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Old 28-07-2017, 13:56   #1
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Why is my boat faster on a stbd tack?

Hi,
This has been going on for quite a while and I just cant figure out why? And if I recall my previous boat was also faster on one tack. My rigging is perfectly square, equal tension on all the shrouds, Head sail always completely unfurled. The boat is leveled at the dock. Last weekend, we had 12 to 14 Knots true wind and consistently 1 to 1.6 Knots faster on Starboard Tack. I'm very curious to getting feedbacks on this!
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Old 28-07-2017, 14:12   #2
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Re: Why is my boat faster on a stbd tack?

Jib sheet blocks equal?
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Old 28-07-2017, 14:20   #3
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Re: Why is my boat faster on a stbd tack?

Make sure you're comparing SOG on each tack vs. speed from a transducer. The paddlewheel transducer being off center can often read differently on different tacks. Also make you're not in a high current area because tacks will often be affected differently by current. If you account for those and it's still very different then it pretty much has to be the rig setup. Even if it's square and even at the dock, you'd need to compare sail shape on the different tacks under sail.
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Old 28-07-2017, 14:25   #4
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Re: Why is my boat faster on a stbd tack?

If your rigging is exactly the same side to side then your mast is not centered. Given the performance its probably falling off more to starboard while on port tack.

If you rigging stays centered on both tacks then its very possible that your keel and or rudder are attached off center, or that you have more ballast on one side than the other.
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Old 28-07-2017, 14:55   #5
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Re: Why is my boat faster on a stbd tack?

Assymetry somewhere
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Old 28-07-2017, 14:57   #6
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Re: Why is my boat faster on a stbd tack?

Ive also sailed boats with notable performance differences with no obvious reason. Different performance on different tacks is surprisingly common.

What make/model boat?

Aside from rigging anomalies, hull fairness differences, etc...one rather pedestrian cause is uneven hull fouling. Quite often boats get more growth on one side than the other due to angle relative to sun. Take a peak below the waterline too.

I once had dock crew clean the bottom of a small boat before I took it out to teach a class. Performance was DRAMATICALLY different on one tack versus the other. Jumped in and checked at lunch...dipstick had only cleaned one side!
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Old 28-07-2017, 15:01   #7
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Re: Why is my boat faster on a stbd tack?

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Originally Posted by leftbrainstuff View Post
Assymetry somewhere
Likely. Serious racers get their hulls faired...sometimes with significant results.
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Old 28-07-2017, 15:03   #8
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Re: Why is my boat faster on a stbd tack?

where is the speed transducer? Is it angled properly?

Do not use GPS speed it is useless for comparing speed on port and starboard tacks.

Is this discrepancy for all points of sail or just when wind is forward or the beam?
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Old 28-07-2017, 15:08   #9
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Re: Why is my boat faster on a stbd tack?

Like Gjorgsen I think there is probably a problem in your instruments.

I gave up on paddle wheels after I couldn't get mine to read the same speed on either tack upwind - smooth conditions and no tide. Something about the small amount of leeway was mucking it up.

I have also written in another thread how a friend who had sailed halfway around the world was trimming by the instruments. His wind angle sensor was way off and yet he used to to steer to windward when his sails were telling him contrary tales to the instruments. Look up man, look up.

Then there is tide and conditions. Often on one tack you will be punching into a small amount of headsea, or the waves will rock the breeze out of your sails more than the other. This is where racing gets interesting.

My advice is to ditch the instruments - the best and only infallible instruments (except when it rains) are the sail and shroud telltales. Your face is a great guide too. Get the boat trimmed well, with telltales streaming, in flat and non tidal water and the asymmetry in speed will disappear. Electronics look accurate but they are a guide only, use them AFTER you have got the boat sailing well with visual sheet trim.

cheers

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Old 28-07-2017, 15:14   #10
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Re: Why is my boat faster on a stbd tack?

OP: are you comparing SOG (GPS) or SPEED (tranducer)?
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Old 28-07-2017, 15:40   #11
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Re: Why is my boat faster on a stbd tack?

Tide / Current ?
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Old 28-07-2017, 15:49   #12
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Re: Why is my boat faster on a stbd tack?

My Cheoylee goes tighter to the wind on starboard tack. I believe the wind instrument is slightly off line, about 5 degrees.
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Old 28-07-2017, 16:27   #13
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Re: Why is my boat faster on a stbd tack?

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My Cheoylee goes tighter to the wind on starboard tack. I believe the wind instrument is slightly off line, about 5 degrees.
you can and should calibrate the wind instrument...
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Old 28-07-2017, 16:34   #14
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Re: Why is my boat faster on a stbd tack?

Quote:
Originally Posted by belizesailor View Post
OP: are you comparing SOG (GPS) or SPEED (tranducer)?
The displays in his pix show "SOG", and that is certainly one reason that speeds could differ.

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Old 28-07-2017, 17:07   #15
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Re: Why is my boat faster on a stbd tack?

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The displays in his pix show "SOG", and that is certainly one reason that speeds could differ.

Jim

If so this is rubbish GPS and shows there is current... good catch Jim... I suspected the same... He obviously is repeating from his ray MFD. Can it display speed???? Who knows...

On my dash you can see the 3rd instrument from the left is a GPS repeater (from ray MFD) and reads SOG of 7.2 and the center instrument is the B&G boat speed and it read 6.72.... so it looks like I had some fair tide of about .5 knots. Not bad for 9,5 knots true and apparent 13.5 wind speed.
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