DIY mooring buoy advise

[Fisherman Rob]

Thinking of putting a mooring buoy out for a 17 foot Double Eagle. Thinking of using a concrete block, but not sure how much weight I need. It's a very protected spot, occasional summer use only, muddy bottom in about 10-15' of water. This would be a DIY project (to limited cost), and am pondering the best technique to sink as heavy a block as possible.

At the moment I'm thinking of pouring the concrete on the beach just below high tide line, then at high tide float it into position using a couple of 45gal plastic drums. Not sure if there would be enough time for the concrete to set, and how big a concrete block I could float, and how to release it...

Anyone have any experience with this?

 

[Fisherman Rob]

Couple of quick calcs:
-18x18x12" Concrete block = 450lbs, and will be about 270 lbs once submerged.
-45 gal drum exerts 375lbs buoyant force fully submerged
-two drums should float a 450lb block off the beach when partially submerged

So questions are:
- Will 450lbs be enough for mooring a small boat for short stays? I'm thinking probably, maybe...
- How to safely release the block once floated into position?
- How long should the concrete cure before sinking?

 

[Fisherman Rob]

Ah ha! This is interesting:
https://www.youtube.com/watch?v=jbADlhTEONo

 

[Dogbreath]

Ah ha! This is interesting:
https://www.youtube.com/watch?v=jbADlhTEONo

Cool stuff that Guy really thought things out.

 

[Fixit]

sounds like a pretty basic/easy mooring.

id go 24x24 x6" thick instead, especially with a muddy bottom,
better suction.

for 15 ft of water id use 20-25 ft of 1/2" galvanized chain or 1" poly steel rope w/ galv thimbles spliced in on each end

 

[NautiGirl]

I have used multiple tubes of concrete with large galvanized eyes, then used a chain to join them. They look like those sono" tube foundation posts for under a deck. When they are laying flat on the sandy bottom in several directions, they get suctioned right in and hold well. The big benefit is they can be lifted into a boat or raft one at a time or even rolled down the beach at low tide to your location. I used about five of them 2.5ft long and 10 inch diameter to anchor a small seasonal dock 6ftx12 ft.

I have another mooring that a neighbour installed at a very low tide on a sandy bottom. It is a slab 6" thick, about 2ft wide and 4or 5ft long. There is a piece of stainless bar bent into it that I have attached my stainless cable to. It has worked great for many 16 and 18ft fishing boats and a larger sailboat.

 

[scotty]

Rob, I have used a 5 gallon bucket, bought a stainless eye bolt 12 or so inches long and some rebar in side the bucket tied to the bolt laying sideways so the eye bolt doesn't just slide out. Held a 18' Lund no problem. Cheap easy and carry with a handle. 15' of chain and then rope, just keep an eye on the chain it will eventually wear. Atleast mine had some wear in it rubbing on the sand.

 

[reid]

I recently redid mine. I built a barge on the beach from logs and poured the concrete into a big 185l bucket. I was also lucky enough to get a bunch of old bc ferries chain that was very very heavy for the ground chain. I wont be able to pull it and inspect it, but I can dive on it. I filled most of the bucket with the chain, then poured concrete all around it. I left about 10 feet of the heavy chain out of the bin, and set my top chain on to that. I also made sure that I left a couple other links partially extending from the concrete so that I could grab onto them later if needed. However with the link size of that chain ( about 40lbs a link ) i don't think that it will be eaten through any time soon.

When I did it, i towed it out in position with my boat. I then had a person tie off the barge to the beach to hold it in approximately the right position. I used a long line tied to the end of the mooring ball and towed it off. It was scary as hell, to think of doing it, but in reality it was easy and safe. I had so much extra line that nothing could really go wrong. It came off really easy and turned into a non issue. Fairly redneck, but all worked well.

I let the concrete dry for one day, sitting near high tide, tied off to the shore. I had to fix the barge a little the next day, from the waves, but not too much. According to my father, who is a bridge man by trade, the concrete is fine to get wet after about 8 hours. However it is still weak, so I wouldn't moor to it yet. You can also get special concrete that you can poor fully wet. Cant remember the type, but if you are interested, I can ask him again.

I also bought some cheap foam tubes from Princess Auto that I used to level out the raft once it was floating, as the logs floated the raft all differently. Probably wasn't needed at all though.