Better on one tack than the other upwind

[danstanford]

We are finding the boat a full knot quicker on port than we are on starboard and for sure we have a fairer shape to the main on port with quite the bubble in the luff of the main on Port. 

We tuned the mast using the North Guide and a Loos Gauge when we stepped the mast and I plan to go back to review it now in pursuit of a solution. Looking at the sail it occurred to me that a hook in the middle of the mast might cause this but sighting up the mast one is not obvious. 

Where would you Folks look first for a solution? We are comfortably hitting our polar target on the weaker tack though perhaps not able to point as high as we might like, especially at higher wind speeds where we are managing the traveller to keep the heel in range and the rudder engaged. 

Dan

 

[10thTonner]

Ok, the mast is symmetric - now how about the jib sheeting angles? (Bubble in the luff…) 

BTW, there was a full threat about exactly that just a few weeks ago. Try the search. 

 

[nolatom]

That previous thread was this one:

 

[danstanford]

I had read that thread with interest and perhaps I should have added my question to it, but I have excluded virtually all of the elements of it by ignoring the instruments other than speed and steering to the telltales with frequent looks to my windex which is as centred as I can make it. I had also read a fairly long set of responses on a J/99 having similar problems. 

I had focussed on the main and mast as the issue but will try to spend some time on the jib sheeting angles to make sure the jib settings match and the shape looks good. 

Thanks for the feedback, 

Dan 

 

[Steam Flyer]

I had read that thread with interest and perhaps I should have added my question to it, but I have excluded virtually all of the elements of it by ignoring the instruments other than speed and steering to the telltales with frequent looks to my windex which is as centred as I can make it. I had also read a fairly long set of responses on a J/99 having similar problems. 

I had focussed on the main and mast as the issue but will try to spend some time on the jib sheeting angles to make sure the jib settings match and the shape looks good. 

Thanks for the feedback, 

Dan 

Measure the jib sheet track to see it if is symmetrical.... for that matter, measure everything, chainplates too, to see if it is actually the same on both sides.

Something is out of whack

FB- Doug

 

[Nettles]

Check to see if your partners are in the center of the boat.  This can absolutely give you the shits.  You didn't say, but I'm assuming the masthead is in the center?

 

[danstanford]

Measure the jib sheet track to see it if is symmetrical.... for that matter, measure everything, chainplates too, to see if it is actually the same on both sides.

Something is out of whack

FB- Doug

Doug, I had not even considered that the jib tracks might not be symmetrical but I will do some measuring there for sure. As I think about it, should I measure from the bow for fore/aft placement and the outside of the deck for P-S? 

 

[danstanford]

Check to see if your partners are in the center of the boat.  This can absolutely give you the shits.  You didn't say, but I'm assuming the masthead is in the center?

Not having ever owned a keel stepped boat, I am not exactly certain what partners are. My boat is deck stepped with a plate on deck bolted through to a compression post. 

We measured to the rail with the main halyard to try and establish center for the masthead and think it is there but it is difficult to be very precise due to stretch in the halyard as we pulled it down. The North Tuning Guide suggests hanging a bucket on the end of it down the topsides to get it more precise and so I am going to try that. Certainly we are currently within a half inch at most. 

 

[Bobjanander]

Which speed sensor do you use?

Do use twa as refference?

is it centreline?

Are the electronics well calibrated

etc

 

[longy]

From your comments about different sail shapes tack to tack I would concentrate on measuring the boat first to see if it is symmetrical. Many are not. Then see if mast is truly vertical in boat - the measurement points you used to center the mast may have been different.

 

[dbcorbin]

Not having ever owned a keel stepped boat, I am not exactly certain what partners are. My boat is deck stepped with a plate on deck bolted through to a compression post. 

We measured to the rail with the main halyard to try and establish center for the masthead and think it is there but it is difficult to be very precise due to stretch in the halyard as we pulled it down. The North Tuning Guide suggests hanging a bucket on the end of it down the topsides to get it more precise and so I am going to try that. Certainly we are currently within a half inch at most. 

On my J88, I use a fish scale and a meter stick.   hook the fish scale to the main halyard and pull it down to say 25lbs.  they have a little marker there that you can measure from... then you can reach your port side chain plate bolt at say 25" and 25 Lbs... then measure the starboard with the same halyard pressure.   the bucket works but is unwieldy.   mast head is centered pretty well this way as long as the deck/step/chain plates are also pretty good.

