this post was submitted on 02 Nov 2023
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I'm confused, why does this tide clock use a 10/20 hour duration instead of a 6/12?
Because tidal clocks at based of of lunar days which are 24 hours 50 minutes and 28 seconds. Aka a tidal cycle every 12 hours 25 minutes and 14 seconds.
I'm not familiar with this exact clock, but the clockwork is probably designed to extend the period of time the needle is on tide until it's ready to start aligning with the countdown hours. So 4 hours 12 minutes and 37 seconds on tide.
Since this is a tidal clock for a specific town, the times are likely important to the Digby harbour.
The face of that clock is confusing. It suggest that it's about 10 hours between high and low tide which, if the tide in Digby is not fundamentally different from anywhere else in the world, is plain wrong.
As a tidal clock it would need to make a full turn every 12h50m14s. So they probably took a stock clockwork with just an hour hand, and just slowed down the balance spring or pendulum by about 3.5% to achieve this.
They could just have it display the water level
Tide is 80% of peak right now... Tide is 60% of peak right now... Tide is 40% of peak right now...
~~Yeah but 80% of peak low tide seems weird. The less low tide you get means the higher the tide?~~
Nevermind I looked closer and it's clearly labeled 'hours' so it's more of a countdown than a percentage, which makes total sense.
Ah, yeah, you're right, I didn't notice the hours label either. So yeah, percents don't make sense. Good call.
It’s also ８-６-４-２-０-８-６-４-２-０... as opposed to ８-６-４-２-０-２-４-６-８-10. But is low/high tide not every 6.2 hours or something?
Not sure, never thought about it. I’m sure there is a reason as that town has some of the highest tides in the world. Digby is located in the Annaoplis Basin, which is in the Bay of Fundy, which claims the highest and lowest tides. The tides are closly watched as it is a fishing town and boats can be beached alongside the pier.