British National Grid Reference

I don't have the Instinct, but my Fenix 7 has similar functionality. When British Grid is selected the watch expects you to input coordinates with 5-digit precision, which gives 1-meter accuracy. Your example is 4-digit, which means that it has 10-meter accuracy. If you don't have more precise coordinates, then just enter 0 (zero) as the last digit. So in your example you need to enter "SS", then "20450" in the first field, and "06620" in the second.

ChrisB said:

it wants the SS ref and the BNG ref?

You misinterpret what is shown, which - I admit - might be confusing. It wants two letters, and then two sets of 5 digits. The "BNG" is there just to indicate that BNG is selected.

ChrisB said:

If I change the setting to decimal degrees minutes, the number of digits to input is different to what comes up on Google searches?

First make sure that you have selected the correct format. It can be ddd.ddddd, ddd mm.mmm or ddd mm ss.s. These are not interchangeable, and you need to match this to whatever google shows. Then, again, there can be the matter of different precision. If garmin wants you to enter more digits than are provided in google coordinates, then just enter zeroes for the least significant digits.

Thank you so much! This has now worked for the beach I was attempting to input, but is not working for another location. Any idea why it fails to find tide location if using the same format?

Two things I need to clear first:

• I am no specialist on British Grid, so whatever I write here is just an educated conjecture based on my general experience with various coordinate systems.
• Without knowing what exactly you type into the garmin it is hard to tell where the problem is, if any.

Anyway, the coordinates you provided seem to point to a point on the English Channel about 250 m south of Cuckmere Haven beach. Am I correct? I tried typing TV 51679 97450 into my garmin, and indeed, garmin seems to show this point much further west, somewhere in the Celtic Sea, in an area which actually falls outside of the British Grid coverage, and certainly outside the TV square. So this seems incorrect, i.e. garmin for some reason incorrectly interprets those coordinates, unless there's a flaw in my line of thinking.

Yes, where the Cuckmere Haven enters the sea is my local surf spot. Not sure why the co-ordinates are not working?

Not trying to pretend that I'm an expert, but looks like a bug on garmin's side.