How fast is my F18?

I've always wondered how fast we are realy going. In an advert i saw a great device, Velocitek S10 (velocitekspeed.com).

This tool promises to show real time speed and even has a velicity made good function.

Can anybody, who has bought it tell me how it performs in the real life?

if you do a search for speed, there is plenty of advice on how to measure your speed. In short, GPS speed readings are at best, suspect. I once registered a speed of 73 knots on the GPS during the tybee.

And you REALLY believe you where 73 knots? Maybe in your dreams!!!! LOL. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />

Doug

The GPS on my fishing boat has read as high as 45kts, the boat is 20' with a four cylinder inboard. No way it goes over 20kts with a tailwind. Can't be trusted. Measured and timed is the only way to get solid numbers. 74kts on a cat, what a ride.

I've heard good things and some bad things about the units. I haven't used one on a boat but I have had an opportunity to play with one briefly. The developers of the thing really seem to be intune with what people want and I know they've been making changes to the device based on feedback...so some of what I say might be out of date.

The unit I saw displays only two digits of speed data. If you are at 5.4 knots - great. If you are at 15.4 knots - you only got to see "15". In order to establish VMG, you first much tell the unit the wind direction by clicking a button at a downwind point, then clicking a button after sailing to a point directly upwind. IMHO, this would be very difficult to do accurately and/or in a timely fashion before a start - especially on a lake where the wind shifts regularly and often dramatically.

As far as the build quality, the unit is bulletproof. I was very impressed with the construction. I wish they would come out with a unit that functions like the basic tactic unit with a magnetic compass instead of a GPS compass. A unit with angled displays and some better mounting options to provide some competition with tactic would be a market killer.

I'm very certain that was tongue in cheek.

True, if you're course is "square" to the wind .... If you had time to mark "C" and "A" buoys (or anywhere along this line that is a sufficient distance apart for the GPS to calibrate) wouldn't the VMG be displayed as the fastest point of sail to this (imaginary) line?


Ex: If the wind is backed then port-tack is favored and your VMG will be very high. When tacking to stbd-tack, you're VMG will be much lower. Compared to a perfectly square course you'd expect your VMG on either tack to be similar.

Gadgets are cool and all. BUT, my take on this is to get my head OUT of the boat. If I am passing boats I am going fast. If I am falling behind I am going slow.

These items are all good for number values, but around the race course I have no time to be looking inside the boat. It is just another thing to distract me.

OF COURSE! this is my take on this matter.

True, but what if you're practicing with no other boats to pass (or pass you).

Time and place for everything <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Gosh, I don't know, wouldn't it be really hard to keep your tongue in your cheek at 73 knots? I'd think your lips would be flapping in the breeze a little too much... Must be true.

Are you going to do this before the race starts or chalk the first leg up to setting up the GPS? There is no time to program in the marks around the course before the race since racing usually starts shortly after the RC has a course set. Additionally, I don't have a hand free at any mark rounding to be pushing buttons on a device. If it automatically could recognize when I rounded a mark - that would be something (until the race committee moves A due to a wind shift...then it becomes useless again).

I think it is a decent training device, but I don't think I would find it practical on a double handed spin cat around a race course.

No... you set your down wind position ... where ever you are on the course.

You sail one minute on port... you sail one minute on starboard. Stop... set the upwind....

This device extrapolates the wind bearing to infinity.. and caclulates your VMG to the wind. your GARMIN is always trying to send you to a fixed point.... not infinity,. so your VMG is to the bearing... not to the wind.


If the wind shifts during the race... You will see it as different VMG's on port and starbord... Hmm... you may not have noticed this shift.

I use the Velocitek for training. I use the VMG mode as that is the fastest way to get around a course. Who cares if you are going 25 in the wrong direction?

I think it helps a bit in determining and getting the feel for the fastest angle of attack in different wind and sea conditions.

I have sent in my list of things I would like it to do but have not heard back on whether they were programmed.

Later,
Dan

The newer GPS units that are WAAs compatible are far more accurate then the older units. You may still receive some erroneous readout, but none the less your speed will be more accurate.

From the Garmin website

The origins of WAAS

The Federal Aviation Administration (FAA) and the Department of Transportation (DOT) are developing the WAAS program for use in precision flight approaches. Currently, GPS alone does not meet the FAA's navigation requirements for accuracy, integrity, and availability. WAAS corrects for GPS signal errors caused by ionospheric disturbances, timing, and satellite orbit errors, and it provides vital integrity information regarding the health of each GPS satellite.

