Folding Fisherman Anchor

For a while I’ve been pondering what anchor to carry in my dinghy. It needs to hold reasonably well, yet also be compact and stow nicely. My boat don’t have a lot of room and I really want something that will fit in the space between the mast and semi-bulkhead at the front of the centerboard case which is about 20″ wide. I also don’t want a lot of sharp corners and protrusions that are apt to punch holes in the boat. I went on an exhaustive search through Bruce, Danforth, Fortress, Northill, CQR, Delta, Ronca, Manson, Grapnel, Mushroom, and Fisherman anchors comparing size, weight, cost, and general opinions.

Most of these are awkward to stow in the space I have available and the ones that do fit don’t seem to hold very well. But the biggest problem is that they’re all well over my budget of zero dollars… So, when you can’t find what you’re looking for, go make it!

I was thinking of making a folding Northill but the Fisherman/Admiralty pattern has a more pleasing classic look, so I’m going to go with one of those. Most styles have an “L” shaped stock allowing you to fold them down flat against the shank which helps in the storage department, but it’s still not much better than a Danforth. However, some versions also have folding flukes, so I added that to the design.

Looking around on the internet I found a few drawings of homemade Fisherman anchors and a page detailing key dimensions of Herreshoff anchors. I also read through the Northill patent (#2,075,827 and #2,905,128) for any insights. Taking all this information into account, I made my own design which is mostly based on the ideal anchor dimensions drawing converted to easy fractions and the Herreshoff bill angle.

Chuck’s Anchor, Ideal Anchor Proportions, Northill Patent, Herreshoff Anchor

After a lot of pondering and tinkering around in CAD, I came up with a model that wouldn’t be too hard to make, yet folds up into a convenient size. In the folded position it is 18.5″ long overall, 5″ wide, and 3.5″ tall. It weighs 8.3 pounds, although I can change that by welding on more mass to the cheeks that hold the pivoting flukes. It is made from 1/2″ x 1.5″ flat bar for the shank, 5/8″ round bar for the stock, and 1/4″ and 3/16″ plate for the cheeks, arms, and flukes. The pivoting arms are held open or closed with a single pin, rather than two as in Chuck’s Anchor.

My anchor

Schematic and flat patterns

I cut the parts out with my CNC plasma cutter, drilled a 1/2″ and 3/4″ hole in the shank, bent the 5/8″ rod with an acetylene torch, and scrounged up some 1″ steel ball bearings from another hobby of mine. I like machining working scale models of naval artillery and I use ball bearings as ammunition.

The parts welded together. Gotta remember not to get so excited that you weld the final ball on before assembly!

Whenever you have to weld a ball to the end of a rod or something, I find it helpful to drill a shallow hole to help center it.

Since these are hardened I pre heated them so hopefully the weld won’t crack. Press down on the top with something and put a few tacks along the joint and it’ll stay centered.

Pretty good for materials from the scrap pile!

And it fits perfectly in the bottom of the space. That’s the benefit of spending the time to make a 3d model of mechanical contraptions to hopefully iron out any design problems. Plus it’s a lot cheaper and easier to make digital models than real life prototypes.

Once I determined the anchor seemed to work as I expected, I bent a piece of 3/8″ round bar around a 1″ round bar to make the ring to take the anchor rode. I split the ring with a cutoff wheel, beveled the edge for a weld prep, stuck it in the anchor shank, bent it back into a circle, and welded it up. I got most of the excess off with a flap disk which left just a little bit of filing on the inside of the circle.

There’s a small stream behind my shop, so I took it down to a sandy patch and gave it a try. I pulled at about a 3:1 scope and it buried right in. Wet sand is ideal, so we’ll have to wait and see how it performs in real life. It will be easy to make new flukes with different angles or proportions and swap them out if need be. If it works well, I’ll make another in stainless steel. Or maybe bronze.