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Old 19-12-2015, 14:05   #46
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Re: Cats Can't Sail to Windward....

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Originally Posted by belizesailor View Post
Important for multi's too to differentiate between tacking angle and sailing angle. After coming thru a realtively wide tacking angle, and building some boat speed and thus lateral resistance, you can bring them up to a much tighter sailing angle. For example, tack thru 110 and then come back up to 45 apparent.
In a fastish boat, 45' apparent is a beam reach!
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Old 19-12-2015, 15:28   #47
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Re: Cats Can't Sail to Windward....

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In a fastish boat, 45' apparent is a beam reach!
Huh? 45 apparent is 45 apparent no matter how fast you are going???
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Old 19-12-2015, 16:12   #48
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Re: Cats Can't Sail to Windward....

45 apparent on a fast boat is where the apparent wind is at 90 true, hence you are on a beam reach. 90 apparent on a fast boat will equate to somewhere around 140 true. I should say "semi fast" boats. Now the fast boats never go below like 40-45 apparent.


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Old 19-12-2015, 17:05   #49
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Re: Cats Can't Sail to Windward....

Hey guys,

it's not just the performance cats. We do routinely 30 to 31 degrees AWA upwind on autopilot for extended periods of time. And when we have to tack (which is admittedly rare) we can do 90 degree tacks. But then our Lagoon is 12 years old, and back then sailing performance was still important. Sails are now 3 years old (and have just made it through unpleasant weather from Tahiti to Hawaii)

That having been said, we obviously try to avoid upwind like the plague - it's sooo much nicer to go West...

Oliver
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Old 19-12-2015, 17:14   #50
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Re: Cats Can't Sail to Windward....

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We do routinely 30 to 31 degrees AWA upwind on autopilot for extended periods of time.
The L470 is a terrific boat. What AP do you have? My vintage 2001 Raymarine ST 7000+ on response level 1 cannot handle really close hauled angles very well. For some reason it has a tough time seeing those lifts and headers.....

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Old 19-12-2015, 18:04   #51
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Re: Cats Can't Sail to Windward....

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45 apparent on a fast boat is where the apparent wind is at 90 true, hence you are on a beam reach. 90 apparent on a fast boat will equate to somewhere around 140 true. I should say "semi fast" boats. Now the fast boats never go below like 40-45 apparent.


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Huh? 45 apparent is 45 apparent regardless of boat speed...the same whether you are doing 5 knots or 500. At 45 apparent you are close reach/close hauled depending on boat. Apparent wind is not at true anything...its an angle relative to bow of boat. True wind is prevailing systemic winds which have nothing to do with boat speed.

Apparent wind does indeed rarely get aft of beam on true high performance boats, but its stil apparent, not true.


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Old 19-12-2015, 18:54   #52
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Re: Cats Can't Sail to Windward....

Obviously there was some rum involved in that post........


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Old 19-12-2015, 19:01   #53
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Re: Cats Can't Sail to Windward....

Don't really agree with the "at 45 apparent at a close reach". So, the mod 70's never go downwind? I've always considered myself on a beam reach if the true wind is at 90*. Below that, in the gusts I'm turning downwind. Above that, in a gust, I'm turning upwind.


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Old 19-12-2015, 19:15   #54
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Re: Cats Can't Sail to Windward....

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Huh? 45 apparent is 45 apparent no matter how fast you are going???
Yes, but 45 apparent isn't necessarily sailing to windward.

If you have a boat that can sail at true windspeed at 90' true, then you're sailing at 45 apparent.

ie. 6 knots boatspeed in 6 knots true wind at 90' true = 45' apparent.

So 45' apparent is actually a beam reach.

The AC 72's sailed downwind at around 25' apparent.
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Old 19-12-2015, 19:40   #55
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Re: Cats Can't Sail to Windward....

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Yes, but 45 apparent isn't necessarily sailing to windward.

If you have a boat that can sail at true windspeed at 90' true, then you're sailing at 45 apparent.

ie. 6 knots boatspeed in 6 knots true wind at 90' true = 45' apparent.

So 45' apparent is actually a beam reach.

The AC 72's sailed downwind at around 25' apparent.
Yes, 45 apperent may indeed not be going to windward relative to true wind.

No, 45 apparent is not a beam reach, point of sail is defined relative to apparent wind not true.
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Old 19-12-2015, 19:55   #56
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Re: Cats Can't Sail to Windward....

Hi Dave,

I relegated our old Raymarine to "cold standby" and installed a Furuno AP. Much faster responses, very few unwanted tacks and you can control it from the chart plotter inside. I am very satisfied...and I just did not feel very good crossing oceans with a 10 year old autopilot. Naturally, just a week ago, the coil on the hydraulic ram quit, which got us 48 hours of hand steering from Hilo to Honolulu. With the waves in the channels it was definitely a challenge - so I nowordered a replacement and a spare...

Oliver
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Old 19-12-2015, 20:05   #57
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Re: Cats Can't Sail to Windward....

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Yes, 45 apperent may indeed not be going to windward relative to true wind.

No, 45 apparent is not a beam reach, point of sail is defined relative to apparent wind not true.
Well by my reasoning, when I'm sailing at 60' apparent, (120' true) I'm not sailing upwind. Nor is 45' apparent. (TWA 90'.)

Or, to put it another way, if I'm going to sail north, and the wind is coming from the east, I'd say "It'll be a beam reach today". (At 45' apparent.)
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Old 19-12-2015, 20:31   #58
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Re: Cats Can't Sail to Windward....

So this is down to a semantic argument: is the "point of sail" described by true or apparent wind? There is a reasonable usage either way IMO, so the answer is to simply say "beam reaching apparent" when applicable, etc.

That out of the way, we can go back to serious stuff, you know... cats can't do it or whatever.

And even in our monohull cruising boat, the apparent wind is an elusive creature. It has taken me a long time to sorta understand how it all works out in a fairly quick mono, and I can well imagine that it is worse in a quick cat or tri.

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Old 19-12-2015, 20:45   #59
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Re: Cats Can't Sail to Windward....

Yep, it was easier in our old steelie. Apparent and true wind angles were always just about the same...


But really I was just responding to the post that said "Tack through 110' then come back up to 45' apparent"


To go from 45' on port tack to 45' on starboard I'd have to tack through around 180'!


Real fast boats even more.


AC 72's, well they'd really take some getting your head around!
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Old 19-12-2015, 21:30   #60
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Re: Cats Can't Sail to Windward....

I wish everyone would use the "compass tack thru angle" when describing how high their boat will point. With the addition of boat speed info, we have everything needed to easily compare upwind performance and VMG.

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