The triple 8" splash gives you an idea when you are shooting over water, the biggest problem is that when shooting at shore targets all you see is a little puff where the shell hits. If anything, the shore hit sprite needs to be adjusted.
If you've ever watched old footage of shore bombardment, one thing that stands out is the SMOKE - not from smoke rounds, but from the explosion / fires caused by the HE rounds. If we could model that somehow, it would solve the problem and add a dimension to the game as well as shore bombardment of an airbase would put smoke on the field.
I'd suggest adding a small black smoke puffer to the 5" and 8" HE rounds - it would not have to last as long as a "real" smoke round, and it should be a different color as well. In actuality, this helps both sides of the bombardment - the gunner gets a more visible hit sprite initially, but the field and it's targets will gradually be obscured by the continuing bombardment.
EagleDNY
$.02