How it Works

WAAS consists of approximately 25 ground reference stations positioned across the United States that monitor GPS satellite data. Two master stations, located on either coast, collect data from the reference stations and create a GPS correction message. This correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere. The corrected differential message is then broadcast through one of two geostationary satellites, or satellites with a fixed position over the equator. The information is compatible with the basic GPS signal structure, which means any WAAS-enabled GPS receiver can read the signal.

Who benefits from WAAS?

Currently, WAAS satellite coverage is only available in North America. There are no ground reference stations in South America, so even though GPS users there can receive WAAS, the signal has not been corrected and thus would not improve the accuracy of their unit. For some users in the U.S., the position of the satellites over the equator makes it difficult to receive the signals when trees or mountains obstruct the view of the horizon. WAAS signal reception is ideal for open land and marine applications. WAAS provides extended coverage both inland and offshore compared to the land-based DGPS (differential GPS) system. Another benefit of WAAS is that it does not require additional receiving equipment, while DGPS does.

Other governments are developing similar satellite-based differential systems. In Asia, it's the Japanese Multi-Functional Satellite Augmentation System (MSAS), while Europe has the Euro Geostationary Navigation Overlay Service (EGNOS). Eventually, GPS users around the world will have access to precise position data using these and other compatible systems.

GPS speeds are a pretty simple distance/time calculation... and erroneous results are easily explained. Most units track position at fixed increments of time, default is usually 10 to 30 second intervals. When you export your track and look at the table of data, you can identify where the errors are introduced. Here is an example from a recent bicycle training ride... Notice that for one interval, the unit lost reception and placed my position with no movement and then calculated the speed as double when it found the position in the next interval. This often happens under bridges or very large trees. On a boat it can happen when your handheld is blocked by your lifejacket. You will notice that the odd max speeds are an even increment of your expected speed on a boat for the conditions... 2, 3 or 4 times expected.

391 9/21/2006 19:02 909 ft 299 ft 0:00:10 20 mph 111° true N40.12869 W83.15433
392 9/21/2006 19:03 902 ft 312 ft 0:00:10 21 mph 109° true N40.12839 W83.15333
393 9/21/2006 19:03 901 ft 309 ft 0:00:10 0 mph 109° true N40.12839 W83.15333
394 9/21/2006 19:03 898 ft 303 ft 0:00:10 42 mph 114° true N40.12781 W83.15124
395 9/21/2006 19:03 891 ft 288 ft 0:00:10 20 mph 119° true N40.12748 W83.15025

A friend of mine also logged a rediculous speed whilst participating in the Fast Cat I.O.W race. Whilst having a few beers after the race we discovered his GPS was placed on a string around his neck, whilst tacking our gybing we reckoned it might have swung to a radical speed but are they really that accurate? I doubt it.

On one race in the Keys, I think it registered "999" for a second.

I was tempted to put aluminum foil on my head to prevent the brain scan by the aliens who had obviously placed a tractor beam on the boat .... <img src="http://www.catsailor.com/forums/images/graemlins/ooo.gif" alt="" />

Turns out the batteries were crapping out...

Does this mean you have found your unit to be accurate most of the time Mike? and what brand was it
regards

Yes, I have found it to be very accurate when it has a clear view of the sky. It is a Garmin Etrex Vista C. I use it for a range of land, water and air activities and am quite satisfied. Unfortunately they have discontinued it but did replace it with the somewhat pricey Vista Cx It is my 4th garmin as I have upgraded several times.

I ride with a wheel speed sensor and they are almost always identical to the tenth of a mph. Errors are usually explainable by having it in a bad spot or under bridges and dense forest.

The lanyard attaches to the bottom of the unit so it will hang upside down with the antenae pointed down... not so good for best reception even in open water on a boat. It is best to keep in a pocket pointed up.

