How to use a snubber with a bowsprit?

[dlj]

Excellent point on seabed quality. Of course you need good holding power. Interesting about the smaller scope in deeper water - I've not heard that before.

I completely agree on having as heavy an anchor as you can afford to put on your boat. Of course Dashew has tons more experience in that than I do.... As does Harries... Sometimes I find that time to research things is beyond what I'm afforded so I simply listen to others that have clearly more experience than I have... But I do put on my thinking cap when listening to any and all suggestions..

I am very intrigued with your observations of running heavy chain and no snubber. Lordy would that make live easier... I have a pretty good system down currently so I'm not changing anything soon. But it's an area that I'll keep in the back of my mind for when the day comes that I may have to replace all my chain. I would have to change my gypsy though to go up in size on chain. I'd also need a chain break, I currently just tie the chain off on a cleat after setting the chain and rode system up. Who knows what the future will bring..

It would be really interesting to lean more, have some nice data on "best" chain size and the like... I'll clearly leave that to others...

dj

[Dockhead]

Originally Posted by dlj

. . . I'd also need a chain break, I currently just tie the chain off on a cleat after setting the chain and rode system up. Who knows what the future will bring..

So you DO belay the chain, not depending on the snubber as your only attachment to the boat. Then there's nothing whatsoever wrong with your system. I understood differently from your previous comments. It doesn't matter how you do it -- chain lock, belaying strop, or tying off the chain to a strong cleat (what we used to do on our old boat too).

Originally Posted by dlj

.It would be really interesting to lean more, have some nice data on "best" chain size and the like... I'll clearly leave that to others...

I don't think there's any clear answer about this. Dashew says one thing, and he's right that catenary is all very well right up to when it isn't. But my experience with heavy chain is that it is extremely effective at damping motion right up to very rough conditions.



But I'm on a 54 foot, about 25 long tonnes boat. Anchoring stuff doesn't scale exactly. I wouldn't want 1/2" chain on a smaller boat. With smaller chain I think the range of feasible snubberless anchoring is much narrower.

[dlj]

Originally Posted by Dockhead

So you DO belay the chain, not depending on the snubber as your only attachment to the boat. Then there's nothing whatsoever wrong with your system. I understood differently from your previous comments. It doesn't matter how you do it -- chain lock, belaying strop, or tying off the chain to a strong cleat (what we used to do on our old boat too).

Oh good lord YES! I have a cleat for my chain and a separate cleat for my snubber... I would like a chain lock, but my bowsprit geometry makes for a complicated setup. Basically, there is no off the shelf chain break that will work, at least none that I've found. I've figured I'll have to custom build one - not a bad idea anyway as I'm pretty good at that "stuff"... But, time and so many other pressing projects...

Originally Posted by Dockhead

I don't think there's any clear answer about this. Dashew says one thing, and he's right that catenary is all very well right up to when it isn't. But my experience with heavy chain is that it is extremely effective at damping motion right up to very rough conditions.



But I'm on a 54 foot, about 25 long tonnes boat. Anchoring stuff doesn't scale exactly. I wouldn't want 1/2" chain on a smaller boat. With smaller chain I think the range of feasible snubberless anchoring is much narrower.

It would be interesting to see if a clearer answer could be discovered.

I'm on a 41 foot boat weighing about 22,000 pounds. So notably smaller than yours. Very comfortable boat though. I'm trying to remember what my chain size is - it's a DIN size - I'm thinking 10 mm, then there is the link length. Last time I bought chain the place where I bought it looked at the dimensions of the link and immediately knew what it was... But I don't remember...

dj

[noelex 77]

Originally Posted by Dockhead

But it's very hard and perhaps impossible to make it really as strong as the chain, once you consider weakening from cyclical loading (nylon is very susceptible to this), from being wet (nylon again), and from chafe (nylon). The sudden failure of nylon ropes at far less than their rated strength is well-documented.

Great points . The snubber’s primary job is stretch. Periodic breakages and/or replacement is necessary. They are disposable items.

I have broken many snubbers over the years. They break with an enormous bang so you are unlikely to sleep through the event. In strong conditions there is an argument for rigging two snubbers in case one does snap, but I do not always bother. Using oversized Dyneema in areas of chafe does seem to help substantially increase the reliability.

