Does it snub?

[Gypsyjoss]

Been observing (Meltemi time) the snubbing line (or not) that folks put on their bow anchor chains.

Mine is about 5 metres long taken to a centre cleat. I can see it stretch.

Most folks is about a metre long to a bow cleat. Is that long enough to do anything, apart from stopping the chain from grating over the bow roller?

Stern to moorers don't seem to use a snubber at all, all the strain is taken by the windlass, so that they can periodically tighten it up as the anchor drags!!!! I was under the impression that this is bad for the windlass. Comment!
As a bow to moorer using a kedge on a stretchy line I'm aware of how much movement there can be!

Pete

 

[vyv_cox]

I share your comments. I see people every day with snubbers less than a metre long. Some are in quite large diameter rope, type unknown. Mine always extends to below the water and I take it back to the midships cleat in rough weather. It is 11 mm nylon, boat is 35 ft, 7 tonnes. I watch it stretch in a blow, but I have owned it for many years and never broken it.

We have used the snubber for stern-to berthing but it has caused some problems, particularly when the hook straightened and our transom hit the wall, in very heavy surging. Although the windlass makers seem to advise against it, I believe that with a worm and wheel gearbox it is quite safe to let it take the load provided that the chain does not slip over the gypsy. A better arrangement, that we will use next year, is to fit a chain lock just aft of the bow roller.

 

[cobolt]

Guys,

Talking with my Lewmar hat on here.

Vyv, we would certainly recommend that a snubber or chain stopper (lock) is used whenever at anchor for any real length of time.

Whilst you are correct that a worm and wheel gearbox has an inherent ability to prevent backwind, there is a certain amount of backlash in the mesh of the gears. Over time, if left with the full load on it and as the load snatches on and off, the worm and wheel are constantly wearing against each other in the same spot.

In extreme cases, this can cause the teeth to grind away and basically buggers your gearbox.

 

[Ex-SolentBoy]

Snubbers perform two roles.

1. To take the strain off the windlass and transfer it to a post or cleat
2. To reduce snatch loads by adding elasticity

Short snubbers just do the first job and perhaps a little bit of the second.
Long snubbers do both jobs.

 

[machurley22]

Professor Knox recommends that the spring should be approximately the same length as the boat.

 

[Norman_E]

It depends what you are doing. If like me a lot of your anchoring is with the yacht stern back to a quay then all you need is to unload the windlass, for which I use a stainless chain hook on a fairly short three strand line with one end having a spliced loop over one forward cleat, and the other end taken to the opposite cleat. For free anchoring with no line ashore I would use a longer snubber.

 

[vyv_cox]

Guys,

Talking with my Lewmar hat on here.

Vyv, we would certainly recommend that a snubber or chain stopper (lock) is used whenever at anchor for any real length of time.

Whilst you are correct that a worm and wheel gearbox has an inherent ability to prevent backwind, there is a certain amount of backlash in the mesh of the gears. Over time, if left with the full load on it and as the load snatches on and off, the worm and wheel are constantly wearing against each other in the same spot.

In extreme cases, this can cause the teeth to grind away and basically buggers your gearbox.

I was talking specifically about stern-to berthing in the Med. There is no snatching and the load remains constant in the vast majority of circumstances. However, as I said in my first post, I agree that leaving it in the way that we have for the past six or seven years is not ideal.

 

[wotayottie]

Professor Knox recommends that the spring should be approximately the same length as the boat.

It would be difficult ( but not totally impossible) to arrange a snubber that was longer than the boat. But length does matter. The longer the snubbing rope, the more energy it can absorb.

Had a mooring in Helford last year and that place is notorious for waves in easterly winds. To avoid snatch loads from the mooring chains I rigged a snubber that ran through snatch blocks on the toe rail back to the sheet winches. The snubber was 14mm nylon. Worked like a dream with no shocks at all felt whilst I was on board. You could see the rope stretching as much as a foot and then returning to normal length as tensioned by the winch.

 

[Iliade]

Compounding the situation

It would be difficult ( but not totally impossible) to arrange a snubber that was longer than the boat. But length does matter. The longer the snubbing rope, the more energy it can absorb.

I have visions of a multiple-fall pulley system hoisted up the mast like some gigantic compound bow... :0)

 

[GrahamM376]

Guys,

Talking with my Lewmar hat on here.

Vyv, we would certainly recommend that a snubber or chain stopper (lock) is used whenever at anchor for any real length of time.

Whilst you are correct that a worm and wheel gearbox has an inherent ability to prevent backwind, there is a certain amount of backlash in the mesh of the gears. Over time, if left with the full load on it and as the load snatches on and off, the worm and wheel are constantly wearing against each other in the same spot.

In extreme cases, this can cause the teeth to grind away and basically buggers your gearbox.

Gears may not always be the weak point. A mate tore the rear mounting studs out of his (alloy cased) Lofrans one rough night, he had never heard of a snubber! I had to drill the holes oversize and re-tap.

Another advantage of a long snubber is with wind over tide, the rope will do less damage to the hull than a taut anchor chain.

 

[Pleiades]

This is the set up I use on Pleiades for a single anchor - one 3 m length of chafe protected nylon multiplat attached with a chain hook as the first stage snubber. I also have a one metre length of thicker 3 strand nylon as the second snubber again attached with a chain hook. Normally the longer line takes all the load. In extreme anchoring situations the 3 metre length goes to full stretch and the shorter length then takes up the spring ensuring that no load gets to the windlass. The loop of chain on the foredeck would allow the thick snubber to go to its full stretch if necessary and when digging in the anchor in going astern the short snubber usually starts to take up some load when the anchor gets a good grip.

No snatching and very quiet even when anchored in a hooligan as the chain seldom works hard on the bow roller.


Robin
Pleiades of Birdham
MXWQ5

 

[penfold]

It's not the gears which are the major concern it's the shaft the gypsy is mounted on; it is not designed to take shock loads, the combination of shear and bending is very bad. Add in salt water and stainless steel's tendency to work harden and you have a recipe for failure sooner rather than later.

 

[chinita]

I use one of these on a six foot long line with a chain hook attached to the chain:

http://www.force4.co.uk/3783/Force-4-Rubber-Snubber---Up-to-15-Ton-18mm-rope.html

One winter, moored stern to, in Gozo I used scooter tyres. Very effective.