[Rhodes22-list] Anchor Chain Question

[Bill Effros]

Mary Lou,

Thank you for engaging in this discussion, it's been quite useful to me,
too.

Wally's comments, also.

I prefer to sail on weekdays when there are almost no cruising sailboats
on my side of the Sound, and plenty of  space to fool around.  Of
course, I normally can't see my anchor either, so I pull close to shore,
and drop the anchor where I can see what's happening.  It's
interesting.  I recommend it.

At my mooring the only time the anchor line goes slack is when the
direction of the current is reversing and there's no wind.  This is most
likely to happen early in the morning.  There are thermals most of the
rest of the time.

It's hard for me to believe that your anchor chain is actually holding
you in place most of the time.  But if you honestly believe it is, I
would suggest that you get a 10 or 15 pound mushroom anchor, vinyl
coated, which should do a better job, and come up clean.  I would attach
an all-line rode.

Please understand that in my heart I believe a rusty chain is stronger
than a brand-new rope.  But in my head, I know it just isn't so.  Adding
chain to line doesn't make the line any stronger.  In fact, it weakens
the line at the point where the two are joined.

Modern line is monstrously strong.  The stuff just doesn't pull apart.
It may chafe, it can age in the sun, it can rot; but if it's in
reasonably new condition it won't fail from the amount of strain our
boats and ground tackle are capable of exerting.

I still have chain on board, but thanks to this discussion, I think I'm
going to try not using it for this entire season.  Instead, I plan to
mix up my use of anchors, setting multiple anchors in overnight
situations.  I'm going to put multiple all-line rodes of varying lengths
in a container under a cockpit seat along with half a dozen different
anchors.  Then I will select the appropriate rode and anchor for each
situation.

I, too, have been relying too heavily on my Danforth anchor.  In an
emergency situation, that would not be my anchor of choice -- I think a
grapnel has a far better chance of quickly setting in a Hail Mary
emergency.  I have 4 grapnel anchors of differing weights that would
quickly go overboard in an emergency.  After that, I would dump my
mushroom anchors, of which I have three of differing weights.  After
that I would use my Danforth anchors, of which I also have three, again
of differing weights, and currently all attached to rodes with chains
segments.

Also, as I become more comfortable with all-line rodes, I plan to
experiment with kellets, although I anticipate that multiple anchors on
separate rodes will be both easier to handle, and more effective.

The Chapman I referenced is the 61st edition.  I mentioned it only
because someone made a statement that no reputable reference had ever
recommended an all-line rode.  The point made in the book is that for
smaller boats an all-line rode is preferable to an all-chain, or
chain/line rode in many circumstances.  Chain is preferable only when
its weight won't upset the balance of the boat, or in instances where
the boat and ground tackle are so large that the diameter of rope
required becomes unwieldy, and the weight so great that a windlass is
required.

The catenary, kellet, and shear explanations for partial chain rodes are
never adequately explained to my satisfaction, and have not proved to be
valid in my experience.  This year I'm going to put my anchors where my
mind is.  I'll let you know how it turns out.

Bill Effros







Mary Lou Troy wrote:

