I've been fiddling around trying to get my 6.6m sail & 7.2m to feel comfortable. Yesterday I had the lines in the spot for the 7.2m which is how they were positioned when I bought it.I have found that ok in the past.
Someone told me the lines stay in the same place no matter the sail size but that doesn't feel right to me.
I used the 6.6m yesterday and felt really uncomfortable.
I moved the lines forward and that helped a bit but I still had trouble putting my weight in the lines to go upwind.I shortened them a bit. It wasn't a great day to experiment as I was on too large a board for the chop & too big a sail & it was driving rain but it felt really 
.
I was also using a 460 mast with it for the first time and trying a higher boom height..prob too many changes at once..?
Anyway the other thing is I move the mast foot further forward for chop does that means the lines have to move forward?
Also how does changing to a weedfin change everything..Too many variables ..Argh!
I used harness lines for the first time on the weekend so I am no expert but I was told to have a look at guy cribbs harness lines...its a pdf with instructions on how to measure where ur harness lines should go worked a treat..
I used the 6.6m yesterday and felt really uncomfortable..
Harness lines need to move when you change sails. If the sail is the same type and it's just the next size the move will be minimal. Get that right on the beach and then you can worry about the other things.
Move the mast track back a bit to adjust for a weed fin.
Agree, change one thing at a time or you'll just get confused.
The other important thing is to have the sail rigged correcxtly to start with. ie. DH & OH. Otherwise you end up trying to compensate for poor sail tune with all the other settings. If you're not sure what the sail should like like rigged correctly, then the manufactures spec is a good starting point.
But yeah, tweaking can be a never ending task the weasher and water conditions are allways a variable.
The position for your harness lines will change as you change sails and will also change as you change the settings on your sails. If you use more outhaul, you will have to move your lines a little further forward. What I do is to set up my sail and then see if you can hold it with one hand in the middle of where your harness lines are. You will soon tell if it isn't balanced correctly.
Was having the harness line prob a few years back (along with the changing too many things at once
Started looking around at others' rigs and everyone was sailing with lines much closer together on boom - about a hands width (simply not possible with the 80's and 90's sails I learnt on).
Tried it - felt really weird and uneasy to start with but got used to it quickly. Turns out wide apart hides the poor positioning in terms of front or back hand pull and just makes it feel unbalanced. Closer together and you can't hide from having them in the wrong place. Also read most people tend to have them too far forward.
Mine move around an inch for each sail size 5.0-5.5-6.3.
Oh, also I have stopped moving mast track for different conditions (only for sails). Boom height does the trick - higher = powered up off the fin flat water, Lower for choppy upright stance.
I used the 6.6m yesterday and felt really uncomfortable..
Just another point, mast base. I reckon the board manufacturers probably know what is the best position or close to it (I may be wrong). If you accept that theory, I rig mostly in the middle of the mast track, if I am using a bigger sail than normal, I put the track forward a bit, a smaller sail, I put it back a bit. I do fiddle with it when conditions change but for most of the time this works for me. I am not someone who has to have the optimal performance from my kit, you only have to see the condition of the sails I use to guess that, to get the extra couple of knots seems to be too much hassle for me. My advice would be just to get an average set-up get used to that and then maybe experiment.
the correct harness line position is where it balances the sail all that stuff about measuring off other things is a waste of time .The correct position will change with different down haul and out haul settings . I try and get mine neutral or front hand pressure as i find pulling in on the back hand makes me spin out and try to catapult me. I find a higher boom is good for flat water and the rougher and more over powered it is the lower i go with it it really helps hold the board down. I always just put the mast base in the middle , works well on my boards my isonic even has a circle of where the middle is and thats where it should be .
I used the 6.6m yesterday and felt really uncomfortable..
I've started to put my mast foot almost right at the front in higher wind as I am generally on too big a board for the chop .
I had a nasty stack last season when I decided to move it to back near the rear a bit as result of something I'd read.The board was skipping along only on the tail and the wind caught under it and me & trashed us.
I find sailboard tuning a lot like Kart tuning when I used to race. Your looking for that sweet spot when eveything is working together and performance comes naturally
As above I only ever change one thing at a time, and only in small increments. If you can't feel the difference in a 5-10 mm out-haul or down-haul adjustment something is miles out. Harness lines allways feel like there in the wrong spot like this IMO. You can learn to ride and deal with a bad setup, getting it right makes it heaps more fun and less work.
An example. When I got my last 4.2, I chucked it on the board same place as the last one. I used to leave the mastbase in the board after packing up and it was up FRD. I went out and all it wanted to do was throw me around the handlebars. It was woefull. Moved the base back in increments until the problem disappeared then tweaked the sail until it felt nice.
My gear is all a few years old now and I still always fine tune at the start of a sail. Just because it felt nice last time doesn't mean its right next time
I don't alter the downhaul on my koncepts much, tuning for conditions is by altering the outhaul. Boom height I don't alter much. Then I balance my harness lines on the beach by standing the sail up and holding the line where my hook would be, then moving the harness lines until the sail doesn't try to twist away.
Then I'll sail in and out and adjust the position a bit more if there is uneven pressure on front or back hand, adjust the harness line length if necessary.
Then for the mast base position. Middle of the track for average to light wind, back of the track for strong wind. Back 1 cm further for a weed fin. Go for a sail, then try the mast base 1 cm forward, test, then 1 cm back. You're looking to have the weight balanced between your feet. The difference in performance can be amazing. I might add an extra 1 cm in the direction that worked best and retest until performance drops off again, then go back to the best setting.
Now you're ready to sail... if you have any energy left.
Yep you can spend alot of time messing around with stuff, I started writing on mail sail foot next to the specs the other stuff that I knew worked for that sail eg mast extension length, where optimum d/h is for the sails optimum wind (usually +-1cm covers any variance, boom length to use just to save moving it twice on the cam sails. The other thing I was going to do but never have is start a log of which board / fin / sail / mast foot posn etc worked nicely for certain conditions.
As for the harness lines, yep just as windy says, to save time I also write the sail size on my boom in the middle of the lines after I'm happy with the possy for that sail in its average conditions.
I haven't been changing it for the weedfin though so I need to start accomodating that.
