It is the
warhead of an anti-jet ski & anti-tube towing PB sonic blaster.
Tubers have become worse than jet skis. I scored one for a citation this year. I'd paint them on the side of the boat like a fighter pilot:dance: - but that would probably be considered bad behavior

. It was a tough job to sail along at 1kt in very light winds to bait the thing . OTH: when they cut within 2-3 boat lengths

of your bow and don't notice the other boat nearby named "Ranger"

, they kind of deserve that loooong discussion

.
If I remember correctly, the USCG recommends 5 blasts

.
OC
:2cool:smokin in CO