I know concrete blocks aren't the best thing to use.... well I've got a chance to buy a 1000 pound mooring from someone. It sits in about 12 feet of semi protected water. The current owner used it to moor his 22 foot sailboat and possibly a 25 foot powerboat. I know that I shouldn't go by the previous owner so I'm wonder what are your opinions? The mooring is about 6 years old. Would this be enough to hold my O'Day 22 which weighs in at about 2200 pounds? What do you think I would need for chain and ropes? The chain needs to be replaced. Other ideas and opinions? Thanks for any advice you can give I really appreciate it. Don
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It is probably enough ...
it depends on the bottom to some extent. If it is a mud bottom and the block is buried, I don't think anything you could moore in 12' of water would move it. If it is on hard sand, you may be marginal. There is table that somebody posted once that gives a very good description about what is required. I bet you could find it on line with a little googling. My anecdotal opinion is that if you are on a lake with no likelyhood of waves or tide, you are probably fine. If you are on a body of salt water that has a tidal range and good chance of gale force winds, I'd be far more cautious. Plenty of Catalina 22's in our harbor (about the same weight as you) are on smaller blocks than you describe, with little trouble, but I have seen a few drag in a hard blow (I'm guessing some of them are on blocks that may weigh as little as 300 pounds. Our boat is 5,500 pounds and our block is about 1,800 pounds and we have had no problem on sand bottom. But we are relatively protected from wind (max winds are probably no more than 40 knots and that would be gusts not sustained) and we have no waves under any condition. If we were in a place with more exposure in a salt water area, I would want a heavier block that matched the guidelines that I found which recommends close to 4,000 pounds for a sand bottom at our weight.
it depends on the bottom to some extent. If it is a mud bottom and the block is buried, I don't think anything you could moore in 12' of water would move it. If it is on hard sand, you may be marginal. There is table that somebody posted once that gives a very good description about what is required. I bet you could find it on line with a little googling. My anecdotal opinion is that if you are on a lake with no likelyhood of waves or tide, you are probably fine. If you are on a body of salt water that has a tidal range and good chance of gale force winds, I'd be far more cautious. Plenty of Catalina 22's in our harbor (about the same weight as you) are on smaller blocks than you describe, with little trouble, but I have seen a few drag in a hard blow (I'm guessing some of them are on blocks that may weigh as little as 300 pounds. Our boat is 5,500 pounds and our block is about 1,800 pounds and we have had no problem on sand bottom. But we are relatively protected from wind (max winds are probably no more than 40 knots and that would be gusts not sustained) and we have no waves under any condition. If we were in a place with more exposure in a salt water area, I would want a heavier block that matched the guidelines that I found which recommends close to 4,000 pounds for a sand bottom at our weight.
Concrete block mooring
Remember that concrete will absorb water when submerged so it will be heavier than advertised. Also, with a mooring weight, it's all about the suction the object creates with the bottom material. That's where the holding stength comes from. Even sand will hold solidly if the weight is dug in. I actually poured my own concrete weight for my mooring and had several rebar extensions coming out of the bottom to dig into the sand bottom of my lake and help create the suction. My boat is a Hunter 19 that displaces approximately 2,100 pounds ans it has never moved the mooring - even in 25-30 knot winds! I use 6 feet of 1/2 inch chain at the bottom and 15 feet of 3/8 inch chain up to the ball in 15 feet of water. My pennant is eight feet long. Hope this helps. Norm
Remember that concrete will absorb water when submerged so it will be heavier than advertised. Also, with a mooring weight, it's all about the suction the object creates with the bottom material. That's where the holding stength comes from. Even sand will hold solidly if the weight is dug in. I actually poured my own concrete weight for my mooring and had several rebar extensions coming out of the bottom to dig into the sand bottom of my lake and help create the suction. My boat is a Hunter 19 that displaces approximately 2,100 pounds ans it has never moved the mooring - even in 25-30 knot winds! I use 6 feet of 1/2 inch chain at the bottom and 15 feet of 3/8 inch chain up to the ball in 15 feet of water. My pennant is eight feet long. Hope this helps. Norm
WHY
My boat weighs 10,000lbs and I use a 300lb mushroom anchor with 30' of 1/2" chain and 20' of 3/8" chain to the ball. This setup is fairly easy to service and recommended by Chapman for a mud bottom. How would you service a 1000lb block of concrete? Either you would need a crane or you would have to dive down to check or service the chain and shackles. I will have to check the specs. but I believe concrete looses close to 1/2 its weight in water. Thats why you have a 1000lb block. "In water, concrete loses almost one-half its weight; granite loses almost one-third, and iron loses only an eighth. This is significant. If a mooring is designed to withstand a 4,000-lb. pull, one needs 8,000 lbs. of concrete, 6,000 lbs. of granite, or 4,500 lbs. of iron. At a minimum, over one ton is needed for even a small, 25’ yacht. To handle weights of this magnitude, a barge crane is needed." Hope this helps. Visit www.inamarmarine.com for the PDF on Moorings for reference.
