"Result should be 21.55729613 Kts "
So then, not only is it a wee bit BEEGER than a Tornado, but also a wee bit SLOWER ! (Don`t hit me, Mr. Roberts.)

Please tell me there`s only one kind of mile. I can deal with the fact that many countries have "dollars" and they are all worth surprisingly different amounts, from the US$ to the Zimbabwe $ (which has no value, really, not even in Zimbabwe), but I`m hoping against the odds that when someone mentions "miles" they are referring to the same thing. I get all nervous when someone says "statute miles", is that like miles wearing traffic police uniforms ?

Last I knew, one mile = 1,609km = 0,868 knots, or 1knot = 1.1516469857054070851460534493474 mph.

Answer to Mary : If you know the conversion factors, you can sail a race in miles or km, convert the distance to nautical miles, calculate nautical miles per hour, and you should get your average speed in knots.

Steve

But you can't convert something if you don't know what it is in the first place.

Miles (land, statute, imperial, whatever) = 1.609 mtr
Nautical miles = 1.848 mtr

So there is a big difference between land miles and nautical miles

Roman miles etc are yet different again. That is why the distance of a km was invented, to make an end to the confusion as well as to end 12 inches in a foot, 3 feet in a yard and ??? yard in a ??? mile

Wouter

Is that relevant? Are kilometers the same whether measured on land or on water? If so, assuming a race is 100 kilometers, don't you still have to convert the kilometers to nautical miles before you can get average speed in knots? Or convert the kilometers to statute miles in order to get miles per hour?

Compounding the problem with getting statistics about distance races, besides confusion about distance measurement used, is confusion with wind measurement. Wind over the water is supposed to be measured and reported in terms of knots, while wind over the land, even if it is only 50 yards away, is supposed to be measured and reported as miles per hour. And it is often hard to know which it is.

Wouter, I am talking about the United States. I know you think we are archaic.

So in order to understand a certain speed claim, the whole formula used and all the criteria used has to be spelled out so we know how the answer was derived. (Somebody did that earlier in this thread, and that made sense, because you could see the elements used in the formula all the way through. Then if there is a faulty assumption in the mathematics, it can be corrected.)

We all know that 20 mph/knots on a sailing cat is faster than 20mph/knots in a powerboat, so the real problem is that there are too few flexible units available. I would estimate a sailboat mile to be about 3000 feet (914.4 metres). Could we get consensus on this?

Well Steve, it looks like you've lost another thread. Better luck next time! I enjoyed it while it lasted.

GARY

Sorry, don't mind me. I was just trying to figure out how to make sense of the figures. But I guess it doesn't really matter one way or the other, because I don't think much can really be determined from a long-distance race, as far as achievable speeds in optimal conditions.



Okay, here is one for you, Steve to get your thread back on track. This is an excerpt from a story in Catamaran Sailor about the 1998 Key Largo Steeplechase:

"In steady, screaming-reach winds of 20 mph, the Key Largo Steeplechase's long-standing speed record was broken by every boat that finished. The previous record of 7 hours, 58 minutes was broken by more than two hours.

"Enrique Rodriguez and Hans Meijer sailed their new Worrell 1000, Nacra 6.0NA to a new record for the 110-mile course of 5 hours, 4 minutes, 25 seconds, an average speed of 19.5 mph. Meijer said their GPS was registering some pretty steady 29 mph speeds."

And here is some more historical data:
Record for the Sandusky Steeplechase (Sandusky, OH to Put-in-Bay, OH on Lake Erie) is about 57 minutes, and that distance is supposedly about 21 miles. It was done on a Nacra 6.0 NA that used a Hooter for about two-thirds of the distance and main-jib on a reach for the last third, except for a beat to the finish line once they got to the Bay. Wind was 15-20. The time could have been a few minutes faster if not for the beat to the finish and some time lost during a near pitchpole when the crew made an excursion around the forestay.

And, of course, with that wind Lake Erie is not exactly flat water.

And, of course, we don't know the actual distance sailed in that 57 minutes because they did not sail directly point to point on the open-lake portion of the race.

Hi Steve,

hope this is on track. Was talking to Simon McKeon (Yellow Pages, Maquarie Inovations, A class and sometimes Taipan4.9 Sloop skipper) at Taipan titles last weekend about speeds with this thread in mind.

He said handheld GPS are unreliable for reading speeds, backed up by some of the comments in this thread. His experience is that off the beach cats top out at 23kts. Also backed up by comments in this thread and my experience. I did ask him if it would be possible to include some cats when next record attempts are on, he wasn't to interested Macquarie Inovations syndicate have other priorities, very serious about getting record back of Sailboards, currently rebuilding craft for next speed season. Around Sept. Nov. in Vic. OZ.

Haven't given up though might try and arrange something, get Glen Ashby A class/Hobie Tiger/Tornado, Greg Goodall Capricorn/Taipan, Rowan Veal Moth Foiler (has recently been written about as beating A class around course?) and my F16 Altered there for a shoot out, have to be worth some promotion ?

Regards Gary.

"Record for the Sandusky Steeplechase (Sandusky, OH to Put-in-Bay, OH on Lake Erie) is about 57 minutes, and that distance is supposedly about 21 miles."

