Who Needs a Snubber, Anyway?

[Dockhead]

Someone on here, some years ago, suggested that with a decent amount of heavy chain out, no snubber at all is needed in reasonable conditions. Based on his experience on ships, I believe, which obviously don't use snubbers.

I was taken aback by the idea -- snubbers protecting the boat from snatch loads has always been doctrine, which was beaten into my head practically in the cradle.

But I do have heavy chain -- 12mm or 1/2", weighing 3.3kg per meter, so 330kg or more than 700 pounds for all 100 meters of it. Besides that, I never anchor in crowded anchorages and practically always have the ability to let out as much chain as I want.

So I've been experimenting with leaving the snubber off.

Surprisingly -- even in 25 knot winds and choppy water, as long as I have at least 60 or 70 meters of it out -- it does not ever seem to come anywhere near snatching, and works just fine, without a snubber.

Yesterday, the wind shifted and deprived me of my shelter, exposing me to a long fetch, with wind gusting in the low '20's. It was uncomfortable, so I moved, but with 80 meters of chain out, I felt no need for the snubber. The chain catenary was fully damping out all snatching.

I do put on the snubber now if I expect any kind of weather -- just not to take the chance. But in in calm weather -- you know, those high pressure days when there won't be more than 10 or 15 knots, and you have good shelter -- it's a no-brainer to leave off the snubber and save the time of rigging it, and unrigging it later.


I do of course strongly belay the chain, taking the load off the windlass. I use a length of SS chain made off to my inner forestay chain plate with a heavy shackle, and a chain hook on the other end. But I do that whether or not I'm using a snubber.

[Mirage35]

Interesting - the reason I've always been given for using a snubber was specifically to take the load of the windlass. Since you're doing that by other means your logic makes sense to me.

Not that I have any experience with the kind of conditions where snatch loads would be a serious problem.

[fallingeggs]

I noticed the same thing recently when on a boat with much heavier chain than I have (my 5/16 to his 1/2). In 20 knot winds with near 175 feet out in 30 foot of depth, the chain never got close to becoming tight.

The skipper did not, however, take the load off the windlass. Didn't seem to matter when the windlass only saw the weight of, maybe, 60 foot of chain.

I guess the question is "what if..."?


Sent from my iPhone using Cruisers Sailing Forum

[Tetepare]

I have snubbers everywhere including dock lines and the dinghy painter. Call me nuts.

[Kenomac]

We always use our custom "super snubber" because one never knows. When I left the anchorage in the dinghy to take my wife to the airport two hours earlier, nothing like this was in the forecast, it began while I was away. Also, we never get the grinding chain sound which trasmits through the foreward cabin caused by the chain rubbing side to side across the bow roller. With the snubber, the boat is silent.

https://m.youtube.com/watch?v=9lyypubKVrU

[Dockhead]

Originally Posted by AnglaisInHull

Interesting - the reason I've always been given for using a snubber was specifically to take the load of the windlass. Since you're doing that by other means your logic makes sense to me.

Not that I have any experience with the kind of conditions where snatch loads would be a serious problem.

There has been a lot of conversation about using the snubber to take the load off the windlass.

Many people do it, but in my opinion it's very bad practice, because the snubber by its very nature is weaker than the rest of the system and introduces a weak point. Snubber are almost always nylon, and are designed to stretch and absorb shock and after enough of this, they can break.

Belaying the chain should be done in a way NOT designed to stretch and flex, and which will be as strong as the chain, otherwise why have chain that strong at all? Two different and separate tasks -- snubbing, and belaying the chain, have very different requirements, and shouldn't be done with the same device.

Apologies to anyone who's heard this rant of mine before, and are tired of it.

[conachair]

here's a graph I did a while ago looking at scope. The Y axis is scope and the X axis is depth of water. What it shows is how much scope is required so that 230Kg just lifts the last link of 10mm chain off the bottom.
(Blue line is 2 x depth plus 24m, close to the equation)

https://www.desmos.com/calculator/uay5wg7p31




One major drawback about the catinary as a shock absorber is that when the forces get up it takes a very short distance to go from chain on the bottom to bar tight, what a snubber does is decelerate the boat over a longer distance so keeping the force on the anchor down.
Properly sized it shouldn't break.

