[fatlazyless]

This is what people over in Maine do. Maine is loaded with small ponds, rivers and big lakes. Some of those small ponds are simply a stream that got dammed up, 200-years ago, by building a rip-rap, home made dam, using paper bags of concrete mix piled up, interlocking style, to make a dam.

Back in 1818, they maybe were using cotton bags filled with sand-cement-gravel.

Here in 2018, you use the 70-lb concrete paper bags.

As already mentioned, it works great, with the water soaking thru the heavy paper bag, and the concrete mix sets up in place, under the water.

So, how many 70-lb bags of dry concrete can be loaded into a 12' rowboat before it sinks?

Quikrete really stumbled onto something when it designed the heavy paper bags because the heavy brown paper allows water to permeate through, but stops the sand, gravel and grey powdered cement, all mixed together, from permeating or osmosifying out into the lake water. You just plop the heavy bag into the lake, and 24-hours later it will be a solid block of concrete within a paper bag that tightly hugs whatever is below it ..... pretty danged good.