Welcome aboard Thomas. I have a couple of observations/comments.........
1.) What happened to the drivers and co-drivers front hatches? It looks like the co-drivers was smashed and destroyed ,but the other drivers hatch is missing (?) These hatches were pretty rugged, not thin metal.
2.) Your Sherman (which looks like the Verlinden submerged M4A2 BTW) is missing alot of the turret fittings (front lifting lug above the mantlet for example) or miss-placed. Is that the vane sight in front and off to the side of the gunner's periscope? It also needs the cupola replaced with a late split hatch cupola to be accurate.......
3.) Your Sherman doesn't have ANY wading equipment attached, trunks, waterproofing etc.... would be the order of the day
I applaud your efforts in the sea sculpting department, just keep in mind that with practice you'll get better. The shells exploding in the water are a bit too small in my opinion
Chris