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Old 19-12-2015, 21:36   #61
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Re: Cats Can't Sail to Windward....

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Originally Posted by Panope View Post
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.

Steve
Everything except leeway, which can make a significant difference... but I agree that the tacking angle is a useful metric, and one that can be fairly easily determined, whereas some of the others are subject to difficulties in instrument calibration and reading.

Jim
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Old 19-12-2015, 22:21   #62
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Re: Cats Can't Sail to Windward....

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Originally Posted by Jim Cate View Post
Everything except leeway, which can make a significant difference... but I agree that the tacking angle is a useful metric, and one that can be fairly easily determined, whereas some of the others are subject to difficulties in instrument calibration and reading.

Jim
Jim, true enough. Since my boat probably makes the most leeway of any of us, I suppose I was subconsciously avoiding the subject.

Cheers,

Steve
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Old 20-12-2015, 03:40   #63
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Re: Cats Can't Sail to Windward....

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Originally Posted by Panope View Post
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.

Steve
Ok, tack thru compass angle of 110d and then head up to 45d apparent.
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Old 20-12-2015, 03:45   #64
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Re: Cats Can't Sail to Windward....

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Originally Posted by 44'cruisingcat View Post
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.)
Ok, "by your reasoning", but point of sail is defined by apparent wind angle...though you may indeed be sailing down wind relative to true wind at a 45d apparent wind angle you are not on a downwind point of sail or thus sail trim.

Enough...:beer:
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Old 20-12-2015, 04:13   #65
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pirate Re: Cats Can't Sail to Windward....

Alt key + 0176 =
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Old 20-12-2015, 04:59   #66
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Re: Cats Can't Sail to Windward....

Not on my computer ≠0176
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Old 20-12-2015, 06:41   #67
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Re: Cats Can't Sail to Windward....

Defining the sailing angle by AWA or TWA was discussed recently with no definitive result. There's a few internet pics here and there that show it as defined by TWA, and visa versa, but for me it's always been AWA, and I would guess when the terms like beam reach, close hauled etc were originally used it was probably in the 1800's where there would be little difference in the two. For me you set the sails and instruct crew simply and quickly by saying we will go around the mark, then head off on a beam reach, broad reach etc. either way it's not a huge deal unless you're sailing very fast boats I guess.
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Old 20-12-2015, 07:49   #68
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Re: Cats Can't Sail to Windward....

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Not on my computer ≠0176
Nor on mine. Try 'alt 248'.
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Old 20-12-2015, 08:07   #69
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Re: Cats Can't Sail to Windward....

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I agree that the tacking angle is a useful metric, and one that can be fairly easily determined, whereas some of the others are subject to difficulties in instrument calibration and reading.
Yes, probably useful when comparing very similar boats. As an extreme example the AC foiling cats have "poor" tacking angles - only about 100-105 degrees (because their apparent wind is so far forward). I doubt many sailors would call them poor upwind performers, however.

VMG is the best metric, but when determined by instruments can suffer from instrument error/cal. A case for paper charts, pencils, and dividers.....

Dave
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Old 20-12-2015, 12:53   #70
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Re: Cats Can't Sail to Windward....

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Ok, tack thru compass angle of 110d and then head up to 45d apparent.
Still doesn't work...
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Old 20-12-2015, 16:07   #71
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Re: Cats Can't Sail to Windward....

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Still doesn't work...
I do it all the time, tack thru a physical angle of 110d (even have my AP programmed for that), then after gaining some speed, sheet in and head up to 45d AWA.

How does that "not work"?
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Old 20-12-2015, 16:23   #72
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Re: Cats Can't Sail to Windward....

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Originally Posted by Training Wheels View Post
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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Try triming your sails based on TWA...you actually sail and trim based on AWA.

Conceptually, you could think of the boat as being on a beam reach relative to TWA, as obviously some folks here do, but historically points-of-sail have been defined relative to AWA. But you can't trim sails based on TWA.

High performance boats do of course sail downwind relative to TWA, almost never relative to AWA, but are still trimmimg based on AWA, regardless of TWA.

An experience I posted earlier was making a full 360 the first time I tacked a high performance tri. We were in fact sailing on a broad reach realtive to TWA, but trimmed close hauled relative AWA. From a simple practical perspective AWA is what you actually sail and trim to.

My perspective is that we were on a close hauled point of sail, but heading down wind relative to TWA.

TWA is meaningless to actual sail handling, but useful for navigation and tactics.
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Old 20-12-2015, 16:33   #73
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Re: Cats Can't Sail to Windward....

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Originally Posted by monte View Post
Defining the sailing angle by AWA or TWA was discussed recently with no definitive result. There's a few internet pics here and there that show it as defined by TWA, and visa versa, but for me it's always been AWA, and I would guess when the terms like beam reach, close hauled etc were originally used it was probably in the 1800's where there would be little difference in the two. For me you set the sails and instruct crew simply and quickly by saying we will go around the mark, then head off on a beam reach, broad reach etc. either way it's not a huge deal unless you're sailing very fast boats I guess.
Vessels from the 1800's could still rack up some impressive speed, just look at all the records set by traditional sailing vessels that are only fairly recently being broken.

Ive sailed on vessels built in that era, and while sail handling is radically different, AWA will still move well forward when you are rolling along at double digit speeds. Those big heavy beasts could still rack up some impressive performance once you got them going on a favorable wind angle. So, even then AWA vs TWA could be quite different.

Ironically, sailing a square rigged ship and a high performance multi does have a few similarities: tacking destroys your boat speed, and they both do their best on a long straight course at a favorable AWA.
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Old 20-12-2015, 18:08   #74
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Re: Cats Can't Sail to Windward....

An experience I posted earlier was making a full 360 the first time I tacked a high performance tri. We were in fact sailing on a broad reach realtive to TWA, but trimmed close hauled relative AWA. From a simple practical perspective AWA is what you actually sail and trim to.

My perspective is that we were on a close hauled point of sail, but heading down wind relative to TWA.

TWA is meaningless to actual sail handling, but useful for navigation and tactics.[/QUOTE]


So, if you were trimmed close hauled, but on a broad reach to the true wind, how can you sail upwind?
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Old 20-12-2015, 19:14   #75
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Re: Cats Can't Sail to Windward....

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Originally Posted by Panope View Post
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.

Steve
Yep, a lot of variation with currents come into play though I guess, as well as sea state and wind strength. Here's a track from today in green, as opposed to our previous sail here in red. A lot better angles, but similar VMG, maybe a bit faster. Winder today at 25-30kn TWS and rougher sea for a while. Maybe better angles because we were feathering the full jib a bit for the gusts etc. The red track was 20-25kn TWS. Maybe got luckier with a bit less adverse current as well. The instruments showed around 1kn against mostly which is probably about right, but i don't really trust the log for accuracy
Average SOG around 5kn port tack (straight into the waves) and 7kn starboard
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