Ballintoy church and sheep

On the hill above Ballintoy harbour, on the north coast of Antrim, stands Ballintoy Parish Church. It is a beautiful building in a beautiful setting. Much admired and much photographed. This church has appeared in countless calendars over the years.

I had planned to take a photo of the building on its own, but couldn't resist including the sheep who was obviously used to have its photo taken along with the church.

However, there's one item on the outside of the church which puzzles me. Which is why I've put it up on this your place and mine site in the hope that someone can shed light (no pun intended) on this mystery. On first inspection it appears to be a vertical sundial.

Arrow shows position of device

Moon

But it isn't a sundial and looks more like a device for telling the tides. But surely you can't tell the tides using a sundial? But maybe it is not a sundial but a moon dial? I guess a full moon would be strong enough to cast a shadow. I tried photographing the device from several angles but the inscribed lettering is too worn away to be clear, so instead I have resorted to making a sketch.

Tide table tablet drawing

Erected as you see in 1817. On one face (Right side in the sketch) appears to be a normal vertical sundial. But it is the other, near, face which intrigues. At the top are the words "High Wat" Presumably meaning High Water. The lettering beside those words is indistinct but it looks like a small letter "c" followed by a gap then "06" Incidentally I was standing below the item to sketch this using a pair of binoculars to try to decipher the writing. Then there are the series of eight diagonal lines. Each marked both along the top and down one side with consecutive numbers. But why eight lines/figures? Would that be for the number of hours of darkness?