Anchoring caution

[String]

The way its done over here is far simpler in my book, the boat just drops a shot line to the wreck (weight on one end, rope and a buoy on the other end) and moves off.

When divers are ready the boat drops them next to the shot line.

To surface they either come back up the shot line or send up delayed marker buoys. In either case the boat comes to them when theyre on the surface.
If the brief was for divers to surface under their own marker buoys the last pair down "bags off" the shot (ie attaches a lifting bag to make it easier to haul up).


No issues with anchors being dragged there and the boat is always ready to move immediately should there be a problem.

Certainly in the sea conditions common here and the currents a permanently anchored dive boat would not be pleasant for anyone onboard.

 

[pasley]

Often anchors drag because the boats fails to either have a big enough anchor or more commonly fails to observe the suggested ratio of scope to depth. That is a minimum of 7 feet of anchor line for every 1 foot of depth including the boats freeboard with a 10:1 ratio recommended with at least the boats length in anchor chain. My dive buddy uses all chain for his anchor, makes a heavy anchor line, but dragging the anchor is a rare thing (hasn't happened yet, but I suppose it could). http://powerboat.about.com/library/weekly/aa031303a.htm
http://www.miami.com/mld/miamiherald/sports/special_packages/outdoor_guide/4389692.htm?1c

So over a 100 foot bottom that would be 1,000 feet on anchor line over the side! Even at the not recommended 3:1 ratio tha is still 300 feet of scope over the side.

Then of course there is the old, diver down flag and the common courtesy of observing it and not comming withing 300 feet of the anchored boat with divers in the water.

 

[alemaozinho]

better an achor on your back than a fishing hook in your cheek.Peace

 

[Chuck Tribolet]

My experience (400+ days with my Boston Whaler in
Monterey) is that the anchor only drags if it gets fouled in
the chain on the way down, which prevents it from digging
in. I use a five pound Danforth, and 13' of SS chain.
The first diver down checks the anchor.

Other anchor types are another story. At first I had
an 18 pound river anchor (mushroom with notches in
the side). It almost always dragged in sand.