Thanks Mary, that`s just the kind of stuff I was looking for. Average speed = 19,2 knots (according to my maths, everyone can do their own and we can see how many different answers we get.)
So an average of 19,2 knots for almost an hour of sailing, assuming they sailed a dead straight line, which they didn`t as they had to beat for a while. I think we can safely say they averaged approx. 20knots for almost an hour of sailing, given that they sailed a bit of a longer distance than the actual course ?
We could be conservative and say the race distance is only 19 miles, but they covered 110% of the distance of the race, and we`d get a similar result either way.

Mary,

Actually the race distance is about 16 statute miles. You can give about another mile to the start line and the distance from the finish line to the landing area. See attached pic for measured linear distance...and I'll try to attach a race track from a few years ago too.

Jake

and an actual race track. This was a few years ago on my 5.2. The GPS recorded peak speeds just touching 20mph (sorry, no time to convert to knots). Two years ago I forgot my GPS but we did it on my 6.0NA and once clearing a pretty calm sandusky bay, we screamed out on a jib reach in the fog (I was really regretting not having the GPS - but we nailed the compass heading to the island). I think our time was just a little over an hour. Two spin boats (an I20 and an 18HT) ran their spinnakers all the way and beat us there by 10 minutes or so.

Hi Gary,
Thanks for the effort, can understand why Simon McKeon doesn`t want beach-cats on his course, doing half his speed. A bit difficult to dodge them at 45knots plus
I`d suggest if he wants the record back badly enough, he takes up windsurfing.

"Is that relevant? Are kilometers the same whether measured on land or on water? If so, assuming a race is 100 kilometers, don't you still have to convert the kilometers to nautical miles before you can get average speed in knots? Or convert the kilometers to statute miles in order to get miles per hour?"
See now this measurement thing is getting confusing. Kilometres are always the same, no matter where you measure them. If you have ten fingers you can figure out the metric system quite quickly.
Mary, in my case, every time someone quotes mph I have to convert it to km/h, then to knots . Depends what you`re familiar with.
The common language for sailors and pilots is knots, so lets try keep it that way. People who quote windspeed in mph, or km/h, or metres/sec always get me, I have to find a calculator to figure out what they mean.

"Wind over the water is supposed to be measured and reported in terms of knots, while wind over the land, even if it is only 50 yards away, is supposed to be measured and reported as miles per hour. And it is often hard to know which it is."
See now I`m totally lost, and I`m beginning to fully understand the following :
"Wouter, I am talking about the United States. I know you think we are archaic. "

So, if the wind passes from the land to the water, you guys change the unit of measurement. Does the wind then speed up, or slow down ??

You see? That is exactly why I think historical information about distance and time for a distance race is not very useful for determining average speed. For 40 years the organizers of that race have been saying it is about 21 miles, and it takes modern instruments to give us the correct distance. (Maybe the original distance was from a car driving from Put-in-Bay to Sandusky over the ice in the winter, and maybe it was a zig-zaggy path along the Christmas-tree trail .)

Sorry if anyone thinks I`m dragging this one out a bit.
Here`s an image of the race I described in the first post, it`s a map of the Vaal Dam, showing the course.
Race organisers call it a 24nm race, I measure 44,967km in a dead straight line around the island and back, assuming NO tacking or gybing, = 24,26nm, or 27,93miles. The dotted line shows the track that almost all the cats followed in order to stay in flat water as long as possible, it measures 49,25km including some tacking, =26,58nm = 30,6 miles. Now, if we take an average of the two that should iron out any discrepancies. 24,26nm + 26,58nm /2 = 25,42nm.
The recordholders took 1hour,1min 27sec.
Average speed = 24,82nm/h, which is 24,82 knots. Even if they somehow sailed a dead straight course their average speed would have been 23,68knots.
I don`t think it will get beaten anytime soon. I believe a cat on a close reach main + jib is faster than spinnaker + main on a broad reach.

Steve

This video about the Bacardi Blast mentions 27 miles per hour.
Cool video of Brundock and Forbes o...ze and getting hung up in the trap wires

GARY

Gary,
Looking at that video it looks very gusty, hard to get the power set up well, and they look like they are struggling just to keep the boat upright. Not good for speed.
I think catamarans can sail at up to 1.7 times windspeed in 10 knots, probably close to windspeed in 20 knots, and a quarter windspeed in 30knots (daggerboards make very small sails )

I did a little compensation for the upwind leg and come out at 26.9 knot average speed over the whole course using data you provided Steve.

I think this may well be the best example of a top speed. Relatively sheltered and flat waters, very large portion of beam reaches and ideal windconditions with a Tornado that still has the optimal jib cut for reaching (the old cut)

I don't think that any spi equipped boats is faster under spi than the same boat on a flying reach.

I would put the top sustainable speed for a beach cat at 27 knots with this example and expect most modern cat to be slightly below that (around 23 knots) due to optimation to windward-leeward courses.

I think you guys got some very optimal conditions for that record attempt and therefor very rare conditions.

So were still some way off the Tornado class claim of 33 knots.

"The Tornado sailboat has the ability to reach speeds of 15-18 knots upwind and downwind, and 33+ knots reaching!"

The key here is the proviso "the ability to reach speeds of..."

The claim is effectively max speed of 33+ knots NOT sustained or average speeds of 33+ knots.

Ok, here's what I'm thinking: Measure the distance between two stationary marks with gps waypoints to gauge an accurate distance. Go out in good conditions and do several beam to broad reach runs using a stopwatch. Do the math, report back here. This sounds like a great way to kill time, no?
I'll report back my results as soon as we get an ideal day (and once the ice melts, of course).
It's still snowing here, so don't hold your breath.
Al