Hi All,
I rebedded my first chainplate, but not before first putting too much butyl tape beneath the chainplate cover and stripping the screws as I tried to tighten it down to the deck. I ran out of time to finish the job the first time and had to go home and did not return to drill out and re-epoxy the screws until a couple of weeks later. In the meantime, I left my [B]aft-most starboard (lower) shroud[/B] disconnected and tucked under the sail cover.
When I returned and finished the job, I reconnected the loose lower shroud to the chainplate and turned the turnbuckle until the distance between the turnbuckle threads matched what I measured with my digital measuring caliper.
When I finished tightening the turnbuckle I noticed that the shroud in question was extremely tight, with virtually no give when I pushed on it. I pushed on the other shrouds and they had more give, including the identical aft shroud on the other side. However, not knowing anything about rigging I figured maybe that is the way this particular shroud needs to be tightened for the whole rig to be tuned properly. But I have had this gnawing suspicion that something went wrong when I put it back together after the rebedding.
Is it possible that the shroud has shrunk during the couple of weeks that it was tucked in my sail cover awaiting my return to finish the job? Is it possible that the whole rig shifted to the opposite side a tad because of the uneven tension? Could this explain why there is so much initial tension on this shroud?
Any insights on what might be happening would be most appreciated!
All the best--Joel S.
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
Your rig can't shift forward if the mast is stepped, wedged in the partners, and the long wires are tight. Mast bend (technically camber) is controlled by the lowers. For furling masts, generally no or low dockside bend is recommended, i.e, in-column for smooth furling. For non-furling masts, a bit more dockside bend is allowed. Bend is usually added by having more tension on the forward lowers than on the aft lowers, but it would abnormal to have a lower with significantly different tension than the one directly athwartships from it. As a general rule, the lowers will deflect a moderate amount when pushed at about shoulder height. Not loose, but not bar tight either. Loosening one lower on a properly tensioned rig will result in some change in tension in the remaining lowers. Re-tightening a lower to the exact same length should have returned the tension on all lowers to pre-loosing tension.
So, this leaves us with three possibilities. (1) the tension was not equal to begin with, or (2) the measurement was in error, or (3) the length of a component changed. I'd go with #1, but one possible cause of #3 could be that the starboard aft chainplate/tie rod length changed. If you totally re-bedded your chainplate and not just your chainplate cover, then you might have loosened the tie rod inside the boat. If you over-tightened the tie rod adjusting nut, this could have moved the eye on deck further away from the spreader, resulting in a tighter lower. Kinda far fetched because the amount of rod tension needed to oil can the side deck would be very high. Although that is why we have that little turnbuckle on our mast in the salon - to prevent deck oil canning....
Regardless, all is not lost. Just do a dockside tune and go sailing. In case you have a Charleston spar, [url]http://www.sparcraft-us.com/us/products/masts/furling_masts/recommendati...
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Joel,
I'm pretty sure that your shrouds did not shrink. In my experience the uppers are the most tight, the forward lowers are medium tight, and the aft lowers are the least tight. This manual explains a lot and might help:
[URL]http://www.seldenmast.com/frameset.cfm?id=6740&randnum=984901594[/URL]
Tom Sokoloski
C36/375IA Past Commodore
Noank, CT
Tom
Do you use their recommended method for tunning the rig?
Enrique
Talisman
Enrique
Talisman
1998 36 MK2 Hull #1673
Tall Rig Wing Keel
M35BC engine
Old Saybrook, CT Summer
South Glastonbury, CT Winter
Enrique,
Yes, I do, especially the part about "Tuning Under Sail".
Tom Sokoloski
C36/375IA Past Commodore
Noank, CT
Thanks for you insights, Nick. If memory serves I don't think I lossened the nut at the bottom of the tie rod at all. I just spun the chainplate off the top and pushed the tie rod down into its compartment to give me room to work. But what you say does make me wonder if maybe the setup of brace and wood block just above the bottom tie rod was put back in place the same way. Luckily I had the presence of mind to take a picture of this before I took things apart, so I will definitely give it a looksee when I get back to the boat. And boy oh boy do I hope it wasn't tensioned incorrectly over the past year. Yikes...One can only imagine what kind of damage that could have caused while out at sea!
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
Thanks for the link, Tom. Is that the company that actually made our masts?
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
In addition to the Selden manual, there is OMG an actual rig tuning set of instructions RIGHT IN both the C34 and C36 boat manuals!!! :eek:
It's actually one of the better ones around.
RTFM - F stands for Funny. :)
Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)
LOL...who would have thunk it? A tutorial on mast tuning right in the good ole Catalina manual. I'll check it out...thanks Stu!
Joel Schwartz
s/v Get-A-Grip
1993 Catalina 36 Hull #1259
Newport Beach, California
Joel. Did you ever find out the root cause for your rigging issue?
Nick Caballero
Retired C36/375IA Mk II Technical Editor