I need to make a mooring.

NYSail · Oct 4, 2022

Ha….. 3,000lbs? Think they were pulling your leg on that. Does your boat even weigh that much? I have my 20,000 lb on an 800lb and that is more than adequate. 200 would easily do the trick I’m sure. Why not go around to local marinas and see if you can pick up a used mushroom mooring cheep. I know our yard has them available.

good luck

Scott T-Bird · Oct 4, 2022

Not even close to enough. Basically, you are making it with concrete that weighs 150 pcf. Your block will only be 2 cf. Water is displaced at 62.4 pcf so you are displacing 125 pounds of water. Your block in water only weighs 175 pounds. The boat would virtually lift it right off the bottom and float away ... especially if you are on a hard bottom and it can't settle in.

Scott T-Bird · Oct 4, 2022

Anecdotally, I had a concrete block for a mooring that weighed about 1,350 lbs (3' x 2' x 1.5') to secure my 27', 5,500 pound sailboat in a bay on a small lake, with the concrete block settled in soft mud. During a wind storm once, it dragged about 20'. this was no do-it-yourself project. The park district made the block for my boat and they use a barge to set and retrieve all blocks every season.

Georgian Bay? You will find yourself not removing your boat quick enough to save it in a storm eventually. The bottom condition makes a huge difference. A block on a hard sand or rock bottom will skate very easily. I had an iron flywheel for an anchor a long time ago. It probably weighed a few hundred pounds but once it settled in the mud, there wasn't anything on the lake that could move it. It was set for eternity.

rgranger · Oct 4, 2022

Yeah.... what @Scott T-Bird is getting at is density and displacement. If you are going to build it yourself and can get some lead shot (maybe talk to a tire shop and see if you can get the scrap lead balances) and/or iron scrap and fold that into your concrete. You need to get the density up.

Here is some math conversions that will help.

A gallon of sea water is approx. 8.56 lbs.

The density of concrete is approx.. 150lb/ft3.

And a ft3 is approx. 7.48 gallons.

So if you start with a five gallon PVC bucket full of concreate on land it will weigh in at

If you don’t fill the bucket all the way up… or you just want to keep the math simple, we can call it 100lb per 5 gal PVC bucket.

But since sea water weighs 8.56 lbs per gallon, … the bucket displaces 43lbs so once you drop that PVC bucket into the ocean it will only “weigh” 100-43 = 57 lbs.

If you can jack up the density of the filler in the PVC bucket… 250lbs/bucket.... then a 5 gal PVC bucket “weighs” 200lbs instead of 57 lbs when you drop it in..

In olden days, people used to go the junk yard and get an engine block, run a chain through the cylinders and toss it over. But the environmental issues with that makes that a non-option anymore.

If you can find some scrap iron and have a welder make you an anchor point and embed that in cocreate...

note this difference....

500 lbs or iron only displaces 1.01 ft3 of water or about 7.5 gallons = 64 lbs. Your anchor now weighs in at 400+ pounds

For reasons that are not well understood, concreate inhibits the rusting of iron.... so the main week point w.r.t corrosion is the chain. You would want to use high quality chain and inspect it regularly.

Scott T-Bird · Oct 4, 2022

rgranger said:
In olden days, people used to go the junk yard and get an engine block, run a chain through the cylinders and toss it over. But the environmental issues with that makes that a non-option anymore.

A big reason why people used to look for engine blocks and such aside from the weight was the density and the cavities helped to get the anchor firmly in the seabed. Once an engine block is settled in the mud, there is virtually nothing that can break it out. A concrete block just loves to skate across the bottom on it's nice, smooth surface. Put a grappling hook on the bottom of your 300# block and you might have a chance!

BarryL · Oct 4, 2022

Hello,

Here on the Long Island Sound EVERYONE uses mushroom anchors for moorings. When I had a 22' Catalina I used a 200lb mooring. For my 35 and 36' boats I used a 350lb mooring. These are dropped and recovered every year by a large boat with a crane.

Make sure you have good chain from the mooring to the float, use some extra chain to account for high tides and high winds.

Good luck,
Barry

JamesG161 · Oct 4, 2022

rgranger said:
For reasons that are not well understood, concreate inhibits the rusting of iron

What did you say, Mr Chemist.

Rust or Oxidized Iron has been used as a cement additive for YEARS!

Check your periodic Chart for the Answer.
Jim...

Scott T-Bird · Oct 4, 2022

BarryL said:
Hello,

Here on the Long Island Sound EVERYONE uses mushroom anchors for moorings. When I had a 22' Catalina I used a 200lb mooring. For my 35 and 36' boats I used a 350lb mooring. These are dropped and recovered every year by a large boat with a crane.

Make sure you have good chain from the mooring to the float, use some extra chain to account for high tides and high winds.

Good luck,
Barry

I'd agree with you but I think the location requires local knowledge. A mushroom works great in a soft bottom because to pull it out requires lifting a ton of material that settles over it. I'm not so sure it works in a rocky environment where it can't get a foothold in the bottom. If the locals are exclusively using screw anchors, there is a reason for it. I think a small block of concrete is about the worst idea ... he may as well throw out a fender!

jon hansen · Oct 4, 2022

railroad wheel from scrap yard with 1' steel rod bent in a hoop welded to it works well. they are available . look around.
there are train scrap yards all over the place. i got one 50 miles away

has served me well

dLj · Oct 5, 2022

nothingventured said:
the boat will be in the Georgia straight so to exactly the wild pacific but we do get some gales. I will probably not have it out on really bad weather as I can trailer it out. the bottom is sandy unless I end up putting it on a rocky bottom.

