Epropulsion Navy Pod Motor

Epropulsion Navy EVO 3 & 6kW POD motors are effectively the bottom section of a Navy EVO outboard, with a separate control module, designed for permanent mounting on the bottom of your boat’s hull.

In contrast to other pod motors at this size (including Torqeedo Cruise) {link}, and OceanVolt, the Epropulsion Navy EVO series all use direct-drive brushless DC motors. This means that the motors are directly connected to the propeller shaft, there is no delicate or noisy gearbox in between. And the motor is housed underwater, in the “pod” at the bottom of the leg – so there’s no driveshaft or belt or cooling system running up the leg. It’s important to understand what kind of pod you’re buying, the term “pod” covers a lot of variety in design.

The main benefits of Epropulsion’s direct drive pod motors are very quiet (all-but silent) running, mechanical robustness/simplicity, and greater efficiency (meaning longer run times from your batteries).

Compared with a diesel-powered saildrive, besides the silence, they also cause very little vibration (which is the next thing you notice once the noise has gone) and don’t spout toxic fumes into your cockpit when you’re going downwind…

The Epropulsion pod motors can also be set up to “regen” or recharge your batteries when fitted to a sailing boat. It’s only really useful if you can average 5 knots or more, and does cause some drag (rules of physics, nothing is free!) so if your boat is slower than that you may decide to switch it off. However if you can average 10 knots and have a Pod 6.0 installed you can put charge back into your batteries at up to 1000W (or 600W at 8 knots).

The direct translation of kW (kilowatts) to hp (horsepower) is 1.34. That would suggest the Navy 3.0 pod is equal to a 4hp combustion engine, and the Navy 6.0 to 8hp. BUT… electric motors have much more torque, from very low revs. To utilize that torque they turn relatively large propellers, relatively slowly – and that’s what you want if you’re driving a displacement hull.

AND… direct-drive pod motors don’t have the losses inherent in combustion engine systems. With a pod motor the propeller is vertical, not angled as on shaft drives (so all the thrust is directed horizontally). A saildrive gets around that issue but there are still losses in the drive shaft and right angle gearbox – in an Epropulsion pod the motor is underneath the boat, directly in line with the propeller.

Another factor to consider is that the peak power/torque of a combustion engine comes at quite high revs, a peak that many owners never reach because it is so unpleasant to do so (and/or fearing that it will explode!).

In practice we’re finding 1kW of electric seems to function at least as well as 2hp of combustion motor, and often more.

The example we know best is our own Sadler 29 (9m long, 4 tonnes). In 2020 we took out the 40 year old Bukh 20, and replaced it with an Epropulsion Navy Pod 6.0. We’ve found that:

• at about 1000W we get around 3.5 knots
• at 1500W we get 4 knots, this is generally our cruising speed
• at 3000W we get 5 knots, which is about as fast as we ever dared to push the old Bukh
• at 6000W we get 6 knots, which is clearly pushing the limits of hull speed on this boat
• So whilst we took out a 20hp diesel engine, we very rarely use more than 3kW of our electric motor. We didn’t go any faster when we had the diesel, so the actual propulsion power we were achieving (after all the losses) was equivalent to that 3kW of electric.

We’ll talk about range in the next section but one other factor to mention if you’re considering re-powering a sailing boat is motorsailing. When the motor isn’t noisy and making half the interior shake itself to pieces, applying a little “electrical assistance” soon becomes very tempting. You actually continue “light airs electric motor sailing” in conditions you’d have given up in with a diesel, and electric motorsailing is very range efficient. We find 150 to 200W enables us to point about 10 degrees higher and a knot or so faster… with the added advantage that other boats think we must be sailing gods! It’s also very beneficial to apply a little electric power when trying to make progress against a short sharp chop; running an electric pod motor doesn’t intrude on the experience, in fact often seems to improve it.