Boat lifts

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oldsparky52

Senior Member
Location
Wilmington, NC USA
OK, I was in a CE class yesterday and got into a discussion with another contractor about wiring boat lifts. We specifically discussed how the conduit was installed between the inboard pilings and outboard pilings (where the lift motors are installed). With the blessings (actually the idea came from an inspector) of inspectors I have in the past weighted PVC conduit (3/4") by installing them through the holes in building bricks and wire tying them so they didn't slide around too much, one every 4'-5'. Strapped the conduits at low tide water line and the rest of the conduit below the low water level was unsupported. Passed inspection.

This guy really gets into his work (I was quite impressed). He puts on scuba gear, goes down to the bottom and digs a 4"-6" trench and installs the conduit, he also straps the conduit to the piling below the low water level.

I'm throwing this on the forum just for conversation and comments. I commend this gentleman for his dedication to a quality installation, but ..... do you think he's taking it a bit too far? Do you think the conduit weighting is wrong (even though it passes inspection)?
 
How many boat lift motors are there? Is there one on each corner? How far is it from the dock?
 
It would look something like this, 2 motors, one side up against the dock, the other side 10-12' or so.


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oldsparky52 said:
It would look something like this, 2 motors, one side up against the dock, the other side 10-12' or so.


08.jpg

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I don't think a 4-6" trench under water is gonna last with tides and prop from the boat washing sand. If it's weighted it should stay in place. That's how we do it and never had an issue. Just strap conduit at low tide.
 
1haz said:
I don't think a 4-6" trench under water is gonna last with tides and prop from the boat washing sand. If it's weighted it should stay in place. That's how we do it and never had an issue. Just strap conduit at low tide.
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I think the trench will last because the sand tends to accumulate, but if they (boat owner) "blew out" the slip, then you are spot on. Bottom line for me is my way passes inspection, I've not heard about problems, and I don't need to go swimming, lol.
 
1haz said:
I don't think a 4-6" trench under water is gonna last with tides and prop from the boat washing sand. If it's weighted it should stay in place. That's how we do it and never had an issue. Just strap conduit at low tide.
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I would simply lay Type G or G-GC cable on the bottom of the sea or lake bed, assuming that the water level never gets to the point where it is exposed or could be subject to physical damage. I'd put it in a PVC conduit sleeve as it comes up on the side of the piling.

We use Type G and G-GC cable for marina work all the time, and it is used in mines, it's VERY durable stuff. It's flexible too, which is important in a marine environment.
 
buzzbar said:
I would simply lay Type G or G-GC cable on the bottom of the sea or lake bed, assuming that the water level never gets to the point where it is exposed or could be subject to physical damage. I'd put it in a PVC conduit sleeve as it comes up on the side of the piling.

We use Type G and G-GC cable for marina work all the time, and it is used in mines, it's VERY durable stuff. It's flexible too, which is important in a marine environment.
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Kind of a pricey way to wire that since G and G-GC don't come smaller than #8 and you can get by with (5) #14's to the motor instead of #8's.
 
oldsparky52 said:
Kind of a pricey way to wire that since G and G-GC don't come smaller than #8 and you can get by with (5) #14's to the motor instead of #8's.
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Suppose you had to replace those #14's under warranty; how pricey would it be now?
 
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