wire size

[charrette]

i have a 1988 hunter legend 35. i recently attempted to tune the rig and noticed that the shrouds on this boat are of different wire sizes. the lowers are 9/32" the intermediates are 1/4" and the uppers are 5/16". i would think the larger wire would be the longest wire but that is not how the rig is set up. is it common for the wire sizes to differ?

i set it up roughly with the lowers (9/32") at 10% of the breaking strength, the intermediates (1/4") at 15% and the uppers at 20%. it sails much better. although i wasn't sure if the process is the same if the wire sizes differ. any input would be appreciated.

[Brion Toss]

Hello,
Is this a discontinuous rig? That is, do your "uppers" stop at the lower spreaders? Is it a B&R rig? The tune you put on makes sense for a conventional Bermudian rig, but it isn't optimal for disco. Any degree of tune will make your boat sail better, but we need to know the details and the reasons behind them, to get to an optimal tune.
Also, yes, it is usual, and for good reason, to have different wire sizes, as the loads are different at different points in the rig, regardless of type.
Fair leads,
Brion Toss

[charrette]

thanks for the reply,

i don't believe it is a discontinuous rig.

the rig is similar if not the same as the hunter 37 in your video "tuning your rig". it is a conventional fractional rig with aft swept spreaders. i don't believe it is a b&r rig. the upper shrouds go up over the both sets of spreaders and terminate on the mast in line with the headstay. the intermediates go up over the lower sreaders and terminate at the mast/upper spreader attachment. the lowers terminate at the mast/lower spreader attachment.

i had the rig tuned by a local rigger and since then the boat has sailed with weather helm on a starboard tack and no helm on a port tack at 10 -12 knots of wind. i decided to do some research on rig tuning, buy a loos wire tension gauge and tackle the job myself. what i found was the mast was not square to the boat. it leaned to the port side and the tension in the shrouds were minimal and uneven. on average the uppers were at about 10% of the breaking strength, the intermediates were at 9% and the lowers were at 5%. when sailing the leeward shrouds were very slack.

i have read that a fractional rig with aft swept spreaders should have tight upper shrouds (20% of the breaking strength no higher than 25%) in order to keep the headstay from stagging too much. where as the intermediates and lowers are to be just enough to keep the mast straight without being too slack to leeward.

without going all out i increased the tension in the shrouds and set them equal and took the boat out for a sail and it performed better with better balance but not completely balanced. so then i started from scratch and set the mast square to the boat, set the rake and prebend, and tensioned the shrouds. i won't be able to sail it until this weekend to see how it worked and do some final tweaking.

[mrgnstrn]

Brion,
Along the same lines as the above.
I have a C&C 35 (1987) with rod rigging and inline spreaders (not swept).
Does your video cover rod rigging (or...is there any difference at all in the process?)
Also, is there a reasonably priced alternative to the $$$$ loos rod rig tension gauge?
Thanks,
-M

[Brion Toss]

Hi again,
The Hunter in the video is a B&R with a backstay. For your boat, how much tension goes onto the backstay will be determined by how much the spreaders are swept, how stiff the mast is, and whether or not you have runners; 20% or so could work on a tall fraction, where the backstay might be counted on for most of the forestay tune, though even this might be moderated by the relative sizes of the two wires. Remember, what we are after here is not percentages of backstay loads, but straightness of the forestay. If you get a good shape with intermediates and/or runners and/or a jumper, plus 10% on the backstay, then you're home.
Also bear in mind that, on a fractional rig, the backstay's other important function is to shape the mast. On many rigs, tensioning the backstay does little to tension the forestay; instead the mast will bend, with the forestay as a fulcrum. Adjustable backstays are just about mandatory on fractional rigs.
Selden's free tuning brochure has nice details on this. You can get one from my shop for S&H.
Let us know how the sail goes!
Fair leads,
Brion Toss

[Brion Toss]

Originally Posted by mrgnstrn

Brion,
Along the same lines as the above.
I have a C&C 35 (1987) with rod rigging and inline spreaders (not swept).
Does your video cover rod rigging (or...is there any difference at all in the process?)
Also, is there a reasonably priced alternative to the $$$$ loos rod rig tension gauge?
Thanks,
-M

Hello,
Those gauges are expensive. Worth it for us, as they are fast, plus they look impressive. But remember, they're just a way to get in the neighborhood of what little-by-some tightening will get you. What you are after is minimal slack to leeward, and the mast straight laterally. So snug to your best guess, equalizing by ear or by measuring stretch, then go sailing. Adjust as necessary.
Fair leads,
Brion Toss

[charrette]

brion,
thanks for the tip on the selden guide on rigging and tuning. it confirms other literature that i have been using as a basis. i think i am headed in the right direction. i am puzzled about the b&r rig though. the hunter manual indicates that the 33, 35 and 37 hunters have conventional fractional rigs and the 28, 40 and 45 hunters have b&r rigs (1988-1994 vintage). the b&r rig, i thought, has additional diagnals between the base of the mast and the spreaders creating a diamond pattern with the stays. i am not sure but i thought the hunter 37 in the video did not have these extra stays.
thanks again,
charrette

[charrette]

after performing a dockside tune we sailed the boat this weekend and it sailed really well. i only had to do some minor adjustments to the lower shrouds while under sail to keep the mast straight. we were able to get to hull speed (7.2knts) with apparent wind at 13knts. we were never able to get to hull speed since we have owned the boat (2 years). the only thing that still bugs me is that there is slightly more weather helm on a starboard tack vs. the port tack, neither is excessive. is it normal for boats to sail differently on different tacks? i am going to check the squareness of the mast once more using a different method. i got a tip from another rigger who uses a sail slug attached to a metal tape measure that he hoists with the main halyard and checks for squareness at each spreader and the top of the mast down to the chainplates. he said this was a more acurate method than using the halyard alone. any insight would be appreciated.

[osteoderm]

Here in our boatyard, I am always surprised how many boats are markedly assymetrical below the waterline. It may be possible that your rig tune is spot-on, while an irregular rudder or keel could accound for the difference in helm on different tacks.
Go ahead and continue to tune, but don't drive yourself nuts trying to fix something that may be unfixable, and check the bottom carefully next haul-out.