Sealing device for a propeller shaft of a marine vehicle propulsion unit including a plurality of sealing lips axially offset relative to each other, with a receiving space for a hydraulic fluid delimited by two adjacent sealing lips, at least one buffer space axially offset with respect to the receiving space and delimited by two adjacent sealing lips, whereby the sealing device includes suitable feeding means for supplying the buffer space with a buffer fluid. The device includes a sampling circuit able to sample fluid included in the buffer space and a monitoring device able to check parameters of the fluid sampled by the sampling circuit.

An arrangement for sealing a propeller shaft of a marine vessel are specifically applicable in preventing oil leakage via propeller shaft sealing in cases where the draught of a marine vessel is, for some reason, reduced beyond its ordinary value.

A seal device for sealing in a liquid medium includes a first seal assembly disposed on a primary side facing the medium and configured to seal a stationary component with respect to a rotatable component, a second seal assembly disposed on a secondary side facing away from the medium and configured to seal the stationary component with respect to the rotatable component, and a sensor connected to a volume located between the first seal assembly and the second seal assembly and configured to detect a change of a moisture level in the volume. The stationary component further includes a bore located axially between a contact surface for the first seal assembly and a contact surface for the second seal assembly, and the volume is connected to a pressure tank by the bore.

Provided is a ship propelling apparatus including a rotation shaft on which a rear propeller is fixed; a front propeller rotatably supported on the rotation shaft in front of the rear propeller; and a counter-rotating device through which the rotation shaft passes, which includes a gear box including therein a plurality of gears configured to reverse rotation of the rotation shaft and transfer the reversed rotation to the front propeller, and which is installed in an installation space formed at the rear of a ship. The rotation shaft includes a measurement hole formed to pass through a center of the rotation shaft for centering of the counter-rotating device installed in the installation space; and an individual lubricant path separated from the measurement hole.

A seal system includes a face seal rotor ring including a wide sealing face preferably made of tungsten carbide. The stator ring includes a narrower sealing face confronting the rotor ring wide sealing face. The stator ring sealing face is preferably made of polyamide-imide and tapers to narrower widths rearwardly.

A sealing system for sealing a shaft located under water includes a bush mountable on the shaft and fixed to the shaft, a housing fixed with respect to the bush and surrounding a first portion of the bush, a lubricant chamber and an air chamber in the housing and open to the bush, the lubricant chamber being sealed with respect to the air chamber by a seal ring, a mechanical seal outside the housing and surrounding a second portion of the bush, an air supply line and an air discharge line connected to the air chamber, and a quantity of lubricating oil in the lubricant chamber, the lubricating oil being in fluid communication with a lubricant tank via at least one oil line, wherein an air pressure in the air chamber is greater than an oil pressure in the lubricant chamber.

In a stern tube sealing device, slurry contained in outboard water is suppressed from depositing on sliding portions between a wall surface of a seal ring chamber or an outer peripheral surface of a propeller shaft and a sealing surface of a seal ring. A first seal ring (121) is arranged in a first seal ring chamber (111), and a second seal ring (122) is arranged in a second seal ring chamber (112) which is formed at an inboard side of the first seal ring chamber. The first seal ring chamber and the second seal ring chamber are in communication with each other through the sliding portions between a wall surface of the first seal ring chamber and a sealing surface (121a) of the first seal ring. Outboard water is filled into the first seal ring chamber, and clear water is filled into the second seal ring chamber.

Disclosed are a propulsion system for a ship, a method of assembling the same, and a method of disassembling the same. The propulsion system for the ship includes: a rear propeller fixed to a rotary shaft; a front propeller that is rotatably supported on the rotary shaft in front of the rear propeller; a contra-rotating device that is mounted in an installation space at a rear end of a hull so as to reverse the rotation of the rotary shaft and transmit the reversed rotation to the front propeller; a propeller connecting member that connects the contra-rotating device and the front propeller to transmit a rotational force; and a thrust supporting device that is provided between the contra-rotating device and the propeller connection member to support thrust of the front propeller.

A method and an arrangement for sealing a propeller shaft. The propeller shaft is rotatably supported with a bearing arrangement inside a pod that is suspended at a hull of the marine vessel. The bearing arrangement includes at least two seal rings axially spaced apart from each other such that at least one lubricant seal chamber is delimited. The arrangement includes a lubrication arrangement for conducting lubricant to and from said bearing arrangement. The lubrication arrangement includes an additional lubrication circulation line for conducting a part of said flow of lubricant to and from said at least one lubricant seal chamber. The lubrication arrangement being additionally configured to create a flow of lubricant in the additional lubricant circulation line and in said at least one lubricant seal chamber.

A seal device for sealing in a liquid medium includes a first seal assembly disposed on a primary side facing the medium and configured to seal a stationary component with respect to a rotatable component, a second seal assembly disposed on a secondary side facing away from the medium and configured to seal the stationary component with respect to the rotatable component, and a sensor connected to a volume located between the first seal assembly and the second seal assembly and configured to detect a change of a moisture level in the volume. The stationary component further includes a bore located axially between a contact surface for the first seal assembly and a contact surface for the second seal assembly, and the volume is connected to a pressure tank by the bore.