Who Needs a Snubber, Anyway?

[Wind Shadow]

Yes, if you have the room a long scope of chain you don't need a snubber. but for short scope in a tight anchorage it would be good. I've been at anchor with a hundred or more feet of chain and by the time the shock gets to the windless it's minimal. No snubber is needed as the chain takes the shock.

[powsmias]

Originally Posted by a64pilot

I usually anchor in less than 10' of water, yet my snubber is actually a bridle, but is 25' in length minus the foot of so it took to tie a loop in it.
If I have the snubber on, then there is enough wind to keep it off the bottom, but so far even if it touches bottom, no harm as I use the Mantus chain hook and it will stay on.

I have not anchored in coral or rock, that may change my attitude that no harm if it touches the bottom of course

Same here.. just picked up a bridle from mantus with the chain hook and think it's a no brainer .. nice setup, think i'm gonna be happy..

[leftbrainstuff]

You only need a snubber if your chain goes taught.

If the weight of chain is greater than the largest steady state load the vessel experiences then you wont need a snubber. (Allowing for the appropriate force vectors)

We use a stretchy line through the cleats to take the load off the windlass. This acts as a snubber due to stretch avoiding the need for a dedicated snubber.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[tomfl]

Just finished the whole thread. What strikes me as not being addressed yet is that there is no one size fits all solution. 100 meters of 1/2 inch chain weighing 700 pounds is significant ground tackle but I have to wonder just how many CF posters are using it. While we would all like to be the only boat in an anchorage the reality is that not many of us can do that. Not trying to start a cat v mono thing but every cat I see seems to use a bridle which is a defacto snubber. Lots of cats I see not only use a bridle but wrap the line around some of those rubber things West Marine (and other places) sell as snubbers. The bridles on monos are often shorter and may have problems with hitting the bottom. We also see some folks are in places where anchoring in 10 feet of water with a nice sand bottom is the norm while others are in places with deeper water and not uncommonly more crowded.

To figure out if you should, or should not need or, use a snubber you need to know what boat is anchoring and where it is anchoring at a minimum. Making a blanket statement about use of a snubber is silly.

[Kenomac]

Originally Posted by SVTatia

Kenomac, is that reel part of your custom super snubber? Can you share the details?

The reel is part of a spinnaker furling system, Our snubber looks like the one pictured on steroids. One inch braided rope, two lines running back to large deck cleats over the bow rollers with anti chafing gear. The rubber shocks are the biggest docking shocks I could find, maybe two feet long and two inches thick. 12mm Ultra chain grab on the end.

[Dockhead]

Originally Posted by thinwater

Why Dyneema? Does it do anything better than polyester or a lashing in this application, other than harder to cut? I'm not feeling the usefulness. Personally, I find Dyneema to be overused.

I don't think dyneema is overused at all. It's perfect for this kind of use because it's a snap to splice, like 10x easier to splice than polyester double braid, and because it's highly resistant to chafe, two huge advantages over other kinds of rope for a use like this.

Dyneema has few downsides, not even really cost if you downsize the rope, and by next year, my boat will have almost no polyester left on her, other than dock lines. I will not really be using polyester rope anymore except where some stretch is specifically needed, like for anchor rode, dock lines, etc.

[Dockhead]

Originally Posted by Kenomac

The reel is part of a spinnaker furling system, Our snubber looks like the one pictured on steroids. One inch braided rope, two lines running back to large deck cleats over the bow rollers with anti chafing gear. The rubber shocks are the biggest docking shocks I could find, maybe two feet long and two inches thick. 12mm Ultra chain grab on the end.

That's cool -- and I was thinking about the rubber buffers myself.

They work terrifically well on dock lines. Why not for snubbers?

And taking it one step further -- why could you not have a hydraulically damped rotary spring to take your chain? It would be easy to design it so that you could "tune" it for different conditions, and it could be designed to be strong enough to belay the chain at the same time.

[Dockhead]

Originally Posted by tomfl

Just finished the whole thread. What strikes me as not being addressed yet is that there is no one size fits all solution. 100 meters of 1/2 inch chain weighing 700 pounds is significant ground tackle but I have to wonder just how many CF posters are using it. While we would all like to be the only boat in an anchorage the reality is that not many of us can do that. Not trying to start a cat v mono thing but every cat I see seems to use a bridle which is a defacto snubber. Lots of cats I see not only use a bridle but wrap the line around some of those rubber things West Marine (and other places) sell as snubbers. The bridles on monos are often shorter and may have problems with hitting the bottom. We also see some folks are in places where anchoring in 10 feet of water with a nice sand bottom is the norm while others are in places with deeper water and not uncommonly more crowded.

To figure out if you should, or should not need or, use a snubber you need to know what boat is anchoring and where it is anchoring at a minimum. Making a blanket statement about use of a snubber is silly.

I agree completely, and I don't think anyone has made any blanket statements. The title of this thread is somewhat tongue-in-cheek.

For the record -- not using a snubber is NOT good practice, because, as someone said, once the chain starts snatching hard up -- where the snubber will not only improve comfort but will be preventing actual damage -- it's too late to rig it.