My boat weighs 10,000lbs and I use a 300lb mushroom anchor with 30' of 1/2" chain and 20' of 3/8" chain to the ball. This setup is fairly easy to service and recommended by Chapman for a mud bottom. How would you service a 1000lb block of concrete? Either you would need a crane or you would have to dive down to check or service the chain and shackles. I will have to check the specs. but I believe concrete looses close to 1/2 its weight in water. Thats why you have a 1000lb block. "In water, concrete loses almost one-half its weight; granite loses almost one-third, and iron loses only an eighth. This is significant. If a mooring is designed to withstand a 4,000-lb. pull, one needs 8,000 lbs. of concrete, 6,000 lbs. of granite, or 4,500 lbs. of iron. At a minimum, over one ton is needed for even a small, 25’ yacht. To handle weights of this magnitude, a barge crane is needed." Hope this helps. Visit www.inamarmarine.com for the PDF on Moorings for reference.
Submerged concrete
The unit weight of concrete is about 150 pounds per cubic foot, while the unit weight of water is 62.4 pcf (say 60 pcf in rough terms). The approximate submerged unit weight would be 150-60 pcf or 90 pcf, or a loss of 60/150 or about 20%. Most concretes are not very porous, so the amount of water that could be absorbed is small. As Norm pointed out, the key to a good mooring is penetration into the bottom. Mooring anchors are shaped to take advantage of the bottom characteristics. CQR anchors work in most bottoms except rock and soft mud. Fisherman anchors work better in rock and weeds because the smaller flukes penetrate better than a CQR. Similarly, the larger flukes on a Danforth work better in muds and soft sand bottoms. Screw-pile anchors are effective for permanent moorings because they can be advanced deep enough into most bottom materials to mobilize the significant resistance of those materials to pullout. The problem with a screw-pile anchor is that you usually need a specialist contractor to install it. Peter H23 "Raven"
The unit weight of concrete is about 150 pounds per cubic foot, while the unit weight of water is 62.4 pcf (say 60 pcf in rough terms). The approximate submerged unit weight would be 150-60 pcf or 90 pcf, or a loss of 60/150 or about 20%. Most concretes are not very porous, so the amount of water that could be absorbed is small. As Norm pointed out, the key to a good mooring is penetration into the bottom. Mooring anchors are shaped to take advantage of the bottom characteristics. CQR anchors work in most bottoms except rock and soft mud. Fisherman anchors work better in rock and weeds because the smaller flukes penetrate better than a CQR. Similarly, the larger flukes on a Danforth work better in muds and soft sand bottoms. Screw-pile anchors are effective for permanent moorings because they can be advanced deep enough into most bottom materials to mobilize the significant resistance of those materials to pullout. The problem with a screw-pile anchor is that you usually need a specialist contractor to install it. Peter H23 "Raven"
Screw Type Anchor Mooring
When I was living in the USVI, I had a friend that set up mooring balls. The screw type anchors looked exactly like a typical doggie style screw. Wait !!! What I mean is that it looked like the corkscrew type thing that you twist into the ground. They were about 12 feet long and 3 of them placed about 20 feet apart in a triangular pattern. Each had a chain and were joined together at the mooring ball. I think all that a diver did was more or less screw these things into the sea floor. They started off working out of the boat until it went in far enough for a diver to be necessary. Dont remember how big of a boat they were designed for but they were at least 40 footers. These did quite well during hurricanes. Tony B
When I was living in the USVI, I had a friend that set up mooring balls. The screw type anchors looked exactly like a typical doggie style screw. Wait !!! What I mean is that it looked like the corkscrew type thing that you twist into the ground. They were about 12 feet long and 3 of them placed about 20 feet apart in a triangular pattern. Each had a chain and were joined together at the mooring ball. I think all that a diver did was more or less screw these things into the sea floor. They started off working out of the boat until it went in far enough for a diver to be necessary. Dont remember how big of a boat they were designed for but they were at least 40 footers. These did quite well during hurricanes. Tony B
weights for floating docks
Thius is just a comparison of what you have 1000# in protective waters for a 22' boat. our yacht club has a 100' long main floating dock that is 5' wide and has 4-40'x3' fingers attached to it. with 9 boats of various sizes between 28' and 35' tied to the fingers, to make this even more interesting it is located in the little niagara river with a curretn of about 3-4 knots, all this is held wit 3- 5000# cement blocks and 2" chains in 20' of water. I think you'd be ok.
Thius is just a comparison of what you have 1000# in protective waters for a 22' boat. our yacht club has a 100' long main floating dock that is 5' wide and has 4-40'x3' fingers attached to it. with 9 boats of various sizes between 28' and 35' tied to the fingers, to make this even more interesting it is located in the little niagara river with a curretn of about 3-4 knots, all this is held wit 3- 5000# cement blocks and 2" chains in 20' of water. I think you'd be ok.
The view from here
My mooring is a 55 gallon drum filled with concrete. I think it weighed out at 857 pounds .I had it installed for my Catalina 22.I use it for my 25 Oday now. This is in Lake Michigan. It's never moved.
My mooring is a 55 gallon drum filled with concrete. I think it weighed out at 857 pounds .I had it installed for my Catalina 22.I use it for my 25 Oday now. This is in Lake Michigan. It's never moved.
Mooring question....
Do you folks need a mooring permit of sorts or do you just claim a spot? Tony B
Do you folks need a mooring permit of sorts or do you just claim a spot? Tony B
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