Mooring-building one

[aldiver]

I need to put down a mooring in 30-45 foot of water, bottom composition is clay/mud, boat that will be on it will be a 52' cat with high freeboard, lots of windage.....though in a sheltered bay and small if any swell or chop. I have heard all sorts of opinions of screws to a huge anchor, to old engines and much more.....I am totally unsure....what sort of thing should I be using on the bottom and all the way up?.....as much specific detail as possible would be appreciated thanks.

[rebel heart]

The two permananet styles I know of are mushrooms and concrete blocks. All the ones in town here are just massive concrete blocks; to the tune of a couple tons.

[Tnflakbait]

You need something big and heavy. A mushroom anchor is good because it will sink into the mud best. A cheaper way to go is an old tractor or something like that. Surplus ship anchors are a good bet as well.

[rebel heart]

Here's a link: Mooring (watercraft) - Wikipedia, the free encyclopedia

There are four basic types of permanent anchor moorings; dead weight, mushroom, screw in, and triple anchor. These moorings are used instead of temporary anchors because they have considerably more holding power, cause less damage to the marine environment, and are convenient. They are also commonly used to hold dock floats in place.
Example: On The Great Barrier Reef off the Australian coast, a vast number of public moorings are set out in popular areas where boats can moor. This is to avoid the massive damage that would be caused by many vessels anchoring in close proximity.

• Dead weight moorings are the simplest kind of mooring. They are generally made as a large concrete block with a rode attached which resists movement with sheer weight; and, to a small degree, by settling into the substrate. The advantages are that such moorings are simple and cheap. A dead weight mooring that drags in a storm still hold well in its new position. Such moorings are better suited to rocky bottoms where other mooring systems don't hold well. The disadvantages are that they're heavy, bulky, and awkward.
• Mushroom moorings are the most conventional moorings for mud and silt substrate. They are shaped like an upside down mushroom which can bury itself in these materials quite readily. The advantage is that it has up to ten times the holding power to weight ratio as compared to a dead weight mooring. The disadvantage is that they're more expensive than dead weight moorings, don't hold well on rocky or pebbly substrates, and they take time to settle in before reaching full holding capacity.
• Screw in moorings are a modern method. The screw in mooring is a shaft with wide blades winding around it so that it can be screwed into the substrate. The advantages are that it gets the best holding power to weight ratio. Weight isn't really an issue, because even an eight foot screw can withstand 20,800 pounds of force without breaking out in a muddy substrate, which is about 10 times as much force as a 2,100 pound concrete dead weight can take (Helix Mooring Systems Inc.). An additional consideration is size. Screw in moorings are so small that they're relatively cheap. The disadvantage is that a diver is needed to install and maintain these moorings.
• Triple anchor mooring systems are 'unconventional.' This mooring system" (Chapman) uses three lightweight anchors (also known as Danforth) set in an equilateral triangle and all chained to a common center from which a normal rode extends to a mooring buoy. The advantages are that it's light, relatively cheap, and holds quite well with any direction of force. The disadvantage is that it's difficult to install.

[2divers]

The ones I saw in the BVI and some places off Florida were a combination of a screw anchor to hold everything in one places and a 'mass' anchor to keep the boat in one spot. In the BVI off Marina Cay it was common to see that the mass anchor had destroyed an circular area around the screw anchor as the boat had moved around in windy conditions. We never had a problem with the exception of a chaffed through line on the morring ball. I would guess that the mass anchor was not large enough for those locations, but it did keep everything in one place 95%+ of the time.

Concrete is cheap to frame and pour, but it would be a hell of a job to get it out in the water and down to where you want it it which is a weakness of any mass anchor. The cheapest would be the three point anchor mentioned previously. Make sure you have a good swivel at the connection! That is typically the weakest point in the chain and the most constantly loaded and stressed.

Another advantage to a screw mooring is that it can be installed from the surface. The screw is lowered on a long attachment and you use a long lever arm on the surface to screw it into the bottom. You do have to go check it to make sure it set completely and to detach the extension, but you have a good idea as you are putting it down how well it's doing.

