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Diagnosing Upwind Performance on Port vs Starboard


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I have a suspicion that my boat performs better on port tack vs starboard tack when sailing upwind.  Right now this is just a suspicion because all of the times we are usually beating, there is typically a component of current that is not perfectly aligned with or against the wind but it just feels not as good, consistently, on starboard tack.  I don't have any fancy VMG, apparent wind stuff on my boat.  This little track from today actually did have a fairly well aligned current (tail) vs wind, but we were not on both tacks long enough to really get a good feel for it.  Assuming I do indeed confirm one tack is performing better than the other, where do I start to diagnose why?

Maine Cat 22
Jib is on self tacking track
Full batten main

Rig tension? Old Sails? Hull?, Foils?

While this track is from today, it's mostly just for "you get the idea" not perfectly executed data.

image.thumb.png.7123906e7fb9402c78a5735d65a48dbc.png

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any assimetries in the sails, hulls, rudder, dagger/centerboards, rigging, etc etc etc, could be the source... 

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hmmmm - not sure if I am reading this correclty, but:

according to your “Alleged wind direction”, on port tack you sail upwind at what ... 20 degrees from real wind ?

Pretty good, indeed.

Then, surprise - on starboard, you sail upwind at something like, 80 degs ? I understand that you are disappointed.

If I were you, I would be happy that I sail more or less square tacks (100 degs ?). 

Assuming you want to elucidate this mystery, may I suggest that you analyze your tracks with:

 the “true” wind direction as the average of the port/strbd headings (BTW this is what Race QS does by default, I believe - this is RaceQS right ?)

add speed to your data captures, to qualify your  “perform better upwind”

 

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28 minutes ago, Ganzi said:

hmmmm - not sure if I am reading this correclty, but:

according to your “Alleged wind direction”, on port tack you sail upwind at what ... 20 degrees from real wind ?

While this is a real track from my race ques from today and a real screen shot from Windy at the time this track was happening, I mostly did this just to exaggerate how I feel the boat sails.  I'm confident we don't point to 20deg on port.

28 minutes ago, Ganzi said:

Pretty good, indeed.

Then, surprise - on starboard, you sail upwind at something like, 80 degs ? I understand that you are disappointed.

If I were you, I would be happy that I sail more or less square tacks (100 degs ?). 

Assuming you want to elucidate this mystery, may I suggest that you analyze your tracks with:

 the “true” wind direction as the average of the port/strbd headings (BTW this is what Race QS does by default, I believe - this is RaceQS right ?)

add speed to your data captures, to qualify your  “perform better upwind”

 

Will try and get some long tacks on a slack tide in an open stretch of flat water with a good true wind direction.  

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Remember you have a component of the apparent wind equal and opposed to the current velocity ! you have to account for this to get a corrected "true " wind direction. You can also have an effect relating to a gradient of wind direction with altitude which may gives tack assymetries. This look more likely an apparent wind assymetry effect than a boat assymetry.

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Forget the instruments and enjoy sailing your boat.

My most successful racing season the instruments were shot!

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Windshear= different angle of atack for the upper part of the sails on different tacks...??

Mast not vertical...??

Current influence  or current shear closer to the shore..??

Lots of possibilities that is why they used 2 boats for tuning  America,s cuppers

Don,t bother , enjoy jour sweet catamaran!

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So close to land and a bay entrance...

- current, tidal effects

- wave / wind angle

- gusts "lift" vs gusts that "knock"

For example, in one bay

- typically the wave patterns are not aligned to the wind, so upwind on Port tack sucks because you get awful short chop, but on Starboard tack, same conditions, you get a long wave period which you can steer nicely through. Same (reversed) on downwind legs!

- in E/ENE, gusts contain a shift towards N. So on port tack, the gust lifts, you can work each gust aggressively up. Starboard tack, each gust knocks! 

 

 

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Thanks for all the comments.  Im liking the "it's all in your head" trend.  

I want to reiterate this is a feeling I've had over two years of getting to know the boat not just one random trip using windy and race qs.

-I do like the wind shear thoughts.

-I'm sure current and other factors play into this perception

-I will definitely check my mast alignment and stay tension. 

-And for those who say "just enjoy it" this is enjoying it!  We love sailing this thing as much as possible.  We will beat up the narrow waterway if we can to avoid using the motor.  We have tacked upwind through marshes.  Our family like to ride and because the way the boat is laid out, we can "work" while the fam relaxes.  Plus I'm a pathological tinkerer.

IMG_20210529_094214.jpg

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12 hours ago, martin 'hoff said:

For example, in one bay

- typically the wave patterns are not aligned to the wind, so upwind on Port tack sucks because you get awful short chop, but on Starboard tack, same conditions, you get a long wave period which you can steer nicely through. Same (reversed) on downwind legs!

- in E/ENE, gusts contain a shift towards N. So on port tack, the gust lifts, you can work each gust aggressively up. Starboard tack, each gust knocks! 

 

 

 I like this theory a lot.  Since we only consistently work upwind in 4 or 5 spots this might be a big part the case

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On 6/2/2021 at 3:50 AM, patmo141 said:

Plus I'm a pathological tinkerer.

Nah. Don't pathologize it. :p

It ain't a disease... it is rather its very own destination in and of itself. I love to fettle, fuss, and fix boat bits, bike bits, 4x4 bits, etc. Much of this can be done in my backyard on a weeknight when I cant actually get the boats/bikes/etc. out on the water/road/trail. It is all part of the hobby, IMHO... and the guys like Groucho and racinginparadise do it best: play, putter, play, putter, and on...

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My sailing location has current (tidal basin).  Been sailing here for decades.  Sometimes I swear I'm faster on port tack than starboard, it just feels slow.  Other sails it is the opposite tack that feels slow.  I routinely look at gps speeds and tack angles after each sail.  Bottom line, each day is different, the boat is fine, it is the water, waves and wind that changes my feelings.  

One thing to check though, check the position of your jib track distances from the mast base and centerline.  A jib slot size change will affect upwind speeds. 

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I had similar concerns on pretty much all boats with wind instruments. Every time it was the wind angle sensor. On the trimaran there was this upwind groove that you're clearly in or out of, and the trim was consistent because I was alone. And the AWA diff was pretty constant, so an easy 2.5 degree offset tweak. On the racing mono Expedition logs helped, if you know how to average and scatterplot readings.

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