In TWA how close to the wind can a TP 52 sail effectively?

Bob Perry

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How high can you point in a TP 52 in "normal" conditions, measured in True Wind Angle? Thanks.

 

us7070

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How high can you point in a TP 52 in "normal" conditions, measured in True Wind Angle? Thanks.
TWA 43-44deg in light to 36-37deg in medium wind and flat water, to over 40deg in more wind and waves.

This is for Med Cup style boats

The boats that were designed for the transpac are probably not as close winded

 

Frogman56

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Yup. But dont forget, this is at bs of over 9 knots.

Ye olde 12m, upwind at 8.2 (Australia II) would tack through 68, i.e. twa 34 degrees

IACC boats not much different, albeit with leeway close to zero.

 

SF Woody Sailor

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Yup. But dont forget, this is at bs of over 9 knots.

Ye olde 12m, upwind at 8.2 (Australia II) would tack through 68, i.e. twa 34 degrees

IACC boats not much different, albeit with leeway close to zero.
That it interesting because the sheeting angles on the TP52's appear to be much narrower than on the 12s or IACC boats.

 

Left Shift

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Two data points for discussion:

2nd Gen TP in flat water, 8 knots of breeze, TWA of about 40-42°, lead about 4.5° off center line with an amateur driver and trimmer.  7.8 knots boat speed.  Helm at 3°

Med Cup boats in mid-teens breeze of 14 knots, TWA of 36°-38°, Jib lead about 3.2° off centerline with a pro driver and trimmer.  9.1 knots boat speed. Helm 

3-degrees-of-seperation-768x432.jpg

 
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SF Woody Sailor

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Two data points for discussion:

2nd Gen TP in flat water, 8 knots of breeze, TWA of about 40-42°, lead about 4.5° off center line with an amateur driver and trimmer.  7.8 knots boat speed.  Helm at 3°

Med Cup boats in mid-teens breeze of 14 knots, TWA of 36°-38°, Jib lead about 3.2° off centerline with a pro driver and trimmer.  9.1 knots boat speed. Helm 

View attachment 383105
So is 22 the AWA?

 

DickDastardly

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That it interesting because the sheeting angles on the TP52's appear to be much narrower than on the 12s or IACC boats.
You gotta think vectors.  In general:

1) I very much doubt 12 metres got down to 34 degrees, maybe 36 or 37.  Instrument calibrations being what they are TWA is always a bit suspect, and especially so back in 12m days when the systems were a lot less sophisticated than they are now.

2) AWA is the limiting factor.  A soft sail (jib), no matter how expensive will struggle to produce lift much below around 21 degrees AWA - and that in flat water.  Plug that into a vector equation with boat speed, wind speed, current and leeway and you will get a minimum TWA value.  For TP52s I'd guess its around 36-37 degrees - and that pic seems to support that. I understand upwind TWA values for the AC75s are around 55 degrees, simply because they move so fast relative to wind speed.

3) TP52s do big numbers upwind relative to wind speed.  9.3 or 9.5.  At this speed relative to wind speed the apparent wind angle closes down rapidly and TWA is limited.  An old 12m went much slower relative to wind speed hence could probably manage tighter TWA values for similar AWA values.

4) In bumpy sea states other factors apply - you need to aim for a TWA that provides good drive over a range of AWA angles (say 23-27) as it's not possible to steer as precisely as in flat water.  Aiming for tight AWA values like 21-22 degrees means the sail will be at times operating at AWA below 20 degrees and drive drops off rapidly when that happens and you really don't need that when the boat is trying to climb up waves.  So bumpy sea generally means a few degrees lower, with sails more twisted.  More so for a light boat like a TP52 than a lead mine which has better momentum and isn't thrown about as much by waves.

 

SF Woody Sailor

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You gotta think vectors.  In general:

 I understand upwind TWA values for the AC75s are around 55 degrees, simply because they move so fast relative to wind speed.
The only interesting thing about the monster foiling multihulls racing in SF Bay was that the vectors yielded completely non-intuitive results. For example, those of us who grew up sailing monohulls on the Bay go to great lengths to stay in relief from the adverse current. But the AC72's were the other way around. Going downwind they eventually learned to search out the worst current possible because the increased apparent wind speed from, say, two knots of adverse current increased their boat speed by four knots. 

 

Left Shift

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You gotta think vectors.  In general:

1) I very much doubt 12 metres got down to 34 degrees, maybe 36 or 37.  Instrument calibrations being what they are TWA is always a bit suspect, and especially so back in 12m days when the systems were a lot less sophisticated than they are now.

2) AWA is the limiting factor.  A soft sail (jib), no matter how expensive will struggle to produce lift much below around 21 degrees AWA - and that in flat water.  Plug that into a vector equation with boat speed, wind speed, current and leeway and you will get a minimum TWA value.  For TP52s I'd guess its around 36-37 degrees - and that pic seems to support that. I understand upwind TWA values for the AC75s are around 55 degrees, simply because they move so fast relative to wind speed.

3) TP52s do big numbers upwind relative to wind speed.  9.3 or 9.5.  At this speed relative to wind speed the apparent wind angle closes down rapidly and TWA is limited.  An old 12m went much slower relative to wind speed hence could probably manage tighter TWA values for similar AWA values.

4) In bumpy sea states other factors apply - you need to aim for a TWA that provides good drive over a range of AWA angles (say 23-27) as it's not possible to steer as precisely as in flat water.  Aiming for tight AWA values like 21-22 degrees means the sail will be at times operating at AWA below 20 degrees and drive drops off rapidly when that happens and you really don't need that when the boat is trying to climb up waves.  So bumpy sea generally means a few degrees lower, with sails more twisted.  More so for a light boat like a TP52 than a lead mine which has better momentum and isn't thrown about as much by waves.
The above is true, but there are drivers and then there are driver teams.  A TP52, driven up wind by a Bora Gulari, with Ken Read calling for 1° helm adjustments and some other rock star calling wave trains is a different world.  

(But, fuck, they are fun to drive!!!  Just do NOT try to do anything else.)

 
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SF Woody Sailor

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Yep.  Can't get a whole lot finer than that with soft sails.

TP52s hit kind of a magic spot for monohull design..  Remarkable upwind and also pretty remarkable off the wind.   They would likely embarrass a IACC boat around a course and demolish a 12 meter.
In fairness, that was not the point of the 12s or the IACC's. They were intended to provide good match racing which they did. A match race downwind is a lot more tactically interesting in non-planing symmetrical spin boats than in planing asym boats due to the smaller gybing angles and smaller speed differentials. The ultimate proof is the catamarans which are so boring to watch going upwind all the way around the course.

 

danstanford

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I had this same question watching the videos. I noticed the on screen tracks showing tacking angles fairly close to 90 degrees. perhaps these were lighter air days but looking at those jibs made me imagine much smaller tacking angles than I saw on the screen. To be fair, they were only in high mode when they were trying to get up to the mark.

 

DickDastardly

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The only interesting thing about the monster foiling multihulls racing in SF Bay was that the vectors yielded completely non-intuitive results. For example, those of us who grew up sailing monohulls on the Bay go to great lengths to stay in relief from the adverse current. But the AC72's were the other way around. Going downwind they eventually learned to search out the worst current possible because the increased apparent wind speed from, say, two knots of adverse current increased their boat speed by four knots. 
Yeah I remember hearing that. Had to think about it a bit but it made sense eventually. 

 

Frogman56

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The 12s and the IACC designs both had trim tabs, and both therefore close to zero leeway, probably around one degree for foil wash separation.

Grant Simmer A II navigator widely reported as stating 'overlaid at 70 degree tacking angle'

 
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