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Old 06-06-2020, 08:44 AM   #1
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Anchor bridle-above or below the water?

I have a slotted anchor chain plate attached to the chain with two lines attached to the bow cleats for a bridle. Should it be lowered to the water level or below the water? If below, how far below? Iíve done it both ways and donít notice any difference. Which is the preferred method and why? Thanks for your responses.
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Old 06-06-2020, 09:16 AM   #2
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We put the bridle hook a couple of feet below the water surface and let out another five feet or so of chain to add some weight. This works well in normal conditions by increasing the apparent scope of the chain. See avatar to left.

But when the wind really kicks up, the catenary of the chain will straighten out and where you put your hook will make no difference.

The primary purpose of the bridle is to avoid chain noise and add a bit of elastic stretch to the anchor set up.
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Old 06-06-2020, 09:34 AM   #3
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I am not an expert in physics or even in anchoring. But, it is my understanding that for anchoring in severe conditions, you want out as much rope (longer bridle) for purposes of lowering any shock loads. The nylon rope stretches quite a bit under heavy load (something like 15% I think), and it is this stretching that helps reduce stresses on your whole anchoring system. Under light conditions, it probably does not matter. I always put out about 15 feet of length (don't have much more length to work with, but thinking about increasing with a new bridle) on each leg, which puts my chain plate about 6 feet underwater. I also put out a fair amount of slack chain as this also seems to reduce the chain noise that can sometimes be annoying. I think to be effective as a shock absorber as I alluded to, you would need a much longer bridle than what I have. If expecting big winds, I find a safe, well protected spot with little fetch.
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Old 06-06-2020, 04:30 PM   #4
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Quote:
Originally Posted by gsholz View Post
We put the bridle hook a couple of feet below the water surface and let out another five feet or so of chain to add some weight. This works well in normal conditions by increasing the apparent scope of the chain. See avatar to left.

But when the wind really kicks up, the catenary of the chain will straighten out and where you put your hook will make no difference.

The primary purpose of the bridle is to avoid chain noise and add a bit of elastic stretch to the anchor set up.
All true, however an additional and important value of the bridle is it lowers the angle of the chain from the bow to the anchor which helps the anchor - esp important for boats where the end of the bowsprit is high above the water -like yours and mine. So... in those extreme conditions, where the chain is straightened, the lower the attachment point/angle of chain the better. BTW, if the wind kicked in enough to straighten the catenary and lift all the chain off the bottom - my pucker factor would be minus 3
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Old 06-06-2020, 05:50 PM   #5
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It's all about the geometry. There are too many variables with bow height, snubber length and elasticity, wave action and wind to provide a single correct response.

Doesn't matter if it's in the water or not. Whichever gives you the most comfortable ride is right.
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Old 06-06-2020, 06:13 PM   #6
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Seems to work better if it is under water. Like it improves the "scope" reducing the angle of the rode pulling on the anchor. Also, the longer the nylon lines, the more shock absorption one has with an all-chain rode.
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Old 06-06-2020, 07:13 PM   #7
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We put our well below the waterline simply because it gave is more "stretch". I also put a pretty hefty lazy loop of chain behind the hook as it was just that more weight for the boat to "lift" as it blew back. Whether the latter made any actual difference? Beats me. But it did serve to keep the plate more firmly attached. Most of the time, especially in fair weather you will be lying to one of the two lines as the boat horses around a bit. See photo below.

So you need to think of your scope and geometry as being the same as if you had a a rope/chain rode, because indeed that is what you have created. Because the rope is light, it actually slightly increases the potential angle of the chain to the anchor vs an all-chain rode and the attendant increased catenary. One other rationalization for the extra chain behind the hook. That said, in my opinion, these are from a practical matter inconsequential nits.

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Old 06-06-2020, 10:44 PM   #8
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I bought a bridle from Mantus. Very high quality, heavy duty, canvas covers strategic locations and long. Depending on which cleats I use it can add about 10-20' to the scope. Below is the link.

https://mantusanchors.com/mantus-bridle/

https://youtu.be/FA_wNBqTYAA
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Old 06-07-2020, 01:13 AM   #9
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My current bridle is about 16' for each leg and has worked fine. But I have chafed one of the 3 strands on both sides where going through the hawse hole so am about to replace it. I'll use the same length, with nylon rope again, as that had the chain hook about 6' under water and seemed to work fine. But as chafe protection this time I intend to use some PVC tubing in the large loop that goes through to hawse hole before I splice the loop.

I think you would need a much longer length to get any of the stretch benefit from nylon. My old nylon bridle is now quite stiff and I think it stretched to its limit, and stayed that way, a long time ago!

Last time I used a single piece or rope, with a "butterfly knot" in the centre to attach to the shackle that connected to the chain hook. But the issue with all knots is that they result in significant degradation of overall rope strength. This article indicates the butterfly is best, but you still lose 20% of the rope strength.
Knot Break Strength vs. Rope Break Strength

So this time around I'll splice a thimble into each of the side lines and use a large bow shackle to hold the thimbles. I'm also looking at making some soft shackles with dyneema to use instead of the bow shackle,
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Old 06-07-2020, 05:31 AM   #10
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"Also, the longer the nylon lines, the more shock absorption one has with an all-chain rode."

YES ,

To me the ideal length is a line that stops a foot short of the running gear and is attached at a robust eye just above the water line at the bow.

Nylon line takes 10 or 15% of its breaking strength to begin to stretch so thin line will give a better ride than heavy line, 3/8, 7/16 or 1/2 inch should be tried.

