What size for snubber?

[Sabbatical II]

My boat is 42' and about 15t loaded with plenty of windage. I have 3/8 short link anchor chain. If I use nylon for the snubber line, what diameter and length is would you recommend?

[Don L]

I use 3/4" x 20'

[estarzinger]

Originally Posted by Sabbatical II

My boat is 42' and about 15t loaded with plenty of windage. I have 3/8 short link anchor chain. If I use nylon for the snubber line, what diameter and length is would you recommend?

'Everyday' snubbers can be quite small. We have used 10mm nylon climbing lines for years and it's been perfect (47' boat with 3/8" HT chain anchor rode) - easy to handle, compact to stow and stretchy. It will need chafe protection - we use fire hose. The only problem we ever had with the climbing line, was in a hurricane near miss in Antigua (+50kts for about 48hrs), where the cover chafed apart but the core still held.

After that Antigua experience, and say about once very couple years, when we get a forecast for lots of wind (say +50kts) and are in a bigger anchorage with some fetch, we do deploy our 'heavy duty' snubber which is two pieces of 5/8" on a bridle to a chain plate. I don't know if its really ever been necessary but does let me sleep better.

[jcapo]

Depends on the wind and sea state. Especially sea state if not in a very protected anchorage. You want a size that will stretch a good bit but not break. That will be different in 15 knots vs. 50 knots and flat calm vs. bow pitching 30 degrees up and down in waves. Longer in higher winds and more sea. One size will not fit all.

[Kenomac]

Our boat is 25 tons and anchor chain is 1/2 inch. We use 3/4 inch nylon rope along with one of those large rubber dock-line shock absorbers placed just above the chain hook.

[Snowpetrel]

I sat out very nasty blow on 60 footer weighing about 16 tonnes. I am pretty sure the 10mm 3 strand nylon snubber saved the chain, or something else from breaking. The snubber was stretching like a bungy as each williwaw hit. It probably wouldn't have lasted long if there had been any chop.

[klem]

As others have suggested, having 2 snubbers for different conditions can be a good option. Snubbers serve 2 purposes, to take the load off the windlass (you should have a chain brake also but that is a different topic) and to provide shock absorption.

A snubber's stretchiness or ability to absorb shock is determined by 3 things, its length, its diameter and its construction type. Nylon makes for a pretty good snubber so once that is set, you only need to pick a length and a diameter. Diameter is determined by strength requirements. Length can then be used to tune the stretchiness with only a few feet acceptable in calmer conditions and 50' being necessary sometimes in bad conditions.

In my opinion, the lightweight snubber should be sized to start providing some real shock absorption around the time where your chain stops being a good shock absorber (my guess is this corresponds to around 30 knots for you but with not too much fetch but this is only a guess). On your boat, I would probably opt for 1/2" with 40' of length. Others will get away with a lighter snubber and therefore be able to use a shorter one but 1/2" should provide peace of mind if the wind suddenly jumps up to 40 knots.

If the rest of your ground tackle is up to it, then having a storm snubber makes sense. This should closely resemble a mooring pendant as they serve the same purpose and are sized for storms hopefully. The major difference between a snubber application and a mooring pendant is that the chain in a good mooring is a lot heavier and will be able to provide some shock absorption whereas your anchor chain will be bar tight in storm conditions. This means that you need to have a longer snubber than you would a mooring pendant. My recommendation would be for 7/8" - 1" diameter with a minimum of 50' available. This may seem like overkill but having snapped many lines including 2" ones, I would rather have a slightly larger diameter and longer one.

[Jimbo485]

What do you do when you have your anchor, chain and snubber out, all is fine, blowing 10 - 15 knots, anchor nicely set and then a 50 knot squall comes in at 2 am and you start dragging towards that reef in the darkness and rain behind you? The reef was 200 m behind you when you anchored, but now it is close enough to hear the waves crashing on it but you can't see anything. The GPS / chartplotter show that you have already dragged 100 m. The depth is 10 m and dropping.

1. Haul in your chain, unhook the snubber, motor upwind in the blackness and 50 knot winds, trying to avoid the coral bombies you saw so clearly in the day, reanchor with greater scope and put the snubber back on.

2. You realise there is not enough scope and you can't release more chain because your snubber is too short, so you attach various mooring lines to the snubber and then increase the scope, hoping the anchor will bite in again before you drag on to the reef.

3. You are prepared for this and have 150' of snubber and just let out more chain and snubber.

4. You throw out your second anchor with much more scope than your first anchoring attempt and pray that this will set before you hit the reef. Your mental calculations indicate this will be a close thing with a depth of 10 m and the coral now significantly less than 100 m away. You watch the depthsounder with fear, peer into the darkness off the stern, listen to the waves crashing on the reef and pray.

5. You have never thought about this and don't want to think about it now, so you go back to your bunk, secure in the knowledge that you have your boat insured and await the crunch of coral on your hull.

[stevensuf]

You turn on the engine and take some of the load of the anchor?

[klem]

Originally Posted by stevensuf

You turn on the engine and take some of the load of the anchor?

This works well on some boats but doesn't work well at all on others. In general, if a boat dances around a lot at anchor (and an awful lot do when it is really blowing), you will only make it worse by powering ahead. I have tried it in pretty wild conditions on boats that do it well and boats that don't and it was alarming how bad it was on the boats that didn't. Unless you have tried it before, I would not recommend counting on it.

While it is a totally different size, the US navy's policy used to be (and may well still be, I don't know) that vessels were to apply slight reverse propulsion when in extreme situations. The idea was that it would keep the ships from surging forwards then shock loading the gear really hard when they got pushed back. The result of the reverse propulsion was that the ships sat nicely basically not moving at all.

[CaptForce]

I use two 5/8 three-strand nylon lines off a chain hook with two leads. Anything with a larger diameter removes some of the stretch that I'm desiring, but then I'm not anchoring in places with a long fetch or refracted waves. There's a wide range of best practices depending upon locations.

[Bash]

Originally Posted by Don Lucas

I use 3/4" x 20'

I subscribe to the opposite theory, and use 1/2" x 20' on a heavier boat than Don's. I want that snubber to stretch. What amazes me is how long my snubbers last. My current snubber outlasted the plastic anchor roller over which it sets.

[GordMay]

My rule of thumb is to size an nylon anchor rode at about twice the diameter of the chain. My snubber would be about one size smaller (±1/8" - 3/16") than the rode. My snubber would be about 50 Ft. long, but often deployed at much shorter lengths.
My rationale was that the snubber should be, both, a shock absorber, and a weak link alarm.
Accordingly; a 3/8" PC Chain might be coupled to a 5/8" to 3/4" Nylon Rode; and be supported by a ± 7/16" - 1/2" Nylon Snubber.

[estarzinger]

In terms of snubbers, I have been trying something new this summer, shown below (see line from one cleat up thru the chain near the bow and back to the other cleat). My objective was to stop having to mess around with the hook or rolling hitch and make it easier both to set and recover. It's worked fine so far, but I still don't know if its a good idea or not. It certainty takes the load off the windless, and adds some elasticity (but less than a much longer snubber).

[Cheechako]

I found 5/8 snubber to be to my liking with 3/8 chain on a 42 cat and a 47 mono. I started with smaller 1/2" and really didnt like the amount of stretch and force on it in a blow. It's a amazing how much the 5/8 stretched at times....