Agree with Mike - I have the original Vista and have used it on the boat for four or five years now. Only major wierd number I ever got was when I forgot to reset all the numbers before the Horn Island Hop one year. We got back to Ocean Springs YC after a particularly hairy, wet, screaming jib reach in flat water on a Nacra 6.0 - my skipper turned to me at the bar where we were in the drip-dry cycle and asked me loudly what our top speed had been. A hush fell over the crowd as I punched a couple of buttons and proudly announced our top speed was 79 mph - in the truck on the way over from Pensacola. <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

User error aside, Garmin makes a good, reliable rugged product, and the Vista with the compass is quite useable for cat racing.

I usually put a GPS in a drybag and tape that to the boom on the Nacra 20 when we're distance racing. I've found that it receives very well as long as the boat is upright! The max speeds and such are very reliable. If you use the larger garmin units, you can even see the displays from the outboard positions of the boat.

Herendeen bought two Garmin Geckos (very simple GSP units) and used electrical tape to attach them to each shroud. You can still program in waypoints and for less than the cost of one fancy unit, he's got two neatly placed and accessible.

And the customer service they offer is World Class. I have returned a few items to them that were replaced and/or repaired with no problems.

Also as an FYI, you can get updates on the unit software etc... from their website.

I have learned from use that the WAAS enabled GPS units are very accurate which is both a source for reduction of errors AND introduction of errors. I have a very small Garmin unit that can be warn on the wrist. It is so accurate that it will record the speed my wrist is moving as I hoist a spinnaker, trim the mainsheet, or make any other high speed arm movements. So I get the max speed of my WRIST, not the boat. If my wrist is moving in the same direction as the boat then it can be a pretty dramatic increase in max speed over what reason would inform me is the boat speed.

We have taken our GPSs downhill skiing and been amused by the amazing speeds that have been produced in some spectacular "skiing pitchpoles". The speed of the hand holding the GPS while the arms go flailing adds to the downhill speed so that my personal record is 132 mph! You can amuse yourself with your GPS by "throwing" it as fast as possible (DON'T let go!) to see what "Max speed" you can produce while standing still. Try it yourself and report your findings back here on the forum.

Mike Fahle Toledo (Had our season first snowfall yesterday)

wave your gps back and forth really quickly and you might reach 73 kts <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Guys, this thread was originally about how fast the F18 actually is, not how reliable gps-receivers are. So let's have it, how fast is the F18!?:) Uphill, around 14 knots? Downhill around 25 knots? What do you think?

I dont have time to let a sinker over the bow and time the knots in the line over <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />. Can you give me your better way of accurately measuring boat speed Jimmi? <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> I will have an F18 and it would be nice to see accurate data from top crew races to help understand the strengths and weaknesses of the different brands of F18
regards

Well, my dad and I use a hand held gps receiver and compared it to the speedometer in our car while driving. And as expected the speedometer showed a few knots faster than the gps, however the difference was not 73 knots and other crazy numbers as mentioned here on the forum. We therefore conclude the gps to be quite accurate (I know some will want to shoot me after writing this, but living in Oslo, Norway with an entire ocean to cross for most of the forum users, I'll take my chances:)).
Up hill we have done 13,7 knots in our Taipan 5.7 in around 12 knots of wind with zero waves. Down hill we have done around 20 knots, wind strength 15 to 18 knots. We did not fly the chute, so I reckon it is possible for a more experienced crew to go quite a bit faster while flying the kite. Opinions?
Regards Jimi

I figure 14-15 up and 20 or so down in good wind. Probably faster if you have the guts to go all out downwind in high wind stuff. This is what i do in my 6.0 and I can't sail it worth a crap so I figure an f18 sailed average should go that fast! maybe I am wrong, but I haven't sailed in too long. this despite being on an island 1 mile from water in perfect weather.

A GPS unit will be pretty accurate as long as it can see the satelites and you don't jerk it around too much. Unfortunately, when you are on a catamaran going upwards of 20 knots, you will be jerking it around and it will not have a good look at the satelites all the time.

I once threw my handheld from one side of my cat to the other (on the beach while rigging, to my crew) and it registerd 53 mph. I just tossed it easy, underhand, so I know it wasn't going over maybe 10, but because it tumbled I think it decided it must have gone 53? The point is, in your car going down a smooth road in a straight line, sure it works great. But on a picthing cat on a rolling sea, not so accurate.

