Making an anchor for a mooring line

[broncobowsher]

Thinking about it, the 55 gallon drum has an issue. If it tips, it can roll. Think bad storm. Even it it doesn't roll that well. All the real mooring blocks I can remember are cubic shaped. By real I mean stuff that was engineered for commercial use, not just a home brewed block.

 

[wetb4igetinthewater]

So some clarifying information. This won't be used in winter during the worst storms. In fact, I will be diving down and detaching the chain (stainless steel, 320 if I can get it, 316 at a minimum) and bring it in for maintenance/monitoring.

There can be some strong winds at high tide during the summer, and this is where the combination of mass of the anchor and length are important.

But the boat that is going to be moored to the buoy is a 16.5 foot / 5-meter runabout, around 1500 lbs / 700 kg.

 

[Wibble]

In that case the twin anchor method may be best. It's used all over the tidal UK for yacht moorings.

 

[wetb4igetinthewater]

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.

In that case the twin anchor method may be best. It's used all over the tidal UK for yacht moorings.

How would that help? Just to keep the boat from staying more in place? Don't really care about that. Most properties have buoys in front of their properties and are thus spread out. While farther out is shallow, everyone avoids that as sometimes people boat at night. It is classic normalization of deviance in my opinion, as sometimes there is driftwood floating in the water. I wouldn't want to hit that at 30 mph.

 

[NW Dive Dawg]

Hey Kosta..... Already having the permit is awesome! I probably would have just bootlegged it on a midnight no moon operation. I'm actually surprised that the State isn't specifying exactly what type of system you need to install. Most permitted moorings in the Sound these days are the Helix type screw anchors since they're supposedly the least impactful......

Anyway......regarding your actual question......instead of stainless, you might consider using a hot dipped galvanized pin anchor shackle for your connection point..... I just went and pulled one out of my shop for a pic showing some scale with a pop can. This one is 1.125 in diameter material and rated at over 9 tons of lifting capacity.... You can easily replace the "pin" with some 1 in rebar to "create" more robust "anchoring" into the poured concrete..

PS...... I have a guy up on the south end of Lopez who had me check his bootlegged mooring every couple of years. His "anchor" was just a cleaned up freeze cracked V8 engine block that he actually got paid to take away......and a chain running through one of the cylinders!

Galvanized Screw Pin Anchor Shackle

Galvanized Screw Pin Anchor Shackle

e-rigging.com

 

[wetb4igetinthewater]

Hey Kosta..... Already having the permit is awesome! I probably would have just bootlegged it on a midnight no moon operation. I'm actually surprised that the State isn't specifying exactly what type of system you need to install. Most permitted moorings in the Sound these days are the Helix type screw anchors since they're supposedly the least impactful......

Anyway......regarding your actual question......instead of stainless, you might consider using a hot dipped galvanized pin anchor shackle for your connection point..... I just went and pulled one out of my shop for a pic showing some scale with a pop can. This one is 1.125 in diameter material and rated at over 9 tons of lifting capacity.... You can easily replace the "pin" with some 1 in rebar to "create" more robust "anchoring" into the poured concrete..

PS...... I have a guy up on the south end of Lopez who had me check his bootlegged mooring every couple of years. His "anchor" was just a cleaned up freeze cracked V8 engine block that he actually got paid to take away......and a chain running through one of the cylinders!

Galvanized Screw Pin Anchor Shackle

Galvanized Screw Pin Anchor Shackle

e-rigging.com

My father went through the process. You could probably have worked at a mill for 50 years and be able to count the number of permitted buoys in the area. There are probably hundreds bootleg buoys. No need to do it at midnight. Everyone does it in plain view!

EDIT: The state's concern is eel grass. There is none where we are. There is some, but about a mile west and east of us. However, we are using small buoys to keep the chain off the bottom. That's another reason why I don't leave the chain there year round. I was teasing my neighbor whose buoy was almost underwater due to the oyster farm on the top half of his line. The bottom of his line is rope, and since that's getting dragged on the bottom, nothing lives close to his weight and his line is clear.

 

[Tracy]

Hey Kosta..... Already having the permit is awesome! I probably would have just bootlegged it on a midnight no moon operation. I'm actually surprised that the State isn't specifying exactly what type of system you need to install. Most permitted moorings in the Sound these days are the Helix type screw anchors since they're supposedly the least impactful......

