Measurement Based Handicapping

I actually think personal handicapping is probably a good idea at club
level and might encourage folk to realise just how much there is to learn.

Huddling in groups muttering about us 'buying' our way to the front of
the fleet when half of them don't even cross the line as the gun goes,
sailing miles further round the course rather than sorting their tacking
angles and spotting the occasional shift.

Correct if if I'm wrong, but the original concept of the handicap was to try
and level the equipment difference and back in those days the difference
was so much less than it is today, so that sailors could compete as much
as possible on even terms.

But again correct me if I'm wrong, but back in that particular day the
standard of sailor even at local level was much much higher than it is
nowadays.

I know there's a bunch of Wednesday Night Laser sailors down Eastbourne
way and they've got some personal handicap system going on, not sure
how it works but it adds to the spice of the event.

Originally posted by G.R.F. I know there's a bunch of Wednesday Night Laser sailors down Eastbourne way and they've got some personal handicap system going on, not sure how it works but it adds to the spice of the event.

Yes it's been very successful. However, it's personal
handicapping on the same boats not between classes. In
fact one of the really positive things about it is that
a lot of people have gone out and bought old Lasers to
sail on Wed evenings. Which has not only revitalised Wed
evenings (as many don't bother rigging more complex
boats for an evening sail, or can't get their crew/helm
out), it's also got a large section of the club all
sailing together as a fleet in the same class for at
least one race week in summer. Having a personal
handicap not only makes it fun, though it's very serious
fun these days, it also means that you don't need a
championship winning boat to win on handicap, and it's a
great way to get newer members and newer sailors
involved as they don't always end up at the bottom of
the results table. It's not likely to replace our normal
mix of class and handicap racing at weekends, but it's
certainly a great thing to do for something like an
evening series, and it's turned our Wed evenings from
something that most people just came down to for the
meal and the bar into a important part of the sailing
program.

Originally posted by English Dave In fact the problems that are now arising in Cat handicapping come from the fact that designers are now flattening the stern sections of modern cats to encourage planing  which screws with the SCHRS ratings. Because Cats also "bang corners" upwind rather than tacking on every shift (a la Laser) the speed of tacking can generally be ignored.

Dave

Got some examples of boats where they appear to be plaining and so out-perform their SCHRS?  Always looking at ways to refine the SCHRS model.

We do need to look at the White Formula 20 at some point as it has 2 sets of dagger boards....

Originally posted by G.R.F. I had to look up that SCHRS thing, my God what complication. Have you seen the Maths? Can you imagine Cat Sailors ever getting to grips with that..

The underlying formulas may be a challenge to some.  None of the cat sailors I have met have complained about the maths.

"But the reason behind flat hull sections has to be about encouraging
planing. Otherwise it just induces greater drag for no effect. Am I wrong
in claiming that a deep narrow hull is the more efficient design for
laminar flow displacement sailing?"

The flatter cat hulls are not about planing AFAIK. They are more about
maximising volume and reducing wetted surface area.

A circle has the lowest wetted surface for volume; as this gets wider, it
becomes elliptical which creates a flatter spot in the sections.

A higher-volume section also allows you to create a narrow waterline and
shallower rocker than a vee section of equivalent flotation. Both monos
and multis have been heading that way for a long time, with the notable
exception of the 9ers which are unusually long for their sailing weight
and therefore can afford a lower-volume shape.

Planing hulls are problematic on cats because most of the lift on a
planing hull occurs very close to the "spray root", which is where the
underside of the hull meets the water surface. Planing lift is simply the
equal and opposite reaction created by the hull bottom hitting the water
and pushing it down. The area ahead of the spray root is out of the water
so it creates no lift; in the area behind the spray root the water flow is
already diverted so it creates much less lift. Therefore it's a very small
patch, fore and aft, that creates most of the planing lift and if it's going to
do much it therefore has to be wide.

The ultimate planing hull is therefore very short and very wide, because
induced drag when planing drops by the square of the wetted beam; see
Daniel Savitsky's work for the theory, or look at Formula Windsurfer
boards (about 2.2m long and right at the class maximum beam of 1m).

On a narrow cat hull, the spray root area is tiny, so very little lift is
created and it's not really worth compromising other areas of the hull
shape. And you need to be hitting the water at an angle of incidence,
which doesn't happen at the stern; there the angle of incidence is
normally negative.

Just my two cent's worth.