Wave action on a beach

snowstreams

Hello, I was wondering if anyone here could help me with a question about waves on a beach.
My fiance lost her engagement ring on Sunday on a beach.
It was 1 hour before low tide when she lost it, right at the waters edge.
The beach has quite large waves on it because it is on the atlantic. Roughly how far down could a gold ring go after 6 tides have passed?
We are going to try and find it with a metal detector. But need to know how deep it could have gone.

El Siglo

snowstreams wrote: »

Hello, I was wondering if anyone here could help me with a question about waves on a beach.
My fiance lost her engagement ring on Sunday on cross beach in Mayo.
It was 1 hour before low tide when she lost it, right at the waters edge.
Cross beach has quite large waves on it because it is on the atlantic. Roughly how far down could a gold ring go after 6 tides have passed?
We are going to try and find it with a metal detector. But need to know how deep it could have gone.

A nice question, with a mixture of geophysics and tidal modelling.
It depends really, she lost it 1 hour before LT, but was it a neap or a spring? What date did you lose it? Have you checked out the admiralty tide tables for it? You can check them out online. Without even looking at tidal micro-environments (tides are incredibly strange sometimes), my best guess is to look between mean low water spring tide (MLWST) and mean high water spring tide (MLHST).
Your're looking at depth but for that you'd need the soundings for the area, these would give you depth to the sea-floor. Whereas chart datum etc... is an 'imaginary' depth so to speak.
Normally, tides tend to introduce marine material into coastal environments (they tend to for sediment anyway). Now, depending on bioturbation, saltation, entrainment etc... with regards the ring, I'd assume it's a fairly dense material that doesn't float well. The chances are it might have moved towards the shore. Now, I doubt very much it's sunk into the sediment to any great depth, so it could still be on the surface between 0 and 10cm (this is the hard and fast rule of forams anyway).

So between MLWST and MLHST of the nearest tidal gauge (there are conversion formulas for distance, air pressure etc... for working out this datum for a non-gauged site);
Probably between 0 and 10cm in depth.

Again there's countless variables involved in this but basing what you've just told me.

Good luck with your search, hope you find it.

snowstreams

Thanks for your help El Siglo. I was wondering where i could get accurate tide times alright. It was on the 15th of August, which turns out to have been a spring tide :eek: It was roughly at 5:20-5:30 when she was there. And the spring low tide was at 3:55. so about 1hr and a half after the low tide. I may have to wait till the weekend to get a decent low enough tide to have a chance at finding it so.
10cm isnt too deep. So it could be detected at that depth alright.
Im not going to give up on trying to find it until all avenues have been explored.

El Siglo

snowstreams wrote: »

Thanks for your help El Siglo. I was wondering where i could get accurate tide times alright. It was on the 15th of August, which turns out to have been a spring tide :eek: It was roughly at 5:20-5:30 when she was there. And the spring low tide was at 3:55. so about 1hr and a half after the low tide. I may have to wait till the weekend to get a decent low enough tide to have a chance at finding it so.
10cm isnt too deep. So it could be detected at that depth alright.
Im not going to give up on trying to find it until all avenues have been explored.

I mean, 10cm is probably even too deep given the time frame you're dealing with.
Go on this website to get tidal datum. This website shows you how to work out high water and low water change over time (although you will need to get the actual tide tables from the admiralty, here's a copy for Ireland and the British Isles).

Ostrom

Would a metal detector be of any use?

snowstreams

Yeah I think she lost it right about low tide. The admiralty website said it was a spring tide that day. So it will be impossible to find till next spring tide.
At least the metal detector is waterproof, so a bit of water could be ok.

El Siglo

snowstreams wrote: »

Yeah I think she lost it right about low tide. The admiralty website said it was a spring tide that day. So it will be impossible to find till next spring tide.
At least the metal detector is waterproof, so a bit of water could be ok.

Well, that's grand then, remember the springs occur when it's a full moon and a new moon (neaps are the quarters).
The best thing to do, would be to get the next high tide mark at Spring tide;
Survey the site and depending on the tide times (i.e. it could be low tide at 12pm, thus the tide would go up the shore or it could be high water at the same time and the tide is going out). Determine this first anyway, the best way to work (going on personal experience) would be to start at high water and work outwards as the tide is going out. At least this way you don't run the risk of be caught as the tide comes in (think Morecambe Bay as the worst case scenario). It gives you plenty of time to survey a large site as well.
Mark of a line transect, this can be nothing more than two sticks and a compass with a bearing and a hand held gps. At least then you can geo-reference the area(s) you've searched.
Also, note how the tide comes in and goes out, is it at right angles to the beach? The tidal direction in this case means it comes in at a different angle (the swash) and goes out sort of perpendicular to this (backwash) so use the swash and back wash as your guide and move position your survey site relative to this.
I would work out a large area (depending on the saltation of the ring in the tide).

blue5000

just a small bit to add, waves usually come in to land at an angle determined by wind or storms, but the back wash always goes out at an angle of 90 deg from the beach. So it is possible for material to move alon the beach. The ring is dense (gold I presume) so will probably go down, depending on what the sand is like.

Good luck,hope it was insured

snowstreams

Ive been down to the beach a few times now during the low spring tides, but with no luck. The sand is so wet, most metal objects seem to sink very fast in it. I reckon the ring is gone down too far for a detector to find by now.
Ive noticed some ancient tree stumps on the beach at low tide sometimes too. They seem to get buried and then re exposed regularly, so the sand is moving alot.
Time to give up I suppose We will have to insure our next ring straight away.

blue5000

Sorry to hear that, give it one more go. Remember to be nice to each other about it in future.

I've had my wife's wedding ring and engagement ring fired at me while I was down in the pit milking cows, I found them ok but I was damn tempted to power hose them down the drain at the time. However we're still together, we'll be married 12 yrs next month.

good luck

El Siglo

Sorry to hear that op. I was going to suggest ground-pentrating radar if you wanted to give it one more try.

snowstreams

It was getting my fiance down so we decided to get a similar ring made up. Hopefully now we can get on with our wedding planning then.
The area that we have to cover is so large that it would take hundreds of hours to cover it all. We concentrated our search where we reckoned it mite be. But everytime we arrived to the beach we couldnt be sure what the likely place was, even with GPS.
An automated robot with radar is probably the only way to find it at this stage.
Thanks for your help and tips during the search.

feicim

Sorry about your ring.. re using a metal detector, as far as I know its illegal to use one in Ireland with some kind of permit. (although I presume like many laws in Ireland it goes unenforced).