> Bill.
> A few more thoughts. You've raised some very practical points beyond 
> the theory. I've put a few practical observations below from our 10 
> years of experience anchoring on the Chesapeake. These points are 
> probably not "generalizable" (I can't believe my spellchecker accepted 
> that) beyond anchoring in a mud bottom in mostly shallow water.
>
>> Let's start with John's explanation, which is well written, and 
>> pretty typical.  In order to make his examples work, he's got to 
>> anchor in 30 feet of water.  I have never anchored in 30 feet of 
>> water, nor have I ever paid out 200 feet of rode.  (When I first read 
>> explanations of anchoring like this I bought 300 feet of line on a 
>> single anchor rode, but most of it has never been in the water.)
>
>
> We've only anchored in 25 feet of water once. It was notoriously bad 
> holding ground so we put out most of our 200 feet of rode. There are a 
> few places on the Bay where you get to anchor that deep. We are 
> usually anchoring in 5 - 6 feet of water mid-tide. Tidal range on our 
> part of the bay is usually around a foot.
>
>> In practice, I would be happy if I could anchor in 10 feet of water, 
>> pay out 70 feet of rode, + my 22 ft. boat = 92 feet x 2 = 184 
>> feet...I would need a circle greater than 184 feet in diameter with 
>> no other boats encroaching to be sure we would not foul each other's 
>> rode or bump in the night.  (John's circle would be larger than a 
>> football field.)  I've never been in a busy anchorage where boats 
>> stayed a football field away from each other.
>
>
> We also routinely anchor in crowded anchorages. Even in 5 feet of 
> water we sometimes do not get 142 feet (5 feet of water + 2 feet of 
> freeboard x 7 = 49+ 22 feet of boat = 71 x 2) between boats. 
> Fortunately most boats swing with the tidal currents and you don't 
> need that kind of distance. If it's windy enough to overcome the tidal 
> currents most boats swing with the wind - same effect. We try to have 
> enough distance to allow for variations in how boats swing.
>
>> In fact, in most busy anchorages you are lucky to get a 100 foot 
>> circle.  22 feet of boat, 28 feet of rode, 7 foot depth, 4:1 scope.  
>> If this is the way you are anchoring, then your 16 feet of chain 
>> represents more than 50% of the rode--however it weighs only around 
>> 10 lbs, and would not be sufficient to create a catenary shape 
>> between your bow and the anchor.  If you actually anchor in 30 feet 
>> of water, your 16 feet of chain would still weigh only 10 pounds, and 
>> could still not create a catenary between your bow and anchor.
>
>
> In reality, most of our 16 feet of chain ends up flat on the bottom. I 
> see the muddy evidence every morning. Catenary effects would only come 
> into play as the wind picks up. After a particularly windy night we 
> will have a lot of mud embedded in the chain - mud that helped us stay 
> put. After a 35-40 knot t-storm I was glad to see all that mud on the 
> chain the next morning. We rode that one out with the engine running 
> in case we needed it to take the strain off the anchor. Fortunately we 
> didn't ever need to put it in gear but the pop-top enclosure and the 
> bimini create a frightful amount of windage in a storm.
>
>> When I look around my harbor at hundreds of anchored boats what I see 
>> are very short scopes, no catenary shape, a straight line between the 
>> anchor and the bow, no chain on the bottom, constant pressure on the 
>> flukes of the anchors, and very little drifting.
>
>
> Do boats in your harbors generally turn with the wind or the tide? I 
> expect your conditions are routinely more extreme. We rarely see a 
> straight line between the anchor and the bow. We sometimes see a boat 
> with all chain where the chain drops straight from the bow to the 
> bottom. We know he didn't set his anchor there because we watched. 
> Having spend many a minute watching the rode as our boat swings at 
> anchor, I am certain that the pressure on the flukes is not constant. 
> Having hauled many a muddy anchor and chain in the morning, I know 
> that the chain spent a lot of time digging in the mud - it wouldn't do 
> that if there was a straight line between the bow and the anchor. The 
> Chesapeake waters are not clear enough to see the anchor even in 5 
> feet so I have to go by other evidence.
>
>> I think everyone should anchor in a manner that allows them to sleep 
>> in the night, but I find it interesting that so much of what we read 
>> turns out to be wrong in practice.  As Wally has mentioned, the 
>> biggest benefit of the all line rode is that it comes up clean.  It 
>> is much easier to handle and store, and it is light enough so that 
>> even a child can haul it on board.
>
>
> I don't want my anchor and chain to be clean. I want it dug in so that 
> the chain is part of the system that holds the boat in place. If I 
> were anchoring for lunch I might consider an anchor with no chain but 
> most of our anchoring is overnight - and we have two people on board - 
> one to man the tiller and motor - one to haul anchor and wash down the 
> chain and rode. If we were single handing we'd be setting and/or 
> stowing anchors differently.
>
>> Anchoring on coral is a frowned upon practice in most places that 
>> still have coral.   Danforth anchors are the wrong type to use on 
>> rocky bottoms.  Again, like Wally, I have never seen abrasion on my 
>> all line rode.  I don't think line abrasion is a valid reason to use 
>> chain.  I don't think either the chain or the line spends much time 
>> on the bottom.
>
>
> My only experience is with the Danforth. We have yet to find a rocky 
> bottom on the Chesapeake. We'd have to learn all over again somewhere 
> else. Our chain spends a lot of time on the bottom. When we had the 
> shorter chain the first 3 or four feet of rode where it was attached 
> to the chain would occasionally have a lot of mud as well.
>
>> I was surprised to find on our boats that all line rodes worked just 
>> as well as chain/rode combinations.
>> Bill Effros
>
>
> It's interesting to hear your experiences and observations because 
> they are so different from mine. I'll file them away in case we ever 
> come sailing on Long Island Sound. I've forgotten - which anchor do 
> you routinely use?
>
> Mary Lou
>
>
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