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Old 02-02-2021, 13:05   #1
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Cruising cat - sub 90 degrees tack upwind

Hello everyone,

there seem to be a bit of disbelief about our L 400 doing sub 90 degrees tacks. Typical condition - AP set to 41 TRUE, apparent wind 22 kn, boat speed 6 kn. This skill I acquired recently, repeated several times so now i am convinced it is for real. Posting about it, realized there is only one other cruising cat that posted sub 90 degrees tacks - Django. At least that is what i could find. As both boats are Lagoons and we all know what is mass opinion about lagoons going upwind, I wonder if you can post your sub 90 tacks upwind , of course without help of motors or current.


Link Django
https://www.cruisersforum.com/forums...ml#post3333350

me

https://www.cruisersforum.com/forums...ml#post3333612
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Old 02-02-2021, 15:12   #2
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Re: Cruising cat - sub 90 degrees tack upwind

You left out the bit where you said you were sailing against 2kn of current.
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Old 02-02-2021, 15:34   #3
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Re: Cruising cat - sub 90 degrees tack upwind

References

Lagoon 400
https://www.katamarans.com/lagoon-400/

Lagoon 380
A polar situation! - Lagoon inside
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Old 02-02-2021, 16:00   #4
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Re: Cruising cat - sub 90 degrees tack upwind

Quote:
Originally Posted by arsenelupiga View Post
Hello everyone,

there seem to be a bit of disbelief about our L 400 doing sub 90 degrees tacks. Typical condition - AP set to 41 TRUE, apparent wind 22 kn, boat speed 6 kn. This skill I acquired recently, repeated several times so now i am convinced it is for real. Posting about it, realized there is only one other cruising cat that posted sub 90 degrees tacks - Django. At least that is what i could find. As both boats are Lagoons and we all know what is mass opinion about lagoons going upwind, I wonder if you can post your sub 90 tacks upwind , of course without help of motors or current.


Link Django
https://www.cruisersforum.com/forums...ml#post3333350

me

https://www.cruisersforum.com/forums...ml#post3333612
Just so I understand:

You were sailing with a TWA of 41 degrees, a AWS of 22 knots, and a STW of 6 knots.

That would give you an Apparent Wind Angle of 31 Degrees.

That's just not possible without magic. Your jib sheeting angle is just nowhere close enough to allow that.

you can post it ten more times, and the math STILL will not work.
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Old 02-02-2021, 16:21   #5
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Re: Cruising cat - sub 90 degrees tack upwind

If you really want to prove your point, next time you are out in your boat take a video of the instruments showing wind speed direction both TWA and AWA boat speed and SOG etc and sail as close as possible to the wind without stalling jib tell tales, sail that way for 10 minutes and then tack and sail for another ten minutes, keep recording, then video the results on the chart plotter track, also video the tachometers so people do not claim you are using motors.
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Old 02-02-2021, 16:31   #6
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Re: Cruising cat - sub 90 degrees tack upwind

Reference:
https://www.katamarans.com/lagoon-400/


Polar provided near the bottom of the link above.

Snipet:

Sailing
Sailors won’t be disappointed with the Lagoon 400, especially off the wind. Sure, there is a trade off for all of that living space, but you should comfortably achieve 7 knots and over in a breeze, even upwind. She tacks well if you boost the speed before coming through the wind. The genoa is easy enough to handle (later Lagoons have a self tacking jib) and you have the option of a Code 0 if you have the bowsprit. But don’t pinch her too tight. Just like any keel cat, she’ll sail up to 45 degrees apparent, but you are best off bearing away 5 degrees or so to keep your speed up and minimise the leeway. If you head too close to the wind, you might see the leeway build up to 20°.

You may get some the odd slam going upwind in a seaway, but she is certainly not bad in this regard.

In a breeze, she’ll comfortably claw off a lee shore.

A Good Sailor in a Breeze, Especially Off the Wind
In moderate winds (10-20 kts), the Lagoon 400 sails well from 50° to 140° TWA.
Like most cats, running directly downwind is not really an option unless you have a parasailor or spinnaker as the shrouds stop you from opening up the mainsail. You are better off “tacking” downwind and moving the apparent wind forward, especially if you have a gennaker to fly off the bowsprit. You can expect a SOG of around half of the apparent wind, up to 10 kts of boat speed.
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Old 02-02-2021, 16:38   #7
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Re: Cruising cat - sub 90 degrees tack upwind

To the OP A further point of clarification are you saying that your autopilot (AP) in wind vane mode can be set to true wind? In my experience they work off apparent wind as True wind is calculated and relies on water speed to calculate TWS and TWD so these can be dodgy if water speed sensor is malfunctioning.
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Old 02-02-2021, 16:49   #8
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Re: Cruising cat - sub 90 degrees tack upwind

Just as a point of comparison, if the OP's quoted performance data was correct, then an L400 could easily beat a J-105 to the windward mark in 17 knots of true wind.

