OK, then I think your sketch is reasonable. I'd make the weights go as far below the float as possible, since that will increase their impact on torque for any given amount of weight. If you're relying on them to hold it vertical, the guy wires(s) can be at or just below the water line.

I'd be tempted to use an open bucket on the bottom so I could just add rocks to set the flotation level.

I think I'll take my 3-foot threaded rod back to Lowes and get a 5-footer. Everyone seems to be suggesting longer is better. I've heard that before somewhere.

 

Your last comment suggested something to me. Get ten foot lengths of conduit, in two sizes. So that one slides inside the other.

Paint with enamel to minimize rust.

Insert the smaller one into a bucket of concrete. Cut it 3 foot lower than the mean depth attach the larger conduit to a floating base for the lighthouse. Cut it as long as possible and definitely more than three feet. but maybe the bucket height less than the lowest depth of the water.

Hence, the floating base will be held upright and in place by the two concentric pieces of conduit.

Just roughed out the idea on my phone to present it as an alternative.

 

Oh yeah. Much better than going up the side of the lighthouse to find the magic spot.

Or by adjusting the angle to the anchor?

See the attached pdf. I accept no responsibility whatsoever if you spend a lot of time, effort and money and this turns out to be wrong.

 

See the attached pdf. I accept no responsibility whatsoever if you spend a lot of time, effort and money and this turns out to be wrong.

The bucket diameter is 12" so if the tether were attached at the lip of the bucket then X=6. And the angle would then be about 72 degrees, and the anchor would need to be placed about 2.8 feet away from directly below the lighthouse (assuming a depth of 9-ft) to create that angle. A lot closer than I thought it would be. In fact, that won't allow for my pond depth to increase to 12' when the cloudburst hits. Mmmmmm....

And Albert, your disclaimer is too late. You've already commented, which I appreciate a great deal.

 

Paint with enamel to minimize rust.

Is there no better option? Schedule 40 PVC (or heavier) is pretty darn stiff and would stand up well. I think copper pipe would work but would cost a small fortune.

I would use the larger diameter pipe for the longer span (to the floor of the pond). Less deflection than the other way around.

You'd also need to prevent the bottom anchor from tipping when the wind blows on the lighthouse. An old tire full of concrete might do it.

 

Is there no better option? Schedule 40 PVC (or heavier) is pretty darn stiff and would stand up well. I think copper pipe would work but would cost a small fortune.

I would use the larger diameter pipe for the longer span (to the floor of the pond). Less deflection than the other way around.

You'd also need to prevent the bottom anchor from tipping when the wind blows on the lighthouse. An old tire full of concrete might do it.

I just happened to finish a project where I used 1/2" EMT conduit, so it was in my head. I like your alternatives and improvements.

 

Your last comment suggested something to me. Get ten foot lengths of conduit, in two sizes. So that one slides inside the other.

Paint with enamel to minimize rust.

Insert the smaller one into a bucket of concrete. Cut it 3 foot lower than the mean depth attach the larger conduit to a floating base for the lighthouse. Cut it as long as possible and definitely more than three feet. but maybe the bucket height less than the lowest depth of the water.

Hence, the floating base will be held upright and in place by the two concentric pieces of conduit.

Just roughed out the idea on my phone to present it as an alternative.

Without a great deal of effort I don't think it's possible to attach anything to the bottom of the pond and expect it to remain vertical. It would have to be sunk really deep. There is easily 2 feet or more of muck at the bottom of this pond. If you fall in it's extremely difficult to walk out of it. Just ask my wife.

 

Without a great deal of effort I don't think it's possible to attach anything to the bottom of the pond and expect it to remain vertical. It would have to be sunk really deep. There is easily 2 feet or more of muck at the bottom of this pond. If you fall in it's extremely difficult to walk out of it. Just ask my wife.

Which is the exact purpose of the bucket full of concrete. It will sink through the muck until it hits the solid clay beneath.

Think raft or boat anchors. They don't float about on top of the muck.

 

The bucket diameter is 12" so if the tether were attached at the lip of the bucket then X=6. And the angle would then be about 72 degrees, and the anchor would need to be placed about 2.8 feet away from directly below the lighthouse (assuming a depth of 9-ft) to create that angle. A lot closer than I thought it would be. In fact, that won't allow for my pond depth to increase to 12' when the cloudburst hits. Mmmmmm....

And Albert, your disclaimer is too late. You've already commented, which I appreciate a great deal.

You can increase X as I said above by having a horizontal rod (actually rods, one for each tether) attached to the top of the bucket to decrease the angle and increase the distance to the anchor.

 

In fact, if you made a tapered mold, the narrower bottom would cut through the muck.

 

The more I think about it, the more I like the diagrammed solution with nothing on the bottom except a wire anchor.

