NavList:

.... And in the Caribbean ( volcanic geology ) the sea bed rock heaves up and down quite vigourously ... the area is on the move .... not to mention the coral coming and going.

Once on a warship in the middle of nowhere, pre gps etc, in the Carribbean we came to a halting screech - the OOW had been told to keep a particular eye on the echo sounder and did - we parked on the spot for 3 hours while  the navigator did two sets of sun sights to confirm our position - we could see the sea bed ( and the circling sharks ) from over the ship's side - the chart did not agree with the reality at that time. Ship intact and 'less water' report sent in to UKHO....

On another occasion, a pair of yachts on a joint charter cruise from the Grenadines to St Lucia, yacht 1 skipper suggested a lunchtime anchorage sheltered behind an islet, used a year ago. I was yacht 2 and got there first and was verbally torn to shreds on the VHF as yacht 1 approached, for anchoring in the wrong place. Ten minutes later apologies to me over the VHF as yacht 1 struggled to find any water to anchor in.....

There's nothing unique in these experiences, it's all part of the 'fun' of going to sea. [Aside - you look over the side of the boat trying to spot a patch of sand among the majority rock to anchor in, find a big patch, only to realise after half an hour trying to get the anchor to bite that the sand is only six inches deep - Enjoy!] 

Michael Bradley