J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Jib/Spin Halyard Sheave Box

A question about the proper leads for the jib and spinnaker halyards at the exit box at the top of the forestay. Foghorn (Hull #62) has an original Kenyon spar. The spinnaker exits above the forestay fitting, the two jib halyards vertically in line just below the forestay with the port above the starboard on our setup. We always replace the halyards with messengers each fall but this year we removed the whole fitting this spring because we were repainting the mast. Unfortunately my crew who removed the fitting didn't pay enough attention to the internal leadings of the halyards to know exactly how they should go back together. Our fitting has six sheaves. Three bigger ones where the halyards exit the mast and three smaller ones and a small roller that are set back inside the mast for halyard(s) to fairlead over before dropping down. When we put it back together, we ended up using one big sheave and one little sheave per halyard but this has caused a lot of friction one chute takedowns almost to the point we can't pull down the halyard, plus we were getting a lot of twists in the spin halyard. So yesterday I got to spend an hour or so up the mast taking it all apart, looking it over, scratching my head, making a best guess and then rerunning the lines. (Of course it blowing about ten to fifteen the whole time, deosn't it always?) We now have the jib halyards dropping directly down from their single large sheaves while the spinnaker halyard runs over its large sheave, the three little ones plus a roller at the bottom of the halyard box. This seems to be a big improvement for the spinnaker halyard in ease of use and appears so far not to be detrimental to the jib halyards. It seems logical but does anyone know for sure?

I just pulled my sheave box this winter because most of the sheaves had stopped turning. I replaced all the sheaves. My sheave box has pretty much the same setup and was rigged as follows:

The lower jib halyard just ran around one large sheave (slightly larger than the rest). The second jib halyard ran over the next large pulley up, then to the lowest idler (~1") sheave. The spin halyard is run over the uppermost large sheave, and the uppermost idler sheave. The middle idler sheave is not used. It looks like it was put there with the intention of having a second spin halyard as well. There is space in the sheave box for a lower spin halyard large sheave.
I'm not sure about your small roller, but my sheave box did have a support between the two plates above the idler sheaves that the spin halyard runs below.
If you have any other questions, I could draw it for you and fax or e-mail it.

Thanks, Ed. Your description sounds pretty much like my sheave box although I don't think there would be room for a second spin halyard sheave in mine. The internal small sheaves sound the same though. That being the case, I guess my only semi-major mistake was to not run the upper jib halyard over the internal small sheave. I guess that it means another trip up the mast for an hour or so the next time it's blowing so I can have a look at the geometrics to make sure your solution will work on my box and then rerun the upper jib halyard (again). Gee, and I managed to take off the forestay and all twelve screws holding the sheave box and put it all back together without dropping any parts or tools on the crew's heads or overboard last time. I might as well press my luck. Oh well, at least all the winching is getting my crew in shape. Thanks again.

Along these same lines, I'm planning on replacing the wire jib halyards with the new, lighter weight technora or spectra lines. Will the existing (original) sheaves handle a
5/16" Technora cored line? What about using just the core with no cover? Or have the cover just on the part that has to hold on the winch and through the rope clutches? I'm also planning on doing the same with the main and spinnaker halyards. Any comments on making these changes?

Tom Eskridge
#469 Twister

For the past two years I've used 3/16-in. Technora, Vectran, and Spectra halyards with 5/16=in. dacron covers spliced on where they run through rope clutches and cleats or around winches. The sheave box only sees the 3/16-in. line when the halyard is under load and there seems to be no problem. Have not noticed any particular wear areas.

Jim, What length of the halyard do you leave covered? Any preference between Technora, Vectran, and Spectra lines? What about UV protection?

Tom Eskridge
#469 Twister

Tom, these are the finished lengths and materials I used for the various lines.

Main halyard: 3/16 Technora core, 5/16 Dacron cover, 100 ft total - 45 ft uncovered, 55 ft covered, 10 ft overlap. Technora because it is strongest.

Jib halyards: 3/16 Vectran core, 5/16 Dacron cover, 90 ft total - 40 ft uncovered, 50 ft covered, 10 ft overlap. Vectan because it is lighter than Technora but no stretch.

Spinnaker halyards: 3/16 Spectra core, 5/16 Dacron cover, 96 ft total - 38 ft uncovered, 20 ft covered, 38 ft uncovered, 20 ft overlap. Spectra strong enough and lightest. Cover in middle so ends can be swapped if one end gets worn.

Topping lift: 3/16 Spectra core, 5/16 Dacron cover, 60 ft total - 36 ft uncovered, 24 ft covered, 14 ft overlap.

I use "luggage tag" splices so I can replace shackles without shortening halyards. I use halyard stop balls so the splice doesn't get sucked in to the sheave box and stuck.

I use reeving splices on the cockpit end of lines and replace the high-tech halyards with 1/8 dacron pull lines when the boat isn't in use. This avoids UV related problems and only takes a few minutes once you get used to it.

Checking Harken.com's Compuspec "load report", the sheet load on the Genoa in 20 knots is 507 lb and 1355lb on the #3 in 40 knots, with an end boom load of 1818lb. That's 1/7, 1/3 and 1/2 respectively of the 3800 lb tensile strength of 3/16" Spectron 12. Figuring 100 feet from Layline, Spectra is $55, Technora $70 and Vectran $83, it's hard to justify the additional cost for the extra performance. Spectra is a bit lighter and there is no concern about UV. Creep, the supposed Achilles' heel of Spectra, has not been a problem, though we do regularly adjust halyard tension when racing. We've had the same jib and main halyards for over four years and they were pulled only for one winter. Ours are covered only at the clutch; before you locate the covers, be sure to consider that the luff of the #3 is 2'3" shorter than the #1 and you might reef the main! We use covered Spectra for the spin halyard and sheets for ease of handling.

We just pulled our jib sheave box and while the four spinnaker sheaves are fine, all three jib sheaves need replacement.

My box actually has sheaves installed for four halyards. I read earlier in the thread that only the uppermost one is the one used for the single spinnaker halyard configuration on a J/30?

Of the two jib halyard exits on the mast, which corresponds to the upper jib sheave + idler, and which corresponds to the lower jib sheave?

And it appears that the axles for the sheaves are riveted in place. Replacing them with standard clevis pins would mean I'd have to cut notches in my mast to get the box back in, which I'd rather not do. Can you buy these rivetable clevis pins, and what kind of tool does one use to install them?

Thanks,

Ryan Pierce, #337

Ryan,

I also need to remove and replace the sheaves from the box. It's not clear to me how to do it either (dealing with the "pressed-in" pins). Did you ever get it done? How? Does anyone else have any input? I have some ideas but I'm curious how others have done.