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Old 22-04-2008, 15:55   #16
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My impression is that when you do find a set of polars, they do not show VMG but actual speed through the water. I have never seen official postings of how much drift the boat will have.

As a rule of thumb, the French boats I have sailed on like FP and Lagoon etc. manage 45-55% of windspeed at best when lightly loaded. Maybe a bit more on a deep reach with an asymmetric.
Hard on the wind you will probably have 100 degree tacking angle at very best (flat water) with good sails. Expect more like 110 degrees.

The Catana should be better as it has daggerboards.

As the fastcat has been mentioned, i just did a comparison with the Catana 50.

Catana 50: SA = 1417 ft2. Displ. 36383 lbs. SA/D = 0.03895
Fastcat 435: SA= 1180 ft2. Displ. 14300lbs SA/D = 0.08252

Difference is: 0.04356 or 112% lower!!!

Catana data from YBW website, and fastcat data from their website.

Regards

Alan
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Old 22-04-2008, 16:29   #17
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Originally Posted by catty View Post
Joli I've tried googling for catamaran polars and haven't had much luck. The Catana one I located had no wind speed mentioned but from the data points it must have been cyclonic. I see Bob Oram talks of supplying polars with his plans but I couldn't locate them on his web site. I may have been guilty of having a "boys Look". Can you point me in the right direction, it will be interesting to compare them to what we see occurring in the mixed fleet racing.
I have the Orana 44 but it is meaningless, there are no notes regarding wind speed, if it is true wind angle or ap wind angle, true wind speed, app wind speed. It is from the FP web site.

Fastcat has a polar for the 435. I think it is for twa and tws but there are no notes? I don't know?

Here's the Privlage 445:

Sheet1
Page 1
AWA BS AWS TWA
170 8 12.1 174
150 8.5 12.2 162
130 9.5 12.5 163
110 11 13.4 141
90 13 15.2 131
70 11 20.9 101
45 7.5 24.6 60
TWS=20
AWA= apparent wind angle
BS= boat speed
AWS= apparent wind speed
TWA= true wind speed
AWA and BS from polar diagram of Privilege 445

Looks like 3.75 knots upwind in 20 knots to me?

Polars, rally passage times, and race results tell the story.
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Old 22-04-2008, 16:32   #18
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Fastcat looks very popular at this forum but I dont think that is really much faster than Catanas
I don't know without a polar?
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Old 22-04-2008, 16:34   #19
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I do not have a polar - but I'm collecting data for one. As for weight, I'll report back after this Friday assuming the load cells on the travel lift are working.

Are you considering S/V Pacific Bliss?

Dave

Pacificbliss owner are here in Turkey right now and I touched them but they want to sell her in September after finishing their trip where they started..I think she must be very tired also..I dont want to wait that much..I have tried to make this decision for five years and this summer I want to sailaway

I will be waiting for your report impatiently
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Old 22-04-2008, 16:41   #20
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Originally Posted by Nordic cat View Post
My impression is that when you do find a set of polars, they do not show VMG but actual speed through the water. I have never seen official postings of how much drift the boat will have.

As a rule of thumb, the French boats I have sailed on like FP and Lagoon etc. manage 45-55% of windspeed at best when lightly loaded. Maybe a bit more on a deep reach with an asymmetric.
Hard on the wind you will probably have 100 degree tacking angle at very best (flat water) with good sails. Expect more like 110 degrees.

The Catana should be better as it has daggerboards.

As the fastcat has been mentioned, i just did a comparison with the Catana 50.

Catana 50: SA = 1417 ft2. Displ. 36383 lbs. SA/D = 0.03895
Fastcat 435: SA= 1180 ft2. Displ. 14300lbs SA/D = 0.08252

Difference is: 0.04356 or 112% lower!!!

Catana data from YBW website, and fastcat data from their website.

Regards

Alan
Polars are very easy to read once you understand. Look at Fastcats polar and draw a horizontal line across from the furthest point north and south. That is your upwind and downwind VMG. So at 8000kg the 435 goes upwind VMG at 6 and downwind VMG at 8 in 16 knots. Reaching, follow the curve to see the speed.

Like I said, if your upwind VMG with 20 knots of breeze is in the 3's you are not going to publish it.
African Cats: comfortable lightweight performance leisure catamarans
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Old 22-04-2008, 16:58   #21
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Thanks Joli, I learnt something yet again!

I agree with your point of view that performance figures for cats are grossly exxagerated alot of the time.

When I sail in company with comparable size monohulls, I have a tough time sailing away from them in less than 16 knots of wind. Only on a nice reach can I get away from them or at least 20 knots to windward (TWS) This means that I need conditions where I can get above "hull speed"

But for comfort over the long distance, and in rough conditions, they can't keep up when sailing short handed.

This is on a 35 ft FP Tobago, which is very "safely" rigged

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Old 22-04-2008, 17:03   #22
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Originally Posted by Nordic cat View Post
My impression is that when you do find a set of polars, they do not show VMG but actual speed through the water. I have never seen official postings of how much drift the boat will have.

As a rule of thumb, the French boats I have sailed on like FP and Lagoon etc. manage 45-55% of windspeed at best when lightly loaded. Maybe a bit more on a deep reach with an asymmetric.
Hard on the wind you will probably have 100 degree tacking angle at very best (flat water) with good sails. Expect more like 110 degrees.

The Catana should be better as it has daggerboards.

As the fastcat has been mentioned, i just did a comparison with the Catana 50.