Best practice is to ALWAYS rig a snubber. I was just sharing the results of my experiments in laziness, which have been surprising to me. What I learned was that with my ground tackle, the point where the chain starts snatching hard up comes much later than I expected. With lighter ground tackle, shallower water, etc., that point will come sooner.

[Dockhead]

Originally Posted by leftbrainstuff

You only need a snubber if your chain goes taught.

If the weight of chain is greater than the largest steady state load the vessel experiences then you wont need a snubber. (Allowing for the appropriate force vectors)

We use a stretchy line through the cleats to take the load off the windlass. This acts as a snubber due to stretch avoiding the need for a dedicated snubber.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

I agree with the first statement -- the point where catenary comes out has nothing to do with the depth of the water, contrary to what someone posted above. It is a function of load vs length and weight of the chain. Simple catenary function; can be worked out mathematically.


As to using a stretchy line to "take the load off the windlass" -- hmmm, I'm biting my tongue here. You are an engineer -- is the "stretchy line" as strong as your chain? If not, then do you know what the strength of the whole system is? I guess in your first day of engineering school, or even earlier, you learned that a chain is only as strong as its weakest etc. Do you know that "stretchy line" is subject to chafe and internal heating and is well known for failing at a fraction of its rated strength? I sure hope that "stretchy line" is not the only device you have "taking a load off" your windlass; i.e. belaying the chain, or you have created a drastic weak point in your ground tackle.

[/SERMON MODE OFF]

[GordMay]

Greetings and welcome aboard the CF, Mike.

[boatman61]

Originally Posted by tomfl

Just finished the whole thread. What strikes me as not being addressed yet is that there is no one size fits all solution. 100 meters of 1/2 inch chain weighing 700 pounds is significant ground tackle but I have to wonder just how many CF posters are using it. While we would all like to be the only boat in an anchorage the reality is that not many of us can do that. Not trying to start a cat v mono thing but every cat I see seems to use a bridle which is a defacto snubber. Lots of cats I see not only use a bridle but wrap the line around some of those rubber things West Marine (and other places) sell as snubbers. The bridles on monos are often shorter and may have problems with hitting the bottom. We also see some folks are in places where anchoring in 10 feet of water with a nice sand bottom is the norm while others are in places with deeper water and not uncommonly more crowded.

To figure out if you should, or should not need or, use a snubber you need to know what boat is anchoring and where it is anchoring at a minimum. Making a blanket statement about use of a snubber is silly.

Having owned cats in the past one learns pretty quickly that a bridle is the way to go with a cat at anchor.. it gets the bows facing square into the wind which in turn stops the sailing around and reduces loads on one or the other hulls deck cleats.
As for long snubbers/bridles on mono's.. longest I ever go is about 4-5 metres.. just long enough to hang a decent bight of chain aft of the snubber to aid in keeping the chain as low as possible without the chance of being hooked by a passing boat or snagging the bottom.. to my mind 30+ft is pointless overkill.
But.. each to their own thinking.

[conachair]

Originally Posted by Dockhead

They work terrifically well on dock lines. Why not for snubbers?

Because of the energy involved.

A boat at a dock never really gets much speed up, in my experience the worst anchor loads are when the boat tacks and gets some way getting stopped by the chain. A decent length snubber allows this stopping to happen over a longer distance/time than a rubber mooring dogs bone. Force = mass X acceleration , so the force on the anchor is less.

[Dockhead]

Originally Posted by conachair

Because of the energy involved.

A boat at a dock never really gets much speed up, in my experience the worst anchor loads are when the boat tacks and gets some way getting stopped by the chain. A decent length snubber allows this stopping to happen over a longer distance/time than a rubber mooring dogs bone. Force = mass X acceleration , so the force on the anchor is less.

Sure, but why not for the initial compliance? No one suggested using it INSTEAD of a stretchy snubber line.

This would allow a stouter line to be used for the snubber itself, providing more total energy absorption, but giving some soft initial compliance for the smaller impacts. I like the looks of Kenomac's system.

[conachair]

Originally Posted by Dockhead

I agree with the first statement -- the point where catenary comes out has nothing to do with the depth of the water, contrary to what someone posted above. It is a function of load vs length and weight of the chain. Simple catenary function; can be worked out mathematically.

Maybe I'm reading that incorrectly, but it sounds just plain wrong. It takes much more force to lift the chain off the seabed in deep water than it does in shallow.

Try playing around here,
Cable Sag Error (Catenary Curve Effect) Calculator

A 1000N (about 100Kg) horizontal force will just lift the chain in 26m of water, in 12m of water 200Kg is needed.

It has everything to do with depth of water.

[Kenomac]

Originally Posted by Dockhead

Sure, but why not for the initial compliance? No one suggested using it INSTEAD of a stretchy snubber line.

This would allow a stouter line to be used for the snubber itself, providing more total energy absorption, but giving some soft initial compliance for the smaller impacts. I like the looks of Kenomac's system.

Dockhead,

Here's a picture of our snubber in use, it shows how the snubber lines lead back to the cleats. They run over the bronze bow rollers through anti chafe protectors, then outside the railings and back to the cleats. We have set up so that all I need to do is drop the loops over the cleats.