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Boats

The Truth About Shafts and Pods

For nearly a decade, pod propulsion looked like it would render inboards obsolete.
boat shaft and podSo why hasn’t it happened?

At the 2005 Miami Boat Show Volvo Penta introduced its Inboard Performance System (IPS) and changed forever not only the way we run our boats but the way we think about running them. Before, maneuvering required forethought, logic, coordination, and strategizing; after, it became mere intuition: Look where you want to go and point the joystick that way. They said it was so easy a child could do it, and sure enough, it wasn’t long before a lad barely out of kindergarten deftly maneuvered a 40-footer into a slip all by himself.

But point and shoot was only part of it; IPS also claimed more speed and better fuel efficiency (the precise amount of each is still up for discussion), and thanks to its aft engine placement, more interior space and lower interior sound levels. Still, many boaters weren’t convinced. One described his skepticism like this: “It’s just too good to be true. There’s no free lunch, so there must be a hidden cost that no one’s factored in.”

Is there some X Factor or Factors that negates the pod’s proven advantages? You need go no farther than your marina to hear a list of suspects.

The Unknown

Everyone fears the unknown, especially boaters, many of whom still consider pod drives something alien. Hang around a boatyard, and you’ll hear at least one horror story about some unfortunate soul who was stranded, or worse, because his pods failed. These are often second- or third-told tales with a questionable provenance and few verifiable facts. Over the years, I’ve found online forums to be some of the most ready places for first-hand accounts of engine-related problems. Sure the stories are one-sided, but as an aggregate source of information, they’ve led me to conclude that pods are no more prone to failure than inboards but that when a pod breaks, the repair bill’s going to be higher.

Yes, pods have sheared off upon striking something immovable (as they’re designed to do), leaving the hull intact and the owner with a five-figure repair bill. Such tales are grist for boaters’ imaginations, as is the mere idea of components made of expensive, finely machined alloys dangling below the boat, protected by neither keel nor shaft. Yet catastrophic groundings are rare for all boats, although again, the financial consequences for the pod owner are usually steeper. (Power & Motoryacht once had a company boat powered by inboards with which the publisher at the time rammed a sunken fuel barge at a healthy clip. The bill to undo the resulting carnage came to $46,000, a figure that couldn’t have been much worse if pods had been involved.) 

Pods are comprised of some very costly components, but theoretically, their modular design should yield some countervailing savings in labor costs. Theoretically. 

Complexity

Pods have more parts, both mechanical and electronic, and conventional wisdom says that means more problems. The inboard has simplicity and ubiquity. Pull into any port in the world, and there’s probably a guy there who can fix it. (Stranded in Guaymas, Mexico, I watched a guy true up a dinged prop using just a single jack and anvil. We didn’t have to touch it until we got back to San Diego.)

But conventional wisdom no longer applies. Today electronics are inextricably entwined with every aspect of our lives, and whether it’s commercial jet engines, cars, home appliances, or chartplotters, we expect and receive virtually bulletproof reliability. So the fact that pod systems are loaded with electronics actually makes them less prone to failure—and unfortunately an unfathomable mystery to most mechanics. Alas, the fact that electronics don’t respond well to brute force may mean some service challenges, at least in the short term, which is why long-distance cruisers have, as a group, been wary of pods. 

Maintenance

Inboards are virtually maintenance-free, while pods require lots of servicing. Of course neither of these statements is true. Inboards require sacrificial-anode replacement, prop adjustment, cutless bearing repair, shaft alignment, and a method of controlling marine growth. Pods require drive-oil changes every 250 hours or annually. Also demanding periodic attention are hydraulic steering, transmission, and lower-unit oils. All told, figure $500 per engine annually, plus haul-out fees.

Most pods also require periodic removal and inspection of prop sets and seals, and re-greasing of the propshafts—figure $250 per pod. (It’s not a bad idea to do the same—minus the seals—for inboards.) 

Sacrificial anode maintenance is both cheap and easily performed by the average inboard boat owner. Fifty dollars per prop should do it. Each IPS has anodes as well, one up inside the exhaust tunnel (the other is on the transom); both Zeus anodes are on the trim tabs where they’re easy to reach. Allow $450 per IPS pod, $350 per Zeus. Finally there’s antifoulant for the drive. Ignore it and you can forget about that edge in fuel efficiency over inboards. Most yards will repaint a pod for $300.  

All up, pod owners can expect to pony up something like an additional $2,500 for scheduled maintenance. That’s not chump change, but neither is it likely to produce heart palpitations in the owner of a million-dollar vessel. And while it’s hard to nail down the amount of that fuel-efficiency edge, everyone agrees it does exist and can compensate you for at least some of the additional maintenance costs. 

Oh, and if you’re a do-it-yourselfer, you’ll discover that a lot of pod maintenance requires specialized tools and training. Disappointing, but then again when’s the last time you worked on your car?

Inertia

Like long-distance cruisers, sportfishermen have been slow to accept pods, in this case not because of perceived deficiencies but rather a reluctance to try anything that might reduce chances of success. Better fuel efficiency? More interior room? If they don’t increase the odds of hooking up, who cares? And maneuverability—well, any good sportfishing captain can put his ride wherever he wants—without a joystick.

Nevertheless, pods are making inroads. Viking offers four versions of its 42, all with pods, and according to company director of communications Peter Frederiksen, they sell well. “The 42 Convertible is up to Hull number 10 but we are up to 36 hulls for the Open version,” he says. 

Initial Cost

Pods cost more, period. But how do you compare boats? Imagine a 44-footer with three cabins, two heads, and inboards priced $20,000 less than an identical 44-footer with pods that, thanks to its aft-engine placement, has one more cabin or head. Wouldn’t accommodations be the more relevant yardstick? And what of resale? How much of the additional initial cost will you get back at trade-in time? We’re still trying to sort through the answer to that one.

There are many reasons why everyone’s not on the pod bandwagon. But tick them off and it’s hard not to conclude that the trend is undeniable: More boaters prefer them every year, and while they’ll never completely replace inboards, they are the future of boating. As one broker told me, “It’s like automatic transmissions. At first no one trusted them; now you can hardly sell a car without one.”

This article originally appeared in the February 2014 issue of Power & Motoryacht magazine.

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