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talking with another Hobie sailor and
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=55977		 Page 1 of 1
Author:  greensnopro [ Thu Sep 10, 2015 4:48 pm ]
Post subject:  talking with another Hobie sailor and
And he mentioned sailing his A cat. I've searched but can't figure out what he was talking about. So what's an A cat I'm just curious as he said it was a faster boat than a 16 and I Can't find a thing about it.
Author:  Matt15 [ Thu Sep 10, 2015 11:02 pm ]
Post subject:  Re: talking with another Hobie sailor and
http://www.a-cat.org/

I'm surprised you didn't find anything via google - A-class catamarans are well known all around the world. For comparison to a H16 thou??? You can't compare the two, they are both very different designs with different parameters.
Author:  SabresfortheCup [ Fri Sep 11, 2015 11:23 am ]
Post subject:  Re: talking with another Hobie sailor and
Well, you can't compare them as similar catamarans, but as a comparison of speed, the A-cat is definitely faster. If you can get the boat up out of the water on foils, like the AC72's and (later) the AC45's, you're going to be much faster than the guy that has to contend with all that wetted surface area and form drag!

Though it's not perfect, many yacht clubs will use the portsmouth yardstick as a measure of overall speed of the boat in order to handicap boats for sailing in a mixed/combined race. The idea is that the numbers represent how long it should take each boat to sail an identical course. For example, the Hobie 16 has a D-PN of 76.0 and the A-cat has a D-PN of 64.5. Therefore, it should only take the A-cat 64.5 minutes to sail a course that would take the Hobie 16 76.0 minutes to sail. So the handicap evens the playing field - If he crosses the line first with an elapsed time of 65 minutes and you cross after him with a time of 75 minutes, with the handicap you win. Here are some other common catamarans and their ratings:

59.0 Tornado
62.1 Hobie Tiger
62.4 Formula 18
64.5 A-Cat
65.0 Hobie 20
67.0 Nacra 5.5
71.4 Hobie 18
73.0 Shark
74.8 Prindle 18
76.0 Hobie 16
77.0 Nacra 5.0
77.5 Prindle 16
83.3 Hobie Getaway
86.4 Hobie 14

http://www.ussailing.org/racing/offshor ... l-classes/

http://www.ussailing.org/racing/offshor ... yardstick/
Author:  greensnopro [ Fri Sep 11, 2015 1:06 pm ]
Post subject:  Re: talking with another Hobie sailor and
ok well thank you guys, thats a very interesting boat, no wonder it's fast! To bad he keeps it in florida where he goes in the winter I think I'd like to go for a cruise on one for sure!
Author:  Tom Kirkman [ Fri Sep 11, 2015 3:04 pm ]
Post subject:  Re: talking with another Hobie sailor and
Here's the actual formula involved:

CT (Corrected Time) = ET (Elapsed Time) X 100 / HC (Handicap)
Author:  MBounds [ Sat Sep 12, 2015 5:43 am ]
Post subject:  Re: talking with another Hobie sailor and
Modern A-Class catamarans are very light (165 lbs - almost 100% carbon construction), very fragile racing machines.

There are only a handful of rules that govern the class - length, width, weight, sail area and a couple others that control the configuration (for example, the daggerboards must be inserted from the top of the hull - preventing many of the L and J type foils). Otherwise, anything - and everything - goes. They are a tinkerer's dream.

They are also very, very expensive. A competitive A-Class cat will set you back something north of $30K.
Author:  Tim H16 [ Sat Sep 12, 2015 9:09 am ]
Post subject:  Re: talking with another Hobie sailor and
CT (Corrected Time) = ET (Elapsed Time) X 100 / HC (Handicap)

In the Portsmouth yardstick multihull current tables, what are the columns: "Wind HC For Handicap Range: 0-1/2-3/4/5-9"?
and what is the difference between these Wind HCs and the D-PN HCs?

For example if a Hobie 16 and Prindle 16 are racing, which HCs do you use (the D-PN values 76.0/77.5 or the Wind HCs)?
Author:  SabresfortheCup [ Sat Sep 12, 2015 9:33 am ]
Post subject:  Re: talking with another Hobie sailor and
D-PN is the basic, "all around" handicap number for each boat. The wind HC columns are specific handicaps based on windspeed, and the numbers are Beaufort scale numbers. https://en.wikipedia.org/wiki/Beaufort_scale

If you can reliably measure/monitor/estimate wind speed, the recommended numbers to use are the wind handicap numbers.
http://www.ussailing.org/racing/offshor ... h-numbers/

The handicap numbers for a Hobie 16 and a Prindle 16 are as follows:

Boat Class | D-PN | 0 - 1 | 2 - 3 | . 4 . | 5 - 9
Hobie 16.. | 76.0 | 81.5 | 78.7 | 74.1 | 71.3
Prindle 16 | 77.5 | 84.1 | 80.7 | 76.3 | 71.3

So by basic numbers, they're pretty evenly matched, with a slight advantage to the Hobie 16. The Hobie 16 has the largest advantage in very light air, a slight advantage in a light/gentle breeze and a moderate breeze, and the boats are exactly evenly matched in a fresh breeze or stronger.

If you were racing in a moderate breeze, with wind speeds of ~10-15 kts (beaufort 4), you would use 74.1 for the Hobie 16's handicap number and 76.3 for the Prindle 16.
Author:  Tim H16 [ Sat Sep 12, 2015 9:47 am ]
Post subject:  Re: talking with another Hobie sailor and
Thanks for the explanation SabresfortheCup.

Are there any HC adjustment for solo vs two persons, or for any other differences (crew weight, age of boat, etc.)?
Author:  SabresfortheCup [ Sat Sep 12, 2015 4:52 pm ]
Post subject:  Re: talking with another Hobie sailor and
There are adjustments to the handicaps based on non-standard equipment or crewing, but that I am less familiar with.

The information for such adjustments can be found here:
http://www.ussailing.org/racing/offshor ... actors-iv/
Author:  rattle 'n hum [ Wed Sep 16, 2015 12:07 pm ]
Post subject:  Re: talking with another Hobie sailor and
Slight correction to Sabre's last post.....the MH (multihull) Modification Factors are here:

http://www.ussailing.org/racing/offshor ... n-factors/

Crew/boat weights, etc. are here:

http://www.ussailing.org/racing/offshor ... l-weights/

Keep in mind that, when using the Portsmouth system, a basic tenet is that the rated boat is in compliance with its class rules (or takes an appropriate correction for noncompliance). It can get complicated because some class' rules (like the Hobies') are much stricter than others.
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