The second in my series about anchors and anchoring in small sailing boats.
In this post i am going to talk about anchoring fails that i have either had myself or have heard about from sailing friends. In my own boats i have had anchors drag 3 times that i definitely know about and from memory have had 4 other experiences with dragging anchors aboard other boats. Several of those experiences involve just one type of anchor that i initially thought was a good anchor but now wouldn’t recommend for a sailing boat. The first anchor to discuss then is the one that i have had more problems with….the Bruce or Claw anchor. For a little bit of boating history here the original Bruce anchor , named for it’s designer, was first produced in the 1970’s in large sizes and originally intended for large fixed structures such as oil rigs.
I first came across the Bruce anchor type when it was being marketed aggressively to boaters by way of the chandlery that i occasionally worked in at the time and i was one of the staff that got the selling ‘spiel’. I never anchored with this type of anchor until around 1989 when we had one as the main anchor aboard the old maxi-yacht i sailed in the Whitbread race and the ensuing circumnavigation. That anchor on that boat i know dragged several times because i was on board for 2 of the incidents and have heard about other times too. In those incidents i happen to think that the anchor was under-sized for the boat anyway and had an inadequate rode. Because i still had faith in the type, and that i was able to buy them at a decent price i bought 2 for my Frances 26 : a 10 kg and a 15 kg. From memory i think they were made under the Lewmar label at that time.
In this picture of my Frances 26 you can just see one of my Bruce anchors stowed on the rail, from memory that would have been the 15kg anchor as i had the lighter one set up as my primary anchor and kept the second one for harder conditions. I quickly changed that around after my first experience of the smaller 10 kg anchor dragging in fairly benign conditions.
What i will do is detail the anchor set-ups, the boats and the situations where the anchor dragged and try to offer an explanation for each one.
My first experiences of a Bruce anchor dragging involve the same boat and same set-up in several different situations. The boat was an Ocean 80 maxi at around 76 feet and i think about 38 tons. * The anchor that we had was the 50 kgs 110 pounds on about 10 metres of 10 mm chain and then a long length of 20mm nylon warp. My opinion now is that the anchor was undersized and the gear inadequate regardless of any other factor. A sizing chart which i think is optimistic only shows the makers recommendation and on that we would have been undersized in storm conditions. Looking at sizing charts today i can see one problem in that the next size up would have been 80 kg, that would have been a much better anchor but potentially a beast to handle and stow with the systems we had. The anchor was very rarely stowed on the bow except during local cruising when we would be moving from anchorage to anchorage. The boat did have a fixed anchor roller but no windlass. To get the anchor up we had to run the warp back to the primary winches and manually wind it in on the grinders. Most of the time we stowed the anchor in the bilge just forward of the mast, in fact towards the end of my time with the boat i built a dedicated stowage system just under a hatch just forward of the mast so that the anchor could be lifted out on a halyard. Up until then i used to hook the anchor over one shoulder and climb out of the main hatch with it and it’s chain…..i must have been fit or really stupid in those days. On deck we would then, at first, struggle to get the anchor up front and over the roller, later on i learnt a technique of dropping it off the sparcraft shackle on the end of a spinnaker halyard and then retrieving it over the bow.
The first time that i am aware of that the anchor dragged was in the Solent one evening in about 20 knots of wind but not much tide so plenty of pressure on the rig but little on the keel and underside. I don’now remember the scope ratio but the anchor simply and slowly dragged through the seabed. I think the bottom there was a mixture of mud and shingle. The second and much faster drag was off Ascension Island in the South Atlantic in the recognised anchorage there. The bottom there was just about the worst anchoring surface aside from solid glacial rock….soft coral sand. The anchor never did grip or bite even once but just pulled through the seabed. I don’t know if there was a harder or more compact layer under the coral sand but we never got the chance to dive and take a look as we were told to move onto the only fixed mooring buoy there.
By the time i took this photograph i had already swapped over to Delta anchors on my own boat but i will describe 2 of the incidents with the Bruce.
My own dragging experiences with the Bruce anchor and my Frances 26 were both with the 10 kg anchor. The Frances, as it says on the tin, is 26 feet and about 3 and a half tons. The boat has a semi-long keel. My anchor set-up was 15 metres of 8mm chain and a solid hundred metre nylon warp.
My first ‘drag’ was when i had deployed the anchor as a stern anchor and then moored the boat fore and aft between 2 anchors. After the turn of the tide when the boat lay to the stern anchor, but slewing across the tide slightly, the load on the warp increased to such an extent that i couldn’t budge it and the anchor simply started to pull steadily through the soft mud. On that occasion i had to buoy that anchor and then go back and retrieve it. That was the time when i decided to have a go at setting a bahamian moor and have used that technique much more successfuly since that time.
My second drag was in simply harder conditions of wind and tide in a moderately sheltered position (not much fetch) but on a very soft silty-mud bottom. The drag was slow and consistent even with a scope increased to greater than 6 : 1. I didn’t have the space there to increase the scope further so simply shipped out. I know the bottom type on that one from what came up on the anchor which just washed straight off rather than being the heavy and ‘clumpy’ mud of most of that area. It was soon after that second experience that i realised that i couldn’t rely on a set-up of 2 similar anchors and so bought one and then a second Delta type. The Delta anchors i will talk about in the next post in the series.