5/16" or 3/8" Chain

[rslifkin]

Originally Posted by GrowleyMonster

I have always felt that the chain is more important than the anchor. The anchor holds the end of the chain. The chain holds the boat. The weight of the deployed chain is important. The catenary lowers the pulling vector to near horizontal and provides shock loading protection.

This has been proven to be false except in very deep water. Catenary helps with comfort and holding up to a point, but when it's blowing like crazy you'll most likely have pulled the chain close to straight. 20 extra pounds of anchor adds far more holding power than 20 extra pounds of chain.

[hlev00]

I moved from 30' of 3/8" BBB + 150' three strand to 275' of 5/16" G4 on our 20,000 lbs Beneteau. I made the change to all chain anticipating cruising between Maine and the Caribbean. I chose 5/16" G4 to save weight and space in the anchor locker. In all this as worked quite well. Yes, there may be less catenary effect before the chain goes tight but I trust my long snubber for those conditions. The one caveat is that I originally had an additional 150' of 3-strand at the end of the G4 for extreme depth/scope conditions. The problem is that between the splice and what our Lewmar gypsy can handle, the largest 3-strand is really smaller than I would like. After two trips to the Bahamas, not yet making it to the Caribbean, I removed the three strand as we never got close to needing more than 200'.

Another consideration is that the Acco G4 started showing a lot of rust after five years and two trips to the Bahamas. I swapped end for end and that has kept rust off the deck for now. I have looked into regalvanizing in the Boston area. One facility will drip / shake the chain but I am concerned this may still result in clumps of links that need to broken apart, damaging the galvanizing in those spots. It isn't inexpensive either. With BBB I would just buy new chain sooner.

[sailingharry]

Originally Posted by rslifkin

This has been proven to be false except in very deep water. Catenary helps with comfort and holding up to a point, but when it's blowing like crazy you'll most likely have pulled the chain close to straight. 20 extra pounds of anchor adds far more holding power than 20 extra pounds of chain.

In further support of this idea, if catenary were helpful with comfort and shock loading, snubbers would be of little value. Catenary is helpful when it isn't needed, snubbers are helpful when it is needed.

[SV__Grace]

This is good info and explains why I use 5/16 G4 on my 20 ton (fully loaded) Nauticat 43 as we cruise the PNW and I want 500 feet of chain for deeper anchorages which would be too much weight in 3/8.

We've weathered gales up to 60 knots without a problem. Use of a good snubber that is long enough to provide the stretch needed to absorb shock loads is critical.

Our storm snubber is a bridle of 5/8 line, each leg is 30 feet, cleated to the mid cleats with @10 feet extending through either side of the bow pulpit. Too much stretch and you get a bungee effect, too little and you get jerked with shock loads. Determining the right length depends upon your boat and your line and observing under real conditions.

Originally Posted by fourlyons

The 5/16" G4 has a SWL value half way between 40 knots and 60 knots. How often do you realistically expect to anchor in more than 40 knots, with no protection? And remember, this is the SWL, breaking load is 5 times that. I personally would not want to haul all that extra weight around, in the bows, for an extremely rare event. And I don't, my boat is 40', 11 tons, and I use 200' of 5/16" G4.

And lastly, the same source, Rocna, claims you can reduce loads by a third with a good snubber.

[Bowdrie]

Originally Posted by rslifkin

when it's blowing like crazy you'll most likely have pulled the chain close to straight.

Originally Posted by sailingharry

Catenary is helpful when it isn't needed, snubbers are helpful when it is needed.

Originally Posted by SV__Grace

Use of a good snubber that is long enough to provide the stretch needed to absorb shock loads is critical.

All true enough.
An all-chain rode is the cats meow until things go sideways, then snubbing/stretch/elasticity take on real significance.

[sailingharry]

Originally Posted by SV__Grace

Our storm snubber is a bridle of 5/8 line, each leg is 30 feet, cleated to the mid cleats with @10 feet extending through either side of the bow pulpit.

I don't use a bridle, I only use one line. I'm not clear on the advantage of two. I run mine out the anchor roller with the chain, putting it as far forward as possible (and thereby as much leverage as possible to pull the boat back into the wind).
A bridle, when into the wind, provides double the strength. Until the boat veers.
As soon as the boat moves to one side, the weather bridle becomes slack, and the leeward bridle carries 100% of the load. It also rubs against the bow/bob stay. This is, at best, as good as a single snubber and probably worse (on my boat, the anchor roller is about 3' forward of the bow, although since a bridle would be rubbing on the bob stay it isn't 3' better -- although large side stresses on my bob stay aren't a good idea (my bobstay is solid rod, so doesn't "flex" like cable would).

What advantage does a bridle provide?
Catamarans are an entirely different story, of course.

[MJH]

Originally Posted by SVgoinCoastal

Trying to figure out whether to go with 5/16" or 3/8" G4 to go with the 55lb Mantus M2 I'm about to buy. Looking at getting 200ft of chain.* Boat weighs 20,000 dry and I'm wanting this setup to be our better/stronger setup (already have a 35lb CQR, 40' of 1/2" chain + 3/4" nylon rode for normal day stuff) but eventually looking to replace our manual windlass with an electric one and there's a pretty big cost difference between 5/16 and 3/8 there too, so just trying to figure out if 5/16" will be good enough or if i should go with 3/8".* Thanks for any advice.