Here is what you can do: Have your crew hold the GPS unit somehow that the antenae will have a good look at the sky for a few minutes while you sail upwind, bear off and set the kite, now have him get out on the wire with the kite sheet in one hand and the GPS in the other (better tie it to him) and now you heat it up and get it going as fast as you can for as long as you can, and have your crew read off the speeds as you go. You might see 20 knots on an F18, just before you swim. (insert picture of the Hobie Tiger pitchpole during the speed run in the French Ditch). I have found a handheld GPS will only give you accurate numbers in a steady state. Once you start tacking and gybing if the boat is bouncing all over the place in waves, the "max speed" number is no good. At the end of the day you can use the distance and time it records and do your own math but that also includes all the slow sailing while tacking.

I have the Velocitek. I have seen 8 knots VMG upwind and 16 knots VMG downwind. I have timed upwind legs and downwind legs and get, pretty consistantly two times faster downwind than upwind. The boat is gybing and tacking about the same angles. That speed is in about 15 to 17 knots of breeze. That means that the straight line speed is about 23 knots with the chute up, based on algebra.

Dan

Not that it really means anything, but Marstrom's M20 advertisement saids: "GPS- verified 30 knots" ... What do you guys reckon?

In good winds and double trapped we typically log 14-16knots max on the GPS upwind. Downwind we typically max out at 25knots or thereabout. This is on a Tornado with almost 200Kg on trapeze. During gybes and tacks the readings are sometimes far above the typical values of that day. I suppose all the movement of the crew carrying the GPS unit confuses it (didn't we just have this discussion, two or three months ago?).

Perhaps the M-20 and other beachcats can reach 30knots for some seconds. Perhaps even the Tornado has done it, but not for any significant time or distance. I think the drag and stability limits will be reached before you go that fast. I think "GPS- verified 30 knots" is just a sales pitch, but the GPS has probably logged 30knots for them at some time. If we got to see the log and normalized the data, I think it would show a max speed around 25knots downwind like the rest.

To get back on track, I think the F-18 is almost as fast as the Tornado in a breeze, and faster in some conditions, so I expect the upwind speed to max out at 12-16 knots and downwind around 25knots. Crew quality really makes the difference.

Hei Rolf, satt og ventet på når du skulle slenge deg inn i diskusjonen!:)
14-16 knop er utrolig bra på kryss da! For ikke å snakke om 25 nedover! Får frysninger av å tenke på det!:) Far og jeg har et stykke igjen til sånne hastigheter, det står i alle fall ikke på båten. Som nevnt over er alle "topphastighetene" våre satt i nokså små briser, vi må bare bygge opp rutine og ferdighet (og baller) til å dra utpå når det blåser spiker. Dessverre er vi bare ca 150 kg på ripa, og med styrketrening kun to til tre ganger i uka over stusselig studentkost, ser det ikke akkurat ut til at jeg kommer til å rase opp i vekt den nærmeste tiden:) Taipanen var jo designet til å ta tunge mannskap på 150 kg+ så riggen er kraftfull og har oss begge i trapes innnen 3-5 m/s.
Ettersom vi nå endelig har fått ordnet ordentlig snuffer til båten, er vi nå også mer tent på å kjøre mer gennaker. Vi hadde en super tur sist helg, da jeg tok en langhelg fri fra studiene for å få seilt litt og pakket ned båten. Logget over 16 knop i 4-5 m/s med gennaker, vanvittig gøy å fly ett skrog nedover vinden! Skikkelig booster for motivasjon til studiene med sånne turer!
Hold oss oppdatert på hastighetsmålinger da.
Geir Magnus

Geir Magnus, 150kg er da gode greier det. Skulle ønske vi også hadde det, så kanskje vi virkelig kunne få opp farten. Jeg mener det er en større fordel å kunne kjøre depower enn å lesse på med vekt <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />
Å seile i mye vind er bare en vanesak, man må komme seg utpå og tøye grensene litt så blir man fort vant til det.
Vi seiler med GPS kun i distanseseilaser for tiden, og da som et navigasjonsinstrument. Vi brukte den tidligere til å finne de beste vinklene for VMG, og det var i den perioden vi logget de hastighetene jeg refererte til. Vi er ikke så opphengte i hva slags fart vi gjør, så lenge vi kommer i mål før de andre tornadoene <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" /> Dette har blysvingerne her store problemer med å forstå, de tror vi seiler båten kun for fartens skyld, mens det er samspillet og å få båten "in the groove" vi setter mest pris på.
I think we should keep to english on the forum, out of courtesy to all our friends here. They are probably very curious about what we are discussing in our quite "off the mainstream" language. Hope to get to sail with you next season (or this season, boat will not be put in storage for 14 days, so if you want to visit us in Molde..).