Catana 50: SA = 1417 ft2. Displ. 36383 lbs. SA/D = 0.03895
Fastcat 435: SA= 1180 ft2. Displ. 14300lbs SA/D = 0.08252

Difference is: 0.04356 or 112% lower!!!

Catana data from YBW website, and fastcat data from their website.

Regards

Alan
Thats easy to figure. Run a horizontal line across the highest point on the top of the speed curve for whatever wind velocity you choose. Extend the line out to zero degrees angle of attack (where this line intersects on the Y-axis) and this is your speed of advance (your speed directly upwind). Knowing this is also useful for determining your boats optimal angle of attack when sailing to weather.

Just to make Gideon smile, I would be willing to bet the FastCats are significantly faster to weather than the newest Catanas if and when Catana sends me their polars. All bets are off for Gunboats.
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Old 22-04-2008, 17:07   #23
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Reading these posts one would think speed alone is all that matters. I could recommend a number of really fast beach cats.

Back to reality, there's a lot more than speed to consider and the relative importance of such things as safety, durability, comfort, resale value, etc. are determined by the respective boat buyers. One size does not fit all.

Can mamo find a faster boat than the 431 he's considering? Quite likely. Can he find a faster, safer, more durable, more proven world voyager production cat that will hold its value pretty dern good vs other production cats and will claw its way off a lee shore? Much less likely. That's why these things are so expensive.

Dave
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Old 22-04-2008, 17:09   #24
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May I suggest starting with the basics, looking at stuff like the SA/D ratio.
Alan
Alan- I read this advise before here maybe it was yours again but I dont think there is only one basic parameter to drive them faster. Coz that would be very easy way for me buying a FP and increasing SA..and one more, lots of cats SA/D ratio looks close eachother but their performance is different.
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Old 22-04-2008, 17:14   #25
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Reading these posts one would think speed alone is all that matters. I could recommend a number of really fast beach cats.

Back to reality, there's a lot more than speed to consider and the relative importance of such things as safety, durability, comfort, resale value, etc. are determined by the respective boat buyers. One size does not fit all.

Can mamo find a faster boat than the 431 he's considering? Quite likely. Can he find a faster, safer, more durable, more proven world voyager production cat that will hold its value pretty dern good vs other production cats and will claw its way off a lee shore? Much less likely. That's why these things are so expensive.

Dave

Well Mamo,the original poster did ask for performance figures and polars.

But I agree that Catanas are lovely boats with a great reputation, and good resale value. If going for a standard production cat, they would be at the top end of my list with the Privilege, maybe a Freydis or a large Outremer, despite their limited room in the hulls.

Regards

Alan
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Old 22-04-2008, 17:30   #26
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There are so many Africancater here
But I think that Catana is Catana..I wish this isnt a mit..
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Old 22-04-2008, 17:33   #27
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Africancater??
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Old 22-04-2008, 17:34   #28
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Alan- I read this advise before here maybe it was yours again but I dont think there is only one basic parameter to drive them faster. Coz that would be very easy way for me buying a FP and increasing SA..and one more, lots of cats SA/D ratio looks close eachother but their performance is different.

Sure there will be variations, but basically it's pretty sound information to use as the first "filter" level.

I doubt that there will be much performance difference on the same waterline length for the same SA/D. Given similar hull shapes.

Sail aspect ratio does influence a bit.

Yes daggerboards for windward work, a rig design that lets you trim the foresail for optimal windward sheeting angles, and lets you let the boom out more than 35-40 degrees for downwind work.

Another important issue is wind resistance when your AWS increases. It increases with the square of velocity.

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Old 22-04-2008, 17:52   #29
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There are so many Africancater here
But I think that Catana is Catana..I wish this isnt a mit..
Do you mean african catters, or fans of them?

I respect the work and openess of Gideon in sharing his information, and I did have a look at his boat in La Rochelle in 2006, and it's not on my personal list for a number of reasons.

I just did the comparison figures to save us a complete set of specifications again

Are you saying that you hope that the Catana performance isn't a myth? If so, then I'm afraid that you might be in for a bit of a shock/let down. marketing and reality are not always the same.

Yes, the Catana myth is the high performance, for some reason, but these are well performing good quality cruising cats and not racers.

There are practically no standard production cats that will give you anything like 75-80% of TWS sailing, even in flat water!

Regards

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Old 22-04-2008, 18:13   #30
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Do you mean african catters, or fans of them?

I respect the work and openess of Gideon in sharing his information, and I did have a look at his boat in La Rochelle in 2006, and it's not on my personal list for a number of reasons.

I just did the comparison figures to save us a complete set of specifications again

Are you saying that you hope that the Catana performance isn't a myth? If so, then I'm afraid that you might be in for a bit of a shock/let down. marketing and reality are not always the same.

Yes, the Catana myth is the high performance, for some reason, but these are well performing good quality cruising cats and not racers.

There are practically no standard production cats that will give you anything like 75-80% of TWS sailing, even in flat water!

Regards

Alan
It seems the sizzle was sold very well but the reality is apparant when looking at polars.

That said, I would be happy owning a Catana, or a Privlage, or and Africanter LOL. The boats are well made and are very nice cruising machines.

A trick from racing distance. When working upwind and the mark is a long way away, you look at the polar from the favored board. If you are 10 degrees favored then you rock the vertical line 10 degrees and look at the highest point on the polar. That is the angle you sail (ie sailing the rungs of the ladder)
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