When I upgraded to an electric windlass in 2010 I went with 300' 5/16" Grade 43 Galvanized High Test chain which has 3900lb. MWL and 11600lb. Breaking Strength. That extra 100' length has come in handy over the years in my Northwest waters. I reversed the chain after five years. Make sure it is U.S. made like an Acco (Peerless) chain; don't buy foreign. My boat is longer and heavier than yours.

Good Luck.

[David Mathis]

Our 43' power boat weighs about 30,000 pounds, uses about 40' of 5/16 chain and 200' of 9/16 three strand nylon with a 44 pound sharpened Bruce. (Sharpening the leading edge has greatly improved the ability to penetrate hard sand.)We've been through a few significant storms and never had the anchor drag more than a few feet while burying. Remember, what goes down must come up. It's must easier to remember after you've hauled heavy chain after anchoring in a deep bay. Does having more and heavier chain than needed help hold the boat or help you sleep?

[KetchJohnB]

5/16" G4. Great stuff and the right fit for you boat. Used it for 10 years on a 40Klb boat with a 73 lbs Rochna. 20K miles. When we got a 50Klb boat, it came with 3/8" Heavy stuff & same Rochna anchor! Best, John

[donradcliffe]

Originally Posted by Bowdrie

All true enough.
An all-chain rode is the cats meow until things go sideways, then snubbing/stretch/elasticity take on real significance.

Not quite true. A rope rode will be sliced in half by rocks or coral well before things go sideways. Pulling up a rope rode with 2 out the three strands cut made all chain the no brainer choice for me.

[Bowdrie]

Originally Posted by donradcliffe

Not quite true. A rope rode will be sliced in half by rocks or coral well before things go sideways. Pulling up a rope rode with 2 out the three strands cut made all chain the no brainer choice for me.

You're searching for something that is/was outside of what I said.
Nowhere did I say that one should have an all-rope rode.
A prudent shipper has a pretty good idea of the bottom, (or should have).
Of course, in rock/coral one wants some chain, whether it be 10 Ft. or a 100 Ft. or even more.
Those are questions that only conditions can answer, and I stand by the language I used regarding the necessity of something for elasticity.

[sailingharry]

Originally Posted by Bowdrie

A prudent shipper has a pretty good idea of the bottom, (or should have).

In many thousands of miles across many states and several countries, I've never really had a good idea of the bottom (well, except for the Chesapeake, where it is usually mud but sometimes sand -- and I don't know until it comes up full of mud, or clean).


In the rocky north, it is either rock, or mud, or sometimes sand.


In the Lakes, it is sand, I think -- but often so much grass you never know what the grass is growing in.


How does one know what the bottom is? The charts have scattered markings, but the bottom changes quickly.


The chart for the creek in front of my house has no markings for at least a 1/2 mile in either direction. I've always assumed it is mud, but at extreme low tide, boats lift out of the water leading me to think it is sand or at least sandy mud.

[Bowdrie]

^Sailingharry, you're right, unless one dives on their anchor it's a guess.
But one can still have a "pretty good idea" of what's down there.
Lowering a sounding lead that's armed with some wax to sample the bottom is quaint and old fashioned but it does still work.
Of course, with my luck the lead would drop in the sand 6 inches from a huge rock,
Alas, why can't the bottom and the boat/rode/anchor just be perfect for any and all conditions?
We have to do the best we can with what we have.
If one can carry really big anchors and 3>400' of heavy chain together with a large windlass that would be nice, but that's a tall order for a modest size boat.
And if you start to lose catenary you're still up the creek without a paddle if you can't add elasticity, (Nylon,) to the chain.

[sailingharry]

Originally Posted by Bowdrie

^Sailingharry, you're right, unless one dives on their anchor it's a guess.
But one can still have a "pretty good idea" of what's down there.
Lowering a sounding lead that's armed with some wax to sample the bottom is quaint and old fashioned but it does still work.
Of course, with my luck the lead would drop in the sand 6 inches from a huge rock,
Alas, why can't the bottom and the boat/rode/anchor just be perfect for any and all conditions?
We have to do the best we can with what we have.
If one can carry really big anchors and 3>400' of heavy chain together with a large windlass that would be nice, but that's a tall order for a modest size boat.
And if you start to lose catenary you're still up the creek without a paddle if you can't add elasticity, (Nylon,) to the chain.

Ah, but you can have it all! A nice appropriately sized (not oversized) newer anchor, with a bunch (or all) appropriately sized G4 (no need to go to a larger BBB), with a nice snubber if you don't have any nylon out. Sticks everywhere (and if you catch a nice rock, too good -- we almost had to pay a diver, and then it just fell out) nylon gives you surge protection, and life is good!

[Kettlewell]

How does one know what the bottom is? The charts have scattered markings, but the bottom changes quickly.

One reason cruising in the Bahamas is so fun is you can see your anchor most of the time, the bottom is pure sand, and if you snorkel down in the shallow water you can know exactly what is going on. It's like having your own personal anchor testing YouTube channel! One time anchored in Nassau, which is pretty deep in places, I dove down to see what my anchor was tangled with and it was the remains of a huge Junkanoo costume. But, I will say that at least on the old raster and paper charts I have found the bottom material notes pretty good in most cases, then I also have all the cruising guides onboard, and there is often someone to ask as you get ready to anchor. Southern New England, south of Cape Cod, is 90% mud or sandy mud, with an occasional place where it is weedy. One way to figure out what you've got is to simply drop the hook on short scope and pull it back up to take a look. Modern scoop type anchors often pull up a good chunk of the bottom.