What is this and what do I use it for?

[chouliha]

A few years ago we weathered a few days of very swelly conditions in Papeete city marina. Floating docks were breaking up. We blew thru a bunch of dock lines mainly from chafe around the dock cleats even though we had the dock line running thru fire hose. The boat next to us (French) had the large springs hooked up. It made a huge difference. I watched for at least an hour as we jerked around. They do work! Don’t get rid of them

[David B]

Originally Posted by Muaddib1116

I bought my boat from a European who was in a hurry to get back to Europe, so he left the boat with a TON of stuff in it, which is great, but there's so much stuff that I'm trying to go through and organize. I just found these and I'm not really sure what they're for or how to use them. I assume it's some sort of setup for relieving shock loads on docklines in rough weather? There are two lengths of chain, probably 7/16" (I didn't measure) and the two large springs, and two ~15' lengths of 1" 3 strand, and a few shackles. All the hardware looks to be 316 SS. The two lengths of line seem a little short for docklines, especially for 1" 3 strand. I was thinking maybe the chain is supposed to go around a industrial style dock bollard?


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Yes, exactly. The springs are for shock load relief at a dock, and the chains go around a mooring bollard or cleat on the dock. These are seen a lot in Europe, but most are plated steel, so most are a rusty mess I would not want my name associated with. Nice set you have there, so hang on to them!

I would imagine going by those mooring lines and snubbers, that you will be finding some more treasures on your new boat. Sounds like a lot of fun you will have!

[Jack C]

The chain is connected in parallel to the spring so that if the spring breaks you are still attached. Springs are surge protectors, work well and are VERY expensive. Typically short line goes from spring to shore cleat. Long line from spring to boat cleat. Keeps the spring away from the hull.

[Haddock1]

Spot on with the answers. I have a set on my boat in Spain. Short lines for stern cleats. Still need to set a crisscross spring from boat cleat to opposite mooring bollard. Tighten up on the bow mooring line you are sorted. Nice and snug.

[Ron Bailey]

Originally Posted by Muaddib1116

I bought my boat from a European who was in a hurry to get back to Europe, so he left the boat with a TON of stuff in it, which is great, but there's so much stuff that I'm trying to go through and organize. I just found these and I'm not really sure what they're for or how to use them. I assume it's some sort of setup for relieving shock loads on docklines in rough weather? There are two lengths of chain, probably 7/16" (I didn't measure) and the two large springs, and two ~15' lengths of 1" 3 strand, and a few shackles. All the hardware looks to be 316 SS. The two lengths of line seem a little short for docklines, especially for 1" 3 strand. I was thinking maybe the chain is supposed to go around a industrial style dock bollard?


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Attachment 220666

These are used in Europe,in marinas to take any surge out when tied to shore!

[Sailorman4009]

These look very similar to cable tensioners used in garage doors on houses. Keeps constant tension on the cable before it wraps around the drum.
I prefer rubber tensioners as they do not rust and mar surfaces.

[GarryD]

Definitely an alternative to a rubber snubber for mooring lines, to take out "snatching" from waves caused by, for example, passing craft.



Two possible problems with them - they may rust depending on composition and they squeak like mad if not lubricated, great at 3 in the morning!

[thezephyrboy]

Take care with the chains. Some marinas dont allow them because they can grind away the alloy cleats leaving them broken or at least sharp edged for the next guys docklines.

[Franziska]

Just pull a piece of fire hose over the chain and they do not pose any problems.

[CarinaPDX]

As can be seen from the posts there are 2 usages for the chain: 1) parallel to the springs, for when they are overloaded and explode apart, and 2) around the marina attachment points, for chafe. These springs are sold in different sizes and it is important to get the right size for the boat, as too small and they can compress until there is no more room and they explode (seen it) - hence the safety chain. A heavy line around a bollard or cleat or through a ring is the proper way to do it. Using a chain causes excessive wear and in some Med marinas will get you in big trouble - it can be expensive to replace these parts. Ask first, or better just don't do it.

The problem with springs, and snubbers generally, is that they are energy storage devices, not shock absorbers (dashpots). For handling a single surge they work fine to allow the boat to move a bit with the water and then return to place. But with an in and out surge the first movement stores energy, and when the water reverses the boat accelerates with the combination of the pull of the water and the stored energy (like a child on a swing), causing the boat to move much further than normal. In the Med this usually means that the boat then hits the quay. I spent a year in Marina Bay, Gibraltar, which is justly famous for the sudden surges, and got a front row seat to all the things that go wrong with snubbers. It was there that I sold my nice rubber ones, and was able to improve the way the boat handled the surge (hint: don't use taught mooring lines).

Greg

[Fidsplice]

Interesting discussion. Could it also be used as a towing bridle?

[jimellifritt]

Originally Posted by Muaddib1116

I bought my boat from a European who was in a hurry to get back to Europe, so he left the boat with a TON of stuff in it, which is great, but there's so much stuff that I'm trying to go through and organize. I just found these and I'm not really sure what they're for or how to use them. I assume it's some sort of setup for relieving shock loads on docklines in rough weather? There are two lengths of chain, probably 7/16" (I didn't measure) and the two large springs, and two ~15' lengths of 1" 3 strand, and a few shackles. All the hardware looks to be 316 SS. The two lengths of line seem a little short for docklines, especially for 1" 3 strand. I was thinking maybe the chain is supposed to go around a industrial style dock bollard?


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Stern mooring in Med

[Xanthe]

Shock relief for stern to Mediterranean mooring. Usually these replace the lines used initially if staying for any length of time. The lines are short because the stern is very close to the dock for the passerelle to reach. Because the lines are short you need the springs. Med ports are busy with ferries and other traffic. Its acceptable to use chains on bollards or on dock rings.
You won't hear the noise of the chains. The disco across the quay will drown out the squeaks well into the early morning

[Haddock1]

Mine are permanently attached to the bollards and I leave them on the pontoon when I go sailing and reattach upon return. Obviously you need to be marina based.

I use normal mooring lines when returning, get the boat positioned, slime lines on and then attach the chain lines and then undo the mooring lines and use them as springs crossing to the opposite bollard to keep the stern fixed. Hope this makes sense.

[sycheckmate]

Chain is also used to go around rocks to prevent rope chafe when not in a marina or town dock