Actually my class visited Molde two weeks ago, but only for half a day as we were on a trip with "hurtigruta" to do an assignement in "marine tech.", one of my courses at NTNU. However, we mostly drank beer and chill out instead of working on the project while in Molde.
As you said, my dad and I need to get more comfortable in strong winds. Problem is, there really is not stable, good breezes in the inner Oslo fjord, so when the wind picks up, it usually is extremely gusty. But more experience and balls will give us confidence to go out in the big stuff as well. I think we are getting closer, so next year...
I totally understand what you meant about getting the boat "in the groove". It truly is a wonderful feeling looking up at the rig, all tell-tails are flying, and the windward hull just kissing the water. However, I don't think there's anything wrong in wanting to go fast in a straight line as well! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
Regards Jimi

You were in Molde, and did not give me a call? Shame on you!

PS: In the groove is not just about making all the telltales stream. There is a certain sail/boat trim and helming technique that makes the boat faster than any other trim/technique. Finding this "groove" in all conditions is a real challenge.

Please, do not let this brief post hijack the discussion
but it seems that many cat-sailors want to measure the fantastic speed they are doing.
We have found that placing the GPS receiver on the boom one metre from the mast seems to produce correct numbers. We have not seen any strange figures on our Magellan Meridan or Garmin Foretex when placing them (antenna up) on the boom.

Back to the speed discussion: the Weymouth speed week has seen many cats thunder down the 500 meter course. Tornado sailors have had speed contests after regattas. However, rarely have speeds in excess of 20 knots been recorded.
Why? What are the limiting factors to maintaining speeds > 20 knots in beach cats?

Stein

Stein

I think the single biggest obstacle to going faster than about 20 knots on a beach cat is the sea state. In order to get going that fast on a typical beach cat, you need at least 15-20 knots of wind, which will kick up some waves wich will keep you from going much faster. That is why the French built the ditch for speed runs, to keep the waves to a minimum.

In the ocean where there are already "seas" and you find wind waves to add to the seas, a 20' beachcat has a lot of trouble getting past any SUSTAINED speeds of 18 knots.

I have had bursts to 22 knots. I have had short moments of sustaining 18-19 knots. (no spinnaker in either case)

I am always happy if I can maintain an average upwind plus downwind speed of 10+ knots. As a cruiser, I am pretty pleased if my speed is above 8 knots in any direction.

My Mystere 6.0 (Whisk) will probably never go faster than 24 knots unless she is riding on a body of water that is not being affected by the wind, the same wind that is pulling her along at such high speeds. (ditch run?)

Whisk won't go faster than 24 knots in the six years that I've sailed her on the ocean. Gross weight = (minimum) 615 pounds to (approx. maximum) 1175 pounds.

GARY

Stein,

we had a heated discussion on a related topic some months ago: http://www.catsailor.com/forums/showflat.php?Cat=0&Board=Test&Number=77114

I'm sorry Rolf, I just can't help myself! If you guys are going to let reality enter into your reverie, don't forget what the H-16s did in the last Miami/Key Largo race! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

All this talk about speeds in excess of 20knots should be relegated to theory! Who really cares how fast you're going for a millisecond! In the real world 8-10 is far more likely.

I would be pretty shocked if you get to 25knots on an F18. During the Tybee500 last year on a Nacra 20 with a stiff offshore breeze and us hugging the shore, we were death reaching (main and jib only) while Frank was reading constant speeds in the 19-20knot range. A "gonzo" blast, that didn't show on the water, nailed us and the boat nearly accelerated out from under us. Frank dropped the GPS to his chest in lieu of something to hang on to and I was busy kissing my butt goodbye. I couldn't believe that the decks stayed above water. Frank checked the GPS later and the max speed was now slightly above 25knots. 25knots is narly.

What did the 16s do? Win?

8-14 knots is where we spend most of our time, agreed. As long as I finish before my competitors, I am more than happy <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />
Being able to sail circles around the monohullers is a bonus, but what I really enjoy these day is having a working team onboard and finding the groove (this is app. the message I wrote in norwegian while chating with Jimi earlier in the thread).

