F16 wings

You get LESS RM as the mast is closer to the Pivot point; the leeward hull is the pivot point. by moving the mast towards it you are reducing the RM from the mast (and the hull).

Cats pivot on the leeward hull. To get max RM you want as much of the mass on on the windward hull (or close to it, or further away from the leeward hull).

RM can be broken down into these components (no wings)

1, Boat: 1/2 beam x mass (assuming boat is symmetrical)
2, Crew component = (beam +0.93 (average COG of a person)) x 75kg (average person weight) x no of crew on the trap + beam x 75kg x no of crew NOT trapping

Now add wings (we will calc the wing RM as a step)

1, Boat RM stays the same (but remember that because the beam is MUCH less RM drops)
2,

empty wing

rm = beam + 1/2 width of wing x mass of wing.
2, Crew component = (beam + wing beam + 0.93 (average COG of a person)) x 75kg (average person weight) x no of crew on the trap + (beam + wing beam) x 75kg x no of crew NOT trapping

Steve is correct here guys.

He's got the correct intepretation of the class rules and indeed most rules are written to be self-correcting.

Wouter

Scooby_Simon, been a while since high school physics so please excuse the cloudy brain whilst i remember, but are you considering the calc as a 2nd class or 3rd class lever? If 2nd class, then you are correct, but I always thought as 3rd class. The crew is the lead weight lump at the end of the wing/lever pushing down. The force from the sails/wind/mast is on the middle of the lever pushing up. If you can move this force point closer to the point, the more effective the force pushing down.

Am i missing something?

You been on the Moth a bit too much Taipanfc.... 😛

Decreasing beam from hull to hull despite the addition of wings will reduce your RM significantly. The pivot point for a cat is over the centerline of the leeward hull. By adding wings you through more beam (and weight) leeward of the pivot point. You are also brining the weight of the windward hull closer to the pivot point. Even reducing the beam by a little bit makes a big difference.

So, a Taipan 4.9 would be better investing thier money into a set of wider beams, tramp and stays, forgetting about wings.

If the class rules alowed a max beam and then wings, by all means go for it. If it is just max beam, increase the beam of the hulls.

Jump back on a cat mate, you know you want too 🙂 Sorry, could not resist.

That's the Foiling Cat I've been looking for!

Nice photoshop, now, can someone make it happen for real?

TA, happy to be proved wrong. But logic is that the beam width is made to be 2.5m for a Taipan with the addition of wings. So distance from pivot point is same for Taipan and Viper. But mast for Taipan is 1.17m v 1.25m on Viper closer to pivot. So effect is similar to a wheelbarrow but efforts are reversed. You can move more weight on a wheelbarrow the closer it is to the pivot point, that is the axle. You certainly moved a lot of dirt over the weekend so should have lots of practical experience <img src="<>/wink.gif" alt="wink" title="wink" height="15" width="15" />.

Is this logic right?

I'm sorry Stephen, you post contains so many errors that I don't even know where to begin. In short, if a student would submit something like that as his final report then he would have failed the course basic mechanics.

Wouter

The weight of the luff wing will also go a long way in correcting for the less then optimal position of the mast. Yes, it weights less but its leverage is also significantly more. The intent of the rules is to allows freedom of design without leading to an unfair advantage either way.

I think this result has been pretty well achieved in this case without the use of complicated rules.

Wouter

Sorry Wouter, I sail rather than read about it. Can you fix it for me.

By the way, if I was writing a report it would be nowhere near as crude as this.

All forces balance on the leeward hull. All mass is at a distance from the pivot (leeward hull).

If you JUST have a boat; you can assume the mass (in pivot terms is spread accross the boat. The windward hull is

beam

away from the pivot; the boat is symetric and so 1/2 mass of the boat is acting at the beam. If the boat-beam is reduced (because you have wings to make it back up to the same overall beam), you have less RM from the boat (1/2 mass * beam(remember smaller + (some RM from the wing). Crew provides the same mount of RM as they are the same distance from the pivot.

IF you have wings on the boat, the mast is not in the middle of the boat (+wings) and so the mass of the mast provies less RM. Also; as the boat heels; the mast moves to the otjer side of the pivot more quickly and so reduced RM again.

Heeling moment (from the sails) is balanced at the leeward hull. The heeling moment we are

balancing

is at 90 degrees to the RM and we balance at the leeward hull.

And I think I have gained a few inches length in my arms. Should help with the spinnaker sets.

Not quite as the cat will not pivot on the end of its wing (hope not anyway) but the centre of the hull. Beam alone does not give you RM, weight will also contribute and the further you move it away from the pivot point (hulls and rig) the more RM you achieve.

Do you want to move more weight easier on a catamaran (we are talking healing here, not forward momentum) or resist it.

TA, to clarify with your diagram, the taipan with wings is 2.66m wide as the rules state that the measurement is taken from leeward hull. So I could put 16cm wings on either side.

Scooby_Simon, see your point of taking into account rig weight aloft as this would fall over the pivot point quicker in my taipan v viper example, but have we measured the extra force you able to exert through the lever effect v this force of the mast over the pivot. Would be interesting to see these calcs in the whole picture.

