June 30, 2006 - Ferrocement Mushroom Mooring Anchors
by Michel & Jane DeRidder

We made a couple of ferrocement mushroom mooring anchors many years ago using truck axles as the main backbone, with eyes welded to the shaft, and rods welded to the hub, with several layers of chicken wire completing the structure. A few years later we made two more, using 2-inch steel pipe, 3/4-inch reinforcing rod and fence wire. (See diagram below.)

To make a set of mooring anchors, first weld together the steel skeletons. Dig holes in the ground or in the sand at low tide and line them with polyethylene sheeting. Pour in a little sand and cement mix. Place the steel and wire forms in, and then pour on the rest of the cement mix, tamping it down well. Let it set for a few days. Lo and behold - mushroom anchors with good holding power in mud or sand bottom. Zinc anodes properly connected to the steel will protect them from corrosion.

The first time we cast a set of ferrocement mushroom anchors, we did so at low tide using cup-shaped holes dug in the sand as moulds. When it came time to set them up as a mooring, we were able to tie the dinghy to them at mid-tide so that, as the tide rose, they floated off and we were able to transport them into position suspended under the dinghy. We used the two bridled together with a swivel for our permanent mooring setup in Canoe Cove, when Sidney, British Columbia was our cruising and working base. We felt quite secure leaving our 40-foot sloop swinging on the mooring even in winter gales. As far as we know, they are still there.

The second set of mooring anchors we poured in a friend's Northland, New Zealand orchard. We dug the holes rather larger than we had intended. Each anchor took two wheelbarrow loads of cement mix. We rolled the finished 200-pound monsters up an improvised plank ramp with the help of several volunteers into the back of a station wagon and drove them down to the Kerikeri Stone Store quay. Hoisted aboard Magic Dragon by means of halyard and anchor winch, the anchors were carried on deck and lowered into place further down the river. The buoyed lines were easy to drop or pick up, much quicker and more pleasant than picking up mud-covered ground tackle every time we wanted to pop out into the Bay of Islands or beyond. The mushroom moorings in the Keri River served as our working base for several months while we played the role of river rats instead of ocean wanderers. Pile moorings have long since taken their place, although we still use the one remaining mushroom to keep our bow out of the stream. The other one disappeared we know not where during the flash flood of '81.