Making an anchor for a mooring line

[wetb4igetinthewater]

I need to put in a new anchor and chain for a permanent buoy. The engineer in me likes to over engineer. So I picked up 55 gallon drum. Now I am planning to cut that in half, as cement is about 20 lbs per gallon, and I don't think I need half a ton, but 500 lbs will do the trick.

I'm wondering who might else have done this. With patios I've listed, I've used extensive rebar but I don't think this is the right solution for something underwater. Or am I wrong?

I want the anchor to have a loop of preferably 320 grade stainless steel that is rather thick, about 1/2 inch or so.

Any suggestions?

 

[sea_ledford]

Where is this going to be? What is the substrate? A half 55 gallon drum will roll away in no time if it isn't a relatively soft bottom. What are you anchoring to it?

The concrete anchors I've done before (nothing nearly so large) were just solid concrete. You don't want to add rebar as it will rust, expand and crack the concrete.

 

[broncobowsher]

Location matters. Storms have been known to move whole shipwrecks. There can be legality issues as well. I know all my local waters would be very unhappy if I was dumping a big lump of concrete into them. How would you even get it to the location? 500 Pounds isn't exactly something that is easily moved on land, and gets more difficult on water. You are getting to the point of needing a construction barge to handle that. You are not going to just set it in the back seat of a pleasure boat and flick it off the side. So many questions.

Rebar might work. #6 in salt water, good luck with it lasting a year. #12 in fresh water will last decades. I'm thinking of a loop that you can tie a rope off to. But you would probably still need a clevis to keep the rebar from just eating the rope. And that gets back into location. If you are doing this in a private quarry (I actually have a friend who owns one) there is no concern at all. Trying to drop this in a river with currents, more of an issue. The open ocean, pretty much a lost cause.

 

[Tracy]

If you are installing it from a boat, use an old tire.
Any old junk tire works, you can get them for free anywhere in the world. Shove a piece of plywood in the bottom and stick your hook out the top. Pour it full of concrete. Here in the lakes I use rebar for the mounting ring, but in saltwater, stainless would probably last longer.
Once it is done and cured, you can roll it onto and then off of your boat. It won't scratch up the paint or fiberglass.

 

[broncobowsher]

If you are installing it from a boat, use an old tire.
Any old junk tire works, you can get them for free anywhere in the world. Shove a piece of plywood in the bottom and stick your hook out the top. Pour it full of concrete. Here in the lakes I use rebar for the mounting ring, but in saltwater, stainless would probably last longer.
Once it is done and cured, you can roll it onto and then off of your boat. It won't scratch up the paint or fiberglass.

Had not thought of the tire. We have a couple at work that are set up that way that hold stop signs. They were done when there were issues with digging holes (underground utilities were there first). Those suckers are heavy.

 

[wetb4igetinthewater]

1. We have a permit from the state.
2. There is a gentle slope, a mix of silt, rocks, and sand
3. I planned to cut the barrel in half, so it would be 20 inch diameter, 17 inch height. It would sink a little bit into the bottom. I'd pour the cement into the drum from our bulkhead.
4. Vertical tide flux is 16 feet. Plan would be to roll it down the beach when it is a -4 tide. I'd set up probably 300-400 lbs of lift bags and use my boat for the rest. The design of how to mount the chain to the half-drum is something I'm trying to figure out. Ideally, I'd have a stainless steel U-bolt, that is 18 inches long and 6 inches wide, 1/2 inch diameter where there would be cross bars to secure with the cement.

If you are installing it from a boat, use an old tire.
Any old junk tire works, you can get them for free anywhere in the world. Shove a piece of plywood in the bottom and stick your hook out the top. Pour it full of concrete. Here in the lakes I use rebar for the mounting ring, but in saltwater, stainless would probably last longer.
Once it is done and cured, you can roll it onto and then off of your boat. It won't scratch up the paint or fiberglass.

You bring up memories of our neighbor, Mr. Johnson, putting in his barrel, using innertubes back in the 80s . The outcome was quite humorous, and we and his children laugh about it to this day.

Any suggestions on what would be appropriate mixture of rocks/gravel to concrete to reduce the amount of concrete, like aggregate? Is this stronger or weaker than pure cement?

 

[Bazzathemammoth]

From creative anchoring by Gary(cptn fatty) goodlander

 

[Bazzathemammoth]

This is for a 40ft sail boat. Read the book for more detail if you are interested. I haven’t done this myself

 

[Wibble]

Couple of boat anchors placed 20m/60ft apart inline with the current with a hefty chain between them and a riser chain attached half way running up to the buoy.

 

[Vicko]

How heavy of a boat will you moor to it?
It's always better to have a flat block with a wider surface area, friction helps a lot.