NEB-25 Motor Alignment in the Sailboat

NEB-25 Motor Alignment in the Sailboat

Another nice feature of the motor frame on the NEB-25 Inboard Electric Motor, is its ability to be precisely positioned and adjusted to the alignment of the propeller shaft, during the motor alignment stage of its installation. This alignment feature was added to the motor frame in the Q2-2022 version of the motor.

The mechanics of this are actually quite simple, and a picture is worth a thousand words, so let’s start by looking at a typical diesel engine and consider the way it’s done there.  Standard engine mounts provide a vertically aligned bolt that each of the four corners of the engine rests on.  This gives four points that can be adjusted vertically.

For horizontal alignment of the motor, one must pivot each of the feet on its engine mount slightly using the slots on one of the ends of each of the engine mounts.

In theory, this allows the engine’s output coupler to be aligned with the propeller shaft in every way, except moving it forward or backward, since there is no adjustments provided for that.  For forward and backward (aft) adjustment, the propeller shaft itself is slid in and out of the boat, though the stuffing box. Again, in theory, everything is accounted for.  In practice, it isn’t an easy process at all.  Also, the alignment of the motor with the propeller shaft is critical, otherwise vibrations and excessive wear on the bearings occur.

comparison of typical diesel vs NEB-25 motor alignment


On the Newport NEB-25, much more flexibility for this process has been designed into the motor and its mounts.  We still use the standard motor mounts used with a diesel, however we also provide lateral slots to make horizontal adjustments much easier.  Additionally, the entire output shaft is able to be adjusted, forward and aft, through the motor gearbox.

The forward and aft adjustment is important, especially for retro-fitting to electric, because when replacing the diesel engine with an electric motor, it may be helpful to offset the new motor mounts slightly forward or aft from the original mounts, so they are bolted into a solid location.

The mounts themselves are fastened to the hull with lag-bolts, which can wear down the wood stud encased in the fiberglass, after years of vibration and weathering from a running diesel engine.

The mounting adjustments of the NEB-25 are one of the features that help simplify transitioning from diesel to electric. The electric motor is also smaller, and lighter than the diesel engine it replaces.  This also helps streamline retrofitting your sailboat to electric.

For more information about installations of the NEB-25, and any particular questions you have, feel free to Contact Us, we’d love to talk about your project and see how we can help.

Walt White

Founder and lead systems engineer, working to bring new products to market that make a positive impact to the environment. Our products and services help boats make the switch to battery electric propulsion, harness renewable energy, and solve other challenges involving marine electric propulsion systems.

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