I really don't think so...

Not saying it is a bad boat, or the OP doesn't BELIEVE what he is saying, he just doesn't have the sailing or math chops to understand it is totally unrealistic.
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Old 02-02-2021, 17:01   #9
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Re: Cruising cat - sub 90 degrees tack upwind

Hi arsenelupiga

Some, not all but many ruising boats can sail at 90° or less but not while making reasnoble speed towards a marker point directly upwind from the starting point. (Tides or Current not included )

There was, or is an offer made by a boaty of US$5,000 for anyone who could prove they could get a boat similar to yours to sail the way you describe with 90° tacks. I expect the offer is still available. I would think if you can satisfy him most people will believe but his offer has been around for a few years now and no one has attempted to prove it as far as I know.
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Old 02-02-2021, 17:05   #10
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Re: Cruising cat - sub 90 degrees tack upwind

Quote:
Originally Posted by BillKny View Post
Just as a point of comparison, if the OP's quoted performance data was correct, then an L400 could easily beat a J-105 to the windward mark in 17 knots of true wind.

I really don't think so...

Not saying it is a bad boat, or the OP doesn't BELIEVE what he is saying, he just doesn't have the sailing or math chops to understand it is totally unrealistic.

I would have thought a J105 would go a lot faster than 6 knots in 17knots upwind.
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Old 02-02-2021, 18:15   #11
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Re: Cruising cat - sub 90 degrees tack upwind

A J105 does about 6.5 knots at about 38~39 true with a vmg of about 5.1 knots in 16 knots of breeze.
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Old 02-02-2021, 18:28   #12
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Re: Cruising cat - sub 90 degrees tack upwind

Quote:
Originally Posted by arsenelupiga View Post
Hello everyone,



there seem to be a bit of disbelief about our L 400 doing sub 90 degrees tacks. Typical condition - AP set to 41 TRUE, apparent wind 22 kn, boat speed 6 kn. This skill I acquired recently, repeated several times so now i am convinced it is for real. Posting about it, realized there is only one other cruising cat that posted sub 90 degrees tacks - Django. At least that is what i could find. As both boats are Lagoons and we all know what is mass opinion about lagoons going upwind, I wonder if you can post your sub 90 tacks upwind , of course without help of motors or current.





Link Django

https://www.cruisersforum.com/forums...ml#post3333350



me



https://www.cruisersforum.com/forums...ml#post3333612

What’s the point of pinching up and slowing down so much to keep your tacking angle to 90 degrees? Your VMG given your numbers is not all that good (4.5 knots) and could be increased by bearing off a few degrees, increasing boat speed, decreasing leeway (which at 4 degrees is what seems most unbelievable about your claims). What happens when there’s some sea state?

And note that snap shots of instruments prove nothing: that is just a brag of the best figures that the instruments produced. A video showing overall stats, or a shot of a 10 minute or longer average, is more believable.

The screenshot of your track is compelling, but again we have no way to know the external factors (current, motor, non-standard rig, local wind shifts, etc).

In any case, keep posting, but not sure what you’re trying to prove.
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Old 02-02-2021, 19:05   #13
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Re: Cruising cat - sub 90 degrees tack upwind

Quote:
Originally Posted by Tin Tin View Post
I would have thought a J105 would go a lot faster than 6 knots in 17knots upwind.
Yes, a J-105 can certainly move faster than this, but you end up having to bear off to do it, and even though your boat speed can be much faster, your VMG drops off. But also, it is very unlikely that even a J-105 can hold its best VMG at 31 degrees AWA....

Do a search for "J-105 target boat speed" to see the numbers.
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Old 02-02-2021, 20:09   #14
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Re: Cruising cat - sub 90 degrees tack upwind

Using the numbers from Joli, which sound reasonable and are supported by polar diagrams on the internet, and if I'm doing the math right (not a given) that would be an AWA of 28 degrees or so. I think a J105 could do that.
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Old 02-02-2021, 23:56   #15
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Re: Cruising cat - sub 90 degrees tack upwind

Quote:
Originally Posted by Dave_S View Post
Hi arsenelupiga

Some, not all but many ruising boats can sail at 90° or less but not while making reasnoble speed towards a marker point directly upwind from the starting point. (Tides or Current not included )

There was, or is an offer made by a boaty of US$5,000 for anyone who could prove they could get a boat similar to yours to sail the way you describe with 90° tacks. I expect the offer is still available. I would think if you can satisfy him most people will believe but his offer has been around for a few years now and no one has attempted to prove it as far as I know.
Type in " The great catamaran tacking challenge" into Catamaran Sailing Group on Facebook, his offer should come up, he's offered $2,500 and someone else matched it to make the US$5,000. It sets out what you need to do to win the money but you should contact him first.

All he is asking is in a cat like yours to demonstrate that it can sail upwind and tack at 90° while make good VMG.

Easy money.
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