In my opinion, you need to decide first if you are putting the mooring in sand or on rock. That requires two different mooring types.

Do bear in mind, a mooring is really a stationary anchor. All of the catenary aspects of anchoring apply to moorings also....

dj

rgranger · Oct 5, 2022

JamesG161 said:
What did you say, Mr Chemist.

Rust or Oxidized Iron has been used as a cement additive for YEARS!

Check your periodic Chart for the Answer.
Jim...

LoL
Iron bars in cement do not rust very quickly at all. Adding rust to cement is not the same thing as cement inhibiting the rusting of iron.

What I was alluding to is that all of the cations in a typical cement mix are already in the oxidized state. So the rust inhibition is not (or does not seem to be) due to a redox reaction like seen with sacrificial anodes.

Scott T-Bird · Oct 5, 2022

rgranger said:
LoL
Iron bars in cement do not rust very quickly at all. Adding rust to cement is not the same thing as cement inhibiting the rusting of iron.

What? Corroding re-bar is the leading cause for structural failure of concrete! You've never seen what it does to a bridge abutment or columns? There's a good reason why engineers spec epoxy-coated rebar! Long ago, I was on an inspection with some folks from USDOT, who were disputing the need for replacing concrete columns under the Dan Ryan Expressway in Chicago. They didn't want to fund column replacement when the deck was getting replaced. One of our engineers just wanted to demonstrate the hollow sound by tapping on a column with a hammer when about 500 pounds of concrete came crashing down at everybody's feet exposing the corroded bars underneath! Case closed! No more argument!

JamesG161 · Oct 5, 2022

We have used Iron Rebar in Concrete for years.
The Rebar never corrodes inside the cured Cement.

For this reason

rgranger said:
the rust inhibition is not (or does not seem to be) due to a redox reaction

Back on topic..

1) Mould your mooring block with pyramid shape [less drag and tipping]
2) Bend and wire connect Standard Rebar about 2 layers separated by 3-6 inches-[ 2" off bottom of block going upward for next layer]
3) Weight of Block should be sized per Boat size and buoyancy per above comments.
4) Install large Stainless Eye bolt from top thru bottom of Pyramid

Jim...

PS: Just Read above post. Building bridges that take Vibrational loads is much different
Static loads found in a Grand Hotel built in the 1920 had ZERO Rebar corrosion on it Structural Columns... Case Closed

Scott T-Bird · Oct 5, 2022

JamesG161 said:
We have used Iron Rebar in Concrete for years.
The Rebar never corrodes inside the cured Cement.

What? Are you in an alternative universe? Are you talking about cement or concrete? Concrete failure is universally caused by corroding rebar inside the structure. Concrete is not impermeable. Billions has been expended to repair concrete based on this simple reason. Did you not notice the Surfside building collapse in Miami? Claims were settled within a year of the collapse for just about $1 Billion. Causation ... corroded rebar and failed concrete.

JamesG161 · Oct 5, 2022

JamesG161 said:
PS: Just Read above post. Building bridges that take Vibrational loads is much different
Static loads found in a Grand Hotel built in the 1920 had ZERO Rebar corrosion on it Structural Columns... Case Closed

Hollyberry · Oct 5, 2022

What part/area of Georgia Strait are you planning this? What is the exposure? I kind of agree with the poster above who suggested you might not 'trailer out' in time, esp with the occasional 'unforecasted' condition.

rgranger · Oct 5, 2022

So I got currious and did some digging... found this interesting article.

Cement & Concrete FAQ - Portland Cement Association

Your basic cement and concrete questions answered by qualified experts.

www.cement.org

It does state that iron corrosion is a major issue but it also says that if done right...

Concrete and the Passive Layer
Although steel’s natural tendency is to undergo corrosion reactions, the alkaline environment of concrete (pH of 12 to 13) provides steel with corrosion protection. At the high pH, a thin oxide layer forms on the steel and prevents metal atoms from dissolving. This passive film does not actually stop corrosion; it reduces the corrosion rate to an insignificant level. For steel in concrete, the passive corrosion rate is typically 0.1 µm per year. Without the passive film, the steel would corrode at rates at least 1,000 times higher (ACI222 2001).

Scott T-Bird · Oct 5, 2022

Sure, steel rebar that is encased in concrete that is well-protected from moisture will not corrode for a long time. It's misleading to state that concrete inhibits rust in embedded rebar. Clearly, based on the billions of dollars spent on renovation and the catastrophic failure of concrete when neglected it is a travesty to even suggest that rebar does not corrode when embedded in concrete. Spalled concrete all across this nation is the leading cause for the degradation of infrastructure. Concrete doesn't spall until the corroded steel embedded within loosens the concrete. Carbonation - the process by which the degradation of concrete leads to the corrosion of rebar.

Scott T-Bird · Oct 5, 2022

Is there a practical application of an alkaline environment of concrete actually protecting steel from corrosion? I suspect not. You can't be serious if you believe that embedded steel doesn't corrode in concrete. It is the most common structural failure! Just look up carbonation.
Concrete does not protect steel from corroding ... it is ludicrous to think otherwise! The evidence is all around us!

I need to make a mooring.

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SBO Weather and Forecasting Forum Jim & John

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SBO Weather and Forecasting Forum Jim & John

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SBO Weather and Forecasting Forum Jim & John

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