A lesson learned from dragging anchor
We had been anchored in the same spot for six months as we traveled overland to locations in Asia and Micronesia. VALHALLA was in a secure harbor, depth of 25 feet at high tide, mud over sand bottom, 150 feet of chain rode, 35 pound CQR anchor and dug in solidly. We arrived in January when the trades were blowing and didn't mind the gusts of 25-30 knots, which helped dig the anchor in more and more with each passing squall.
It is now June and the southwest monsoon had arrived. VALHALLA (and the rest of the twenty plus boats in the anchorage) now faced the opposite direction as the wind was holding her against the ground tackle.
One dark and stormy night
As luck will often play a joke on you, this particular night there was no means of mechanical propulsion available. The boat's propeller had been removed for reconditioning and had not yet been fitted. The outboard motor for the inflatable dinghy, which was tethered behind, sat fixed to the stern rail.
Fortunately we were aboard as a squall line passed through, part of the feeder bands into the season's first major typhoon about 500 miles north of us. The awnings were up in anticipation of collecting rainwater for the tanks. Soon after our passage into slumberland we were awakened by the sound of a major squall and the boat on her ear.
Scrambling into the cockpit I watched, with helpless feeling, as we dragged through the anchorage narrowly missing one boat but headed directly for another one. The wind instruments, now turned on, registered 38 knots in the gusts. I later learned that the initial ones were in excess of 45 knots. We had managed to get the awnings down to reduce windage but without power available to check the dragging all we could do was fit fenders, move the inflatable dinghy between us and the boat behind us, and stand by to fend off as best we could. But then our fortunes reversed and we felt the anchor bite, bringing us up short of the boat behind us with 30 feet to spare.
With the help of another skipper (Keith Fletcher on TENACITY II) whose inflatable DID have an outboard motor fitted, we set a second anchor and pulled ourselves well to the side of the boat behind us. Anchor watch saw us safely through the rest of the night. The next day began by fitting the reconditioned propeller and moving to another spot to re-anchor.
The nagging question was why? Why had we dragged after so many months of being securely (or so we thought) anchored? After some serious thinking I realized the answer. The length of time we sat facing northeast, into the trades, the anchor was firmly buried in the bottom. When the southwest monsoon arrived, we did not reset the anchor and had been lying to it 180 degrees from the new prevailing direction of the wind. It was buried so deeply that it had, until that scary night, held the boat nicely through the minor squalls and southwest winds. The force of the wind that night, helped by the awnings, finally unset the anchor and, once moving, took considerable distance to reset. Luck, once again, kept us from hitting anything in the process.
In retrospect we realize we should have
reset the anchor when the prevailing winds changed. We had been lulled
into complacency. We got off lucky and with another valuable lesson