The traditional approaches, measuring, reading charts, etc.. are well and fine, but not foolproof as occasional boat/bridge interactions can attest.
Using a sextant
to calculate bridge height, (simple trig), or taking advantage of modern technology doesn't cause any harm
I personally like the laser pointer approach. They are cheap
, and can be completely sealed in epoxy
just like the led lights
. It would be very simple to wire a remote
switch for problem situations. A red dot can be seen in direct sunlight. It could be mounted slightly up at an angle so you see the dot on the underside of the bridge as you approach, and if it doesnt disappear by the time you approach within a couple of boatlengths, you know to abort in time to turn around.
I have used the pointers to solve a variety of problems.
1. Like matching deck
beams to the house. The old way carefully measure from the ground, using a bubble level measure slope, then measure from new point to the mounting location, (hope you measured everything correctly). The new way, drill mounting hole on post, insert laser pointer, go to dot on house and drill mounting bracket there, perfectly level with no guesswork.
2. Build ledge around pool, old way hire a surveyer to measure and calculate height of terrain to projected water level. New way rent laser level, and draw a line with felt marker over the red line from level. build concrete to felt marker line. finished and perfectly at 6 inches from water line no guesswork.
People use cameras to back up were a rear view mirror is unavailable, like a truck or SUV. I use one for nightvision, using one for mastvision is a novel idea, I say give it a go ad report back how well it worked.