Grande Mastere Dreade
i'm usually better on one tack than the other because the beer holder is on the starboard side...
Nico, it has been the inability to trim the main properly on port while easy on starboard combined with the speed difference that has prompted the questions.Hi,
as others here I do not trust speedo so much. I had the same problem a while back, and I will pass over the advice they gave me: look for something else than the speedo to measure the assymetry.
Do you see anything different from tack to tack if you look somewhere else than your speedometer? Try to look from different angles. I could tell you where I looked, but I am sure you know better where to look: it is your boat.
Generally, I find that I do too much pronostics (actions), and too little diagnostics (measurements).
fifth, learn to spell fourthAssuming your mast is in the middle of the boat , your keel is symmetric and weight distribution is equal
First check your speedo for accuracy
second check your wind instrument for accuracy
third check for wind sheer
forth record your rudder angle ....tack to tack
Not pointing as high compared to what? do you hold the lane on what tack but not the other? If you're hitting your polar then is there a problem? Are you subconsciously creating a problem? How much faster than polar are you on the other tack then? 1 knot up? You recently stepped the mast, was there a problem before you stepped the mast?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.
What a great piece of writing and loads of things to think about.This is another one of those "a good coach in a coach boat would probably see the problem in about 15mins" type problems.
Let's assume the performance difference is real. And that when trimming both sails, exactly the same way on one tack over the other, and sailing the boat exactly the same way on both tacks, you get a bubble in the front of the main on one tack and not on the other.
This means one of two things:
1) the pressure at the front of the main is higher on one tack than the other
2) the angle of attack of the main sail is different on one tack than the other
If it is 1) then the mostly likely causes are:
- Your jib is not sheeted the same way on both tacks.
- The sheeting positions, relative to the main are different on both tacks
- The position of the main relative to the jib is different on both tacks (that is the mast is moving disproportionately on one tack to the other.)
If it is 2) then the most likely causes are:
- The main is not sheeted the same way on both tacks
- The sheeting positions, relative to the mast are different on both tacks
- The position of the tack and luff of the main is different on both tacks.
- The tension on the luff is different between tacks.
The last two points might occur if say the tack is not in the middle of the mast, or say the cunningham pulls the tack to one side.
In lieu of a coach or coach boat. Mount a go-pro to your spinnaker pole ring looking straight up the mast, then go do a couple of tacks. Also, take some photos at the gooseneck looking to the top of the mast on each tack.
Another option is to tie a piece of string to the clew of your main. Run it to the clew of your jib and mark it. then tack and repeat. If it gets longer or shorter then the trim of the main compared to the jib is different.
Other possibilities are you're pinching on one tack more than the other, or something really wonky with your boat.
Not pointing as high compared to what? do you hold the lane on what tack but not the other? If you're hitting your polar then is there a problem? Are you subconsciously creating a problem? How much faster than polar are you on the other tack then? 1 knot up? You recently stepped the mast, was there a problem before you stepped the mast?
My gut feel is a few things:
1) your speedo is reading differently on one tack than the other
2) you're subconciously or unknowingly sheeting sails differently on one tack to the other. Either because of the way you're sailing the boat or because gear is not in the same position on both tacks.
3) your mid mast is sagging between the hounds on one tack more than the other. I would have thought it'd have to do that a lot to make such a big difference. But I could be wrong.
4) some combination of all the above
There are a lot of controls that can affect the way your boat is sailing from one tack to the other, and especially the way alu masts are manufactured (if it's Alu) plenty of reasons why it might be stiffer on one tack than the other. Without pictures or video, if we as a group happen to stumble on an answer in this way I'll be amazed.
But IMHO start with " what is the angle of attack of this main on one tack to the other" and " what might be causing increased pressure on the leeward side for one tack than the other" or even "is the difference real and measurable outside of the boat" and go from there.
You might consider the coriolis force.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.
Depends on what the other settings are. Someone is trying to induce bend lower down the mast. Typically that results in a straighter mast from the spreaders upwards. Means a flatter main at the bottom but fuller mid and top sections. Also might result in less forestay tension as the mast compresses so your jib knuckles up.The tuning guide calls for 7 on the Loos 2 gauge for the D1's and the Euro version of the tuning guide calls for these to be 28! 7 is so loose as to be floppy, why would they be so loose?
Spoonie, the 28 came from the European Tuning Guide from North and the 7 from the North American one. The other settings are different but not so drastically.Depends on what the other settings are. Someone is trying to induce bend lower down the mast. Typically that results in a straighter mast from the spreaders upwards. Means a flatter main at the bottom but fuller mid and top sections. Also might result in less forestay tension as the mast compresses so your jib knuckles up.
Where as tight D1's result in a more rigid lower section pushing the bend further up the mast. That means the mid/head of the main is likely to flatten more and the forestay remains tighter, so a flatter jib.
I'd say, and I could be wrong, the 7 setting is medium to light air in sloppy water and the 28 setting is heavier air/flatter water setting.
With two very different settings between two different tuning guides, I'd say the respective authors have different philosophies on how to sail your particular boat. The 7 guy is probably fatter and likes to sail low "bow down" in the groove while vang sheeting. The the 28 guy is probably lighter and likes to pinch.
Someone is surely going to come along and tell me I'm wrong though I'm sure...
Wrong! Normally compensated for by the sailmaker. Coriolis force is why it is important to inform your sailmaker of your expected hemisphere, N or S. The sailmaker will select either S or Z twist thread accordingly.You might consider the coriolis force.
Well there you go. that makes sense.North says North American made mast and European mast are very different stiffness and this is why the shroud tensions are different.
Here is another tip to check the mast in column. Make sure the halyards, vang and backstay are slack so only the standing rigging is positioning the mast. Stand about 10 feet behind the mast in the center (on my J/109 I stand in the companionway) and take a picture up the mast so you can see the top of the mast and as low on the mast as you can get. Drop the picture in PowerPoint and draw a straight line up the mast track. Easiest if you drop the two end points, then blow up the picture and position each end point on the mast center. It will become very apparent if you have any curves in the column when you expand the view and go up the drawn line.quod umbra said:...
The other thing I would suggest to you, people all the time sight up the main track and try and determine if the mast is in column. Uhhhhhh....okay.
What I do is establish a reference point both port and starboard as discussed above I do believe. Then take a sail slug. run that up the mast on the halyard and tape measure and measure at the termination of the uppers, intermediates and lowers from side to side.... adjust as necessary.
haha!Wrong! Normally compensated for by the sailmaker. Coriolis force is why it is important to inform your sailmaker of your expected hemisphere, N or S. The sailmaker will select either S or Z twist thread accordingly.