Instead of a solid rod I'd use a stainless steel cable between the bottom weight and the top float, and another length of that cable for the guy wire(s). I'd drill a long hole for the cable to pass through the float, or make some other arrangement that uses the vertical position of the cable to set the vertical for the floating lighthouse. (I did a trellis project with SS wire rope last summer and I kind of enjoyed working with the cable.)

If it's not clear what I'm describing, I can draw it out. Something like this:

 

Instead of a solid rod I'd use a stainless steel cable between the bottom weight and the top float

This would lose much of the righting moment that a rigid connection would give, and increase the tendency to tilt.

 

I'm not so sure. With the poundage of rocks the TS is talking about, the cable tension will strongly resist any bending. As my drawing hints (added after your post), you would want something stiff to ride over the cable to whatever depth is required to hold the float vertical. It may be longer than I've drawn it.

 

The more I think about it, the more I like the diagrammed solution with nothing on the bottom except a wire anchor.

Instead of a solid rod I'd use a stainless steel cable between the bottom weight and the top float, and another length of that cable for the guy wire(s). I'd drill a long hole for the cable to pass through the float, or make some other arrangement that uses the vertical position of the cable to set the vertical for the floating lighthouse. (I did a trellis project with SS wire rope last summer and I kind of enjoyed working with the cable.)

If it's not clear what I'm describing, I can draw it out. Something like this:

View attachment 121753

Close but the weight should be attached direct to the float. Like a keel on a sailboat. The float and weight should be as large of a diameter as reasonably possible with the diameter of the weight being less than the float. A plate from a weight lifting set might be a good choice for the weight.

 

https://www.icloud.com/sharedalbum/#B0oGrq0zwGIayhE

Some pictures of the lighthouse and a nighttime movie.

Getting the thing balanced was a chore, and I need to go back out there and make more adjustments. But once set it seems to hold its angle pretty well. Right now I just have it tethered with 1 fishing line to a rope strung across the pond and when the wind blows pretty hard it does tilt some. But I'm OK with that. I have yet to tether it to 3 lines to weights on the bottom.

I hope it doesn't sink.

 

https://www.icloud.com/sharedalbum/#B0oGrq0zwGIayhE

Some pictures of the lighthouse and a nighttime movie.

Getting the thing balanced was a chore, and I need to go back out there and make more adjustments. But once set it seems to hold its angle pretty well. Right now I just have it tethered with 1 fishing line to a rope strung across the pond and when the wind blows pretty hard it does tilt some. But I'm OK with that. I have yet to tether it to 3 lines to weights on the bottom.

I hope it doesn't sink.

Tie an additional line with an additional float. That way if it sinks you could either pull it up or go swimming to get it.

Wish I would have thought a float when I had to cut an anchor loose that was stuck under a log. But that day all I wanted to do was get out of there. Not like the anchor was hugely expensive. Maybe less than $50.

 

when the wind blows pretty hard it does tilt some. But I'm OK with that.

You could stiffen that pipe significantly by filling it. Sand alone would do a lot but something like mortar or plaster would really stiffen it a lot. I think bending of the conduit is why it's tilting.

 

You could stiffen that pipe significantly by filling it. Sand alone would do a lot but something like mortar or plaster would really stiffen it a lot. I think bending of the conduit is why it's tilting.

It's not a pipe. It's a threaded rod. And today it sunk. Explain later.

 

And today it sunk.

Oooohh noooooooo

 

I took the little boat out to it today to attach the 3 tethers to the lighthouse and to refine the balance some. I drilled 3 holes in the lip of the bucket for the tether lines. The last hole was hard to reach and I couldn't see very well (my excuse). I set the drill down, turned around and reached for the first brick with the tether line wrapped around it. As I did I heard a faint hissing noise. (That last hole had just barely pierced the interior of the bucket.) I looked back just as the base of the lighthouse was going under. So I lunged for it and caught it, and immediately ripped the lighthouse off the bucket, lost my grip on it and it went in on its side. I fished it out and brought it into the boat. The bucket and the 35 lb of bricks were gone, but were still attached by a fishing line to the rope I had strung across the pond. Luckily that line was 50b test line. I hauled the bucket & bricks up to the surface but it was all I could do to hold it at the surface, since it was 10 bricks PLUS 5 gallons of water. With me hanging off the side holding all that weight I was close to swamping the boat, so I was kinda just stuck there. After a minute or so of intense back pain (got 2 vertebra with no cartlidge) I started pulling on the rope, and me, boat and bricks slowly started moving to the pond bank. When I got there I managed to get the bricks close enough to the bank to let it rest on the bottom and the bucket resting at the shoreline, and left it there to get later.

Lighthouse didn't work any more. I drained it and let it dry out and a couple hours later it was working again. It now sits on dry land by the pond bank.

Lighthouse 1, Richard zero. But this game ain't over.