My own port-starboard variance is blamed on the paddlewheel not being on center line.  In a blow, with more heel, it gets worse.   However, I am going to take a look at the keel and stern hung rudder for "centerness" when i get it pulled next.

 

[sailman]

Which speed sensor do you use?

Do use twa as refference?

is it centreline?

Are the electronics well calibrated

etc

Are you basing this off Speed over Ground or Through the Water?  Is your speed sensor on center line if using speed through the water.

 

[danstanford]

Really only using the speed log and it is not centered in the boat. I hadn't thought the amount it is off center could show this much difference. The TWA instrument is not correctly calibrated and I was not using it but rather using telltales to get to maximum height with some confirmation from the windex. We seemed to be able to point as high but with less speed and a less wide groove one one tack over the other. 

Next time I will see about using GPS to confirm the speed since we have very little current here. 

 

[danstanford]

On my J88, I use a fish scale and a meter stick.   hook the fish scale to the main halyard and pull it down to say 25lbs.  they have a little marker there that you can measure from... then you can reach your port side chain plate bolt at say 25" and 25 Lbs... then measure the starboard with the same halyard pressure.   the bucket works but is unwieldy.   mast head is centered pretty well this way as long as the deck/step/chain plates are also pretty good.

My own port-starboard variance is blamed on the paddlewheel not being on center line.  In a blow, with more heel, it gets worse.   However, I am going to take a look at the keel and stern hung rudder for "centerness" when i get it pulled next.

Not being much of a fisherman I don't have a scale but this is a genius idea and I will get one! 

 

[IMR]

Doug, I had not even considered that the jib tracks might not be symmetrical but I will do some measuring there for sure. As I think about it, should I measure from the bow for fore/aft placement and the outside of the deck for P-S? 

Don’t measure from the outside, measure from centerline. Some boats are not symmetrical side to side. 

 

[From the Helm]

Make sure you are actually seeing this effect on different days.   It's really common with the cold water and warm air over the lakes right now to have a lot of twist in the wind, add a little current and you will have what you describe, without anything being asymmetric.    You can have days where the wind is twisted 30 degrees in the height of the rig, it's usually lightish air and the water is cold so the air is stuck to the water.   

Most lake sailors have had the experience of a main that is flying every leach telltale and yet the top is twisted off to a reach while the boom is on center.  On the other board you'll have vang on and the trav way down.

Also, as pointed out above, use your GPS and compass to study speed from board to board.   That's not to say SOG is the right tool to use, but it's a great reference when you are not confident of the water speed sensor calibration.

 

[fucket]

On my J88, I use a fish scale and a meter stick.   hook the fish scale to the main halyard and pull it down to say 25lbs.  they have a little marker there that you can measure from... then you can reach your port side chain plate bolt at say 25" and 25 Lbs... then measure the starboard with the same halyard pressure.   the bucket works but is unwieldy.   mast head is centered pretty well this way as long as the deck/step/chain plates are also pretty good.

My own port-starboard variance is blamed on the paddlewheel not being on center line.  In a blow, with more heel, it gets worse.   However, I am going to take a look at the keel and stern hung rudder for "centerness" when i get it pulled next.

Why bother with the meter stick? Hook the fish scale to the halyard and trim the halyard until the fish scale is at the chainplate with a tension reading in the working range of the scale. Without adjusting the halyard, bring to the other chainplate and see if it's the same tension reading.

 

[Lynch]

You dont need any fancy fish scale

Tie a heavy weight ( I use a 12kg kettlebell) to a halyard exiting at the hounds - usually the jib halyard but might be a spinnaker halyard if its just above forestay.

Make sure the mast is central in the boat before doing anything else.

Also check speed with a gps not your log and try doing it in flat water with no tide

 

[F18 Sailor]

Really only using the speed log and it is not centered in the boat. I hadn't thought the amount it is off center could show this much difference. The TWA instrument is not correctly calibrated and I was not using it but rather using telltales to get to maximum height with some confirmation from the windex. We seemed to be able to point as high but with less speed and a less wide groove one one tack over the other. 

Next time I will see about using GPS to confirm the speed since we have very little current here. 

The paddlewheel being off-center has a big (negative) affect on the entire instrument system. I have seen up to 1kt difference from tack to tack with an off-centerline paddwheel sensor. Set your instruments to GPS speed, then take data on long tacks to confirm what you are seeing isn't simply a speedo issue.