Mooring line……

[NYSail]

So will be replacing mooring line. In the past have made my own using triple braid 3/4 and followed maine sails guide. This year I am considering premade lines and will again follow Rods guide. My boat is a 43 ft about 23,000+/- lbs. what tensile strength is appropriate? Saw these from defender and thinking the 5/8 line would be fine. Opinions??
Thanks!
Greg

 

[higgs]

If the old lines worked why not make the replacements out of the same thing?

 

[NYSail]

If the old lines worked why not make the replacements out of the same thing?

I am officially off the dock and full time on my mooring when not traveling so I want to upgrade the pendant strength. And they are a pretty color!

I just have a mental block when considering boat weight/length compared with line working load. Think there would be an easy formula. I am a bit perplexed how the charts I have seen only grid out a boats length and do not consider weight. Not all 43 foot boats are the same……


Greg

 

[Will Gilmore]

The displacement of the boat isn't so important as the windage and area under the water. The forces pulling on docklines will be from wind and current, not usually from gravity. Although...

I can't help but notice which side of the boat the fenders are on.

-Will

 

[twodzusfittings]

Can you provide more detail of exactly what you are looking for? Are you looking to replace your bridle, your pendant or mooring/ dock lines. West marine has a great help page. Go on line to Westmarine.com and type in Constructing A Permanent Mooring

 

[sailme88]

I went with Dynema..4 or more times stronger than traditional products.. so smaller diameter and less stiff make it very easy to bend over a cleat..

 

[Davidasailor26]

I went with Dynema..4 or more times stronger than traditional products.. so smaller diameter and less stiff make it very easy to bend over a cleat..

Dyneema would not be my choice for dock or mooring lines. This is a place where you want stretch to absorb shocks rather than transmitting them straight to the hull. Dyneema also has so little stretch that it doesn’t like being bent around hard points like cleats or tied in any kind of knot. It’s great for low stretch lines like halyards or for soft shackles where it’s spliced and not knotted.

 

[Terry Cox]

Hi Greg. Happy Easter. Rather prefer three strand nylon mooring line over polyester double/triple braid for the same reason when selecting ground tackle, it has flexibility. Please define a welded galvanized sling link; a shackle? If so, do they hot dip galvanize their product? Big distinction between galvanized and hot dipped galvanized in terms of long term corrosion resistance.

Never secure the mooring line working end from one cleat (port), through the mooring ring and securing the bitter end to an opposing cleat (starboard). Rather prefer two mooring lines, one as primary, the other as a backup with some slack in the event the primary fails.

When selecting ground tackle, the maker should spec their product by working load and breaking strength. Our boat displaces 35,000 pounds cruise ready, so I use 5/8" three strand nylon, which is more than adequate. Breaking strength normally doubles the working load.

Regarding the mooring, personal, private or public? How was it secured to the sea bed and what material was used to secure the anchor to the mooring float? Annually inspected/tested? Department of Natural Resource moorings around our precincts rate working load by boat length, with double boat length breaking strength. They inspect them annually, use helical coils to secure them to the sea bed and flat nylon webbing to connect the coil to the float using hot dipped galvanized shackles. This arrangement minimizes sea bed erosion. I've seen mooring conditions where I would not even tie up my dinghy. And others where our buddy boater drifted away due to a tether failure.

 

[TimFromLI]

I'm next door and my 45' uses 3/4" lines. Port Jeff Harbor gets rough with a NW wind. My boat weighed about 25,000# last year when launched. I've never had a problem.

 

[sailme88]

Dyneema would not be my choice for dock or mooring lines. This is a place where you want stretch to absorb shocks rather than transmitting them straight to the hull. Dyneema also has so little stretch that it doesn’t like being bent around hard points like cleats or tied in any kind of knot. It’s great for low stretch lines like halyards or for soft shackles where it’s spliced and not knotted.

I beg to differ...My dynama mooring pennants easily go under and bend over my fore deck cleats...

 

[Davidasailor26]

I beg to differ...My dynama mooring pennants easily go under and bend over my fore deck cleats...

