hi all,
only got a few months sailing on my nacra 5.2 before winter came but made some changes to the jib lead position.
the previous owner had the jib leads running to separate blocks and cleats on the hulls
this was good for reaching and downwind but terrible for upwind as the jib would luff long before the main as it couldn't be pulled in to the center of the boat

in our small lake i find the upwind sailing angles important so i got some combined blocks, mounted them on the factory cross tramp line and brought the jib leads into them

boat now goes upwind better but jib useless downwind
downwind isn't so important to me so fine

but over the winter i've been reading Rick and Mary's excellent, "catamaran racing for the 90's"

in it, pg87-88, Rick says that the jib leads should be tensioned from a point either half the jib clew angle or at 90 degrees from the luff through the clew

hard to visualize that so i've attached a pic.

problem is that half the clew angle means at the rear beam and at 90 from the forestay/luff means BEHIND the beam

i know i'll have to make some compromises but having it as far back as the rear beam isn't practical as i'll get all tangled up in the sheet

so any ideas on where best to place the blocks?

currently i'm thinking to slide them down the cable to as close to the rear beam as possible and pay special attention to not pulling the jib sheet in as far as i normally would as most of the sheet will be tensioning the leech and so choking off the slot...

Erice,
I use a barber hauler to easily transition for upwind to downwind sailing. In the attached picture, you can see it running from the jib sheet to a block on the mainbeam, then across the mainbeam to a jam cleat. I do the same for both sides, this way it can be adjusted from the windward side while sailing. I recommend doing this rather than moving your blocks around so much. I think I learned this set up from Jake who used to sail a 5.2 quite a bit. I don't do any racing with this boat so there may be a better setup out there. From what I have tried, this setup is the quickest and easiest to transition from upwind to downwind and back.

Oops, forgot to attach the picture.

I'm not sure you are interpreting that correctly because there is no way Rick recommends your jib leads to be back that far. A quick and dirty start is to start at a point in the middle of the luff of your jib, draw a line through the clew, and then to the trampoline. You will probably find that you need to be a little more forward than this.

The entire idea behind the sheeting angle is to make the shape of the jib consistent from top to bottom as it us presented to the wind. With a set of tell-tales approximately 1/3 from the top and 1/3 up from the bottom, if you steer your boat up into a luff, both sets of tell-tales should break at about the same time. If the top breaks before the bottom, the bottom is too flat and you need to move your jib lead further forward on the deck and vice versa. That is roughly the ideal power point for the jib. In higher wind, you may want to move the lead further back to let the top twist open a little and so forth.

One more thing-

Without the mainsheet tension your headstay will sag and you will not be making accurate measurements. I take the main halyard and run it to the mainsheet tackle so the headstay can be hardened up.