Taking Advantage of IPS

Custom boats are pushing the performance envelope with advanced technology.

What a difference a few years make. When Volvo Penta launched its Inboard Performance System (IPS) at the Miami International Boat Show in 2005, only four display boats were equipped with the forward-facing pod drive system. All four were cruisers. Today there are 4,000 IPS engines powering boats in North America, and around 12,000 globally. A growing number are ending up in the engine rooms of custom blue-water sport-fishermen. North Carolina-based Spencer Yachts is the leader in incorporating IPS pod technology into its models.

“Not long ago, a 20-knot boat was fast,” company founder Paul Spencer says. “Now if it doesn’t do 40 knots, it’s not fast enough. Boat designs have had to change to accommodate speed. They have to be built differently to handle the seas and stress. We learned, through research, trade shows, talking to different naval architects and our own personal experience, how to accommodate these higher speeds.”

In the not too distant past, custom builders used sticks and strings to layer plywood over jigs when constructing one-off boats. The end result was a beautifully crafted work of art, but each one was slightly different, and often heavy. Now, with computer-assisted design, computer-assisted routers and advanced design software, construction is infinitely more precise. Materials are more advanced as well. Dozens of fiberglass weaves are available for different applications. Custom-made epoxies, such as low-viscosity/high-strength blends for resin infusion, can be ordered. Most significantly, coring materials have gotten lighter and stronger. According to Spencer, cored materials weigh 5 to 6 pounds per cubic foot, versus 12 to 15 pounds for most hardwoods. The weight savings on a 60-foot composite Kevlar/carbon hull over a comparable wood-cored boat is about 10,000 pounds, and that adds up to better performance.


“In the end, horsepower versus weight equals speed,” Spencer explains. “There are always other factors involved, but that’s the large part of the equation. With IPS engines, we’re able to cut down on horsepower and get better efficiency, as long as we’re very careful about meeting our targeted weight.” Spencer has built 75 boats 60 feet and larger since starting his company in 1996. Construction can take as long as 18 months per boat.

To help companies like Spencer’s design for the IPS, Volvo Penta launched its Integration Center in 2005. A couple of years later, a new facility with increased capacity opened in Portsmouth, Virginia. Initially builders brought bare hulls there for on-water testing. With a temporary helm installed, bags of lead shot were loaded aboard for sea trials to calculate the center of gravity and determine precise engine placement. As the size of IPS-powered boats grew, transporting hulls became more difficult and expensive. Today VPIC engineering teams typically work directly with builders at their own sites. Assistance ranges from cookie-cutter templates for immediate full-scale production of engine rooms to one-off custom designs. Fabrication specialists can even offer complete lamination schedules to the builders, including the type of material, length and number of layers. Once the boat is completed, VPIC technicians conduct the initial sea trial to certify the engines’ installation.

“Builders have definitely embraced IPS technology, and their numbers are growing all the time,” says VPIC manager Ed Szilagyi. “We’ve worked on designs ranging from 31 feet with twins up to 92 feet with quads.” The latest generation IPS 3 engines, with horsepower ratings of 1,050 and 1,200, started production in May.


“By paying attention to our construction and using lighter, stronger materials, we gained up to 15 percent more efficiency,” Spencer adds. “With IPS, we can add another 10 to 15 percent with comparable horsepower. On a 60-foot boat, that’s an impressive savings of one gallon of fuel for every mile you go.”

The learning curve swings both ways too. Spencer helped Volvo Penta improve IPS performance with input on the Sportfish Mode software, and he was instrumental in persuading the Swedish engine manufacturer to offer the above-water exhaust option to reduce white water in the wake. Those changes further advanced fishing performance.

“In Sportfish Mode, there’s not a boat around that can keep up with it,” Szilagyi says, based on firsthand experience. He skippers the company boat during billfish tournaments. “It’s fast and totally controllable. I’ve had several hot fish at the back of the boat before the mate could even get to the leader.”


So with all these design advancements, are conventional sterndrive diesels or straight inboards a thing of the past? Not just yet.

“Sport fishermen are superstitious and resistant to change,” Spencer says. “They’re also more demanding than other boat customers because they go out when it’s rough. But they get on the bandwagon eventually. We have to prove this new technology works, and we’re doing that every day out on the water.”

The 70-foot Volvo Penta company boat, built by Spencer Yachts and powered by triple 1,200-horsepower IPS 3 engines, will be making the rounds on the East Coast tournament circuit this summer.


Production Builders






Custom IPS Builders

Caison Custom Yachts

Ritchie Howell CustomCarolina Yachts

Sculley Boatbuilders

Spencer Yachts Inc.