No, the H16s did not win. But they did very well! My point is that beach cats have limited performance capabilities and we've been in that general area for 35 years! Marginal increases in performance require disproportionate increases in expen$e.

My F16 will point higher and will generally perform better down wind, it is also lighter. I make no claim that it is faster.

So, IMHO, how fast is your F18? About as fast as a Hobie 16, depending on the conditions.

I dont think I can agree with you there Pete. Both VMG wise and pure straight line speed wise the modern designs are faster than 35 year old designs. There are some courses and conditions the old designs with relatively large overlapping jibs will excel on, but modern designs usually are faster anyway. But unless we get a breaktrough in technology or start using foils, I agree fully that we will not see large increases in speed.

A-Cat - I've been sailing/training with a Garmin GPS.

Upwind, 10-12 knots in flat water seems around the max.

Downwind - In flat water wild thing mode, I've seen 18 knots. Pete Melvin says 19 knots should be the max, they think the boat has gone 20 knots but not over that.

Last year at the Alter Cup Area D qualifier, I started a downwind leg ahead of Harry Newkirk on an I-20. We both gybed onto port gybe with Harry about 50 yards to weather. We both seemed to be going the same speed forward (I was flying a hull) but he was going five degrees lower so they slowly came down to me. This was in flat water.

I think the spinnaker boats go faster speed wise in waves because the A-cat gets stopped by the waves much easier while the spinnaker tends to power you through.

Not sure what top speed Hakan in Sweden has done with an A-cat with chute.

Bob Hodges
A-Class USA 230

I expect most of you have already seen this, but it's such a great movie, so what the hell.. Check out the speed he's going, the wind is to be no more than 12 knots..
Click on "Marstrom A-Class with Spinnaker":http://www.thebeachcats.com/videos.html

Have you ever put H16's and F18's on the same start during a race?

Unless you're doing reaching legs back and forth, that F18 will be waiting in between races.

Then you admit it! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> There isn't that much difference in top speed! <img src="http://www.catsailor.com/forums/images/graemlins/laugh.gif" alt="" />

Beach cats have increased performance in many ways over the last 35 years, top speed is the least of them.

Bob is not going to like this, but ...

Do you see how Hakan (with spi) is running down that other A-cat (no-spi) in his video ? That is exactly the same view you get from an F16 or F18 when going downwind. It doesn't really matter how far the A was in front at the weather mark. You run him down before the gate.

However I do have some scepsis about Hakan doing 18.5 knots sailing downwind in 6-12 knots winds (average 9 knots?); spi or no spi.

Even if he is sailing at 140 degrees of the wind (a gybe angle of only 40 and a VMG factor of 77%) ; his sails are then operating at an angle of attack of only 28 degrees with an apparent wind velocity of only 12.5 knots. Such angles of attack are typically only found on upwind legs and I've never been able to fly the spi there. It will collapse at angles of attack of less then 40 degrees.

My experience is that not more then 150% of the wind velocity is possible under spinnaker when sailing downwind and in perfect conditions.

Wouter

I wonder if this will turn ugly? LMAO

Hi Wout -

I recorded a 14-mile downwind offshore leg off Daytona this year on the Cap. NOAA called the wind 10 knots and my trusty Garmin said we were doing 16 with squirts of 17.5. All the trigonometry aside, Hakan's number seems completely believable to me.

And try some azithromycin to clear up that scepsis. <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

Sorry to hear your season has ended. <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

Same here John, even on a smaller boat. My f16, if the winds were 12kts that was pushing it. I was averaging around 15mph I saw a top speed of 19mph. It was not a jump, because the logs just before and after were close to 19. The only jumps I saw were 45mph and 62mph, a little high you think? LOL

Scep´sis - n. 1. Skepticism; skeptical philosophy.

Azithromycin - used for mild or moderate bacterial infections.

I have to say that you got me thinking on that one John so I had to do some investigating. Thought I would share the joke.

Dan

And now they make a soothing cream, too!

Miss you, Dano - nobody else gets me. <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

Eu tenho que fazer exame quatro 500 de magnésio Amoxils enquanto profilaxia antes que eu puder mesmo escutar JW

He's gone native, folks.

I'll get my wife's script pad, JC, and we'll get you fixed right up... but am I calling a Portuguese pharmacia? <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />

This thread is on speed - stay on target... (Brian?!)

