Arrangement and method for sealing a propeller shaft of a marine vessel

An arrangement for sealing a propeller shaft of a marine vessel, the arrangement comprising:

• a shaft seal arrangement for sealing the propeller shaft against sea water, and
• a lubrication arrangement comprising a lubricant circulation line for conducting lubricant to said shaft seal arrangement and for conducting lubricant from said shaft seal arrangement, a lubricant circulator configured to create a flow of lubricant in the lubricant circulation line and in said shaft seal arrangement,
• wherein the lubricant circulation line defines a first part downstream of the lubricant circulator and upstream of the shaft seal arrangement and a second part downstream of the shaft seal arrangement and upstream of the lubricant circulator, and
• wherein:
• the first part of the lubricant circulation line includes a connection line that is connected in fluid connection with the lubricant circulation line downstream of the lubricant circulator and upstream of the shaft seal arrangement, and that is connected in fluid connection with the second part of the lubricant circulation line so as to selectively conduct a part of the flow of lubricant past the shaft seal arrangement,
• at least one hydraulically operated pressure relief means configured to control the flow of lubricant in the connection line, wherein said at least one hydraulically operated pressure relief means is configured to be operated by means of the lubricant circulating in the first part of the lubricant circulation line,
• said at least one hydraulically operated pressure relief means is configured to sense characteristics of the flow of the lubricant circulating in the first part of lubricant circulation line,
• said at least one hydraulically operated pressure relief means is configured to be hydraulically operated by means of the lubricant circulating in the first part of the lubricant circulation line in response to the sensed characteristics of the flow of the lubricant circulating in the first part of lubricant circulation line,
• said at least one hydraulically operated pressure relief means being configured to connect the connection line in fluid connection with the lubricant circulation line downstream of the lubricant circulator and upstream of the shaft seal arrangement,
• the characteristics of the flow of the lubricant circulating in the first part of the lubricant circulation line said at least one hydraulically operated pressure relief means is configured to sense a volumetric flow rate of the lubricant circulating in the first part of the lubricant circulation line, and
• said at least one hydraulically operated pressure relief means being configured to redirect a part of the flow of the lubricant circulating in the lubricant circulation line into the connection line if the volumetric flow rate of the lubricant circulating in the first part of the lubricant circulation line exceeds a threshold value for the volumetric flow rate.