Power play: pods
Posted on 01 March 2012
Written by Chris Landry
More builders are installing pod drives for boaters who are eager for the advantages they offer
The push to make powerboat operation easier and more efficient marches forward, with more builders and designers taking advantage of pod drives and joystick helm control.
“There is a fuel efficiency gain, there is definite sound and resonance reduction, and there is an absolutely huge gain in owner confidence in being able to manage a boat and maneuver a boat around the docks,” says Bentley Collins, vice president of sales and marketing for Maine-based Sabre Yachts and Back Cove Yachts. “We’ve had a number of people who have bought 40s with pods, and within two years they have traded up to the 48. Pods have gotten people excited.”
They’ve become so popular that only two of 65 Sabres sold in the last two years have been without pod propulsion. “People in this market in our size range — 38 to 54 feet — think of pods first,” Collins says.
Sabre, which builds express and sedan models, installs pod propulsion from Cummins MerCruiser Diesel and Volvo Penta (www.cmdmarine.com, www.volvopenta.com). CMD’s Zeus can be found in the 42- and 48-foot models, while Volvo Penta’s IPS powers the Sabre 54 and will be available in a new 38-footer, Collins says.
No question, pods have been planted firmly in recreational boating. “I think we are past the point of convincing the boating public that pods are a worthy form of propulsion,” CMD Zeus product manager Rob Mirman says. “All the big boatbuilders are offering pod options in the boats where they make sense.”
Martin Meissner, marketing manager for ZF Marine (www.zf.com), which also offers pods, agrees. “Just by virtue of the number of boatbuilders that are offering pod boats, we know that they have been accepted in boating,” Meissner says.
Pods can be found in boat brands from A to Z: Albemarle, Azimut, Cabo, Grand Banks, Hunt, Lazarra, Legacy, Luhrs, Meridian, Ocean, Regal, Rinker, Rivolta, Sabre, Sea Ray, SeaVee, Tiara, Viking and Zeelander. And the list lengthens after each major boat show. Production, semicustom and custom builders are all playing with pods. Since hitting the market with Volvo Penta’s IPS, pod drives have powered a range of boats, including sport yachts, express cruisers, convertible and express sportfishing boats, even open center consoles. They power boats from 31 to 92 feet.
Volvo Penta introduced its Inboard Performance System in 2005 with two engine options, a 6-cylinder diesel and then a 4-cylinder. CMD followed in 2007 with Zeus, utilizing a 5.9-liter diesel and a pod and transmission built by ZF Marine. ZF, in turn, began offering its own pods — the Pod 2500 and Pod 2800 — in 2009. The 2500 and 2800 can accommodate engines as powerful as 372 hp and 498 hp, respectively. A Sea Ray express cruiser was the first boat with Zeus, while the IPS was installed in boats from Tiara, Cruisers, Four Winns and Regal. ZF Marine’s first pod boat was an Henriques.
In the seven years since their debut, there has been a proliferation of pods. More than 125 boatbuilders (roughly 50 U.S. builders) use Volvo Penta IPS in about 275 models. Forty-five builders use CMD Zeus in 68 models. ZF Marine pods are in boats from five builders, with another production builder planning to introduce a boat with twin 2800s Feb. 16-20 at the Miami International Boat Show, Meissner says. “Plus, we have at least three more boatbuilders currently in production or sea-trialing Pod 4000 boats — one of them is a four Pod 4000 boat.”
Pods have also become larger and capable of handling more horsepower. Volvo Penta now makes the IPS900 and IPS1200, which pack 700 hp and 900 hp, respectively. The Swedish manufacturer offers IPS in nine diesel models and one gasoline package, the IPS550G.
The ZF Pod 4000 can handle engines as large as 1,200 hp. This pod made its debut last October on a Viking 50 at the Fort Lauderdale International Boat Show. The ZF Pod 4000s were mated to twin 1,150-hp Caterpillar C18 diesels in Viking’s 50 Convertible.
CMD’s Zeus is offered with three engines — the QSB5.9 (330 to 480 hp), QSC8.3 (490 to 600 hp), and QSM11 (670 to 715 hp) — and two pods, the Zeus 3500 and 3800. The 3800 is matched with the 8.3- and 11-liter engines; the smaller 3500 works with the 5.9-liter engine.
