A scupper valve includes a frame and a rigid flapper coupled to the frame. The rigid flapper is configured to swing relative to the rigid frame between an open and closed position. A flexible annular seal defines a centrally-disposed circular opening and a first annular projection that surrounds the centrally-disposed opening. The rigid flapper, in the closed position, contacts a distal edge of the first annular projection to create a circular line contact that restricts or prevents fluid flow through the centrally-disposed circular opening in the flexible annular seal. A rigid annular backplate is adjacent to and in direct physical contact with an annular surface of the flexible seal on a side of the flexible seal opposite the rigid flapper.

A watercraft includes a hull, an opening extending through the hull, the opening configured to receive a removable propulsion mechanism, and an insert removably insertable into the opening. The insert includes an inner cavity, an aperture configured to be at least partially submerged in a fluid when the watercraft is positioned on the fluid, the aperture being configured to provide fluid communication between the inner cavity of the insert and the fluid as the watercraft travels in a forward direction, and a surface shaped and dimensioned such that a first pressure within the inner cavity is greater than a second pressure at the aperture as the watercraft travels in the forward direction.

An overflow system for a hopper dredger comprises an overflow tube; an inlet for taking in head water from the hopper; and a collector to collect the flow of head water entering the inlet and guide the flow to the overflow tube. The collector comprises a substantially horizontal top portion which delineates a top of a flowpath for head water into the collector to ensure substantially radial flow into the collector. At least one of the overflow tube and the inlet is adjustable for controlling flow into the overflow system.

An overflow system for a hopper dredger comprises an overflow tube; an inlet for taking in head water from the hopper; and a collector to collect the flow of head water entering the inlet and guide the flow to the overflow tube. The collector comprises a substantially horizontal top portion which delineates a top of a flowpath for head water into the collector to ensure substantially radial flow into the collector. At least one of the overflow tube and the inlet is adjustable for controlling flow into the overflow system.

A marine thru-hull fitting drainage device directs fluid away from a thru-hull fitting in the hull of a vessel. The drainage device includes a resiliently flexible channel body having a substantially U-shaped cross-sectional area, the body shaped to taper from a first flat end proximate to the hull of the vessel to a second narrower end that is distal from the hull of the vessel. The device also includes a flange attached to the first end of the body proximate to the hull having a flat surface area shaped to conform around an edge of the thru-hull fitting on the hull of the boat and an adhesive material formed on the flat surface area of the semi-circular flange, the adhesive material attached to the flat surface area of the semi-circular flange on a first side and having a removable non-adhesive layer concealing a second adhesive side of the adhesive material.

A drainage device for directing fluid away from a thru-hull fitting located on a hull of a vessel includes: a channel body mountable proximate to and extendable away from the hull of the vessel; a groove formed along at least a partial length of the thru-hull body; and a lip protruding from a bottom edge of the channel body at an end of the channel body that is distal from the hull of the vessel when the drainage device is mounted thereon.

A drainage device for directing fluid away from a thru-hull fitting located on a hull of a vessel includes: a channel body mountable proximate to and extendable away from the hull of the vessel; a groove formed along at least a partial length of the thru-hull body; and a lip protruding from a bottom edge of the channel body at an end of the channel body that is distal from the hull of the vessel when the drainage device is mounted thereon.

A marine thru-hull fitting drainage device for directing fluid away from a thru-hull fitting installed through a bore in a hull of a vessel includes: an elongate thru-hull body forming a channel and having a flange formed on an end thereof; a channel body formed on a face of the flange and extending away from the hull of the vessel, the channel body forming a drainage channel for directing water from the channel of the thru-hull body away from the hull of the vessel; a groove formed in the channel body; and a lip protruding from a bottom edge of the channel body.

A marine thru-hull fitting drainage device for directing fluid away from a thru-hull fitting installed through a bore in a hull of a vessel includes: an elongate thru-hull body forming a channel and having a flange formed on an end thereof; a channel body formed on a face of the flange and extending away from the hull of the vessel, the channel body forming a drainage channel for directing water from the channel of the thru-hull body away from the hull of the vessel; a groove formed in the channel body; and a lip protruding from a bottom edge of the channel body.

A method of operating a thruster apparatus involves causing a first propeller to rotate in response to pressure of a first flow of pressurized hydraulic fluid, and causing a second propeller to rotate in response to pressure of a second flow of pressurized hydraulic fluid separate from the first flow of pressurized hydraulic fluid. Thruster apparatuses are also disclosed.