Permanent Anchor for docking

[Seevee]

Hi,

I'm looking for a permanent solution for an anchor that I can put in the water adjacent to my boat that will hold it during storms.

I'm thinking of some sort of huge screw/auger in anchor, perhaps expanding that will just stay on the bottom that I can hook my line to that will hold the boat.

Perhaps a cement base? Thoughts and ideas?

No, I don't want to put a piling in as when not in use, it would lie on the bottom so a boat could just go over it.

 

[Shrew]

What you're describing is a Helical Mooring. There are many manufacturers out there.

 

[ssobol]

Depends on what the bottom is.

I here an old large engine block makes an excellent anchor in softer bottoms once you let it work its way in a bit.

 

[Comodave]

Go with the Helicoil.

 

[TDunn]

Locally we use a several ton block of granite with a steel staple passed through it and a chunk of chain attached to the staple.

 

[Shrew]

Concrete loses approx 40% of its weight when submerged. A lot of places now frown upon using engine blocks.

 

[smitty477]

Depends on the bottom and the area - where we are the typical solution would be an appropriately sized mushroom mooring with a primary and secondary chain attached to a surface ball. From the ball you would have multiple pennants attached to the boat dependent upon size and weight.
In our soft bottom harbors the mushroom, anchor will take a 'set' in a couple of weeks.

 

[DavidM]

All of these have been used for moorings in one place or the other. The proper selection depends on the bottom, availability and local regs.

Granite block, concrete cast pyramid, old engine block, mushroom anchor, helical mooring, probably others. For your boat in a protected cove you will need a 1,000 lb granite block or 500 lb mushroom at least. Chapman’s gives rigging details.

David

 

[Ski in NC]

Need to know what kind of bottom. Hard/sand/mud? Depth?

 

[Seevee]

Need to know what kind of bottom. Hard/sand/mud? Depth?

Bottom is soft mud for about 4 or 5 feet, and then a very hard mud pack. Some sand mixed in.

 

[smitty477]

Bottom is soft mud for about 4 or 5 feet, and then a very hard mud pack. Some sand mixed in.

That is a good bottom for mushroom moorings like in our area.

 

[PMF1984]

Folks switch from mushroom to helix, nobody switches from helix to mushroom. There is a reason why.

 

[smitty477]

Folks switch from mushroom to helix, nobody switches from helix to mushroom. There is a reason why.

There are zero helix anchors in our area.

 

[Benthic2]

One of the drawbacks to a mushroom is that it is usually oriented to the prevailing wind direction and if a storm creates wind from a different direction, it can stand the mushroom up and pull it out. That would not be a factor for you since your boat won't be swinging around it.

Helix anchors are much stronger but require a qualified installer and they may be hard to find, according to this article:

https://www.boatus.com/hurricanes/moorings1.asp

 

[PMF1984]

If there are no installers in your area, then the cost of getting the knowledgeable installer with the specialized equipment may be too high.

In that case you should use a 2 ton cement block.

 

[Seevee]

It's pretty clear that a helix is a superior anchoring solution.


Now, the small one they make with one disc can be installed without the hydraulic installation equipment, if I can't get an installer in my area.



Wondering is 2 or 3 of those could be used for solution, put them in at angles and tie them together at the top with a plate. We do similar with aircraft tie downs.

 

[Benthic2]

I am totally unqualified to speak on this, but, since its the internet......

I'd think if I was going to use 2 of them...I'd put one off the stern and one off the bow. That might do a better job of keeping the pressure off of your pier, and provide completely seperate and redundant solutions.

 

[Comodave]

The new issue of Boat/US Magazine came today. There is an article about hurricane prep in it. It has some stats on mooring anchor systems. Tests done by MIT, Boat/US and Cruising World found that a 500 pound mushroom anchor in mud could be pulled out with 1200 pounds of pull. An 8000 pound deadweight (concrete) block could be pulled out with 4000 pounds of pull. A helix mooring recorded 12000 pounds of pull which was the maximum of their test pull when a shackle broke. Helix appears the way to go.

 

[Boat]

Your anchoring system has to give to unstoppable forces. The alternative is that parts of the boat will give. I'm talking extremes, like hurricane preparation. A weight, maybe a concrete block that rises and falls with the boat can accomplish this. the block keeps the anchor lines near the bottom so the anchors don't pull out. This system also keeps the bow into the wind. The boat can weathervane as the wind direction changes.

I've posted this before and believe everyone should be familiar with these ideas.

How to create an instant hurricane mooring

If another boat breaks loose and blows into yours, all bets are off.


If the water blows out of the river, or bay, and your boat bounces off the bottom, all bets are off.

 

[Boat]

More on mooring. The world according to crisflo.

https://sites.google.com/site/crisflopt/pag2/manobra/sea-anchor

 

[rgano]

I reread the OP several times, and for the life of me, I do not understand the objection to a piling or two, especially the part reading "...it would lie on the bottom so a boat could just go over it." Pilings would extend vertically from the bottom, right? What am I missing?

I have slips for two extra boats here at home outside of my primary boat shed with lift. These two slips are formed two lines of three pilings, one line each side of my boat house and pier and parallel to their long axes allowing boats up to fifty feet long to moor there and not require fendering against the pier/shed because they can secure lines to the pilings and pier/shad to suspend the boat between the two. The pilings are 18 feet from the pier on one side and sixteen feet on the other.

 

[diver dave]

My canal system prohibits any isolated dolphins, pilings etc not connected to a dock, or more than 16' from a seawall. So, UW fixtures are the only way to connect a line to keep a boat off the dock.

 

[Comodave]

Since I painted my boat last year, I no longer wanted the boat sitting on the fenders 24x7 and possibly scuffing the paint. I installed Taylormade mooring whips and they keep the boat off the dock in moderate winds. When the wind blows hard the boat will go onto the fenders. It keeps the boat off the fenders 90%+ of the time. If you are just looking to keep the boat off in normal conditions then the mooring whips are an easy solution.

 

[Mako]

When I was considering mooring a boat in Doha harbor I checked with some dhows moored. They would sink any huge heavy piece of junk they could find. But the key was diving down there with the hose from a construction “trash pump” and jetting the engine block/concrete slab/limestone boulder/dead camel way deep into the bottom.

You can rent the pump from most anywhere, and a simple set of scuba gear gets you there. A lot simpler than driving an auger.

 

[Deckape]

When I was docked in Marathron I had a screw in type mooring installed mid ship out about 30' from the boat. Had a stainless shachle,chain to eye then two lines going to forward and aft springs . Would tighten up in a blow to keep the boat 3 feet off dock. Normally it would just let the fenders do there job. Before leaving slip I would drop lines and let them lay on the bottom and tie off a smaller line on a aft piling. Worked for me.