Does anyone know the luff length of a typical F18 Spinnaker?

Mine is 8.72 meters

Try looking through the French F18 measurement certificates to get an average of all the designs.

I'm asking because I'm trying to figure out what Spinnaker I have on my N570. I suspect it's an F18 but I need to verify, I'm hoping my current spin is slightly larger than a typical F18 spin, blown out perhaps. I'm having problems getting my current spin setup with the right luff tension. So by getting an F18 spin I would solve my problem.

If an F18 is larger than my current spin I guess I need to look at an F17...

Does anyone know the luff length of an F17 spin?

perhaps you can take your boat to a sail maker and rig it.
this way you can find out what is the right measurement for your setup and perhaps order a custom spin.

I know several people who did this with great results.


you should have a bit of flexibility (on the luff size) with the possition of your pole and amount of prebend in it. When i used a f18 spin (on my 30' mast) my pole was Very high. Now that i have a Tornado spin.. it is pretty low, with minimal prebend.

Don't forget there are two size of rigs for F18 depending on crew weight. The small spi is 19m2 and the large one is 21m2.

The aforementioned french F18 measurement certificates are there.

Does the two different sizes of F18 spinnakers have different luff length? I thought they had the same length and just smaller size.

luff is 8.5 m
leach is 7.1 m
foot is 3.6 m

If you want a nice spin the Jeremy at Surf City Catamarans is heving really nice ones cut.
Stiched seams reinforced seams at the luff leach and foot. Really nice corners. On average a lot cheaper than Hobie or Nacra , he can have it cut to any custom dimention 2 or 3 hole ect. I'm verry hapy with my chute for the Tiger he had made.

The luff length is not restricted by the F18 box rules. The only things that limit the spinnaker on a F18 are:

- Hoist height: 8150mm from mast base to pulley
- Pole length: The length shall not be greater than the distance, measured in total from its attachment point from the centre of the front beam to the vertical line touching the most forward part of the hull, with the bowsprit measured when level to the deck of the catamaran, plus an additional 800mm.
- sail area.

That's it. There is no such thing as a "standard" f18 front triangle. Depending where the mast is on the platform the length of the pole may vary and as such the max luff would do the same.

In short there is no such thing as a standard F18 spi.

Some other box rule classes are measuring things differently. The F16 for example limits the hoist height and the full length of the pole. Thus the front triangle are roughly equivalent on all F16 build to the rule, and spinnies are largely interchangeable.

Compared to the measured dimension of a wildcat spi, yours seems small:

luff: 8.85
leach: 7.68
foot: 3.78

20.9945m2

source

Luff lengths are the same for both sizes of F18 spinny

My Goodall chutes have different luff lengths - the small chute is about 4-inches shorter in the luff than the big one. Same sheeting angles for both, but slightly different hoist heights.

John,

THat's a bit poor; you are losing even more on the small kite by having a shorter luff!

You have to cough up that sail area somewhere - the small kite is not slow, IMO. I raced for a season-and-a-half at 275 lbs (125 kg) on the small sail plan and found the field to be quite level. I might tend to even give the small sail plan and lighter crews the edge in everything up to about 12 knots of breeze, especially uphill. I miss sailing light (TIIIIIIINAAAAAAAAA!).

Remember too that you have a skeg hull so you're rake SHOULD be back more than a spinnaker boat since the center of side-resistance of your hulls is further back than a daggerboard boat.

Those are for the 19m sail not the 21.

I thought a mid-girth measurement was important as well...

8.45 luff
7.70 leach
3.77 m
2.89 mid = 76.65
20.63 total
for the big one

I started with the smaller of the 2 since he said his luff was too loose.

It is. Very important. If they do not make this (75%) they are not Spi's!