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Voster · 01-12-2020, 20:45

When I'm on a port tack, the 10mm port rigging cable moves around about 100mm and rattles in the chainplate, ditto with starboard tack, the mast is centred. This happens cruising at 6 to 7 kt's in a 10 to 15kt breeze. I'm fairly new to the boat and sailing in general, and mostly I'm single handed cruising.

Can I just gradually tighten the adjusters at the chainplates until it stops thrashing around. The previous owner replaced the rigging 2 years ago. The rigging on the shrouds is very tight.

Rapanui · 03-12-2020, 04:40

Our shroud goes slack at about 20 kts AWS which is where I normally reef. Yours probably needs tightening a smidge. I am not sure you can ever get the rig tight enough to prevent all flexing,

The danger with the shroud flexing is that the wire could fatigue, particulary near stress points like a terminal.

I have seen an Athena with a line secured to the shroud about 1/3rd the way up and taken aft to a cleat on the side deck. If the line has some stretch, that would keep the shroud from flexing and vibrating.

**tkeithlu** · 03-12-2020, 05:33

Rapanui has it right. You don't want it so tight that there is no evidence of flexing. That could be putting an unreasonable pre-load on the windward shroud. On the other hand, you rig sounds loose. Do your tightening when the boat is sitting without sails up, and equalize it by deflection- how far you can deflect each by pushing with your hand. Riggers may have a deflection gauge to put numbers on this.

Manateeman · 03-12-2020, 06:06

What boat? Any other strange things going on?
M.

Voster · 03-12-2020, 13:23

I will try and tighten it a little, I'm aware there will always be some movement, but it thrashes around and bangs against the chainplate, it is bound to fail the way it is.

Manateeman · 03-12-2020, 13:42

What kind of boat. Model. Photos.
Like to help but not enough info.
M.

Bill O · 03-12-2020, 13:54

Quote:

Originally Posted by Manateeman

What kind of boat. Model. Photos.
Like to help but not enough info.
M.

The subject heading indicates it's an Athena 38 under discussion. If that's incorrect, please advise.

Voster · 03-12-2020, 14:00

Fountaine Pajot Athena 38

Manateeman · 03-12-2020, 18:06

Hi. In 2007 Crack posted on this forum exactly the same problem.
So there is a bungee cord suggestion and discussions.
I just didn’t see your boat type...I just looked next to your name where nothing was listed. I need more coffee in the morning.
You might want to contact SMJ via pm as he knows quite a bit more than me about rigging catamarans and he might have missed this post.
I built them but I’m a monohull sailor...in a huge beer can.
Happy trails to you.
Captain Mark and his “ beer..drain, flatten, weld.” Manatees

Voster · 03-12-2020, 19:31

I have 20 metres of 14mm nylon rope, purchased for another project, that would be perfect as a support tied to the aft cleats, I'd actually thought about something like this on passage. I also have 12mm Dyneema, on the bowsprit for the code zero, that I winched as tight as I could manage for some extra support. One insurance company knocked me back because there are no backstays on my boat, but I have a much bigger mainsail than catamarans with backstays as a trade off.

fxykty · 04-12-2020, 01:42

Quote:

Originally Posted by Voster

I will try and tighten it a little, I'm aware there will always be some movement, but it thrashes around and bangs against the chainplate, it is bound to fail the way it is.

Rapanui in post #2 is exactly correct.

1) In 20 knots AWS (or whatever wind speed your reefing chart tells you to reef), sail upwind with the sails sheeted tight. It’s best if you do this in an offshore breeze in flat water. The leeward shroud should be soft, but not moving around. As yours is very loose, tighten the leeward side to not quite just soft (so a little looser than it should be). Count the turns you made. Then tack. After a few minutes, tighten the new leeward side the same amount of turns (so that you keep the shrouds exactly the same length, assuming your mast is straight to start with). If you can’t get the required number of turns on without going too tight, get it just soft and count the number of turns short. Then tack again and after a few minutes loosen the new leeward side the same number of turns. Repeat as necessary until both sides are just soft when to leeward.

2) Attach a bungy to each shroud a few metres up from the chainplate and lead it aft several metres to the rail (either direction is OK, but so it doesn’t get in the way). This will keep it from flopping around.

Voster · 04-12-2020, 14:32

Thanks for the help everyone.

Voster · 04-12-2020, 15:16

What is the best way to attach a line to 10mm cables.

arsenelupiga · 04-12-2020, 16:13

when tightening your shrouds should get stiffer. If not you have bigger problem and should stop tightening not to do further structural damage and have better look. Else you may crack boat in half.

Apart from tightening as per fxykty, your secondary way to ensure tightening actually does the job is to test vibration of jib or main shrouds when stationary, and count (or record the sound) how many vibration per time period, say 30 per 1 min, then goes to 32 per 1min, or listen to the sound. Tighter should vibrate faster, or pitch should be higher.