Hey, don't let science cloud you minds boys.

Wouter

You call that Science?

GARY

But, how fast is your F18? Not as fast as you think.

<img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

About this quick <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

http://www.formula18alive.com/f18alive.wmv

Stephen and Brent must not be going very fast because they don't have any glasses on. Everyone knows that taking direct spray hits to the eyeballs at speeds that beachcats are capable of, would knock the balls out of your sockets.
<img src="http://www.catsailor.com/forums/images/graemlins/ooo.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />

GARY

Wouter, some corrections to the speed of an A-cat with spi.
* In higher winds I sail 150 deg of the wind not 140 deg.
* The movie stated 6-12 knots and if you watch the waves around the boat it was white caps at the downwind in the beginning and later in the movie the seas was calmer.
* If the wind was close to 12 knots in the beginning the 18 knots of downwind speed is ok according to the 150% rule you stated.

/håkan

Håkan,

As I know you have plotted your speed and course when you won the Roslagen distance race on a Capricorn F-18, I wonder what top speed did you measure then with your GPS?

Oh, another thing.. Isn't it true that you have reached even higher speeds with your new and shiny Hobie 16 than with your A-Cat.. Come on, tell the truth!

gee what a surprise beach cats still go around 25 knots. this endlessly asked question has come around again.
the slalom guys at kanaha have a contest where they pass around a gps and they went around 30knots on a good day. there is no doubt in my mind that they are faster than an F18. it doesn't make sense that a spi. would be a speed sail. they were created to power up a boat in under powered conditions. at some point they must become drag. from my experience, less is more in high winds...bearing in mind that speed sailors do use very large sails, but they do keep the drag low.

Most beach cats will have a similar top speed on a beam reach. That is not where the development of modern cat designs have gone too. These designs have been optimized for pure upwind and pure downwind work and here they will simply KILL any Hobie 16.

Wouter

wow I actually agree with Wout.

When I compare the top speed in flat water for an A-class and the Hobie 16 (I sail both) my feeling is that the Hobie 16 has potential to be faster. The max speed I have reached with the A-class is 19.5 knots without spi and 20.5 knots with spi. I haven't enough gps logs on the Hobie 16 to prove that it is faster, but it has potential for it. Rather low weight (145 kg), short mast and no centerboards.

Anyone that has a good gps log for a well sailed Hobie 16 on a double trapeze beam reach in 20 knots of wind in flat water?

/håkan

So you are saying that a H16 is faster than this beast in a big breeze?
http://www.catsailor.com/forums/sho...01&an=0&page=0#Post88001

Actually Jimi in a big breeze it may be a matter of the last man standing. Those VX40s like to go over when the breeze is up. A 16 could go over and still be righted by the crew to finish the race.

If you are only taking about speed at a moment then that is different. Those big guys like sailing in under 10. They are that efficient.

Later,
Dan

Thanks Dan!
I have seen videos of the VX40s flying a hull in 4-6 knots of breeze, they are crazy!

why bring up the H16?
aren't F18's beach cats?
apparently i'm wrong about beach cats topping out around 25 knots, because the tornado video w/bruce kendall claims a top speed of 33knots. what conditions and point of sail was that done in?
the question: how fast? is dealing with top speed not beating speed or downwind speed the way i read it. i believe most beach cats top out at a similar speed, since there are no production cats designed as speed record craft.
they are all designed to excell in moderate winds on all points of sail. in fact i was under the impression that some cats could go 20 in 10konts of wind.

" in fact i was under the impression that some cats could go 20 in 10knots of wind." - You`ll find cats or any sailing craft designed to acchieve this, will only do 10knots in 20knots of wind. As mentioned by others, the VX40`s can fly a hull in 4-6knots ? I`m assuming they are depowering drastically at 20knots, and tripping all over themselves in 25 plus, unless they reef sails. Unfortunately you can`t have a Lake Garda 5 knot specialist yacht and sail it comfortably in 30 knots, you have to choose the boat designed for a certain windrange, and sail within it.
I`ll agree with the sentiment that says that catamarans are at their most efficient in light to medium winds - you might sail at 1,5 times windspeed in 10 knots, but in 30 knots you will be sailing at 0,5 times windspeed. (if you`re upright.)