One size doesn’t fit all
Despite their benefits, pods are not for every boat owner — or boatbuilder, for that matter. Pods can require major design changes to an existing model. Case in point is the Viking 50. “We had to make significant changes to the hull bottom, which included a modification for the acceptance of the pod installation’s vertical trim tabs,” says Peter Frederiksen, director of communications for New Jersey-based Viking Yachts.
The installation also resulted in a loss of fuel capacity. With conventional inboards, the boat carries 1,174 gallons of fuel; the pod boat holds 846 gallons. Viking will continue to build the 50 Convertible with pods, but only on request. “It’s up to the customer,” Frederiksen says. “It obviously can be done and it is a viable option, but it won’t be listed in our brochure.”
Integration of the pod into the hull shape and designing for the correct center of gravity top the list of design considerations for CMD, Mirman says. “The pod thrust line is parallel to the water, which is one of the reasons they are more efficient,” he says. “With an inboard, the thrust line is pointing up, pushing up on the stern of the boat. So, generally speaking, the pod needs more weight farther forward than the inboard.”
If a boat is being designed for pods, he says, it’s not an issue. “But if you are converting an existing inboard boat, you have to work with the builder to design the hull shape that allows the pod to be mounted, and we are going to want the center of gravity to move forward,” Mirman says. “So those are the two challenges and, depending on the boat, sometimes they can be resolved easily by moving, say, a fuel tank, but other times it might be more of a challenge.”
Repowering an inboard boat with pods makes little sense, pod manufacturers say. “Since the boat was not initially designed for pods, the hull shape would not be correct, and the center of gravity would not be correct,” Mirman says. “To fix those things in an existing boat would be very expensive or impossible. While it could be done, the question is whether it is practical, and in the vast majority of cases it’s not.”
Designing smaller sportfishing boats — about 35 to 45 feet — for pod propulsion is challenging because of space requirements in the stern, says designer Erwin Gerards, who penned the lines for the Release 34, which is expected to be offered with a single or twin ZF pods. “With sportfish boats, it is really important to have the cockpit deck and the covering board height correct to make it easy to fish from,” he says. “So installing pods is a big challenge because you are dealing with jackshafts and you lose some space because of that.”
Pods also cost significantly more than conventional inboards. The new Sea Ray 410 Sundancer with twin CMD 425-hp QSB V-drives is $659,299; the price jumps to $739,049 with the Zeus package with twin CMD 380-hp QSB5.9 high- output diesels and joystick control. The 39-foot SeaVee with twin IPS600s is about $60,000 more than the same boat with three 350-hp Yamaha outboards, says SeaVee president Ariel Pared. “You’re looking at about $367,000 for the base boat with twin IPS600s, and you’re looking at about $306,000 for the outboard boat,” he says.
Boatbuilders say the number of qualified pod technicians also needs to grow to meet demand. “There are some challenges with pod propulsion because it is still so new,” says Tripper Vincent, Cabo Yachts’ director of customer care and service. “On a worldwide scale there are not enough technicians out there that fully understand the pod systems, but it is just a matter of time before they get enough people trained out there. For example, if you are using the pods in South Florida or in a large boating community, there is already somebody there to help you.”
Adds Collins: “The engine and pod manufacturers just need to get deeper into their dealer network in terms of training and understanding of the systems,” he says. “They’re out there working on it, creating good service networks, and things are going well. But old-time mechanics get on board a boat, and they’re trying to figure things out while the new mechanics get on, plug in their computer and find out exactly what they need to know.”
As with any new product, longevity and durability are still unknowns. Some builders of outboard boats say the increased draft of a pod boat — and the possibility of expensive repairs after groundings — have made them leery of the new technology.
Finding the right fit
Pod manufacturers say their systems are best for planing and semidisplacement boats. “When you get into displacement mode — top speed 10, 11, 12 knots — a good inboard design with the right gear ratio and propeller choice is very hard to beat from an efficiency standpoint,” says Kent Lundgren, Volvo Penta’s vice president of new business development. “That’s a reason why we may never migrate into that area.”
Instead, Volvo Penta is looking toward semidisplacement vessels, such as those from Grand Banks, Lundgren says. “When we introduced IPS, we had props and gear ratios for a speed range from 27 to 45 knots,” he says. “But last year we came out with a prop series and gear ratio changes that will accommodate vessels with top speeds from 17 to 19 knots.”