2divers

[mickmul]

I use two 1.5 ton square poured concrete blocks, with heavy eyelets at each top. These are connected with heavy ships chain and are laid at right angles to tidal flow to allow the chain fall over and back with changes in current. Only in a strong blow will the chain lift and put pressure on the blocks, which are semi-submerged by virtue of being dropped in place. A heavy rope riser between ground tackle and mooring bouy has a heavy duty stainless swivel shackle at either end to prevent riser twist.(too many 50 grand boats on 50 cent shackles) and the riser passes through the mooring bouy where a floating strop allows easy pickup and guidance to the samson post. Hope this makes sense. . . I only paid for the job, but noted the elements that went into it!

[delmarrey]

where are you located????

Many harbors have regulations on the types of mooring allowed. You'll need to contact the Harbor Master to see what their regulations are for that harbor.

e.g. Town of Rockport Mooring Regulations

[Fishspearit]

I've found the best thing to be a combination. I'll describe one I built which worked well. The center weight was an old engine block, which I got for free from a garage which had pulled everything off the engine. The open cylinders make great places to attach a chain. Every attachment to the engine block is chain and secured shackles. 10-15' of chain, then to a thimbled 3 strand line. I ran two independant chain/lines up to the surface from the block, just make sure that the lines are not much longer than the highest tide, so that the line doesn't fall and wrap around the block, chafing. You don't need scope from the engine block to the boat.
Attached to the engine block were 4 anchors, secured with chain to the block then line out to the anchor about 50' away at all 4 points of the compass. Dead weights get drug all around, so the anchors are what's holding the engine block in place. Chafe is the enemy. The engineblock doesn't leave the bottom so you always have a flat scope to the anchors. Just make sure you're using chain at every attachment to the block. I built this for about $150 in chain and line, and used large anchors I had found diving. I assembled everything on land, then only had to stretch out the lines and dig in & attach the anchors after dropping the block in the water.
I've also used the screw down type with success. We always carried a mobile home tie down with us, and if we were going to stay someplace for a few weeks I'd dive down and screw it in, and then shackle the anchor chain to it about 10' away from the anchor. Some places you'll find rock under a few inches or foot of sand, and then you're out of luck with the screw tie down. We once road out 110knot winds during hurricane Bertha in the Bahamas, riding on our mobile home screw attached to the anchor chain. It bent the top foot of the tie down which was sticking out, but it held the boat.

[cnj]

My mooring for 35'cat in 7ft at low tide and 11ft at high is a 350# mushroom with 10ft 5/8 chain, swivel, 12ft 1/2 chain,18"ball.
Engineblocks,concreteblocks(dead weight) are a big NO NO here.

[Celestialsailor]

http://www.ecan.govt.nz/NR/rdonlyres...ookletfhmx.pdf

Perhaps this will be helpful. I am in Hilo Hawaii and looking to moor my vessel here soon. We have a lava bottem with little else, so dead weight is the way to go. Skipper John advised me to look into a disgarded forklift counterweight or a Cat D-9 track.

[craigsmith]

Rants and musings About Anchoring
Why We Don't Trust Moorings and Do Trust Anchors (John, 2007)

[Celestialsailor]

Again we find an anchor manufacturer (the same one as in a prior forum about anchors here) bad mouthing CQR's and promoting his product. This is shameful marketing in my opinion.

[GMac]

Originally Posted by craigsmith

Rants and musings About Anchoring
Why We Don't Trust Moorings and Do Trust Anchors (John, 2007)

Oh you're good and a constant amazement x a million.

But John is right in parts, no way you would want to hang a big cruiser off a 900kg square concrete block. A donut shaped one maybe, but it would still be a bit lite. He is also right about picking up any old mooring you find, not the brightest idea as you have no idea what's going on down where you can't see it.

If John wants to anchor through a hurricane more power to him. Personally I'd far prefer to be on a good mooring.

A good simple cheap long lasting mooring -

A big feck off weight - be it concrete, a few trail wheels, a tractor if a soft bottom (I did like that one), anything big and heavy is usually good. Best is a big gear wheel off an old press or similar. The ones about 10-12ft across are magnificent.