It’s not that they won’t bend - it’s plenty flexible. The problem is that the fibers have so little stretch that when they go around a bend the outer fibers take all the load, rather than stretching and letting the inner fibers share any load. The rule of thumb with dyneema is to have a bend radius of at least 5:1 relative to the rope size ( for example Respect the rope- Dyneema lifeline guidelines ). This may be achievable on a cleat depending on the size of the cleat and line; it’s definitely a problem with any kind of knot.

 

[NYSail]

Hi Greg. Happy Easter. Rather prefer three strand nylon mooring line over polyester double/triple braid for the same reason when selecting ground tackle, it has flexibility. Please define a welded galvanized sling link; a shackle? If so, do they hot dip galvanize their product? Big distinction between galvanized and hot dipped galvanized in terms of long term corrosion resistance.

Never secure the mooring line working end from one cleat (port), through the mooring ring and securing the bitter end to an opposing cleat (starboard). Rather prefer two mooring lines, one as primary, the other as a backup with some slack in the event the primary fails.

When selecting ground tackle, the maker should spec their product by working load and breaking strength. Our boat displaces 35,000 pounds cruise ready, so I use 5/8" three strand nylon, which is more than adequate. Breaking strength normally doubles the working load.

Regarding the mooring, personal, private or public? How was it secured to the sea bed and what material was used to secure the anchor to the mooring float? Annually inspected/tested? Department of Natural Resource moorings around our precincts rate working load by boat length, with double boat length breaking strength. They inspect them annually, use helical coils to secure them to the sea bed and flat nylon webbing to connect the coil to the float using hot dipped galvanized shackles. This arrangement minimizes sea bed erosion. I've seen mooring conditions where I would not even tie up my dinghy. And others where our buddy boater drifted away due to a tether failure.

And a happy Easter to you as well!
I have always used 3-strand, however after reading Rods article on his mooring I thought I would switch.... again just trying to add a bit. Also, I have always had a double mooring pendant and not just the double spliced into a single line. Like the fact that two are attached and for me it keeps the boat pointing nicely into the wind. When severe storms are predicted I typically add an additional lazy bridle just in case. Our mooring is a personally supplied. 800 lb mushroom with 45 feet of chain in about 20 feet of water at high tide. Unfortunately it is pulled every year (harbor rules), however at least I do know the chain and all attachments are inspected annually and are good.

I have a call into them to find out some additional specs of the pendants including if the attachments are galvanized and eye size.

Thanks for the input
Greg

 

[jssailem]

The problem is that the fibers have so little stretch that when they go around a bend the outer fibers take all the load, rather than stretching and letting the inner fibers share any load.

This one part of the problems.

Because dyneema (though slippery to feel as each strand is coated) is just that strands the individual strands do not like to be bent. I took a length of dyneema, bluntly cut the ends, then buried them in the line to form a circle. I then took the loop and submitted it to a tension test. While it held to nearly the load strength of the line, it fractured where the buried ends were in the loop. The fiber contraction over the edge of the buried ends was enough fracture the fibers.

I theorize the heat generated by tension on the lines and the sharp turn of the fibers was enough to cause failure.

 

[Davidasailor26]

the sharp turn of the fibers was enough to cause failure.

Indeed. For that reason it’s very important that any splices in dyneema have tapered ends. The taper allows the outer layer to come down to its normal diameter without any sharp transitions.

 

[smokey73]

We had a recent storm at our mooring field. It was strong enough to tear out the Samson Post on one boat but I'm not sure that there might have been some unseen damage already existing. However, there was about a 40 foot center cockpit sailboat with a good deal of windage. I had noticed it had dyneema mooring lines and I had been concerned with that fact for some time since that type of line has little "give." I was concerned that with little give it might just rip out the cleats under shock loading or part where it went over the rubrail. Sure enough, both dyneema lines parted during the storm but luckily he ended aground up in the mud and was easy to get off. This was not a hurricane but a short duration windstorm.

Anecdotal, sure, but for reference, none of the boats in our field with traditional three strand mooring lines or with lines like the Yale Maximoor decided to "leave their mooring." I use dual Yale Maximoor lines rigged like Ron (Mainesail) recommends and take my anchor off the roller when I am going to be away for awhile or when a storm is predicted.