I have my extinguishers laying in the side storage areas of the boat and wanting to mount them so they are not bouncing around. I was thinking maybe under the rear seat or possibly under the helm. Where do you guys have your extinguishers mounted?

Good to have one right under the helm. Mkae sure its up off the floor alittle so you don't bang your feet. I also like another in the passager front seat area. Under the back seat is a good place for a spare but can be hard to get to in a hurry. Trust me seconds feel like hours when you are seeing smoke coming from under the hatch and your passangers are panicing.

I don't have a 28 but mine is under the console in my sport but you definitely do not want the primary under the seat. Coast Guard Regs say has to be readily accesible (if you don't have an auto one in the machinery space) not to mention CIG3's advice.