Why the size of your anchor matters

Most boaties know the size of an anchor must be relative to your vessel, and the depth of water you’re anchoring in. But did you know that getting this wrong, especially in unforeseen weather, could have disastrous consequences?

Complete Marine Consulting Managing Director John Gray spoke to us about a marine insurance claim he assessed in mid-2015, which highlights why the size of your anchor really does matter.

Trident Marine: What was the situation?

John Gray: While en route to Adelaide a yacht was washed onto a rock during a storm at night. When it happened, the yacht was at anchor in an area east of Esperance in the southern ocean. He [the sailor] was air lifted from the wreck, which was intact, yet high and dry on a flat rock.

TM: Who was involved?

JG: One sole sailor, who had built the yacht himself from a proven design.

TM: What challenges were involved with the assessment? 

JG: The boat was high and dry in a very remote location. It was largely undamaged, and it also weighed 14-tonnes, so a quick ‘tug’ off the rock was not an option.

TM: How did they manage to remove the yacht from the rock?

JG: A salvage crew from Perth was mobilised, and a large commercial vessel was engaged to travel to the site. Divers swam ashore with equipment via a small access area, as reefs blocked any type of landing craft.

The boat was turned with hand ‘tirfor’ so it faced the right direction when pulled off the rock. To apply sufficient force to tow the hull off, the crew used a large anchor deployed into sand off the island, which used a towing block to create a 2 to 1 force. 1,000 horsepower was applied to the towrope and the yacht slid nicely into the water without any significant further damage. It was later towed to Esperance then sailed to Albany for repair.

TM: Could the loss have been avoided?

JG: The loss was caused by the vessel’s anchor, which did not hold overnight in the strong blow. Rules for anchors are best observed, for example, use the correct anchor for the geography. Many anchors don’t hold well in weed, sand is for the most part always preferable. If in doubt go bigger! Use 3-metres of rope or chain for every metre of depth under the keel – the more the better in high winds. The angle at which the anchor is pulled by the craft is critical, so the more appropriately sized chain the better. Lastly, avoidance is the best way to deal with high winds, so seek shelter if it’s available!

TM: What did the claim or cost of damage come to?

JG: Damage costs came in at around $60k, with similar costs for the remote salvage – all of which the Insurer covered. The owner was very happy!

TM: Any final insights to share?

JG: Whether a voyage is short or long and remote, a spare anchor and chain is an absolute staple, especially when travelling through deep water. You can never have enough anchor rope as a safety precaution.

If you’d like your marine insurance reviewed, please contact our marine underwriters to discuss competitive policy options.