Abstract: A tail pipe structure of a control type muffler having a first outlet pipe and a second outlet pipe provided with a control valve inserted therein, wherein the first outlet pipe is in communication with the downstream side of the control valve of the second outlet pipe. The mechanism of the muffler is such that when the control valve is opened, the exhaust gases flow into the atmosphere from the first and second outlet pipes. Further, even when the control valve is closed, the exhaust gases in the first outlet pipe flow into the atmosphere therethrough while a part of the exhaust gases flow into the second outlet pipe from the first outlet pipe through the communication pipe and is then discharged into the atmosphere.

Abstract: A device for protecting the inlet or draft port of a water-jet propulsion system is disclosed. In a forward part of the inlet port of a drafting duct of a propulsion pump, a grate is mounted rotatable around a shaft which in turn is supported by a bracket. The bracket is secured to a lower part of the pump casing. A pin, passing through the grate, is urged by a spring to engage a part of the bracket to lock the grate in a position to block large objects from entering the duct. When the pin is disengaged against the force of the spring the grate is rotated to a position to permit manual entry into the duct for repair purposes.