Shroud Tensions

[EmergencyExit]

Okay, I'm losing it - I could have sworn we had a thread on shroud tensions, and that Windward gave a great detailed post on his settings, but I can't pull it up in a search.

Anybody remember ? Or has the mate been adding anti-freeze to my Myers Dark and Cokes (again)?

[NYCSAILOR]

WOW!,

exactly the info I need and I too am surprised it is not int he manual or not ont he other site anywher..

I just paid inthe hundreds to have my mast stepped at the marina and now everyone is saying.."hey your mast looks crooked a.." al I can say is no..it is the boat that is listing to port becasue of teh battery...but I know I am in denial and the mast shourds need tuning so any specs?

[Banshi]

I remember seeing this somewhere....think think think, I know how to adjust the lowers but you have to be sailing to do it. There was a formula, I think I saw it over on sail.net. Check this out........

http://www.sailnet.com/forums/gear-main ... r-rig.html

[ronc98]

I thought there was some info on Avocet's site. If there is some from Windward I would like to see that as well.

[rlmpellc]

The tension is usually specified by the sail maker. I have a J22 and have different setting for different sail makers. Generally the lowers and uppers are set at about 175 for winds in the 0-4 knot range. Then increasing as the wind increases.

Here is a link to Quantum Sails tuning guides: http://www.quantumsails.com/search/search.aspx

Bob

[EmergencyExit]

I'm fairly sure I'm close by feel, although all info is appreciated !

I'm more puzzled by whether the thread got lost or ever existed !

[Banshi]

I would disagree with letting a sail maker dictate my shroud tension, shape/rake of the mast yes but this is dictated by position of the step, fore stay adjustment and back stay tension. The mast on these 20 ',22' and 26's are far to stiff to bend (and the fore stay is attached to the top of the mast) and the step is fixed so the only real adjustment you have is rake with the forestay. The tension on the shrouds should be set to handle the loads correctly according to the design of the boat/mast not the sail. I can see where bending the mast side ways by adjusting the lower shrouds might help but you would have to do it every time you tacked.

[NYCSAILOR]

OK, my professionally stepped mast ( with a crane and four guys working on deck) is not straight. it is over to the port side. also my boat is listing to port. I origianlly thought this was simply from teh battery which is in the port lazerette ( I have to find a more lower centerline place for that heavy battery... but it has to be near teh engine ( starting battery and I really don't want to have it hare the stern lazerrete withteh gas tank ( explosion?))

anyway I moved thebattery all the way outboard to the starboard and the boat still lists badly to port ...thi is a concern since the sink drain is now close to wterline and it is old and has no seackock...
could the mast be tipping the whole boat to starboard?

[Guillaume C.]

Yes the mast have a long leverage arm to tip the boat to one side, make it vertical before tuning everything else

[EmergencyExit]

Quickest way I know of to tell if the mast is plumb is to pull a halyard over to the deck where the upper shroud attaches, mark that place on the halyard, then repeat on the other side. Should be same distance.

Then tie a wrench on the mainsail shackle, and it should hang just off the back of the mast.

When EE was barnacle and growth covered my sink drain was a couple inches under, now it is above the waterline.

The C26 has more structure on the port side normally anyway (galley and the head enclosure), so I suppose its not too surprising if it lists a bit to port.

[NYCSAILOR]

well after my complaints...the yard said they fixed my mast..so I will see the degree of list with a (supposedly) vertical mast...I will also do EE's great advice on checking it for vertical and FOR SURE.... a sink drain Seacock will be added to teh list....I now am looking for a better spot for the battery..I use it to start teh OB and it gets charged from teh OB so it has to be within reach of the cable from teh OB and be away from the gas tank and get good ventalation... a tall order as I would like it on the center line and low as well...I might move the gas tank but that has similar issues...

[Windward]

I was backchannelling to Beau, so I'll just plagiarize myself:

There are lots of theories about rig tension. I don't readjust my rigging based on season, and thus tend to carry more tension than most people I know. While this time of year things are generally quite mellow, in the winter my rig may have to remain perpendicular in sustaind winds 15-30, with sudden gusts 25-50. When she's rail (or leeward winch) down, the leeward shrouds do not flop about. I believe preloading for those conditions protects the system from having to deal with a sudden shock load.

I use a Loos gauge to measure and match my settings... while it may be wrong, it's at least consistently, repeatably wrong. Once I have the rig centered, straight a suitably raked, I start with my cap shrouds around 15% of breaking strength; that's about 750# for 3/16" 1x19 of 302/304. Not sure if this is truly a "magic" number or simply a convenient one that many cling to in order to sound authoritative, but for masthead rigs it's one reference by Loos, many published tuning guides including those by Selden and Ivan Dedekam, and a slew of web resources. When I was discussing rigging with Brion Toss -- a paid arrangement, it's not like we're buds -- he seemed to feel it was a good starting point.

Don't recall the exact settings on the Loos B gauge, but I think the uppers are at 25 or 26, the forward lowers are may 18-20 and the aft lowers are maybe 12-15.

Lowers handle keeping the mast properly in column and managing bend (the C26's spar is quite bendy fore and aft). Forward lowers are adjusted to provide about 1/2" to 1" off prebend, and the aft lowers are adjusted to limit max bend to abouot 2.5" when the backstay's adjusted tightly.

I found that Windward had no compression tube through the mast at the spreaders, and the resulting compression and spreader flex had wallowed the hole and dimpled the mast a bit. I redrilled, added a compression tube, made some reinforcing plates and replaced the spreader brackets. Increased the aft lowers to 3/16" from the original 5/32 while I was at it.

Did extensive masthead reinforcing to correct some cracks I found, too, but I think I got into that in another post. Or dreamed it.