"NOYB" wrote in message
ink.net...


Gulp! 25 feet of chain? What diameter? Can you use a heavier chain to
get
away with a shorter rode? Remember, I don't have a windless.


"Rules of thumb" have their use, but they also have their limits.

As other people have pointed out, one primary reason for chain is that it is
much more resistant to abrasion, which is really important if you anchor in
coral or rocky areas. For sandy or muddy bottoms it is not so important.

Another reason for chain is that it makes the pull on the anchor more
horizontal. If you had no chain at all, when the boat pulled on the anchor
line it will straighten the line out between the boat and the anchor. The
angle you see the rope entering the water will be essentially the same as
the angle it is at when it reaches the anchor. The more vertical this angle
is the more it will want to pull the anchor UP instead of setting it deeper.

With chain, the weight of the chain will hold the line down. If you have
sufficient chain and sufficient scope you will never lift all the chain off
the bottom, and thus the pull on the anchor will always be horizontal. This
will make the anchor set deeper when it drags.

One way to achieve the same effect is to use a "caternary weight", which is
simply a heavy weight that is hanging from your anchor line between the boat
and the anchor. This pulls the rope down so that the pull on the anchor is
more horizontal.

This is all great and wonderful if you need to a good secure anchor. If you
are just dropping the hook for lunch or a little fishing and will be
observing your position all the time then you can usually get by with lots
less. Chain is a real bitch when you don't have a windlass and can be a
safety issue (it is a really bad idea to be handling chain under tension).
If the chain is longer than the water is deep then you may have to deal with
freeing a stuck anchor without being able to cleat it off. With rope it is
simple, you power up till you are over the anchor, cleat off the line and
then use the boat to power the anchor up. If you have reached the chain
when you are above the anchor then you need to have a hook handy so that you
can fasten the chain.

Rod