Each of the E-Pod motors and the 15 hp outboard should be capable of moving the boat under most conditions providing a level of redundancy that was missing in the previous diesel/outdrive combination (see why not keep the diesel for more on this.) While none of them alone will be particularly powerful at moving the boat, each more than meets the minimum for maneuvering at low speeds. Each of the E-Pods is equivalent to current diesel but limited in range. The 15hp Honda is a drop of about 5 hp compared to the usable hp of the Westerbeke 27hp engine (remember outboards are rated based on hp at the prop, versus diesels which are rated before all loads are considered, like alternator, transmission and drive leg friction.)
Why is redundancy such a big issue to me?
Having read every situation that caused a loss of a boat in the SF Bay area or just about anywhere else the last few years, I can say the most common issue for coastal cruisers is losing power near shore. Typically, this while anchoring, entering or leaving a marina when the sails are down and their is little time to raise them should things go wrong.
The saddest story was about a well equipped monohull anchoring for the day in Drakes Bay. The anchor began dragging which is a common enough problem. Unfortunately, when they started motoring towards the anchor poor communication with the crew allowed the line to get tangled up in the prop which was a death sentence in this case. Before you know it, she was on the beach. Imagine that half a million dollars of boat ends up on the beach for lack of a backup or even a simple way to clear the tangle from the prop. This problem could have just as easily been caused by an impeller failure, fuel contamination, or electrical failure preventing the motor starting or fuel pump running just to name a few common problems. Funny how we spend all kinds of money on the latest GPS and entertainment systems yet give little thought to having a backup to the diesel, (even a small one) that would have saved the boat in this situation.
To help avoid this problem, I installed Shaftsharks on the E-Pods which should cut any anchor line that they encounter. This will also reduce the chance of a line entanglement ripping them out of the hull. My brother who often takes his power boat to the delta area for wake boarding and skiing had lost two seasons waiting for the outdrive to be repaired after encounters with heavy lines that caused serious damage. Since then he has switched to a Yamaha jet drive boat, twin 300hp jets... no more line problems....he is much happier except at low speeds where it is a real challenge to maneuver.
Having True Redundancy?
When you talk about redundancy, for it to be meaningful there must be no shared components (no shared fuel tanks; no shared power supply; I mean absolutely nothing.) Each E-Pod motor has its own battery bank, controller and charger; nothing shared. The 15hp Honda outboard itself has nothing shared with the E-Pods so they are all truly redundant.
The biggest weakness with the E-Pods is range, which is a common issue for both E-Pods and a type of failure similar to running out of fuel for the diesel and must be considered, but the typical situation when near shore where you need them to maneuver to keep off the beach does not require long range; just a few minutes getting in/out of the marina or resetting an anchor. Certainly they will buy you that precious time to set another anchor or raise sail (even if the batteries are nearly depleted you can push them a bit to "save the boat.")
In practice, I have found the range issue to be mush less of a concern than everyone imagines. That has to do with me primarily being a day-sailor who makes weekend trips from time to time (which I think is pretty much how 99% of boat owners who have to work for a living use their boats.)