An example watercraft includes a hull that defines a cockpit. A scupper is provided that extends from the cockpit through an exterior surface of the hull. A recess defined by the hull is in communication with the scupper, and the recess defines a portion of a venturi tube. A plate that is attachable to the hull is configured to define another portion of the venturi tube such that when the plate is attached to the hull, a complete venturi tube is defined.

An inflatable kayak is provided with a floor formed of a first drop-stitch inflatable chamber. A port side is formed of a second drop-stitch inflatable chamber and a starboard side formed of a third drop-stitch inflatable chamber. A flexible fabric hull panel covers an outboard bottom of the floor, and at least a portion of an outboard surface of the port and starboard side. A hull portion is flexible and may be attached to the flexible fabric hull at a forward portion to form a bow contour with a sloping ridge. The front hull portion does not extend below a bottom surface defined by the floor. A rigid skeg attached to the flexible fabric hull at a rear portion and configured to be removable.

An inflatable kayak is provided with a floor formed of a first drop-stitch inflatable chamber. A port side is formed of a second drop-stitch inflatable chamber and a starboard side formed of a third drop-stitch inflatable chamber. A flexible fabric hull panel covers an outboard bottom of the floor, and at least a portion of an outboard surface of the port and starboard side. A hull portion is flexible and may be attached to the flexible fabric hull at a forward portion to form a bow contour with a sloping ridge. The front hull portion does not extend below a bottom surface defined by the floor. A rigid skeg attached to the flexible fabric hull at a rear portion and configured to be removable.

Wakeboats that include an aquatic invasive species control apparatus are provided. These wakeboats can include: a wakeboat with a hull; at least one throughhull fitting in the hull of the wakeboat; an irradiation chamber in fluid communication with the at least one throughhull fitting, the irradiation chamber having a radiation source; and at least one water destination aboard the wakeboat. Methods for irradiating invasive aquatic species aboard a wakeboat are also provided. The methods can include: receiving water from outside the wakeboat hull; and irradiating water aboard the wakeboat prior to discharging the water.

A multi-function oar has an oar blade, a large-diameter tube, and a small-diameter tube. The oar blade has a tube-connecting portion. The tube-connecting portion has a through axial hole. The large-diameter tube is movably inserted in the axial hole. The axial hole has an upper positioning portion and a lower positioning portion for positioning the large-diameter tube, thereby changing the overall length of the oar. The large-diameter tube has a first check valve. The first check valve has a bail opening. The small-diameter tube is provided with a second check valve and an operating member having a water outlet, so as to bail water and drain water.

A multi-function oar has an oar blade, a large-diameter tube, and a small-diameter tube. The oar blade has a tube-connecting portion. The tube-connecting portion has a through axial hole. The large-diameter tube is movably inserted in the axial hole. The axial hole has an upper positioning portion and a lower positioning portion for positioning the large-diameter tube, thereby changing the overall length of the oar. The large-diameter tube has a first check valve. The first check valve has a bail opening. The small-diameter tube is provided with a second check valve and an operating member having a water outlet, so as to bail water and drain water.

Embodiments include a retrofit pontoon system including a pontoon, the pontoon having a pontoon body defining a first cavity, the pontoon body having a first aperture; a retrofit assembly, the retrofit assembly including a selectively fillable container sized to pass through the first aperture; and a pump. The pump is operably coupled with the selectively fillable container such that operation of the pump selectively fills and drains water from the selectively fillable container, wherein filling the selectively fillable container lowers the profile of the pontoon in the water and emptying the selectively fillable container raises the profile of the pontoon in the water.

Embodiments include a retrofit pontoon system including a pontoon, the pontoon having a pontoon body defining a first cavity, the pontoon body having a first aperture; a retrofit assembly, the retrofit assembly including a selectively fillable container sized to pass through the first aperture; and a pump. The pump is operably coupled with the selectively fillable container such that operation of the pump selectively fills and drains water from the selectively fillable container, wherein filling the selectively fillable container lowers the profile of the pontoon in the water and emptying the selectively fillable container raises the profile of the pontoon in the water.

A method of ballasting a vessel comprises positioning a vessel having a first draft adjacent to or underneath an offshore installation. The vessel has at least one ballasting tank and at least one port in fluid communication with the at least one ballasting tank. The at least one ballasting tank is arranged to selectively adjust the flow of ballast water in and out of the at least one ballasting tank. The method comprises pushing down from the offshore installation on the vessel to increase the draft of the vessel from the first draft to a second draft. The method further comprises opening the at least one port when the vessel is at the second draft and the at least one port is below a waterline. The method also comprises filling at least part of the at least one ballasting tank.

A method of ballasting a vessel comprises positioning a vessel having a first draft adjacent to or underneath an offshore installation. The vessel has at least one ballasting tank and at least one port in fluid communication with the at least one ballasting tank. The at least one ballasting tank is arranged to selectively adjust the flow of ballast water in and out of the at least one ballasting tank. The method comprises pushing down from the offshore installation on the vessel to increase the draft of the vessel from the first draft to a second draft. The method further comprises opening the at least one port when the vessel is at the second draft and the at least one port is below a waterline. The method also comprises filling at least part of the at least one ballasting tank.