Should the line snap, (almost no chance) the chain or heavy anchor line still holds the boat.
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Old 06-07-2020, 09:32 AM   #11
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Let's see if I can clear up some of the mass of typos from my last post. I don't know where I got "light" from. Anyway, the bridle/hook assembly is pulling the chain up from the angle it would rest at sans snubber. So it reduces that last bit of catenary. That's another reason to have a long one.

I firmly believe you should use the same size rode as you would if you were creating a rope/chain rode. Even in strong winds, you will get seas and wind gusts from different directions that will have you lying to one of the two rope leads. I know of know stretchable underzed line that has the same breaking strength as the properly sized chain. Having something like that snap in storm conditions would be catastrophic to your boatside ground tackle... roller, pulpit/bowsprit, windlass and so on.

I know guys who have played around with the concept of a shorter snubber of smaller size, with a longer "back up" snubber of proper size, but none have fully tested it in real world storm conditions. The abrupt transition to chain or larger rope would still put great stress on everything.
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Old 06-07-2020, 09:35 AM   #12
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Quote:
Originally Posted by markpierce View Post
Seems to work better if it is under water. Like it improves the "scope" reducing the angle of the rode pulling on the anchor. Also, the longer the nylon lines, the more shock absorption one has with an all-chain rode.
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Old 06-07-2020, 09:53 AM   #13
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My snubber rope is quite long. If winds are expected to be mild, I keep the hook and rope above the water, less to clean in the morning. With higher expected winds, the hook is often below the surface. When the winds are expected to reach ugly, I set the length so that the hook is no closer than 2' to the bottom in still wind and current. Don't want the hook accidentally coming off the chain.

My snubber ties to a cleat. So it's a simple matter to lengthen the snubber rope and spool out more chain in the droop loop.

Ted
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Old 06-07-2020, 10:28 AM   #14
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Originally Posted by O C Diver View Post
My snubber rope is quite long. If winds are expected to be mild, I keep the hook and rope above the water, less to clean in the morning. With higher expected winds, the hook is often below the surface. When the winds are expected to reach ugly, I set the length so that the hook is no closer than 2' to the bottom in still wind and current. Don't want the hook accidentally coming off the chain.

My snubber ties to a cleat. So it's a simple matter to lengthen the snubber rope and spool out more chain in the droop loop.

Ted
I have used hooks. I don't like un-moused hooks for lots of reasons including their tendency to come loose with bottom contact. They may or may not have a working load rating. If one were to break, there will be a dent in your boat or you. I have come to prefer braiding a six-foot section into the ends on my twisted nylon snubbers which using a tautline hitch will hold both chain and nylon rode (I have a combination rode on my Pilot).
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Old 06-07-2020, 10:49 AM   #15
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I have used hooks. I don't like un-moused hooks for lots of reasons including their tendency to come loose with bottom contact. They may or may not have a working load rating. If one were to break, there will be a dent in your boat or you.
My hook is a 316 stainless steel forged Suncor with a working load limit of 2,500 pounds. It's never fallen off because it's atleast 2' (usually more than 5') off the bottom. If I were worried about it, I would zip tie it to the link it was grabbing.

https://www.defender.com/product.jsp?path=-1&id=3466475

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Old 06-07-2020, 11:29 AM   #16
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We use a homemade snubber/bridle:

>Mantis 3/8” chain claw - works well. Have used rolling hitch, prusik knot, slotted chain plate and chain hook but had various issues with all of them.

>Twin 3/8”x4’ dyneema slings with spliced eyes & heat shrink splice protection attached to the chain hook.

>Twin 3/4”x30’ 3-strand nylon lines attached to the slings with eye splices and SS thimbles led through hawse pipes to large foredeck cleats. Recycled fire hose for chafe protection.

At the other end is a 125# Mantus anchor. Normally we use about 20’ of the nylon lines but have used all 30’ for heavier conditions.

In the Berry’s this year we were anchored well off Bonds Cay in a fairly large area with 10 depths. Surrounded by shoals and cays but still 2+nm from solid land in any direction.

We expected squalls but began to hear VHF chatter from the anchored cruise ships about 50 kn winds and cruisers dragging in Great Harbour. We put out 200’ of chain and full length bridle. Within a half hour we had 40-50 knots for two hours and 4’ waves in the anchorage. As the bow dipped and rose the chain broke the surface of the waves. Not sure if it was fully stretched but it sure looked like it. Although we swung 180 degrees the anchor did not move and the snubber did it’s job.
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Old 06-07-2020, 11:45 AM   #17
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Quote:
Originally Posted by O C Diver View Post
My hook is a 316 stainless steel forged Suncor with a working load limit of 2,500 pounds. It's never fallen off because it's atleast 2' (usually more than 5') off the bottom. If I were worried about it, I would zip tie it to the link it was grabbing.

https://www.defender.com/product.jsp?path=-1&id=3466475

Ted
It is only good for chain. A fiber snubber can be used for a variety of things including taking the strain on a taut mooring line while you take the line to a windlass, etc, etc. You might just want to have both options aboard to complete your bosun locker.
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Old 06-07-2020, 11:49 AM   #18
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Has anyone mentioned that the snubber removes the load on the windlass?
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Old 06-07-2020, 12:09 PM   #19
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It is only good for chain. A fiber snubber can be used for a variety of things including taking the strain on a taut mooring line while you take the line to a windlass, etc, etc. You might just want to have both options aboard to complete your bosun locker.
I have several choices in my snubber arsenal including 2 different hook and plate setups. Not afraid to tie a modified rolling hitch if needed.

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Old 06-07-2020, 12:24 PM   #20
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Has anyone mentioned that the snubber removes the load on the windlass?
A given.
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