[Dockhead]

Originally Posted by Kenomac

We always use our custom "super snubber" because one never knows. When I left the anchorage in the dinghy to take my wife to the airport two hours earlier, nothing like this was in the forecast, it began while I was away. Also, we never get the grinding chain sound which trasmits through the foreward cabin caused by the chain rubbing side to side across the bow roller. With the snubber, the boat is silent.

That's a good reason for rigging a snubber, and I would certainly do it in those circumstances.

I don't have any grinding sound without the snubber -- my bow rollers are bronze and roll freely. Also, the forward cabin is rarely occupied outside of the summer when I have crew on board.

[a64pilot]

I'm lazy, I never set the snubber unless there is significant wind, I never hear anything from my bow roller either, its a sort of hard rubber. Where I am, any real wind is either from a squall, or almost always well forecasted, and then I run for a Bayou that is well protected from wind.
I haven't yet left the boat for any significant time though, but setting a snubber then would I think be smart

[valhalla360]

Where did the idea that a snubber should be a weak point come from? It should stretch. While I don't object to having a backup if it does break, it shouldn't be designed to break. There's nothing wrong with making it just as strong or even stronger than the chain as long it allows for sufficient stretch.


But to the original point, yeah in moderate conditions where you will be onboard a large amount of chain will act as a snubber, especially with 100m of large chain out. The risk is if you leave for a long period of time or in an area without accurate forecasts a strong storm or even squall will use up the catenary and you get snatch loads. This is also a good reason not to design the snubber to fail. If it does expect a heck of a snatch load when the chain finally does pull the boat up short.

[Mike OReilly]

I occasionally anchor without setting our snubbers, but that is the exception. Setting my snubber bridle is so easy, I don't really think about it. It's just part of the anchoring process.

I don't consider my snubbers to be a weak point, and it's not there to take the load off the windlass (I use a well-backed chain hook for that job). In addition to limiting shock loads the snubber silences our roller noise, and the bridle further limits any sailing around at anchor.

Most of the time I probably don't need the snubbers, but when you need them, they are sure good to have out. I think of it like reefing; it's a lot easier to do it early than to wait until things pipe up.

[boatman61]

I use a snubber for the same reason as Keno.. tho' its to cancel the rumble one gets in the fore cabin as the chain drags across the bottom during tide and wind shifts in the night.. however that's all I use in mild conditions.. if the wind kicks up I will add a short chain stop on deck set with a little slack in case my hitch fails or the line parts.. the noise when the twine snaps and the slack is taken up alerts me to tend the bow.
But snatching with my 'Scope' is only if sea's get to 1 metre plus and I'm usually outa there before that happens.

[mikeo16]

It also seems that there are large variations in use for the length of snubbers. On the east cost of the states, it is quite common to be anchoring in a water depth of less than 10 feet. In these cases, most people tend to have a very short snubber so that it is not dragging on the bottom. So, if you are anchoring in 10 feet of water, then your snubber length will likely by under 10 feet in length. The specs for a 5/8" 3-strand nylon line indicate a stretch of between .1 and .2 which would translate to a 10 foot snubber stretching between 1-2 feet. Most guidelines on snubber length indicate that it should be around 30 feet, but in practicality I have never seen a snubber in use that long. What length snubber are most people using?

[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

[S/V Alchemy]

Snubbers and bridles move the attachment point forward of the bow and down to the WL. Assuming they are fit for purpose, they lessen the tendency to hobby horse because the catenary is, by virtue of being a shock absorber, also a sort of spring in that wave motion stores and then uses energy in the chain.

While I'm a strong proponent of "do what works", I have a nice half-inch steel plate a the WL of the bow for a reason, and while I don't also use it in benign weather, the one thing a sailor knows is the difference between a lubberly forecast and the local reality, as seen in Kenomac's helpful video clip.