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.