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Old 27-01-2020, 07:45   #1
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Closest true wind of cat?

Hi. What is the closest true wind angle a standard Lagoon-type cat can sail?
Thanks
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Old 27-01-2020, 07:58   #2
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Re: Closest true wind of cat?

This thread has several polars for Lagoons, at least the ones I glanced at were true wind, but if any are apparent you have all the data you need to do a little trigonometry to convert to true wind.

The polars show you can point higher than is optimum. Bringing a horizontal tangent down to the highest point on the curve gives you the best VMG to weather. The ones I looked at looked like about 50 degrees off the wind is the best angle to sail, even though they can point higher.

http://www.cruisersforum.com/forums/...ams-63876.html
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Old 28-01-2020, 08:38   #3
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Re: Closest true wind of cat?

Thank you for this. I had thought, from what I read, that cats basically only sailed downwind, but if they can do a 50 degree true wind angle, that's not too bad at all.
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Old 28-01-2020, 09:09   #4
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Re: Closest true wind of cat?

Another point to observe is the boat speed at the various wind speeds. The polars for the 421 show it needs quite a bit of wind to have a decent speed, particularly upwind. I'd be motoring the boat upwind in anything less than 20 knots of wind if I wanted to make some mileage.

These performance numbers are not representative of all cats. There are more performance oriented designs.
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Old 28-01-2020, 11:59   #5
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Re: Closest true wind of cat?

Thanks again.
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Old 28-01-2020, 13:29   #6
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Re: Closest true wind of cat?

Quote:
Originally Posted by Srah 1953 View Post
Hi. What is the closest true wind angle a standard Lagoon-type cat can sail?
Thanks
To start with, which Lagoon are we talking and what are yr perception of "Lagoon type" ?

If you meant charter type of production cats in general, in ideal conditions (flatter sea, 15-20 kts of true, relatively lighter kept boats will point to max 42-43 degrees AWA which is around 60 degrees to the true wind making around 8-9 kts of speed. You can point a bit higher but the speed will go down drastically and you will give excess of leeway. (remember we are talking about fixed keel cats, daggerbord cats which are rarely used in charter is a different game)
If the sea is choppy and or the wind is lighter these numbers will deteriorate vey fast.
You can forget about the polars; they are generated on the computer and on ideal conditions. They yield dream nubers that you can almost never see in real life.

Lastly i you will see quite a bit of difference between various models of Lagoon as well as with FP or Nauthitecs which are somewhat better in this respect.

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Old 28-01-2020, 14:15   #7
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Re: Closest true wind of cat?

I have a Lagoon 470. And generally agree with yeolola's comments...

We are cruisers... If our destination is within 70t we either pick a different or a different day...

And have had some stellar passages close hauled.. 50awa or so..
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Old 28-01-2020, 14:26   #8
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Re: Closest true wind of cat?

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Originally Posted by yeloya View Post
To start with, which Lagoon are we talking and what are yr perception of "Lagoon type" ?

....

Yeloya

Great, thanks. I don't have a specific model in mind but I'm looking into the possibility of moving from a mono to a cat, so I'm basically trying to understand the implications. I can't imagine that I could afford one of the more performance based cats, so that's why I mentioned Lagoon, more as an indication of genre rather than a specific boat.
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Old 28-01-2020, 15:54   #9
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Re: Closest true wind of cat?

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We are cruisers... If our destination is within 70t we either pick a different or a different day...

And have had some stellar passages close hauled.. 50awa or so..
To a certain extent, this is true for mono's as well. They can point higher and VMG upwind is higher than for cats... but who wants to do that for an extended period of time? Racing is different - most of the time you have a bigger crew and a limited amount of time to complete (or endure) the race.

If you are considering a cat for cruising, one good resource is to look at average miles per day for the ARC fleet. Pick a few boats similar to the one you plan to get, look back years for different wind conditions and you will be able to get an idea of what passage making speeds you can expect - Real boats, real conditions, real cruisers.

Just did the calculation myself. Removing the super fast boats and obvious outliers, such as the Catana's, based on a sample of 25 cats, mostly Lagoons and Saona's, 42-47 ft range, I get average passage speed of 5.6 knots.

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Old 29-01-2020, 03:15   #10
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Re: Closest true wind of cat?

Lagoon 380, True wind 15 - 18 knots,
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Old 29-01-2020, 04:19   #11
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Re: Closest true wind of cat?

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Originally Posted by yeloya View Post
If you meant charter type of production cats in general, in ideal conditions (flatter sea, 15-20 kts of true, relatively lighter kept boats will point to max 42-43 degrees AWA which is around 60 degrees to the true wind

I can do much better than that, say 35AWA, in "ideal conditions" which to me is more like 12 TWS. I'd like to see a "flatter sea" in 20TWS. Average, I am trying to do 50-55TWA which is somewhat the best VMG I can get. 120° tacking to the ground (as a correction to 60TWA) is what I get in far less than ideal conditions.
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Old 29-01-2020, 04:28   #12
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Re: Closest true wind of cat?

lagoon 400 fully loaded for remote cruising get this in 10 kn .. really do not understand people saying cant go better than 50 app. My normal/default upwind angle in open seas is 38 app and finetune from there, sometimes less sometimes have to go down all the way to 50app for best vmg.
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Old 29-01-2020, 13:25   #13
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Re: Closest true wind of cat?

You can get most boats to sail pretty high TWA numbers, simply by pinching up. The slower you're going, the less difference between AWA and TWA.
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Old 29-01-2020, 19:27   #14
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Re: Closest true wind of cat?

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Lagoon 380, True wind 15 - 18 knots,
0.4 knots boatspeed isn't very good :-)

Assume reality was better.
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Old 31-01-2020, 18:23   #15
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Re: Closest true wind of cat?

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You can get most boats to sail pretty high TWA numbers, simply by pinching up. The slower you're going, the less difference between AWA and TWA.
i was making 4.2 kn, which gives ~ 3kn VMG. We got some visitors on board that were visibly surprised, after we passed some racy daggerboard cat, especially when one considers our fully loaded boat.

Anyway, this year we had excellent sailing and there were very few cats (and monos) that could hold the tempo with us. Strong weather seem to be L 400 sweet spot. I have made some improvements to the boat so that explains i guess.
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