizes.. Bruce Proctor has a few stories of these events including one where she self righted and he walked on without getting his smokes wet.. They went on to sail her home..

Point two also seems a little dubious.. I take my rig down as do most of the guys who have carbon masts here.. Actually one should wrap any epoxy mast to decrease the UV damage to the epoxy matrix.. Its also good as it keeps the mast below the epoxy softening temp (60-75C).. Unless ones mast is made from prepreg which has a 100degree C postcure temp cycle.. Its not that unusual under our sun to see the mast temp climb into the 60-75 degree levels..

Did you ask him about the 18sq wingsail? Wonde how it would go on a HT or A?

If you want answers to specific questions, you should ask him yourself. I was just asking him about the definition of a wing mast, because that was the thing that I personally needed clarified so I could better understand the discussions on this subject. He was nice enough to take the time to give his additional opinions about the practicality of wing masts for beach cats. I was just sharing his thoughts with all of you.