Considerations - the bottom type. Soft bottoms will take most things and prefer round, donut or flat shapes over square block type. These will sink in and/or create a good vacuum and increase holding a lot.
If using concrete 'spud' it when you pour it. A concrete 'spud' is basically a commercial vibrator and looks and works quite similar to the things seen in XXX shops. With this buzzing away it gets most of the air to the top and out of the concrete so can dramatically increase the wet weight of the block. Done well the block will lose only 10-20% of it's dry air weight when immersed, not the up to 60% if not spudded. The same thing happens, not quite as well though, if you firmly tap or bash the mold as you pour, hard work though as you want to do it a lot.

Hard firm bottoms it's all about weight and irregular shapes. Square blocks tend to work better on these.

Don't forget about the weights height if in shallow water. You don't want to run aground on your own weight.

BIG mooring lug/s. Go as big as you can so it takes forever to wear out. More than one is good for when the 1st one wears out.

From big weight lug the biggest shackle you can fit between that and a length of pre-loved stud link chain, off a ship. Length approx. water depth at high tide. Size for a 30-50fter around 1 1/4" to 1 3/4". Bigger boats go up a bit but not to much or it won't work. This chain could easily last 30 years so a good thing.

Then another 'biggest shackle' from the stud link to some 3/4" to 1" mid link chain. Length about water depth again. Biggest shackle again to a 1" -1 1/2" swivel.

Then off to the 'Head Rope'. Polyester 3 strand with a loop spliced each end. Size 3/4" to 1 1/2" depending on size and comfort level required. Reeve one end onto the swivel and the other loop drops over your bollard. Length of this rope wants to be water depth again so when it's on your boat the swivel is off the ground at all but very low tide. Wear sleeve, chafe protection, wear sleeve, chafe protection.

From the top loop of the Head Rope run a 1/2" polyester 3 strand to a small buoy, one with a handle on loop on top is best. This is the 'Buoy rope' and wants to be long enough that when the boat is not on it most of the head rope is sitting on the bottom. Movement means wear so when everything is sitting doing nothing there is no wear.

When you arrive by boat boat hook the buoy, pull up head rope using buoy rope, drop head rope on bollard, job done.

Dos and don't -
Do remember chafe protection
Do weld up shackles is best, mousing well and things like that are OK done very well.
Do use head rope to pull up swivel for a eyeball now and again, it is the highest wear item.

Don't use galvanised chains, swivel or shackle. They can accelerate wear.
Don't forget chafe protection.
Don't plan on re-using the shackles. They are cheap and expendable, unlike your boat.
DON'T DON'T use polyprop ropes. Evil evil evil. Any here with them are instantly condemned.

With regards to using non-galvanised steel gear. Rust needs O2 and you don't have to go too deep for that to fade away so no O2 no rust. Self-colour (black) gear is also a lot cheaper.

Otherwise a good simple mooring that has few moving parts so less to wear. We have 6000 odd with in 20 miles of me right now and the failure rate is less than 1%, may I add, unlike anchors (sorry couldn't help myself ). More than a few of these moorings are open directly to Chile which is 6000 odd miles away i.e. the open ocean.

All are inspected on a 3 yearly basis which usually includes a swivel swap out and maybe the top chain in some places.

How it works? Simple really. When there is no load the boat sits happily. As the load increases the boat has to lift the top chain which off-sets that load. As the weather goes further bad the boat has to start lifting the bottom chain. Basically the worse the weather the more the boat has to lift and the shock loading are taken out by the increasingly heavier chain.

One easy, cheap, tried and tested well performing mooring, have fun.

[delmarrey]

There are so many variables, no one anchor/mooring is perfect for all places/conditions. That's why one needs to contact a Harbor Master for the area of interest. They should know the bottom and what has worked it that area. See chart below on anchors........................._/)

1995 Anchor Study

[delmarrey]

Originally Posted by GMac

Best is a big gear wheel off an old press or similar. The ones about 10-12ft across are magnificent.

Now I like the sounds of that, but were would be the best attachment point? In the middle, at the edge or halfway in between. I can imagine trying to drag a wagon wheel/press gear, it would tend to dig in. And it surely would be EZ to launch off a boat by just rolling it off a plank.

A mold for cement, reinforced with rebar, in the shape of a spoked wheel would make a great item for moorings on soft bottoms!