Both the Wind direction readout and the photocell’s charging efficiency depend on orientation of the Tempest sensor. Our Tempest is sited on the narrow causeway that provides access to the little island containing our clubhouse and pool, adjacent to our marina, and is mounted on a fence on the top of the causeway’s timber bulkhead, which protects our dock power distribution box. Being mounted on a 10’ pole on the end post of the 8’ tall fence, it is nearly impossible to get eyeballs on the little arrow on the Tempest, and being above metal boxes, it is hard to get a reliable compass reading. However, the pole itself is in the direct sun so the idea of the Sundial came to mind - i.e., to use the fact that the Sun is true South at Midday like you do when adjusting a Sundial to local time.
I would like to propose an inexpensive Sundial Directional Pointing Accessory for the Tempest.
It would consist of a rectangular piece of weather-resistant flat material (perhaps about 2"x4") with a pole clamp attached to its bottom such that the top surface of the flat material is held in a plane perpendicular to the center of the pole (i.e., horizontal to the ground) with the middle of the short side touching and tangent to the outer surface of the pole. The top surface would have a center mark where it touches the pole, and 2 parallel lines running perpendicular to the short side, separated by the pole’s external diameter, and centered on the center mark.
Use instructions would be something like:
(1) Prior to putting up the Tempest, the user would attach the Tempest tightly to the top of its pole
(2) Figure out where on the pole the Sundial could be mounted such that the top surface would be viewable after the Tempest pole is put up but not shadowed by any surrounding structure at Midday and not have mechanical interference from any surrounding structure (including pole and sundial clamps)
(3) Transfer the tip of the arrow on the Tempest device to the center of the pole where it will be just above the top surface of the Sundial (e.g. tape a piece of thin fishing line to the point of the arrow, pull it tight to below where the top surface of the sundial will be while eyeballing the center of the pipe all the way down and tape the other end of the fishing line in the center of the pole, put sharp line masking tape on the pole as close as possible along either side of the fishing line, and paint a narrow line on the pole)
(4) Put the Tempest pole up into its mounting brackets and tighten the pole clamps with the pole rotated such that the middle of the 4 photocells is on the perceived Midday sunny side
(5) Champ the Sundial on the pole such that the center line of the Sundial is precisely aligned with the line you made to transfer the Tempest’s arrow to the pole
(6) Wait until a sunny day and then calculate the local time of Midday (by looking up the time of Sunrise and Sunset for that day near the Tempest’s coordinates and figuring halfway between them as Midday)
(7) Loosen the pole mounting clamps (NOT the Sundial clamp) a few minutes before Midday on that sunny day, such that the pole can be rotated (but won’t slide down)
(8) At exactly Midday, rotate the pole until the pole’s shadow is exactly between the 2 lines on the top surface of the Sundial
(9) Securely tighten the pole clamps so the pole will not rotate - note that the Earth turns 0.25 degrees per minute, so it would be best to have the pole rotated and tightened in its final position a few minutes before/after local Midday
Viola!!! Accurate true North/South alignment with no compass, no matter your local declination!
I figure it would only cost about twice as much to make this accessory in volume as the mounting clamp to attach it to the pole. This device would work in the North and South hemisphere (but it won’t work too close to the Equator, and it can’t be set up North of the Arctic Circle or South of the Antarctic Circle for that part of the year with no direct sunshine).