Hey Lasivian,
I hunt in waist high water all the time. No, you can't see what you are doing. It took me about 4 trips to get the hang of it. I was about to give up and decided to give it one more try. I found that time, it was suddenly fairly easy to dig up the stuff. Now it's not easier than dry sand, but it's not bad. If the waves are small enough, I can last about 2 hours in the surf before digging starts to become difficult.
I see many people selling excals saying that water hunting is not for them. Listen to me "Once you see what you find in waist high water, you won't waste your time hunting dry sand any more!"
I can go to the beach now and find several nice jewelry items in one day. I used to hunt the dry sand and was lucky to find anything nice once a month.
Set your MD so that you can hear a little sound when you are in the water, but don't get alot of feedback from the waves etc. Once you get a signal, do the X to try and pinpoint the location, just as you would on land, except you can't see the coil. Try to estimate the center of your X and put the coil on the spot. Move the foot opposite your detector along side the coil, then move the coil away, put your scoop next to your foot, near the heal and dig it in. Move the scoop away and quickly run the coil over the hole, if you still get a signal, dump the scoop and get another from the hole, you usually don't have to pinpoint again, it is actually not that hard to find the hole once you have made one. When you swing the coil over the hole, try to note mentally if you may have missed the mark by a few inches and adjust your next scoop.
Yes, there are times when you can't get the target. Here are some tips.
1. The target seems to be in the center of the hole, but you can't get it. I have found that sometimes I am digging too deep and the target is actually on the top of the sand at the bottom of the hole. So I keep pushing it out of the way instead of getting it in the scoop.
2. The target gets louder but I still can't get it. This usually happens with iron, the target is actuall in the wall of the hole and I am digging to China for nothing. If you find yourself on scoop 4 without getting the item, try scooping the side of the hole to see if it is stuck there.
3. The sand keeps filling the hole. If the target is large, like a pair of glasses or a watch, it could be deep. Digging a 14" deep hole in the surf is a lot easier said than done. You can do 1 of 3 things: 1) I will dig 3 or 4 scoops out as fast as I can and dump them in the same place, in case I got the target, I know where I dumped it. 2) Bend down and dig quickly in between waves with our hand, this is dangerous, if it turns out to be a sharp edged object. 3) Move on . . .
4. Suddenly the target is not there. This can be two things: 1) it was an aluminum pop top, once you uncovered it, it washed away or 2) It is small and you dug out the hole so that it fell to the bottom out of reach of your detector. Always try one last scoop, not going too deep, to grab the debris at the bottom of the hole check that.
There is also the problem of having the item be too small to get caught in your scoop, such as a sinker or earring. No real good advice there. Many people talk about pulling around an inner tube to dump your stuff in, but that doesn't work in Ocean hunting. That thing would kill you if it were tied to you.
Good luck, water hunting will get you in better shape too!!
Jack