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oldjags 05-22-2008 11:40 AM

Getting data on power line clearance
I do all my sailing on a local hydroelectric reservoir in Alabama. There are several areas where power transmission lines cross the lake. I have contacted the power company and asked what the safe vertical clearance under these power lines is, and all I can get back from them is, basically, 'Stay away from the power lines'. Duh!

I feel like, from a legal liability standpoint, they are not willing go on record and tell me what height mast would safely pass under the lines, just in case they happen to be wrong. Either that, or they have no idea how high the lines are, and don't want to be bothered with having to go out and measure them. All they did was quote me the state law that says it's illegal to get within 6' of any high voltage transmission line.

That's fine, but if they won't tell me how high the lines are, how can I make sure I don't encroach? It's very difficult to judge height from the deck of the boat, and I'm not willing to go anywhere near the lines until I know for sure that it's safe. From a distance, it looks like there's plenty of room, but you never know.

Anybody got any advise on the best way to approach this issue with the power company? I don't want to piss them off to the point that they just decide to ban all sailboats on the lake.

Alabama just passed a law restricting the length and horsepower of power boats on all hydroelectic lakes in the state - a law that was pushed through the state legislature with the support of the power company despite the objections of most of the powerboat community. The sailing community has even less clout than the powerboaters, so I'm sure that if they deem it too inconvenient to go out and put clearance notices under all their transmission lines, they'll just go back to the state and get tall sailboats banned as well.

What's my next step? Contact the state Public Service Commission?

Lee Scott
1987 Catalina 27

Freesail99 05-22-2008 11:53 AM

First off I think you need to look beyond the legal liability standpoint. Hitting one of those power lines could electrify your boat causing a lot of damage if not death. Where my boat is on the hard there is a 440 volt line across the creek. The chart says it is at 50 feet, which I would clear. But time and weather has caused that line to sag badly. So, we plan to place the mast on the boat and motor over to the next marina on the far side of that power line and having them put the mast up, so we don't need to past under it.

PBzeer 05-22-2008 11:57 AM

There should be Corps of Engineer charts for any lakes created for power generation. Particularly the Tennessee River ones. Those should have vertical clearance on them. What lake in particular are you on? Would make it much easier to give proper advice.

Try going here - Corps Lakes Gateway to find the info you need.

merlin2375 05-22-2008 11:58 AM

Do you have a reason to get near or to pass under these lines for navigation purposes or do you just want to or is it a matter of expanding your sailing area?

Boasun 05-22-2008 11:59 AM

A. If you have charts for that lake it should be on the chart, measured from the high water mark of the lake.
B. Measure the height of the towers supporting the wires. Using Trig. and a sextant.
C. Measure the low point of the catenary of the wire with a sextant and the water line of a boat that is directly under the wires. You do need to know your distance from that boat.
D. Shoot a line over the wire. and bring the ends together, trim at the water's level. Carefully retrieve the line, double it and measure.
E. Talk to the PR people of that power company and tell them that you are being given little or no information about the power lines height above the water. Smile when you do so. After all this is for safety. And those companies are always touting their safety concerns. THIS is ONE of THEM! :eek:

sailingdog 05-22-2008 01:28 PM

Just remember that the wires will sag more in hot weather than in cold... since Copper expands with temperature. If the lake is high and the temps hot... and you're close to the clearance height, you might get into trouble.

oldjags 05-22-2008 05:32 PM

PBzeer, I've looked all over for charts that show the line clearance, but can't find any. This isn't a Corps of Engineers lake, so that link didn't help. This lake (Lay Lake) also isn't a navigable waterway, so about the only maps you can get are devoted to fishing, and are just topographical maps with depths marked in 5-10' increments - not real marine charts at all.

Sailingdog, I also just discovered that transmission lines also sag when they are under load, due to the heat generated. So, I think I'll take the minimum required clearance and double it, just to be safe.

I like Boasun's suggestion. I think I'll get a slingshot, some fishing line, and a lead fishing weight and just measure the height myself. Is there any fishing line that will conduct electricity???? Or are they all pretty much safe?

sailingdog 05-22-2008 06:24 PM

Just keep the line very, very dry... :)

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