Synthetic Rigging

Welcome to PocketShip.net! This bulletin board is for builders of the Chesapeake Light Craft-John C. Harris "PocketShip" design, a 15-foot micro cruiser sailboat built from a kit or plans.

For more information on PocketShip, click here: http://www.clcboats.com/pocketship

This site gathers PocketShip builders in one place. Here you can share photos, tips, questions, and---eventually---your sailing adventures in PocketShip! CLC will also post design updates and tips here as they come up.

We'll try to knock down spam as quickly as possible.

Moderator: John C. Harris

Forum rules
Spam or commercial posts will be deleted.
This is a civil forum: no flames or drunken tirades.
Please stay on-topic.
PocketShip's Web Page: http://www.clcboats.com/pocketship
If you need CLC customer service: http://www.clcboats.com/forms/contact_us.html
We'll try to delete spam as soon as it appears.

Synthetic Rigging

Postby TassiePete on Sun Jun 04, 2017 2:03 am

I had a very interesting meeting with a local sailmaker re a set of sails for the PS. The most interesting part of the discussion was the question, why I would bother with 9x17 wires for the stays ( both, mast- and bob- ). An equivalent 4mm Spectra line ( Dyneema, or the like ) is stronger, much lighter, soft ( it doesn't attack the paint work ), less expensive/easier to install. Obviously, the appropriate knots and splices will have to used. Spectra even comes in a silver colour! I am seriously considering this option. Does anyone know, whether there are there any particular reasons that steel is necessary in this application ?

Cheers,

Peter
TassiePete
 
Posts: 46
Joined: Tue May 02, 2017 4:31 am
Location: Port Huon, Tasmania ( Down Under )

Re: Synthetic Rigging

Postby craig on Mon Jun 05, 2017 7:30 am

I didn't think to do that. It would save a lot of money (the swageing tool, wire, fittings, etc). Make sure you get one that is as strong as possible! And watch for chafing damage obviously.

The most important thing I've discovered on Pocketship is to properly tension the shrouds (the forestay will be tensioned by raising the jib, so it doesn't matter). My stays were tight but not VERYTIGHT when I first launched, and a day of really big wind caused some damage to the bulkhead. Now that I've tightened down the shrouds I haven't had any issue whatsoever. So I realize that spectra is low stretch, but if it stretches more than wire rope (??? presumably?), take that into account when you are tightening everything.
Titania, launched January 2015
craig
 
Posts: 252
Joined: Fri Feb 21, 2014 1:04 pm
Location: Chapel Hill, NC

Re: Synthetic Rigging

Postby mark48 on Mon Jun 05, 2017 9:44 am

Hi Craig,

Are you using turnbuckles between the shrouds and the chainplates - or the 2mm Spectra line used in PS #1 - and if so, can you tell me what turnbuckles you used?

Thanks,
Mark
mark48
 
Posts: 111
Joined: Fri Jun 28, 2013 9:55 pm

Re: Synthetic Rigging

Postby craig on Mon Jun 05, 2017 10:02 am

I have turnbuckles but haven't put them on yet. Unfortunately when I did the rigging I made the shrouds too long, so when I later got a pair of turnbuckles I couldn't fit them to the boat. I plan on buying a new set of swage parts and cutting my shrouds to fit, but haven't done that yet. What I did to make sure my rigging was tight was wrap a couple loops of line through the Chainplate in the cabin wall, and through the shroud ending. Pulling that tight, with all the force multipliers of the several rounds of the loop, made it good and tight.
Titania, launched January 2015
craig
 
Posts: 252
Joined: Fri Feb 21, 2014 1:04 pm
Location: Chapel Hill, NC

Re: Synthetic Rigging

Postby TassiePete on Mon Jun 05, 2017 4:27 pm

Stretch for Spectra seems not to be an issue until about 30% of the rated load. For low values, the stretch is about the same as for a steel cable. When the load goes up, the stretch is somewhat higher, but still a lot lower than for any other material ( including pre-stetched varieties ). The loads on a PS are reasonably low, but it is always possible to go up to 5mm line, which will almost double the max load ( and half the anticipated stretch ).
The biggest issue with low tension of stays is that any side-ways load on the mast will be taken up ( or not ! ) by the tabernacle, instead of being taken up largely by the windward shroud. On the other hand, a huge pre-tension on the stays will cause a tremendous compression force and make the whole rig very stiff. I guess ... it is a matter of tuning. If everything stays aloft in all weather conditions, then the setup is right.
I agree, it will be necessary to inspect these lines occasionally for wear. Then again, steel cable doesn't last forever either, and replacing Spectra lines will be less of a hassle than replacing wire cables.
TassiePete
 
Posts: 46
Joined: Tue May 02, 2017 4:31 am
Location: Port Huon, Tasmania ( Down Under )

Re: Synthetic Rigging

Postby Shudoman on Mon Jan 07, 2019 2:37 pm

I'm thinking of retrofitting my PocketShip with Dyneema. Has anybody done this? Or are we still in theory land? :D

Regards,
Bill
Shudoman
 
Posts: 138
Joined: Sun Feb 15, 2009 10:31 pm

Re: Synthetic Rigging

Postby TassiePete on Fri Jan 11, 2019 1:58 am

Hi Bill,

I am using Dyneema (4mm) for the shrouds and the bob stay (6mm). The reason I used 6mm for the bobstay is for looks only - the 4mm line just looked out of place. For the shrouds and the bob stay, I spliced eyes on each end (brummel self-locking) and used cow hitches (think luggage tag) to attach the lines to the hardware. The shrouds (at the bottom) and the bobstay (at the sprit) end in welded steel rings. The rings end up about 5" short. From there a few turns of 2mm Dyneema tighten up the rig. Everything is working fine.

IMG_0969.jpg
IMG_0969.jpg (79.43 KiB) Viewed 693 times


Cheers,

Peter
TassiePete
 
Posts: 46
Joined: Tue May 02, 2017 4:31 am
Location: Port Huon, Tasmania ( Down Under )

Re: Synthetic Rigging

Postby Shudoman on Mon Jan 14, 2019 9:28 am

Thanks Peter,

You've given me a couple of ideas on how to approach this. I've ordered the dyneema and it should be in sometime this week. Looking forward to this project.

Bill
Shudoman
 
Posts: 138
Joined: Sun Feb 15, 2009 10:31 pm


Return to PocketShip Forum

Who is online

Users browsing this forum: Tom G and 4 guests