Anchoring In Sand Over Coral

[rognvald]

I have searched the Forum for this subject and could not find anything. I would like to know who successfully anchors in thin sand over coral and/or coral bedrock and what anchor and techniques they use. We have previously tried to find depressions in the seabottom with more sand and/or weedy patches (for the same reason) to drop the hook. We exclusively use a plow and do not deploy a second anchor even in tidal anchorages. Some of our favorite anchorages for seclusion and beauty fall into this category even though we sleep fitfully.

[Vasco]

The only way is to look for patches of sand. When the bottom is scoured it's impossible to get good holding. Sometimes you can snag the anchor in a hole but I would not depend on this holding when it blows or when the current changes. There are many anchorages in the Bahamas that are scoured out by the current. Your best bet is to avoid them.

[noelex 77]

Originally Posted by rognvald

I have searched the Forum for this subject and could not find anything. I would like to know who successfully anchors in thin sand over coral and/or coral bedrock and what anchor and techniques they use. We have previously tried to find depressions in the seabottom with more sand and/or weedy patches (for the same reason) to drop the hook. We exclusively use a plow and do not deploy a second anchor even in tidal anchorages. Some of our favorite anchorages for seclusion and beauty fall into this category even though we sleep fitfully.

Sand and and broken dead coral generally provides a reasonably reliable holding substate.

A thin layer of sand over rock can be very poor, but most coral anchorages have a deep layer of sand and broken coral caused by a millennia of dead coral.

Be careful not to damage live coral.

[Jimbo485]

This can be difficult. Sometimes we try a few different areas until eventually it hooks on a piece of reef or the point of the anchor gets wedged in a hole. Then we swim down and check it.

Other times it is simply necessary to swim down and physically place the point of the anchor in a hole in the reef. This can get interesting if you are dragging at the same time, so put out a stupidly excessive amount of chain at 90 degrees to the wind direction and the friction of the chain over the sand holds the boat (or slows the dragging) while you put the anchor in a suitable spot. Never easy.

[Jim Cate]

Well, the real answer to this is no, there are no techniques that allow safe anchoring in thin sand over coral or other rock surfaces... especially with a plow. Plow type anchors rely on burial to achieve holding power. In thin sand, burial is not possible, so that answers your question emphatically IMO.

It is a problem in that one can not determine the thickness of the sand layer by observation from the surface. The only method that works is to drop the anchor and attempt to set it, using a lot of power in reverse. If it properly buries, you are anchored. If it does not bury you will drag along... go elsewhere and try again..

Cheers,

Jim

[Stumble]

I have never had any luck. Sometimes you get better grip than others, but I would never trust anchoring in sand over coral. If you have too, and have the space, a grappling hook is supposed to be the best way to anchor in this stuff, but I have never had one available to try since they are useless any where else, except perhaps for shale, or rock bottoms.

[Blue Stocking]

The fishermen around here often use 2 4 prong folding grapnels in series. Up to about 15-20 knots .