- Half gallon plastic jug - Use a bottle with as thick a plastic as possible. The plastic protects your boat's finish when you're pulling the anchor back on board. A squared milk jug works even better because the mouth tends to be larger and it won't roll around in the bottom of the boat.
- Concrete mix with small aggregate.
- Half inch x 6" plus eyebolt with nut
- Half inch nylon or polyethylene rope
- Mix concrete with water to make a thin but not watery mixture - about the consistency of oatmeal.
- Pour the concrete mix into the plastic bottle and fill to the top
- Screw the nut on the bottom of the eyebolt and shove it into the mouth of the bottle so that the eye sticks out the top.
- Allow the concrete to set hard.
- Tie 50 feet of half inch rope to the bottle through the eyebolt or the handle. Use a bowline knot so it won't slip and so you will be able to untie it if you need to replace the rope or change the configuration of the rope in some way.
This anchor is heavy, but it may drag. There are no tangs so if there's a breeze you may move a little bit as the jug drags over the bottom. It's usually easy to drag up at the end of the day for that reason, though. Because it's plastic, the anchor will last a long while. Eventually the plastic bottle may degrade and fall apart. Just peel off the old plastic an the anchor will still work. You'll probably want to cover it with something to keep it from scratching your boat.