"Michael Wright" wrote in message
...
I believe the purpose of the chain is to hold the flukes down to initially
set the anchor. Please correct me if I am wrong MW

Well, you're on the right track, but I think your wording could use some
improvement. There are two purposes for adding chain to a nylon rode. The
first, which is very much related to your suggestion, is to lower the angle
of the pull of the rode on the anchor. Since chain is heavy, it tends to
lie on the bottom and stay there more so than straight nylon would. An
anchor will always take and hold a set much better with a horizontal pull,
rather than a vertical pull. In fact, the most common way to break the set
of an anchor for retrieval is to position the boat directly above the
anchor, thereby changing the pull to pure vertical. Generally, the more
chain that is added to the rode, the less scope is required for a given set
of conditions, because of the increased horizontal pull effect that chain
provides over straight nylon.

The second reason for adding chain is for chafe protection. It stands to
reason that the part of the rode closest to the anchor will be subject to
the most abuse from rocks, coral, or other items on the bottom that could,
over time, chafe nylon to the point of needing to be replaced. By
positioning a length of chain next to the anchor, the chain takes the
majority of such abuse rather than the nylon section of the rode, and the
chain obviously holds up much under such conditions than does nylon.