jib track placement

[Hull376]

I was just reading the July 2010 Sail mag article by Dave Gerr about appropriate sheeting angles. He does all the geometry and then calculates what the sheeting location should be for a jib and a 150% Genoa. I got curious about where his method would place the Genoa track and the sheeting point on an Ariel (see the picture below of 7 degree and 10 degree sheeting angles on an Ariel). Dave's article points out that a 150% is about the biggest sail that you can usually efficiently fly with the close hauled 7 degree sheeting angle: bigger sails have sheeting points that would be off the back of the boat!! Anyway, my surprise is that the sheeting point using his calculations for a 150 Genoa would put it almost to the back of the coaming board. Hummm. I usually sheet my 150 much closer to the standard winch position--- which happens to be about where the 10 degree sheeting angle would be. Not being on the boat right now, I can't get my head around how Dave's far aft point would actually work with respect to the shrouds, etc. Also, he builds the sail design (clew point) based on where the sheeting point is--- so that a line from the sheeting point perpendicular to the headsail luff would intersect the luff about 40% from the tack. Any comments from the racers on this article and what it would imply? What is right about it, and what might be wrong--- or full of caveats???

[SkipperJer]

Interesting. My Commander came with the track out on the toe-rail and well aft. I've tried in my rookie way to experiment and always felt that the 150 and the 170 before it did best when the car was furthest aft even though the sails laid against the shroud. The "experienced" sailors told me I was wrong. Maybe I should not have listened. I also do not have life-lines or stanchions so the sail comes inboard more than it might on an Ariel with lines.

I've since had the 170 cut down to a 150. I've never missed not having that huge sail and have enjoyed running downwind with twin headsails often.

[ebb]

That's what I was thinking - have to take the spreaders into account visavis sheet angle.

[Ariel 109]

The 10 degree jib track rule of thumb is discussed in Arthur Knapp's old book 'Race Your Boat Right'. He gives the credit of it's origination to a sail designing friend who name I don't remember. But it doesn't sound too scientifically derived, it's a rule of thumb. He also talks about double sheeted jib rigging which is having a sheet attached to the jib or one of the jib sheet that pulls the clew downward as well as the regular sheet that pulls backwards (aft). I'd like to try this out one day.

Sail designs have really changed since many of these ideals were formed. Best to be skeptical and learn from experience and experiment.

Ben

[vanguard64]

I have been reading this thread with interest especially since I have been sailing my Ariel for only 6 months and experimenting with different trim settings for the headsails. I have the original SS 30inch genoa track but the PO apparently removed the original jib tracks by the cabin sides. I have a CDI roller furler and have 2 headsails; 150% and 135%. CDI claims that I should be able to furl down to 70% of the original LP and still maintain a decent shape to the headsail although they recommend padded luffs which my sails do not have. In my case, I should be able to get the sails down to approximately 95-100% size. However, if the genoa blocks are not moved forward, I run the risk of the furler jumping up off the bearing and having a big mess to deal with. I wonder therefore, what modifications I should make to the genoa track configuration to make sure that once I furl down I can modify the trim to satisfy the smaller sail size. Can I manage a 100% headsail size with a longer genoa track or will I need to switch over an inner track by the cabin sides as originally set up for the smaller jibs? I feel it would be difficult to furl in and then have to switch the sheets to the inboard side of the shrouds but I am not sure what else would work.
I appreciate your thoughts.
Marcelo