The IPS-Zeus Shootout Has Begun! - 09/12/2007

The only boat in the world currently available with inboard, IPS or Zeus propulsion systems – take your pick.

In mid-August, after’s Director of Testing, Capt. Bob Smith, began winging his way back to San Francisco from Ottawa, Doral engineers, along with those from Volvo Penta and CMD got down to what they had been waiting to do all week – draw down on each other. For the first time ever, two nearly identical Alegria 45s built by Doral – were able to be tested the same day at the same time at the same place. It was about as apples-to-apples as such a shootout is ever likely to be between these 30,000-lb. + express cruisers.

The CMD Zeus pod drives have aft-facing duo propellers.

The results in the table below are of the Zeus-powered Alegria 45 taken on August 13 by BoatTEST’s captain and are NOT those recorded by the Doral engineers 2 days later during the same-day IPS/Zeus company “trials.” We don’t know what the Doral and engine makers got for the twin CMD 480-hp Zeus package. But here are our numbers. FYI, fuel consumption figures were taken right off the CMD SmartCraft VesselView indicator.

Alegria 45 Performance Table with CMD Zeus Package

After the head-to-head company "trials", we asked Luc St. Onge, Manager of R&D for Doral, if he would be kind enough to send us the test numbers for both the IPS and Zeus-powered boats during the tests he and the engine-makers conducted on August 15th. He told us that CMD staff on the scene asked him NOT to release the performance numbers on the CMD-powered Alegria 45 until they had a chance to make sure they had the right props on the pods for this application. St. Onge was as good as his word and would NOT give those numbers to us. But he would give us the numbers produced by the twin Volvo Penta 435-hp IPS-powered boat recorded that day. See the table below:

Alegria 45 Performance Table with Volvo Penta IPS Package

In fairness to CMD, not only was the Zeus system just introduced this summer, a year-and-a-half after the IPS, but it was also just recently installed in the Doral Alegria 45 and this was the “second or third” IPS installation in that model, according to St. Onge. Volvo Penta engineers have had more time to “get it right” both overall and for the of the Alegria 45, specifically. According to other observers on the scene, the CMD crew is still tweaking what is for them a new installation and it simply takes time to dial-in a complicated system.

In fairness to Volvo Penta we should point out that the IPS boat used was a customer owned boat delivered just before the “shoot-out”. Volvo Penta staff had the opportunity to perform one quick sea-trial before the event. Also, the boat was not weighed by crane and may not have weighed what the CAD predicted due to the owner putting personal gear aboard. We asked, St. Onge for salient details of his observations. He said--

  • Both boats had about the same top speed. “Very Close.”
  • IPS was quicker out of the hole.
  • IPS is easier to install, but they have found ways to make the Zeus easier in the future.
  • IPS is slightly less expensive, but “they are close.”
  • Zeus burns more fuel at WOT.

The IPS props face forward which means that the first prop of the two chops through “undisturbed” water which maximizes thrust.


So here we have performance numbers taken on two different days, with boats weighing different amounts. The Alegria 45 was weighed with a crane with the CMD system and tanks full at 32,942 lbs., Luc St. Onge reported. This matched Doral’s CAD projection. The CAD projection of the IPS-powered boat’s weight was calculated to be 31,942 lbs., he said.

When our Capt. Bob Smith tested the Zeus powered boat, it had only been filled with 150 gallons of fuel – considerably less than the 400 gallons carried during the IPS-Zeus shootout. Further, when he tested there were only three people aboard vs. 9 people aboard each of the boats during the shootout. Why so many passengers? Because both Volvo Penta and CMD engineers plus a few other people were aboard both boats so that everyone was sure that there would be no dispute over the numbers obtained.

What all of this means is that the Alegria 45 with Zeus drives that Capt. Bob Smith tested was as light as it is likely to ever be and therefore performing at its best, different props and software “calibrations” notwithstanding.

The Subject is Buoyancy

When Doral designed the Alegria hull in 2003 for the 2004 model year, it was designed with “prop pockets” for conventional inboard diesel propulsion – not for IPS or Zeus systems. Adapting the hull was relatively easy for the IPS drives. However, the Zeus drives require large tunnels which take about 1200-lbs.of buoyancy out of the stern of the boat, or about 4% of the vessel’s total displacement.

Further, the CMD propulsion package weighs 250 to 300-lbs more per engine than the IPS system, according to St. Onge. These two factors cause the 45 to “trim down about 3 inches” at the stern with the Zeus system. St. Onge said that the company was happy with this trim angle and the boat runs well with the Zeus.

St. Onge went on to say that the CMD Zeus drive package takes up more space in the engine room.

This is the pre-pod drive accommodation plan of the Alegria 45. With a pod drive layout a queen bed is placed on the diagonal in the aft stateroom.

What is the value of 47 Sq. Ft. Extra?

Perhaps the most important news is that both of the pod drive systems allow Doral to take 41.5” out of the engine room and move it into the aft guest stateroom, making it into what Capt. Bob Smith says is a “second master stateroom.” The Alegria 45 picks up an awesome 47 sq. ft. of cabin sole space! This is a tremendous amount of space to pick up for living quarters on ANY size boat, much less a 45-footer, and this added room alone assures the success of the pod drive systems.

As far as handling goes, both systems had joy sticks. “The tracking is better with the Zeus,” St. Onge said and “slow speed docking is smoother with the Zeus” because it does not “jerk” when gears change, he said. On the other hand, the Zeus-powered boat is slower to plane and therefore has the bow high longer – cutting down forward visibility -- when getting on plane.

Doral’s speed trials were conducted in increments of about 250 rpms from idle to WOT, and according to R&D manager St. Onge, the data points were not necessarily the same rpm on both boats. So even at the shootout, everything wasn’t exactly lined-up, but nevertheless the speeds of the two boats were “very close,” St. Onge said. Relative fuel consumption at cruise was not reported.

Who Won Round #1?

Changing metaphors to one more appropriate, perhaps the testing in Ottawa was more like a prize fight than a shootout. And just as in a prize fight, different judges will score Round #1 of the IPS vs. Zeus fight differently, and already we have heard from people on the scene who have scored it both ways. Potential buyers should keep in mind a few basic facts: 1) the boat was not initially designed for either system, but seems to perform well with both; 2) Volvo Penta simply has more empirical experience and performance data with over 50 boat companies world-wide now installing the system and CMD has installed their system in just a handful of models.

Our take is that it is still too early to tell which way this competition is going to go, but there is no doubt in anyone’s mind that both systems are better than conventional drives. And, no matter what develops, the consumer is going to be the real winner.

For a full test report on the 45 with Zeus drives… click here.

We’ll keep you posted on Round #2.