Attaching anchor chain to bridle?

[SailRedemption]

Originally Posted by estarzinger

6500lbs is quite a bit of load for anchoring.

I used 10mm climbing line for a snubber for a long time - I'm not sure it's tensile was all that much higher than that (10mm nylon double braid looks to be only 5000lb tensile at NER)

And I might also comment that I have test broken a number of 'Amateur' made soft shackles that came apart before that (primarily knot not set firmly enough and tails cut too short).

No short burys here and my buttons are pretensioned. My shackles are made according to SWL instructions on here. I wasn't implying that 5k lbs was not a lot just that that particular hook looked like it would be stronger than that. Thanks for the other information though, good to know.

[estarzinger]

^^ It is just useful to know what sort of functional load you need to hold, and 6k lbs is just a pretty high load on a typical boat. I could deform quite a few 'strong looking' stainless yachting bits on my test bench in the 5-10k lbs range.

For anchoring - PS published these:



The top two graphs show under 1k lbs at 30-35kts and the bottom graph shows a bit over 2k lbs at 60kts.

I never did as systematic measurements, but those are consistent with what I did measure.

on a slightly different point - I also agree with this comment in the same article " the current crop of anchor tests are telling us that even anchors with less-than-stellar holding power are more than adequate for the typical loads we can expect when anchored."

[svrevelations]

Originally Posted by PaulinOz

I have been using on of these on a 40 kg anchor and 13 mm chain for past 3 years. It has fallen off the chain once in that time. Probably because I had calculated the low tide height wrong and it and us where both sitting on the bottom.

As the chain comes up over the bow roller it hits the roller and drops down off the chain and the bridle can then pulled aboard.

As it is deployed we ease the bridle out until it is taking the weight of the chain then release.

We have the Osculati hook on our 50' catamaran. The hook fell off the chain almost every time we anchored in shallow water when it laid on the ocean floor. However, it is a strong hook and worked perfectly for us once when it blew in access of 55 knots.

[PaulinOz]

Originally Posted by Revelations

We have the Osculati hook on our 50' catamaran. The hook fell off the chain almost every time we anchored in shallow water when it laid on the ocean floor. However, it is a strong hook and worked perfectly for us once when it blew in access of 55 knots.

How long are your bridle arms?

[svrevelations]

Originally Posted by PaulinOz

How long are your bridle arms?

The arms are each around 8.5 meters in length. In shallower water and calm weather we shorten them by tying them off around cleats on the cross beam. The Osculati hook only falls off when it touches the ocean floor.

[PaulinOz]

Originally Posted by Revelations

The arms are each around 8.5 meters in length. In shallower water and calm weather we shorten them by tying them off around cleats on the cross beam. The Osculati hook only falls off when it touches the ocean floor.

Ok that explains it, ours are 4.5 meters each so needs to be quiet a bit shallower for us to touch bottom with the bridle hook than you.

[StuM]

Originally Posted by Revelations

The arms are each around 8.5 meters in length. In shallower water and calm weather we shorten them by tying them off around cleats on the cross beam. The Osculati hook only falls off when it touches the ocean floor.

I prefer each leg of the bridle to be less than the boat's beam. Any more than that and you get this problem and more swinging at anchor.

[mark_morwood]

Originally Posted by PaulinOz

Ok that explains it, ours are 4.5 meters each so needs to be quiet a bit shallower for us to touch bottom with the bridle hook than you.

I would be cautious using bridles that are lot shorter than the beam of your boat. The loads on the individual bridle legs and the force trying to pull your bows/cleats together go up quite quickly. Not a problem in normal conditions, but if the wind gets up, its good to be able to let some more length out on the bridle legs to reduce the stress in the system.

With legs of 4.5m with a 7.5m beam, the load in each individual bridle leg is >90% of the anchor load, and the inward force you are putting on each bow and cleat is >75% of the anchor load.

With legs equal to the beam the load in each leg is <60% of the anchor force and the inward force on the bows and cleats is <30% of the anchor force. If you go to 1.5 x beam, the respective loads are 53% and 18%.

[Dauntlessny]

Originally Posted by Suijin

In my experience it's not what hook you use but how big of a loop of slack chain you let out behind it. It's that weight that keeps it on.

Exactly. I use a Home Depot chain hook. It never falls off, but you must have weight in the loop, so that if your chain goes slack, there is still weight on the hook.

In addition, in shallow water, make sure your snubber can not touch bottom.

Richard on Dauntless

[PaulinOz]

[QUOTE=mark_morwood;2397041]I would be cautious using bridles that are lot shorter than the beam of your boat. The loads on the individual bridle legs and the force trying to pull your bows/cleats together go up quite quickly. Not a problem in normal conditions, but if the wind gets up, its good to be able to let some more length out on the bridle legs to reduce the stress in the system.

With legs of 4.5m with a 7.5m beam, the load in each individual bridle leg is >90% of the anchor load, and the inward force you are putting on each bow and cleat is >75% of the anchor load.


Mark do not make the mistake of using a vessels Beam to calculate the bridle length unless the attachment points are at the widest point of the hull.

In my case
Beam = 7.9 meters
Bridle Length = 4.5 meters
Distance between Bridle attachment points = 4.5 meters.

The attachment points on my vessel are very large eye bolt attached to each end plate of the cross beam. Any inward force would place the cross beam under compression, which would be it's strongest load bearing direction.

So from your figures

"With legs equal to the (separation between the legs) the load in each leg is <60% of the anchor force and the inward force on the bows and cleats is <30% of the anchor force."

Which sounds about right to me .

[mark_morwood]

Good point. Sorry to not be clearer. As you point out, it is the distance between the mounting points/cleats that matter. I'm used to a boat with narrower hulls and using the common mooring/docking cleats which tend to be towards the outside of the hull so the beam was a good approximation to the distance between the cleats (+/- a meter or so).

Also to be clear, I was really just suggesting a caution for when the wind/loads were high. There are circumstances where we would happily use shorter bridle legs, e.g. on a mooring to make sure the mooring ball didn't hit the inside of the hulls, or because of limited swinging room.

[Nomadscot]

Originally Posted by Privleoplag

The large eye is for the bridle retrieval line.

Thank you.

I think I might be trying to read more into this hook than there actually is.

For instance, I'm trying to fnd a reason why that eye is so un-necessarily large, and the 'U' shape at the bottom seems to lend itself to a tripping line.

[mikedefieslife]

I too have one of these. Hate it. It's strong as hell, but I find it very difficult to get on the chain. No chance if there is any tension. It's big and awkward, and will fall off until it's tensioned, so there is the risk of it coming off when the bridle first hits the water.

Goes without saying, this think shouldn't be anywhere near the bow roller.

Defiantly want an alternative.

[stevenit]

Always used the rolling Hitch, bad experiences with a lot of different hooks

[jbinbi]

Anyone have any experience with this from Kong products

Chain Gripper | KONG USA

It has a pin, so you can't lose this and it won't slip with the pin in it. I purchased a manta shackle with their ingenious method of slipping it on, but the thing is huge. This looks very small and seems easy to use...