constructing a mooring

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sscoll
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constructing a mooring

Post by sscoll »

Anybody have suggestions regarding best methods for putting in a mooring in fresh water? I've looked through the Forum topics and don't see any. Maybe I'm not entering the right key words.

Steve
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Tim
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Re: constructing a mooring

Post by Tim »

Here's a common way we do it around here.

Link: Mooring Setup
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sscoll
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Re: constructing a mooring

Post by sscoll »

Thanks Tim that looks simple enough.
sscoll
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Re: constructing a mooring

Post by sscoll »

I can see how to do it from Hamilton's schematic of the various bits they sell, and it makes sense. Their diagrams are very helpful. I'm more inclined to find something here in the midwest to serve as an anchor rather than pay freight for eight hundred pounds of cast iron from the east coast.

I don't have tides to deal with, the lake may fluctuate a foot or two during the season but some hellacious cold fronts come through packing intense on-shore winds. I'll be moored in ten to twelve feet of water.

Suggestions for creating an anchor would be appreciated. I understand that engine blocks are frowned on these days. I'm thinking of casting cement with galvanized angle iron protrusions. I'd appreciate hearing from anyone who has made their own mooring anchor. Thanks.

Steve
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Re: constructing a mooring

Post by Paulus »

sscoll wrote:I can see how to do it from Hamilton's schematic of the various bits they sell, and it makes sense. Their diagrams are very helpful. I'm more inclined to find something here in the midwest to serve as an anchor rather than pay freight for eight hundred pounds of cast iron from the east coast.

I don't have tides to deal with, the lake may fluctuate a foot or two during the season but some hellacious cold fronts come through packing intense on-shore winds. I'll be moored in ten to twelve feet of water.

Suggestions for creating an anchor would be appreciated. I understand that engine blocks are frowned on these days. I'm thinking of casting cement with galvanized angle iron protrusions. I'd appreciate hearing from anyone who has made their own mooring anchor. Thanks.

Steve
You might want to consider a Helix mooring - they don't weigh quite as much and provide for excellent holding.

Image

Here's an article from someone installing his own, with pictures...

http://www.sailnet.com/forums/general-d ... ekend.html
Case
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Re: constructing a mooring

Post by Case »

That helix anchor looks really interesting.

I might go ahead and buy one. It would be for a dock or a small boat in waters that's only 3-6 feet deep at low tide. I would be able to use less scope with a helix anchor. Space is constrained in the area I have my mooring in.

It would be worthwhile to try it out. After installation, I will then proceed and pull it hard with a motorboat and see how it holds. I can tell you from experience that a 150 pound mushroom anchor that's been well set can submerge the stern of a 16 foot skiff with a 25 hp outboard if you are not careful when pulling on the mooring. It took me maybe 10 minutes of motoring in a circle before that anchor let aloose. A similar anchor gave a 20 footer with a 200 hp outboard some fight, maybe 2 minutes of pulling in a circle before it let aloose. I'll comment when I learn anything new in the spring.

- Case
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Re: constructing a mooring

Post by Maine Sail »

Here's the image Tim was linking to:

Image Courtesy Hamilton Marine
Image


At roughly 90 pounds per cubic foot, out of the water, cement loses a lot of weight in the water.. When you submerge cement the calculation for weight changes, and the multiplier is .55. So a 1440 pound mooring is really only 792 pounds below water which is barely enough for a 10-17 footer. 1440 pounds or more may seem like a big mooring but it's not.

To meet the bare minimum dead weight mooring requirement for the town of Rockport, MA, for a 28-30 footer, you'd need a dry weight cement mooring of 5460 pounds to hit the 3000 pound minimum for a submerged cement mooring. 5640 pounds is HUGE!!

Below are some mooring guidelines, this one from Rockport, MA. Note the differences in weight between what you previously though might cut it and what the actual under water weight requirement would be.

Deadweight Anchors:

Deadweight anchors are commonly used in New England. They are usually blocks of granite which hold vessels in place because they are too heavy to be dragged or lifted by the vessel. The holding power of the deadweight anchor is derived solely from it's weight and not by its design. When a deadweight is pulled out of its current resting place, it may settle somewhere else, because its weight provides constant resistance. Blocks become embedded in the harbor bottoms over the years, providing a degree of suction resistance in bottom material which has strong cohesive properties.

It is recommended that the weights indicated be submerged weight of the deadweight anchor. Use the following table to calculate required weight of material submerged. Consult with the Harbormaster before purchasing gear.

Minimum deadweight mooring weight:

Vessel length:

10 - 17 1000 lbs.
18 - 26 1500 lbs.
27 - 35 3000 lbs.
36 - 45 4000 lbs.
45 - 55 5000 lbs.

Submerged Weight Calculations

Concrete = required weight /.55 (example 1000 lbs./.55 = 1818 lbs.)
Granite = required weight /.64
-Maine Sail

Canadian Sailcraft 36T
Casco Bay, ME
http://www.marinehowto.com
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