[Dockhead]

Originally Posted by dlj

Oh good lord YES! I have a cleat for my chain and a separate cleat for my snubber... I would like a chain lock, but my bowsprit geometry makes for a complicated setup. Basically, there is no off the shelf chain break that will work, at least none that I've found. I've figured I'll have to custom build one - not a bad idea anyway as I'm pretty good at that "stuff"... But, time and so many other pressing projects...

Some people don't attach the chain to the boat other than with a snubber. This is a dangerous practice and a pet peeve of mine.


If you can easily make off the chain to a strong cleat then you don't really need a chain lock.


Note also that a chain lock is only as strong as what it is attached to, and how it is attached. Many chain locks are through-bolted through a light section of foredeck with little strength.


A really strong samson post is high up on my list of desires for my boat, but I do have an inner forestay chainplate which is kind of good enough.

[Kettlewell]

Some people don't attach the chain to the boat other than with a snubber. This is a dangerous practice and a pet peeve of mine.

You could always use just a short backup line that would only come under heavy tension if the main snubber broke. I've deployed two snubbers at times when anchored in severe winds, or expecting possible severe wind. Make it Dyneema if you want and have a very high breaking strain. But, whatever you do, make sure that you can both let out chain and retrieve it, even if the snubber and windlass have failed for some reason.

[dan104]

On our 36’ with a big bowsprit the drop to the waterline is maybe 6’, so if I am dropping in 10’ of water reasonable overnight scope would be 50 – 70’ of chain, however that is based on depth or water but my logical depth is 16’ so just basic would be 80’.
To insure that my holding is solid without too much of a swing I have a snubber line attached to the bobstay with a locking chain hook. So with that I feel safe in holding without the extra swing.

BTW: I checked with the boat manufacture, Gozzard, to insure that was a safe point and they actually gave me the specs for the snubber and supported the use.

I have a very interesting snubber design document from the Gozzard World Cruisers group. email me if you want the pdf ( dan @ done-that.com )

[hpeer]

One thing about more scope agitates me. In both boats the chain tends to castle. One day I had the “opportunity” to help a guy with a broke windlass. A smaller cat with 1/2” SS chain. (Go figure eh?) I was shocked with how slippery the chain was. It laid very nice in the small space.

I had just replaced my chain, but in hindsight when I replace chain I think it will be SS. One less thing to push me to short scope.

[Dockhead]

Originally Posted by hpeer

One thing about more scope agitates me. In both boats the chain tends to castle. One day I had the “opportunity” to help a guy with a broke windlass. A smaller cat with 1/2” SS chain. (Go figure eh?) I was shocked with how slippery the chain was. It laid very nice in the small space.

I had just replaced my chain, but in hindsight when I replace chain I think it will be SS. One less thing to push me to short scope.

Chain piling up is the nature of the beast. You have to flake it as it comes in.

I stand inside my anchor locker on top of the divider which separates it into two parts and flake it with one foot as it comes in. There's usually some way to do it on most boats.


I have a stainless anchor but stainless chain scares me -- crevice corrosion. And of course, the cost.

[dan104]

Yes, chain castles, but if the locker is built right it should not be a problem. On my Gozzard it flows in and out very easy without a problem (I have 300' of chain), on cats I have chartered the anchor locker is a square box and they require flaking the chain or it will flow right up to the top without flaking. Thats the result of a cost saving design.

[Fuss]

Another thought to have a thin bit to go through the pipe….
I did not read all of this thread but for my 28 ton mono, the snubber leaves the bow with dyneema 10mm and then has a short section of 16mm 3 strand to provide the stretch.
The dyneema does not stretch and so far does not chafe.
Under 30 kts it’s not used.

[Fuss]

The chain lock to take the load is another 3 strand 50cm loop around the under deck windlass to a chain hook.

[barnakiel]

A fitting below the bobstay fitting is cool. Or else when the bobstay fiting is man enough.


Same thing here. I am rebuilding. I will move the bobstay higher, then re-use the original bobstay fitting.


chers,
b.