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Old 05-08-2021, 06:29   #1
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Pendant for storm mooring

Helping son in law set up a mooring for his 56' sport fisherman. He normally keeps it at a dock but the dock has no pilings to hold the boat off in a wind so he's setting up the mooring for bad weather.

The block, chain and ball are pretty straightforward but some questions about the pendant. Since this will be for nasty conditions he wants to go with something as bulletproof as possible and due to the size and weight of the boat (90,000 lbs fully loaded) he has found nothing off the shelf that seems appropriate. And since my experience with moorings (as opposed to anchoring) is minimal time to ask the CF experts.

From waterline to bow chocks is close to 10' so I think total length of the pendant from buoy to cleat should be about 30'.

My first idea for the design is a single, 15' nylon line from the chain for stretch, from there a double Dyneema bridle to the chocks and cleats for strength and chafe resistance?

Limited experience with Dyneema as well but I seem to recall it can be slippery so would there be a concern with the Dyneema slipping on a cleat? If so, maybe eye splices in the ends? Also am I correct in assuming Dyneema is more chafe resistant?
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Old 05-08-2021, 06:59   #2
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Re: Pendant for storm mooring

I’m considering screw anchors for my situation. You said “blocks”. As in massive lumps of concrete?
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Old 05-08-2021, 07:18   #3
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Re: Pendant for storm mooring

Quote:
Originally Posted by team karst View Post
I’m considering screw anchors for my situation. You said “blocks”. As in massive lumps of concrete?
Yep. A 6,000 lb block but it's sitting deep in soft mud so should have a good bit of suction to increase holding beyond just the weight of the block.

Due to the deep, soft mud in the spot he has permitted it was decided that screw anchors would not be effective.
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Old 05-08-2021, 07:39   #4
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Re: Pendant for storm mooring

Out of curiosity, how do you put a 3 ton block of cement in place? A crane?

And the hardware in the cement block is SS I assume?

Thought this was an interesting paper looking at various grades of SS in concrete.
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Old 05-08-2021, 07:42   #5
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Re: Pendant for storm mooring

Two Fortress 120 and a Fortress 85 . That’s a triangle which will hold him.
It’s my hurricane gear.
Mark
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Old 05-08-2021, 07:55   #6
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Re: Pendant for storm mooring

Quote:
Originally Posted by Bill O View Post
Out of curiosity, how do you put a 3 ton block of cement in place? A crane?

And the hardware in the cement block is SS I assume?

Thought this was an interesting paper looking at various grades of SS in concrete.
Local company that does mooring work: inspection, maintenance and installation has a small barge with a small crane arm mounted on one end. Watched him lift the 4,000 lb block on my mooring to inspect it and, other than sinking that end of the barge about a foot, managed to lift it easily. He tells me that after the block sits for a while he usually has to use a high pressure hose to blow water under the block to break it loose.

I asked about the rings as well. They are all non stainless which makes sense in the sense that stainless tends to be more brittle and lower strength than non stainless steel varieties. Also the top of the block tends to be in the mud so low oxygen environment which prevents rust in regular steel but promotes crevice corrosion in stainless. He claims the rings last many years and he almost never has one fail inspection.
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Old 05-08-2021, 07:56   #7
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Re: Pendant for storm mooring

Quote:
Originally Posted by Manateeman View Post
Two Fortress 120 and a Fortress 85 . That’s a triangle which will hold him.
It’s my hurricane gear.
Mark
In this situation two things. First there is not room for a three anchor triangle and second, the 6000 block is already installed.

What we're trying to decide on is the pendant, the rest is a done deal.
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Old 05-08-2021, 08:46   #8
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Re: Pendant for storm mooring

Quote:
Originally Posted by team karst View Post
I’m considering screw anchors for my situation. You said “blocks”. As in massive lumps of concrete?
Hi. Sent you a PM.
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Old 05-08-2021, 09:31   #9
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Re: Pendant for storm mooring

Quote:
Originally Posted by skipmac View Post
Helping son in law set up a mooring for his 56' sport fisherman. He normally keeps it at a dock but the dock has no pilings to hold the boat off in a wind so he's setting up the mooring for bad weather.

The block, chain and ball are pretty straightforward but some questions about the pendant. Since this will be for nasty conditions he wants to go with something as bulletproof as possible and due to the size and weight of the boat (90,000 lbs fully loaded) he has found nothing off the shelf that seems appropriate. And since my experience with moorings (as opposed to anchoring) is minimal time to ask the CF experts.

From waterline to bow chocks is close to 10' so I think total length of the pendant from buoy to cleat should be about 30'.

My first idea for the design is a single, 15' nylon line from the chain for stretch, from there a double Dyneema bridle to the chocks and cleats for strength and chafe resistance?

