Azipod propulsion systems, such as Volvo Penta IPS and Cummins Mercruiser Zeus, have proven their value with performance, efficiency, and space savings in new builds. But what about for repower?
“When I came on for Volvo as an applications engineer and ever since I started working with IPS, I started thinking about repower,” says Tom Eckel, an applications engineer for Volvo Penta, who is repowering his own 1974 Bertram 38 as this article is being written. “Up until just recently it’s been Well we’re not really ready for that at this point. But now we’ve worked with so many boatbuilders, we know what works and what doesn’t work.”
Interested? “The first step is to qualify the boat,” says Eckel. “We need to take the measurements to make sure it’s going to fit under the cockpit sole without raising the deck. So obviously the lamination is a pretty serious part of the process. If you get into hull modifications on top of laminations, like raising your deck, it’s just not going to be cost-effective.”
Even if your boat has the room in the machinery spaces, the hull design may not work with the system. “When you start getting into 20-degree deadrise, you have to really start looking at your chines, to make sure that you have enough flat area so that when you go into a turn that you’re going to be stable,” says Eckel. “If you’ve got a soft chine and you’ve got a big deadrise, it’s not going to work because you’re going to have too much lean in the turns, it’s not going to be a safe, predictable turn. And we don’t like keels, because they tend to fight the tracking of the IPS drives.”
Eckel may know better than most what to expect for his Bertram project. “Just the rough numbers, my speed increase is probably going to be about 15 percent, the fuel is going to be anywhere from 30 to 45 percent, and the sound level is going to be half of what it was,” he says. “That’s just my gut feeling from what I’ve seen on other boats. There is no vibration with it, thanks to the contra-rotating propellers and the forward-facing props. Those rubber o-rings that keep the water out also isolate the drives.”
Refit Considerations: Less fuel burn and dime-radius turns? It’s worth exploring, though equipment costs are around $120,000.
Volvo Penta; www.volvopenta.com
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