I've got a present from my family: an inflatable fishing boat. They made me very happy. Only thing I had to do before the first trip was to collect the regulated accessories. I could collect them quickly, except the anchor. I want to use it only on lakes, so I needed any type of anchor, but in regulated weight compared to the loaded boat.

Unfortunately I found new anchors in very high price, and found no (useable) used ones. I turned to my friends with my questions, and they told me a 10-15 kg stone or piece of iron can do the job, and these are accepted in case of inspection.

I went around to buy a piece of iron thing, but all of them were too sharp to use them in an inflatable boat. So I went on an alternative: concrete block. Such type what is used in mooring, but in smaller size.

So this is a simple instructable of making anchor weights for a fishing boat (used on shallow lakes).

Step 1: Materials, Tools

Materials / tools:

concrete mix, 20kg
water
mixing box
shovel (or another tool for mixing, pouring concrete)
some recycled plastic tube, or used plastic bucket (*)
iron bars (2 x 50 cm, max 10mm diameter)
saw
file

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* I even heard of using a wellington as a mold.

Step 2: Preparing

I found a 20 cm diameter plastic tube around, and cut it in two.

I wanted to keep the concrete in the tube (not just as a mold), so I scratched their inner surface to create anchor points between plastic and concrete. (It is not necessary. I only thought it can help.)

I bent the iron bars with help of an iron tube. See shape on pics

I also get two pieces of wood, to keep the bended irons in their place.

Step 3: Mixing, Pouring Concrete

Then I mixed the concrete mix and the water well, until it was homogenous.

I poured the concrete into the tubes, then placed the bent bars into their place, and fixed them with wood pieces.

I let them cured overnight under plastic cover. Then I removed the wood pieces.

I kept the concrete wet and under the plastic cover in the next 7 days.

Step 4: Finishing

The anchor weights were ready for finishing after a week.

I simply used a piece of wood to measure the height of surplus tube from inside and copied it to outside. Then I connected the marked dots to a line.

I sawed the plastic slightly beside of the line to avoid cutting into the concrete.

Finally I made fillets around the sharp corners with a file.

Step 5: How to Use

It can be obvious, but it wasn't for me, so for those who are similar to me in this:

Anchoring in shallow water

You need to use two anchors to anchor a boat good in shallow water (less then 3 meter). One for the front and one for the back.

First drop the back anchor at least 6 meters behind where you want to anchor the boat.

Then troll forward about 3 meters past where you want the boat anchored. Keep letting out rope from the back. Then drop the front anchor.

Then, pull the boat backwards with the anchor rope in the back while letting out rope in the front. Once both anchors are out and the back anchor is far behind the boat and the front anchor is far in front of the boat, tie off both ropes tight and the boat is stationary.