The bowling ball mortar uses 4 oz of blackpowder and the ball lands about 1/2 mile out in the bay and you can barely see the splash. I suggested the owner reduce his charge to one oz and shoot into the bay, just make sure he was shootng down wind and not up wind or he was going to get wet from the spray.

I shot my beer can mortar into a pond from 100 yards. Time of flight was 17 seconds. The projectile was a 12 oz beer can filled with cement. the impact geyser was 25 to 30 feet high and soaked everyone on the firing line. (down wind) The Geyser looked just like an explosion in any old 1950's black white WWII Naval war movie.