Q. How long should a seal last?
A. The DrySeal model will last three to five years before the inner lip seal must be changed. If a back-up seal is installed during the original installation, the seal can be easily installed without removing the shaft from the coupling. The “Original” Bellows and Generation II models will last as long as eight to ten years before servicing. Both models would most likely require refurbishing of the seal surfaces. In addition, the bellows on the “Original” model should also be inspected and replaced, if necessary. As in any part, they should be routinely inspected.
Q. Does a Lasdrop seal wear a shaft like the stuffing boxes do?
A. There is absolutely no shaft wear from the "Original" Bellows and Generation II. Because it is a lip-seal design, the "DrySeal" model produces very little wear on the shaft.
Q. How do I mount the unit if I have a flanged stern tube?
A. We offer flange adapters to accommodate any configuration of stern tube. We would need the bolt pattern.
Q. My existing stuffing box is not mounted with a hose.
A. On “rigid-type” stuffing boxes, it is possible to disassemble the front of the unit and turn it around, seal it so that the tube is protruding forward to permit the clamping of the seal.
Q. Does the seal need maintenance?
A. The seal is virtually maintenance-free. Like any part, the seal should be routinely inspected. If the vessel is in dry dock or not operated for a long period of time, it is good idea to wash down the seal with fresh water.
Q Is the seal difficult to install?
A. Installation is easy if you can access the area where the seal is installed. It is necessary to disassemble the shaft from the coupling. The shaft needs to be slid back far enough to remove the old stuffing box.
Q. Do I need water lubrication?
A. At hull speeds of 8 to 10 knots and above, a vacuum is created in the stern tube that draws the seawater used for cooling and lubrication. At slower hull speeds, no water lubrication is necessary. The supply hose can instead be used to purge the air out of the seal when the vessel is put back in the water. If there is no water injection, ensure there is water to the seals at all speeds. Lasdrop does, however, recommend water injection for all seals and speeds.
Q. What do I need for ordering?
A. Shaft size and the outside diameter of the stern tube. Make sure there is adequate clearance between the coupling and the end of the stern tube.