Ahh, got you. Did not read the rule, however all else applies. Disadvantage is just not as small as I thought. Think of the weight of the hull and rig being brought closer to the pivot. Would be like only half trapping or hiking rather then full.

Used to have a pair of sportwings on my FX-One but took them off after a while because it doesnt really add anything other then another piece of kit you have to drag along to regattas.
Downwind those thing where horribly in the way and made it almost impossible to trap from the transom.
Upwind they would hit waves and the tubes would hurt my feet after a few hours, it also ment you would trap quite high which IMHO is not as pleasant (lower the better).

I think Macca is a bit obsessed with banana-boards today, after he spent all of yesterday playing around on the F20 Carbon 😉

Not sure how you increase leverage. please explain.. your distance from the centre of lateral resistance is the same. Please explain to this old mind how you're increasing righting moment..

I asked a while ago and if I recall the crew must have at least one foot on the hull.. Otherwise one could trap on the shoulders of the other crew.. This would increase righting far more than any other option..

I thought the original poster, who asked about wings, was going to do some long distance race (6 days?) and wanted to be more comfortable, sitting on the wings, vs. hanging on a trap wire all day, for 6 days.

So...has anyone ever sailed a long distance race while sitting on the wings vs. trapping out? I know the Worrell guys trapped for 10 days or more, no wings there!

Yep! its awesome, and thats why its so daft to restrict such a good development in the class (if the philosophy is still to have it as a development class...) Right now you can spend a LOT of money on an F16 with carbon beams, mast, pole plus hull construction etc just to get an incremental but definite gain in performance. Yet something as simple as curved boards is not allowed which gives a measurable gain for not much cost increase over straight boards!

the max is 2.5 meters. Having a fixed beam of 2.66 would make the boat class illegal. Wing tip to wing tip.. Not hull to wingtip..
relevant rule. (from website)

1.2.3 Wings may be carried as long as the equivalent overall beam, when measured over the platform, and one fully extended wing is 2.5 m or less.

the main argument when this rule was passed was basically to ban

flying

F16s..

The collective at that time decided there could be an arms race to produce a flying boat.. *shrugs*

Do not understand the comment on pivot point; the pivot point for all forces IS the leeward hull; the only differece wings give you is to make the boat thinner and thus reduce the RM provided by the hull; the mast IS NOT the pivot point on a Cat; the leeward hull is. Remember the RM is there to overcome the lateral force created by the sail; this pivots at the leeward hull; you cannot use the standard

see-saw

diagrams to understand the forces as the heeling forces (sail forces) are at 90 degrees to the RM and so where EVER you put the mast; the heeling moment is the same and always resolves to the leeward hull.

From the original post, which has yet to be addressed:

...I am doing regardless as i am entering a charity fundraiser which requires a 6 day coast sail and the wings as a seat will be awsome i can remove them later if they are just a hinderence thanks...

So, would you add wings as a seat

for a 6 day fundraiser

or not?

maybe.. cruising is different from racing..

The wings will be made from my same wing mast section and be covered so will be fairly wide and nice to sit on and at 115kg my back will be thankfull...But here`s a new one to ponder seems we have so many RM experts here and im not, for years I have considered the value of having the mast on a slide on the cross beam with the stay wires and rather than cant the mast as was done in the AC how about simply slide the whole rig sideways please forget the ruls for a moment, how would this affect the RM? it would be simple to do but add a little weight and time to shift across, should of patented that...slide the base of the mast across to the windward hull stays and all, i have many drawings but not the maths to know if it would increase the RM and if it did then it would be a breakthrough unless you jibed real quick.

no need to move the whole thing, just cant the rig by shortening and lengthening the stays as per most multis, quite efective but you will be penalised on handicap ratings and it all gets a bit of string pulling excercise for little gain.

Thought about rotating the mast base in an arc centred from about the front stay area, lower it down to the leeward ( less RM )when getting overpowered or wanting to point better ( as per the windsurf rigs, it creates lift vertically of a form ), pull it back to the middle on the downwind run, certainly on the Bitsa's to do list.

You just answered your question by quoting the rule. The platform width of a Taipan is 2.34m. One extended wing is 0.16m which would make it to 2.5m. But wing to wing it is 2.66m.

TaipanFC is right

Wouter

I think your missing an issue.. If the wings are fixed you can only have wings that are 0.08 wide. This will take the width to the full 2.5.

If they are folding then yes you can have have the 0.16 wings. BUT if they stop folding you're illegal. I wonder if they stop folding in a race what happens?? Yes you started legally but you sailed illegally so guess disqualified??

As I see it your still only 2.5 meters from the point of lateral resistance.. So the difference standing on a gunwale or standing on a beam is?? What you suggesting is why not make your hulls 0.6 cm apart and only use wings.. Your thinking would suggest this is the fastest config? Tried this on an 18 and swum lots..
So Im still missing the advantage... just dumb I guess..

Stewart,

Taipanfc (james) is right. The rule is not concerned at all with the fact whether the wings are folding or not; it only equalizes the righting moments. To do so only requires the inclusion of one fully extended wing as the leeward hull is the pivot point and not the leeward wing.

Wouter

wouter Im still confused as to the advantage..

either way its just better to have a total beam rule. Wings are crap unless they are upright and replace sails <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />