Re: Maramu anchor and chain suggestions


James Alton
 

Michael,

   Those are some interesting solutions that I have never heard of.  Apparently a lot of thought has gone into how to deal with chain castles.  I really appreciate your input on this.  Did you read Toms simple solution in the next post that has worked for 20 years for him?  I should have thought of that but it never occurred to me.

   Yes, I understand what you are saying about how having more weight in the rode will provide more catenary at the same load, all true.  Of course in higher winds even heavy chain will as you say begin to act like a rod so at that point having a really good snubber that won’t detach when the all chain rode is wanting to act like a rod is really important.  That is another subject that I have been studying since I have had so many chain hooks pop off when conditions got rough and they were really needed.  I have been tying my snubber to the chain in stronger conditions since the caribiner type hook that came with the boat does not look like it is strong enough for strong conditions but at least it never pops off the chain.  The icicle hitch seems to be a little better than a rolling hitch to make this connection but I still worry about the line working free.  I am open to suggestions. There is a lot to this anchoring business. (grin)

   Assuming a proper snubber handles the surge loads, would the same weight  of rode in 8mm or in 10mm provide the best holding?  I think that if this was the only issue that the 8mm would be the clear winner due to the longer scope but of course it is never this simple.  What options are there for instance to attach line to the 8mm that would be as strong as the grade 80 chain?  And what about the strength of the shackle to the anchor at the other end?  Those concerns bring me back to probably using the 3/8” chain.  And of course in a tight anchorage with limited swinging room so that scope is limited, the heavier rode would be better I think.  

   You might check the math on the weight of the 10m of 8mm chain, unless I have made an error (quite possible) I think it is a bit over 16KG so about a 7 KG difference per 10m.  

    I have learned a lot from this discussion, thanks!

James
SV Sueno
Maramu #220


   

On Mar 12, 2019, at 2:29 PM, amel46met <onboardaphrodite@...> wrote:

James
I have 300 feet of 3/8” H.T. Chain. I hand spread the first 100 feet and then pile 200 feet on top of that with the windless no problems with the pyramid although I like hearing it fall over as I retrieve I have tried putting a bulkhead forward and putting 100 feet forward of that but just spreading it seems to work fine for the last 20 years.I do have an old fashion Bruce anchor 50 kg it never drags I like it when people say that is an awfully big anchor.
Tom Deasy 
S/Y Aphrodite 
1983 Maramu # 125


On Mar 12, 2019, at 1:10 PM, "amel@..." <amel@...> wrote:

Hi James,

I _think_ there should be enough space in the locker to install such a partial bulkhead. But remember that the locker hatch is not that big. So I imagine it will be a pain to both install the bulkhead and to put the first 20 m there each time you have used them. That said it might still be a feasible idea.

There are also other possible technical solutions that might or might not work like:
https://www.force4.co.uk/force-4-chain-boy.html
and
https://www.sailmagazine.com/cruising/anti-chain-pyramid-rod
So far I didn't try either of it.

Using 8mm chain would probably eliminate the problem alltogether but it comes with a big caveat:

As I pointed out earlier, with the smaller chain you also loose a lot of weight. While this is a desirable effect for the boat trim (more for light deplacement boats than for an Amel), it is abolutely undesirable when the chain is NOT in the locker but in the water.

10m of 10mm chain weigh about 23 kg while 10m of 8mm chain weigh only 13kg. For an anchor chain weight equals to damping. A lighter chain will come stiff like a rod much earlier than a heavier chain when swell and wind increases. As soon as the chain is solid stiff the damping and force absorption cease to exist and the full force of wind gusts and swell will take effect on your anchor thus increasing the danger for it to break out considerably.
This not so much a problem in light conditions, but in heavy weather it can make a big difference.

I consired switching to a 8mm Chrome Duplex chain myself but gave up on that thought when I realized the consequences.

Michael, SY Sioned, Maramu #148

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