Page 41: of Marine Technology Magazine (November 2024)

Figure 5 Figure 6

In this view, we shovel mortar with steel

Using a ladder as an A-frame, stampings to ? ll the ? rst 1” of the bot- we weighed 15-pounds of dry tom of the bucket. The rebar and chain mortar, then 25-pounds of steel are then set in place. Note the rope stampings. This is enough to that holds the chain vertical. We then shovel in more ferrocement. The blue make a 30-pound water weight tarp will help with clean-up later.

ferrocement anchor.

into the cement, the steel rusts, expands, and breaks down the anchor. We were looking for a speci? c gravity of around 5, double that of concrete.

Figure 7

We ? rst picked up the scrap steel stampings, since that was

The ferrocement anchor is cast.

The top is tamped down, pushing the critical item. We were not disappointed. The steel stamp- any steel below the surface. Some ings were in various shapes and sizes. Some were too large, water will pool on the surface as the ferrocement settles. Let cure while most were about the size of gravel. (See Figure 2) 48 hours.

Then it was off to Home Depot for steel wire mesh, rebar, baling wire, chain, mortar, hoe, a mixing tray, and 5-gallon plastic buckets.

The steel rebar, steel wire mesh, chain and baling wire provide the skeletal structure of the ferrocement anchor. (See Figure 3)

Mortar mix is Portland cement and sand, just what we need for the binder. (See Figure 4) We found the mortar adheres well to the steel stampings.

We worked out the ratio of 25-lbs steel stampings with 15-lbs of dry mortar mix. We used a folding ladder for an A-frame

Figure 8 as we had a hanging scale. A ? oor scale would have been just

When the ferrocement has set, ? ip ? ne, too. (See Figure 5) over the bucket and give the bot- tom a tap. The ferrocement anchor

Using a hoe, we mix the steel stampings and mortar in a mix- will release and drop right out.

ing tray (See top portion of Figure 6) A concrete mixer would be very helpful if you want to make a much larger anchor, or several at one time.

Once cast, the anchor has to harden and dry for a couple of days. Don’t be too anxious to pull the anchor out of the mold, as uncured concrete will crack. (See Figure 7)

The ferrocement should be cured enough to pull it from the mold after 48 hours. It takes up to a week to reach about 70% of full strength. After 28 days, the concrete is considered fully hardened. (See Figure 8)

In 3 or 4 days we measure the water weight of the anchors. (See Figure 9)

One variation we haven’t tried yet is to cast a ferrocement

Figure 9 anchor with a center hole for stacking on top of an anchor with a chain. (See Figure 10). If anyone tries this, please send us

Ferrocement anchors can be made in different sizes. Weigh the ferrocement anchors in water to determine their water weight.

a photo to share.

Landereans might consider the many shapes syntactic foam can be cast in for buoyancy. Similarly, Ferrocement lends it- self to unique anchor shapes to better suit a design.

An environmentally friendly ferrocement anchor does the job while lowering the cost of the expendable weight.

Figure 10

A 43-page PDF with additional details on making ferroce- ment anchors is available free to readers by contacting me at

Barbell weights could be added to adjust the overall weight conve-

Kevin Hardy on email @: [email protected] niently. Try casting a smaller ferro-

Reader Feedback: Comments on this article, abstracts of cement anchor with a through hole in the center. The center hole can stories of interest to the wider Landerean community, or sug- be made by using a PVC pipe ? xed gestions for future topics are all welcome. MTR invites you to the bottom center of the pail.

write to Kevin Hardy .

www.marinetechnologynews.com 41

MTR #8 (34-47).indd 41 11/22/2024 10:50:20 AM