Those props and ratios work with Volvo Penta’s system up to IPS900, and this spring it will introduce props and ratios that will allow the 13-liter IPS1200 to work efficiently in the 18-knot range, Lundgren says. Bottom line: IPS will make a good fit for semiplaning boats from 60 to 75 feet, he says.
CMD hopes to expand in the 50- to 70-foot segment, but with planing boats powered with triple pods. For instance, Riviera now offers three models — from 53 to 58 feet — with triple pods and 600-hp engines. “With larger boats, multiple pods — two or even three — deliver the horsepower without requiring more boat length,” Mirman says. “On top of the efficiency and ease of operation, they save space and make a 50-footer look and feel like a 60-footer or a 60-footer look and feel like a 70-footer.”
Hunt Yachts, for example, added a third stateroom to its 52 IPS. “We were very pleased with the way the stateroom turned out,” says Peter Boyce, C. Raymond Hunt and Associates’ principal designer. “Anyone who has seen the boat has been taken with it. It’s a pretty nice space for a boat that’s 52 feet.”
What are the other advantages of pods and which of them do owners rave about most? “For the boat owner, it is more about the joystick,” ZF’s Meissner says. “People want to be able to control the boat. That is at the forefront of everything. They want a positive, enjoyable experience. What winds up people is having to get their boat into a tight slip in a beam wind in a current.”
The joystick may get the credit, but it’s the pods and their independent articulation and counter-rotating props that carry out the nimble movements.
In addition to maneuverability, Sabre owners appreciate the noise reduction of pod propulsion, Collins says. “With the underwater exhaust, the boat quiets down and the vibration goes away,” Collins says. “If you have a boat with 1,000 hp and it is pretty quiet, it resonates a sense of luxury.”
Owners pay attention to efficiency and performance, too, Collins says. The 42 would require twin 500-hp engines to achieve the same performance as a pair of 380-hp engines with pod drives. “There is a big difference in horsepower, so you are going to burn less fuel,” he says. For example the Sabre 52 Express with IPS900s burns 40 gallons per hour at 25 knots; with twin 865-hp inboards, it burns 54 gph.
In a Cabo 40 cruising at 32.7 knots, the Zeus system burns 46 gph. “Before we went to the pods, most owners were purchasing 800-hp MAN diesels,” Vincent says. “With a pair of those the cruise speed was about 31.5 knots, and we were burning 63 gph. So with 400 fewer horses, we’re getting a higher speed and burning less fuel.”
Many Cabo owners like the station-keeping ability of Zeus’ standard Skyhook feature, which uses GPS to hold the boat in position despite current and wind, Vincent says. “They like it for bottom fishing or if they’re heading down a river and they have to wait for a bridge opening,” he says. Volvo Penta and ZF systems also offer station-keeping functionality.
Refinements on the way
Additional features and refinements from all three pod manufacturers are on the horizon. CMD this year comes to market with an auxiliary joystick station, for example. “We already offer that on our triple- and quad-pod installations, but now it is available with twin pods,” Mirman says.
SeaVee owners have found IPS’s Sportfish Mode a useful advancement, Pared says. It directs the drive units outboard to their maximum for rapid response when maneuvering the stern to fight a fish. SeaVee has been quick to incorporate new technology in its boats. The South Florida builder and ZF Marine teamed in 2010 to introduce the first recreational powerboat — a 34-foot center console — with single-pod propulsion.
It’s unclear whether pods will make their way into boats smaller than 30 feet. “From a technical standpoint a single-pod installation is not an issue,” Lundgren says. “We are struggling with the commercial viability of it. People sometimes forget that we cannot achieve joystick maneuverability with a single pod without integrating a bow thruster. And it’ll work just fine, but people are not going to like the price when all is said and done.”
It is not the bow thruster itself that drives up the price, but the electronic integration of the pod with the thruster so they work together seamlessly, Lundgren says. However, boatbuilders are confident that they will find ways to make such advances economically feasible because competition seems to be increasing. Caterpillar said last fall that it will become a pod player.
“There are a number of wonderful new products on the horizon,” Collins says. “The one that Caterpillar has planned is one with a traditional quick-shift transmission from Twin Disc, and that will be jack-shafted to the pod. So the pod itself will only be a rotating foot and propeller. The pod will be less complex and, because of that, it may be less expensive.”
This article originally appeared in the March 2012 issue.