Anyway......regarding your actual question......instead of stainless, you might consider using a hot dipped galvanized pin anchor shackle for your connection point..... I just went and pulled one out of my shop for a pic showing some scale with a pop can. This one is 1.125 in diameter material and rated at over 9 tons of lifting capacity.... You can easily replace the "pin" with some 1 in rebar to "create" more robust "anchoring" into the poured concrete..

PS...... I have a guy up on the south end of Lopez who had me check his bootlegged mooring every couple of years. His "anchor" was just a cleaned up freeze cracked V8 engine block that he actually got paid to take away......and a chain running through one of the cylinders!

Or, if you get a big enough shackle, you can forgo the mooring block altogether.

 

[sea_ledford]

If you go with the galvanized shackle, spend the additional money to get a good made in USA one, like a Crosby. In my experience, the chinese ones fail at an alarming rate in saltwater.

 

[Wibble]

How would that help? Just to keep the boat from staying more in place? Don't really care about that. Most properties have buoys in front of their properties and are thus spread out. While farther out is shallow, everyone avoids that as sometimes people boat at night. It is classic normalization of deviance in my opinion, as sometimes there is driftwood floating in the water. I wouldn't want to hit that at 30 mph.

The two anchors work in opposite directions, one for the flood, one for the ebb.

The riser comes up in the middle of the two anchors and, when your boat's moored to the buoy, it'll pull against the ebb or flood anchor depending on the direction.

Anchors tend to work in a single direction you see

 

[Fred Tagge]

Ocean Engineer here who has installed a bunch of these.
Bottom and what is to be moored makes a lot of difference.

Hard bottom (rock or coral) use a core drill to set the anchor point. Drill into the bottom with the core drill until the bit get far enough in you can just see the top, then leave the bit in place and bond it into position using polyester or epoxy fiberglass resin. The resin is denser than seawater, resistant to mixing, and can be poured in with just a hose and funnel from the surface mixing support.
For small boats on hard bottom boats a 316 stainless steel eyebolt of an inch or so in diameter and long enough to engage enough rock epoxied into a hole drilled in the rock will last a long time if the mooring line has suitable chafe protection installed.

On soft or sand bottoms there are several easy solutions if you have access to a marine or industrial scrap/boneyard. Ships are required to replace their anchor chains when corrosion reaches a defined level, generally about a 10% reduction in cross section. It is illegal to "de-rate a used chain for use on a smaller vessel, so that can be available for free or scrap steel pricing. Even smallish ships use chain large enough to be effective anchors for boats under 100' long if enough of it is spread out on the seafloor. Chain is easy to load onto a small boat and deploy by allowing it to run free off a plywood guide (I've done this off a 12' Boston Whaler) onto a sand bottom. A buoyant section of line or submerged buoy needs to lift a few feet of chain off the bottom to reduce damage by scour, with the rest of the line being either near neutral (spectra) or slightly negative (nylon). When working off Andros we did all chain and line moors with no buoy such that the top of the moor was submerged by 15 to 20 feet, with a submerged negatively buoyant painter 30 or more feet long to hook to the visiting vessel. Hookup was done by sending a snorkeler down to retrieve the line.
Inland or near industrial areas old worn out railroad wheel sets are handy and relatively inexpensive. Price is generally that of scrap steel, with each wheel set yielding 2 anchors. The wheels are roughly 500# each and work well with a heavy duty 316 stainless hoop or shackle welded to half the axle for mooring attachment. They self embed in sand or mud through natural scour and are highly resistant to dragging if the attachment point is on the axle end. Other things that work well are engine blocks with chain passed through the cylinders (pick your engine size to get the weight you want,) and scrap iron filled concrete blocks. Pure concrete is too light underwater to resist much water movement or ship dragging.
Another option is a propane cylinder full of lead cast around a suitable size of chain. That is real dense and embeds due to scour quickly.
The life of any mooring is related to the relative movement of parts and the corrosion rates. Both steel and 316 stainless steel dissolve at the rate of about 0.008" per year in still well oxygenated salt water. The primary difference is the stainless allows the corrosion loss to be readily seen and measured. There is also the erosion corrosion effect on stainless where the protective film of corrosion is removed by relative movement of the components. You'll either need to use heavy enough sections to handle that or design it to minimize relative movement between adjacent hard parts.