Making and Using a Water Level
Water Level Principle of OperationFor the uninitiated, note that a water level is a very simple device that anyone can make and use. It's principle of operation is very simple: water tends to seek the lowest point possible. Although you can make one simply by buying a length of tubing, there are a couple of enhancements that make the device far easier to use (more below.)
First, take a look at the diagram below (Figure 1). In the water tube, the water is free to flow and will find it's own equilibrium. A moment of thought will prove to you (try it if you don't believe it) that if you anchor one end of the tube and only move the other, that the waterline will always remain at the same point above the Earth. The plastic tube simply moves up and down around a constant water level. The tube can go up and over and around things, and the water level remains constant. That said, note that there are some things that you can get wrong ...the warnings follow the diagram.
Using the Water Level
Building a Water LevelAlthough you can buy a water level for about the same price that you can build it, note that if you build it that you can add a couple of minor refinements that make it easier to use. In particular, you can use narrower tube in the 'measurement region'. You can add a ball valve on either or both ends. And finally, you can use components that use standard hose thread. See Figure 2 below.
The narrower tube shows more of a movement of water should you be doing anything that causes the water level to change. On the anchored end of the water level, make a mark on the upright so you can track changes and verify that you are on the same 'level' before relying on the other end.
The ball valve on either (or both) ends allows you to lock the flow of water so you can more easily move the movable end around without spilling. I like to have a ball valve on both ends, as I find that sometimes I use one end as an anchor and sometimes I use the other. By closing a valve and putting a thumb over the end of the tube, you can carry your water level tube under and over things that you wouldn't be able to otherwise ...a boon for those working in cramped or odd circumstances such as boat building (crawl under hull, climb up and over, etc). Having a valve in the line gives the tube a natural break where it becomes easy to transition to the smaller 'measurement region' tube mentioned above.
By having standard hose threads on the ball valve gizmo, you can fill the tube from your garden hose and close the valve to keep the water in the tube.
In the figure above, the main tube is 5/8" ID and the measurement tube is 3/8" ID. The end of the main tube has a standard hose repair end on it, and the ball valve is a standard type available at most garden stores. The local hardware store should carry the clear tubing. The cost of building the water level is about the same price as buying a quality garden hose ...no big deal considering how useful these things are.
In the figure below, the movable end is actually a short length of MDF that extends beyond the end of the tube. I am shown checking the fore/aft level of a boat hull by crawling underneath (it's upside down) and measuring along longitudinal beams.
RefinementsThe amount of movement in the water level, with movement of the movable end of the tube, is equal to the ratio of the surface area of the water on the fixed end to the surface area of the water on the movable end. Why not use this to your advantage? If you are tired of watching the water level bounce around before settling down after each move, try using the coffee can approach. On the anchored end, rather than just mounting the hose as shown, you can run it into the bottom of a can or bucket that you mount instead. Note that you must place the waterlevel in the bucket at a similar level as you would have with just a tube, but just by placing the (full) tube end into the bucket, the fluxuation at the other end will be very greatly minimized. Some people prefer to place one end of the hose into the bucket and then siphon the water through the hose to fill it. Depending on how long your hose is (mine's 24 feet), this could be a bit of a task ...but if you followed my advice on using standard hose thread fittings on the other end, you can still fill the tube with a garden hose prior to putting the end in the bucket (use a clamp). Voila!
That's about it! Go build one and have fun!
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© Copyright 2004 Brian Dixon