Fastest dinghy?

For a start, how realistic are FDB's ratios? Consensus among skiffies seems to be that they are OK apart from the fact that they include the "lever arm" which is generally thought to be irrelevant or misleading. After all, the Cb is easy to pull up and tall rigs tend to be more sophisticated so they can be twisted off and depowered more easily - this makes up for the supposedly higher C of E. Just compare a Laser rig to a taller sailboard rig, the C of E on the sophisticated board rig is way lower in reality but higher under Frank's measurements.

And surely neither Cherub or 29er are fastest under any calcs. The R Class has no minimum weight limit and has hull significantly lighter than a Cherub (32-35 kg). It also allows wings (but doesn't use them) and it almost certainly has heavier sailors than the Cherub so therefore more power.

In practise, of course, in all conditions the 12' skiff beats the Rs despite the fact that many Rs are built on 12' hulls. Even when the 12 is down to its number 3 rig, the extra weight of the 12 hull (45kg??) is more than compensated for by the fact that it has a very flat, efficient rig designed just for heavy air.

So the 12 is lighter (IIRC) than the Cherub, carries a heavier crew (more power) because it has a bigger light-air rig, and it has a much more effective heavy-air rig.

Finally, it would be a hell of a brave person who'd say a Cherub would blast past an 18. Or even the Skate, an Australian 14 footer with twin sliding seats (the forward hand's on an 11 footer which makes an IC plank look small) and a skinny flat lightweight hull.

Re hotter angles at same VMG equalling a faster boat - doesn't that ignore the question of what happens when the deeper but slower boat heats up? A boat could be better of running deeper but slower to get better downwind VMG, but still capable out a better ultimate top speed.

For example, before they went to assys I think Skates sailed fairly low downwind  so assy boats would go higher and faster - but when it actually came to a top-speed contest the Skates could wipe just about everything, reaching with the power of a 7' (?) and 11' sliding seat.

Wow, lots of positive vibes out there for my favourite toy  !

I think that the numbers might look even better if you put more realistic crew & helm weights in for the Cherub: most of us sail with an all up crew weight of under 135Kg (not 150Kg as shown above), but my maths might be a bit wonky.

If anyone it interested in seeing how fast they REALLY feel, there will be loads of Cherubs at Carsington Water Sailing Club on Saturday November 13th. I can't promise 30 knots of breeze, but anything above 11 knots is usually enough to put a grin on your face for the rest of the day

Lucy (Cherub sailor, so very biased)

 

The numbers for the cherub and 49er are true but they miss one thing, and that is that a cherub is four and a half foot shorter so yes, downwind in a blow the cherub will go faster in a straight line (length not as much of an issue provided you can keep the bow up).  Round the cans the 49er will win becasue the extra hull length makes speed upwind far superior.  Remember also, the most important factor in all of this are the two monkeys trying to hold the thing down in 30-whatever knots of breeze. 

Still have not foujnd what I am actually looking for, but I have found the handicap ratings for various classes used in Aus :

http://www.vic.yachting.org.au/default.asp?Page=1352&Men uID=Handicaps/1023/0

Class	Handicap	Year
PHANTOM	111	1998
18’ Skiff	68.5	1999

I'll concede that the 18' handicap is for 1999, but that is about the time the big rig was first mooted on the Tornado:

TORNADO Big Rig

66

I am still lookning for the article I actually want.....

 

Originally posted by Phil eltringham The other problem is things like how boats performance changes with windspeed.  The most dramatic example must be the flying int. moths, below flight speeds they will be at best as fast as normal ones.  Above it though, and they are significantly faster.  Now I kow this is going down the american route, and it has been discussed elsewher but I am really warming to that idea.

RORC tried wind-strength dependent handicapping under IMS for the Commodore's Cup (an international yacht event). It was a complete fiasco ("Comedy Cup"). Protests rumbled on for days. There are issues like different windstrengths at different times in different places on the course. Windstrength-based handicapping is a nice sounding theory but a complete nightmare for race officers in practice.