Limited experience with Dyneema as well but I seem to recall it can be slippery so would there be a concern with the Dyneema slipping on a cleat? If so, maybe eye splices in the ends? Also am I correct in assuming Dyneema is more chafe resistant?
I would use a pair of 3 strand nylon to absorb as much shock as possible. It might be easier on the deck hardware.
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Old 05-08-2021, 10:18   #10
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Re: Pendant for storm mooring

Hi. I did a post on this subject. Mooring Pendant Chafe Guard 7-18-20 #8.
We had a Dyneema core covered pendant spliced by Capt.Lasky in Westfield MA.
His phone is 877-568-4182. Consolidated Rigging in Jacksonville also can do it.
Rather than tube chafe guard, we used a two part polymer from Industrial Polymers in Houston Tx.
Best anti chafe I’ve ever used. Nothing to slip off. One gallon will do a couple of long pendants. Mix a very small batch and try it first on old line. We hung ours vertical and used a plastic pail to hold open the eye. You cannot believe how well it holds up. Lot of tugs are using it. The best source of really heavy duty hardware are people who sell to big fishing boats. I got my 3/4” and 1” stainless swivel in New Bedford. Used to pull scallop dredges.
Oceanographic equipment suppliers are another good source .
I understood they have a block but some readers might want alternatives which they can set and move without a crane. My bad getting off thread.
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Old 05-08-2021, 10:33   #11
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Re: Pendant for storm mooring

Quote:
Originally Posted by Bill O View Post
Out of curiosity, how do you put a 3 ton block of cement in place? A crane?

And the hardware in the cement block is SS I assume?

Thought this was an interesting paper looking at various grades of SS in concrete.
That is an interesting article. Putting stainless steel in an oxygen deprived environment in the presence of chloride molecules seems like a bad bet so the results of the study aren't surprising.

The industry is moving heavily toward fiberglass and basalt rebar, Neither will be attacked by moisture, disappear due to corrosion or swell from rust jacking which breaks the concrete.

The local box stores are carrying fiberglass rebar. Around me, it is cheaper than the steel.

I'd put a heavy loop of steel completely through the block and unless someone could prove that the block would be in tension, I wouldn't bother with rebar.

By the way, concrete plants make up these types of block from excess concrete and when they clean out their equipment. They can be had very cheaply if you have a truck that can transport the block.
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Old 05-08-2021, 10:34   #12
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Re: Pendant for storm mooring

Good vid on mooring setup
https://www.offcenterharbor.com/hm-hamilton-moorings-1804/

Good article on pendants
https://marinehowto.com/mooring-pendants-thoughts-musings/
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Old 05-08-2021, 10:39   #13
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Re: Pendant for storm mooring

I have a 52' cat that I may have to leave in the water in the Virgin Islands during hurricane season. The (untested) system that we designed with the help of the local mooring company involves six screws in sand, in water depth 10-12', placed in a circle about 15' diameter. They are all linked to a massive shackle and swivel. From there a larger chain to a floating mooring buoy and directly connected to the chain two 50' long 1"lines to take to our bows. A float attached at the end of the loops. These are three strand, going to Dyneema where its on the boat. While these 1" lines are intended to hold the boat (around 15-20 tons), we though we needed more spring if the waves got big so when a storm is imminent, we'll add smaller 5/8 nylon three strand lines which will be cleated slightly shorter so that they'll take the first shocks before the larger lines come into play.

The system is in place; how it's going to work is all theoretical so far.
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Old 05-08-2021, 11:40   #14
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Re: Pendant for storm mooring

Waited for a return call from a fellow Captain who is on Z tugs in NY. He suggests talking to Sampson after spending some time reading their technical bulletins.
They are using a Pro-Moor sewn onto Amsteel Blue. He also likes Chafe-Pro stuff.
R&W Ropes in NewBedford Ma are great guys for any rope questions.
Again, Consolidated Rigging in Jacksonville for perfect splicing jobs. 800-521-9473. Always pleased with their work and prices.
If you are limited in swing, take a look at Hazlett elastic mooring equipment.
A number of harbormasters are using them.
The experts in huge moorings and offshore oceanographics...Mooring Systems in Cataumet MA. They might give you more leads. Nobody has more experience in difficult applications as they do projects worldwide.
The Sampson Technical Bulletin on switching away from steel is directed at ships but the information can be applied to yachts as well. NyloMoor8 ? I’m not sure...
The Sampson guys will get you the right product.
Happy trails to you.
Captain Mark and his manatee crew.
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Old 05-08-2021, 11:51   #15
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Re: Pendant for storm mooring

Much more to think about than the rope. Chafe is the enemy. Here Wayne Hamilton tells how they make a mooring in Maine - https://www.offcenterharbor.com/vide...ayne-hamilton/
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