Spinnaker Area

With the arrival of the asymmetric spinnaker I'm investigating how to best get rated in IRC. IRC likes unmodified boats so I was looking at the standard data.

Are the class kites really 62.2m2 (670ft2)? We're currently 42m2 on ours and using a 3m long pole rather than the 3.45m class pole. Basically I'm looking to see if we can add a short retractable bowsprit without too much loss on our rating.

IRC calculates spinnaker area as SPA = ((SLU+SLE)/2)*((SF+(4*SHW)/5)*0.83
SLU = spinnaker luff longest
SLE = spinnaker leach
SF = spinnaker foot
SHW = spinnaker half width

Another 20m2 to the spinnaker area would be a phenominal presumably big shouldered running kite. Does anyone know whether this is a calculation issue or reality? Has anyone got an IRC rating with the long pole and big kite? Are there smaller kites being used in PHRF?

Thanks

Jez

I am running an IRC certificate with SPA of 40.71 and a STL of 3.11.  I too can't see how one could get another 20m2 bigger than my kite.  We get overpowered as it is!

I shortened my pole last year to reduce the rating and it made very little difference - perhaps 3 points.  My understanding is that a bowsprit that is no longer than the pole has no effect on the rating.

Very interested in your asymmetric experiment.  If yu see another one going cheap, I would be interested in having a play!

As for the Asym experiment, a melges 24 asym is 670 sq feet. So, in Phrf, you shouldn't take a rating hit for using it. Haven't been able to get my hands on one yet, I think that would be the one to try, You can fly asyms deep off of a pole, jybing them can be tricky though. It takes an extra control line in heavier air, so it is a bit more complicated...

Usually the max girth of a symmetrical chute is 180% of the pole length. If our max girth was 6.9 meters a 62.2 square meter spinnaker would be quite possible. I think somewhere along the line the spinnaker size must have been reduced, maybe for a better rating?

Under our LMPHRF rules we can carry a spinnaker that is 180% of our pole length, so a 62.2 square meter symmetrical spinnaker is legal for us, and an asym of similar area is also legal. Bowsprits are another matter.

Under LMPHRF, a 1 foot bowsprit can be used without penalty, but every additional foot costs 3 seconds a mile, up to a total of 3 feet. (that is, if I'm reading the rule correctly)

usually, an asym is the 160% of your J dimension, so when you add a sprit you are adding length on the foot of the sail.

The chute on a Laser 28 is substantially over sized as the pole is noticeably longer than the “J” dimension. In very light air this is a big plus. I have a North Code 0 symmetrical that I really like that allows me to make the boat move and even point above a Beam Reach on those days when everyone else is dead in the water. It appears to me to be much more effective than a light air No. 1 in those conditions, probably in part because it extends forward of the forestay and has excellent shape when boat is heeled slightly.

Like other light displacement boats, however, in higher wind conditions, particularly with gusting conditions, a class chute this sized becomes uncontrollable. In those conditions you really need a Code 4 or 5 symmetrical. These boats and most other light displacement boats just do not have enough rudder to handle anything larger. Some new sailors think they should be able to carry an oversized chute directly down wind, but the reality is the boat becomes very dicey and may start to oscillate (roll rail to rail) even in relatively flat water. On some occasions my boat has just rounded up with no warning. On other boats I usually get some sort of warning. I may feel the rudder stall before the round up. With this boat sometimes there is no warning.

In any kind of wave action you will have problems keeping enough rudder in the water to maintain control without adjusting the chute. I would suggest you try to easy out the chute as you go up the wave (as the rudder starts to come out of the water) and then sheet in very quickly as you race down the wave. It is exhausting for your crew, but it can be done.

When sailing on the edge of the upper wind range with the chute it is important for the new sailors to remember to go deep in the puffs (steer slightly down wind) and come back up in the lulls, otherwise you will most likely run out of rudder and broach. In conditions like this you need to maintain a substantial distance to other boats. I would recommend at least two or three boat lengths separation.   If you broach in those conditions you can cover that distance in a matter of a few seconds.

There are other suggestions for heavy air sailing on other parts of this Forum.

Do you fly spin with the halyard fully hoisted or eased a bit?

We agree with Bill's comments on heavy air spin work. Impact does a fair number of offshore and overnight races on Lake Ontario.
Big wind downwind is great for us.
Full hoist halyard
tweakers fully down both sides
Pole forward and up a little if needed.
Drive aggressively down in the puffs
some crew weight behind the helmsman
In big squalls we have been really fast with Spinnaker up and a reef in the main to keep her under control in big waves
Dousing the kite is always fun in 25+ knots. Bowman will release the guy snap shackle and we retrieve under the boom. If too crazy for weight on the foredeck, release the guy while the foot is gathered behind the main or letterbox between foot of main and boom. Halyard is the last to go in these conditions.

I saw the 670 square foot size on the brochure... but after playing around with a spinnaker design program I found I can't get to 670 using the PHRF max girth either... well, I can get to 670 but the sail doesn't look right. I'll see if I can paste a jpeg or bitmap. I'm curious about that symmetrical code zero chute... I'm having a hard time imagining what that looks like. I have seen asym code zeros before, but never a symmetrical one.

My oops. I called it a Code 0 and it is actually a 1S iaw North designations.