Lasdrop Shaft Seals: Marine Dripless Sealing Systems

A Lasdrop shaft seal is a dripless inboard propeller shaft seal that replaces a traditional stuffing box. It seals around the rotating shaft and stern tube to reduce or eliminate seawater drips into the bilge.

Both are lip seal shaft seals. DrySeal is a compact dripless lip seal with an alignment bearing. EliteSeal is similar but adds a dedicated back-up seal compartment to make future seal servicing easier.

Gen2 is a mechanical face seal, not a lip seal. It seals using a carbon face and a rotor assembly designed to maintain contact and alignment, rather than a rubber lip riding on the shaft.

Measure the shaft diameter, then measure the outside diameter of the stern tube where the seal hose clamps. Choose the matching metric or imperial product and select both measurements as your options.

Choose the system that matches your measurements. If your shaft and stern tube are measured in millimetres, use metric. If measured in inches, use imperial. Do not mix systems.

Some installations require a water feed or a vent line depending on boat speed, layout, and seal model. Correct routing helps lubrication and cooling and prevents air trapping. Always follow the Lasdrop guidance for your specific setup.

Common signs include persistent drips, overheating, squealing noises, or visible wear. If the shaft has a groove where the seal runs, it can also lead to leakage.

A back-up seal is a spare replacement seal sized to your shaft, kept ready for service. It is a sensible spare to carry because it reduces downtime if the main seal becomes damaged.

In many cases, service is designed to be possible without pulling the shaft, depending on model and access. The exact method varies, so follow the correct procedure for your seal type.

Incorrect sizing, clamping to a dirty or corroded stern tube, misalignment, and poorly routed vent or water feed lines are common causes of leaks and overheating. Always recheck clamps and monitor after the first run.

A stuffing box uses packing that is adjusted to allow a controlled drip for lubrication. A dripless shaft seal aims to prevent drips while still managing lubrication and cooling through design and installation.

Check sizing, clamp tightness, stern tube condition, hose condition, and whether any vent or water feed line is blocked. Also inspect the shaft surface for grooves or corrosion.

It should run warm, not hot. If it is too hot to comfortably touch, that can indicate misalignment, lack of water feed or venting, contamination, or a failing seal.

Common causes are misalignment, running dry at start-up, insufficient water feed, blocked venting, or debris on the sealing surface. Overheating accelerates wear and can lead to leaks.

Measure the outside diameter of the stern tube where the seal hose will clamp, not the inside diameter. Measure on a clean section to avoid false readings caused by corrosion or paint.

Lip seals are compact and widely used. Mechanical face seals use two sealing faces and can be preferred for some installations. The best choice depends on shaft size, speed, access, and what spares you want to carry.

Not always, but alignment is critical to seal life. If you have vibration, coupling wear, or repeated seal problems, check shaft alignment as part of the job.

Carry a correctly sized replacement seal, spare hose clamps, and spare hose for any vent or water feed lines. Also keep basic tools and know the emergency steps for controlling leaks.

Most are designed for standard inboard prop shafts, but fitment depends on shaft diameter, stern tube diameter, available space, and the ability to route hoses. Always confirm measurements and clearance.

Match it to your shaft diameter and the seal type you have installed. For many lip seal spares, the part number corresponds directly to a shaft size, metric or imperial. If unsure, check the seal label, paperwork, or measure the shaft.