Ropes
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Hi All,
Just wanted to reach out to discuss growline ropes.
We have been working with the 5 bar spreader system with a few tweaks over the last few years. Our choice of growline ropes has been polysteel (a form of polypropylene). It's been a struggle to keep the tension on our lines as the season has progressed. Potentially the polysteel is elongating under the tension of the anchors. Looking forward using a polyester rope could be a good alternative.
Has anyone had a similar experience and or any recommendations?
Cheers,
Toby
BluGreens
Hi @tobias_stevensfleming47 - we've used dead-tensioners developed by TendOcean/@clifford_goudey to maintain 5-line and catenary systems under tension. You can see a see a brief description here: https://afdf.org/asset/649b26bab7d3b/Kelp%20Cultivation%20Lessons%20from%20Kodiak%20v2%20(2).pdf
But Cliff can provide you with more details and tensioners.
Cheers!
Loretta
@loretta_roberson thats great thanks! Looks like the sort of thing that i need to help tension. What type of growlines are you using?
@clifford_goudey it would be great to hear more about the tensioner if possible?
Cheers,
Toby
@tobias_stevensfleming47 The hub has a section on dead-tensioners here including a video of the system underwater.
@loretta_roberson thats great thanks! Looks like the sort of thing that i need to help tension. What type of growlines are you using?
@clifford_goudey it would be great to hear more about the tensioner if possible?
Cheers,
Toby
@tobias_stevensfleming47, I've never compared the creep or Polysteel to other rope formulations, but I think some permanent stretch over time is inevitable with most synthetic lines. With single-line rigs its a simple matter of re-tightening things at slack low water. With multi-line spreader bar rigs where the individual lines are carefully measured to be equal lengths, system tightening must occur at one of the anchor lines. However, loads there are much higher and things become difficult.
The deadeye tensioning system was developed to solve this and is installed on one or both ends of the array between the spreader bar bridles and the top of the anchor line.
It is essentially an underwater block & tackle with no moving parts. The two deadeyes are molded in high-density polyethylene, which is slippery enough to provide a 6:1 advantage. It's best to use a braided line for the tensioning line, as 3-strand tends to twist things up, increasing friction.
If you reach out to me at cliff@cagoudey.com I can provide you more details. Thanks for the mention, Loretta.
@clifford_goudey thanks very much for this info. I to s very helpful. Is this something that I can buy off the shelf?
@tobias_stevensfleming47 The hub has a section on dead-tensioners here including a video of the system underwater.
@clifford_goudey thanks very much for this info. I to s very helpful. Is this something that I can buy off the shelf?