So How High Will a Cat Point?

[estarzinger]

Originally Posted by daddle

The OpenCPN track plot is real. Honest. It is affected a little by my tacking on shifts if allowed by the shoals.

Out of curiosity, I imported the track into a cad program and measured the angles.

Tack #1 is 80 degrees,
Tack #2 is 79 degrees
Tack #3 is 78 Degrees

Still extremely good, but a bit more understandable than 70 degrees. (BS=7, TWA=40, TWS=10, AWA=24, AWS=16 works out correctly).

There is something funny about tack #1, as you seem to have sailed directly into the wind for quite some distance, rather than making a crisp tack as you did in #2 & #3.

You did nicely tack on small shifts in tack 1 and 2.

If this is a SC50 then I'm not sure what it has to do with "how high a cat will point". The max vmg angle for almost all cat would be much broader than this

[tsmwebb]

Originally Posted by estarzinger

Out of curiosity, I imported the track into a cad program and measured the angles.

Tack #1 is 80 degrees,
Tack #2 is 79 degrees
Tack #3 is 78 Degrees

Still extremely good...

It is enviable. Just for fun I scaled some vmg numbers from a late mode IACC yacht at 5, 10 and 15 knots TWS. By the time they're down to 50' they're certainly a bit sketchy. Still, the SC is looking very, very good. Sorry about the digression.

Tom.

[estarzinger]

Originally Posted by tsmwebb

It is enviable. Just for fun I scaled some vmg numbers from a late mode IACC yacht at 5, 10 and 15 knots TWS.

Interesting benchmark. With the SC scenario (10kt, 40 twa, 7bs) there is a 5.4kt vmg. Which is just about exactly where your scaled IACC50 falls. So, that's a 'world class' performance. I wonder if there was possibly a little current helping.

[tsmwebb]

Originally Posted by estarzinger

Interesting benchmark. With the SC scenario (10kt, 40 twa, 7bs) there is a 5.4kt vmg. Which is just about exactly where your scaled IACC50 falls. So, that's a 'world class' performance. I wonder if there was possibly a little current helping.

Maybe or maybe nicely in cycle with the shifts or a bit more wind than estimated or a fraction less average speed and very likely some scaling error... It really doesn't take much to move the numbers around 20%. I do expect that a SC50 in 10 knots upwind is an exceptionally slippery cruising yacht. What I think we may be seeing more than anything is how hard it is to get really good data from isolated real world conditions because there are so many variables at play.

Tom.

[Leventdelamort]

YouTube - Dramatic capsize for the Wave Muscat - Extreme 40 sailing series - Qingdao Day 3

This extreme 40 points quite high.

[imagine2frolic]

Originally Posted by Leventdelamort

This extreme 40 points quite high.

That's jjust what this thread needed, was some damned funny humor thrown in........i2f

[Captain Bill]

I noticed that they had 4 crew on board to start with and only three sitting on the hull at the end. Did they loose the guy that landed on the mast?

[tsmwebb]

Originally Posted by Leventdelamort

This extreme 40 points quite high.

It'll buff right out!

Ya sure that the bows heading for the center of the Earth isn't pointing low? On the plus side there is the self bailing cockpit and automatic reefing system

Ouch. I think the guys in the 72's will need parachutes.

YouTube - Extreme Sailing Series Qingdao, Jour 3 : Chavirage, collision... Une journée des plus Extreme !

Tom.

[imagine2frolic]

That's more like stock car racing!........i2f

[Nicholson58]

A feature of my ancient Tornado is that the very skinny bows are also very tall. I have found it impossible to pitch-pole. The bows provide huge buoyancy as they are driven into the water. I have noticed that this is lost on all new designs. The Tornado also has a nearly flat bottom at the aft 6 feet of hull so it planes at speed.