Since Volvo Penta introduced IPS several years ago BoatTEST.com has tested over 50 boats powered by the system. It has been a game-changer and has opened up serious boating to a far wider audience than would have ever considered larger boats before. Here’s the latest news about IPS and its features.
With their forward facing twin props, the IPS drives have changed a lot of things for the boating industry, from building to operating. The latest wrinkle is its new “add-on” options.
Captain's Report by Capt. Steve
I've been convinced of the benefits of IPS since its launch, and mostly from a performance and economy standpoint. I don't really have a lot of trouble at the dock, but even I have to admit that my hand is firmly on the joystick when docking, as opposed to just doing it by hand. You may not need it, but it's great to have and use anyway.
First of all, IPS stands for Integrated Propulsion System. It's both an engine and pod system, and IPS pod drives come in various sizes to accommodate different sized boats. As a rule, they're always in pairs, but I've tested one boat with a single pod, so change may be in the air.
Volvo Penta is not the only company producing pods, but they did it first. The pods are usually connected right to the engines, allowing builders to move the engines aft. Often the entire engine room can be moved aft creating more living space forward. That’s why builders and buyers love them. A boat that was destined to have only two staterooms with conventional power now can have three in the same size hull. In the case of some express cruisers and fishboats, where moving the engine aft is not an option, the pods are connected to the engines with jackshafts.
This is the model range of the IPS drives. Notice how the IPS designator is always higher than the horsepower. The reason for the difference is that the efficiencies created by the IPS system gives the propulsion package about the same performance characteristics as an inboard engine with the higher horsepower.
Why Are Pods More Efficient?
If you look at an inboard installation from the side, you can see that due to the straight drive shaft to the propeller the engine needs to be mounted at an angle. That angle carries through the bottom of the hull to the propeller. Because that propeller is pointing downward, as you can imagine, there's a significant amount of wasted energy when moving the boat forward. Some of the thrust tries ineffectually to lift the stern of the boat up.
Because of the angle between the engine above the waterline, and the propeller below, the inboard has to be mounted at an angle, so the propeller is aimed downward.
IPS drives eliminate that problem by directing their thrust horizontally, so there is much less wasted energy. In addition, these propellers are facing forward, pulling the boat, so thet turn in turbulent-free water flow. Conventional inboard props operate in water that has been disturbed by the struts and shafts. Further, the IPS drives have two counter-rotating props on each pad, with greater blade surface area than a single prop of the same diameter. The result of these three basic design elements is significantly better performance.
That is mainly why there is a difference between the model designator and the horsepower engine it utilizes. The IPS600 for example, uses a 435-hp engine. But Volvo Penta would argue that the IPS600 does the same amount of work as a 600-hp engine and a conventional propshaft, and at the same time is far more fuel efficient.
Here you can see how the IPS propellers are directing their thrust horizontally, so they're much more efficient.
How Does All This Affect Maneuverability?
Since you have pods that can rotate instead of fixed shafts, it's a simple (well, relatively anyway) matter of adding programming software to a black box that directs how the pods will react to movements of the helm or a joystick. In the case of the joystick movements, the pods are able to move independently, which means that with a slight push of a joystick, you can easily make the boat go sideways. Now anyone can dock the boat regardless of experience. Again, builders and buyers love it. The size boat you can handle is now limited to your checkbook, and not your experience (or lack of).
The amount that the pods themselves swing is electronically programmed to be relative to the speed of the boat. At low speed, the drives rotate further out, but at cruise speeds, they stay closer to center. In this way, you won't take an abrupt 180 at cruise and toss your passengers about the cabin, or over the side. When you're at no-wake speed, you need that responsiveness, and therefore the throw is increased. And when docking you get the most, and of course even independent, swing range.
Add-On Options: Sportfish Mode
Not being content with simply driving the boat in reverse to chase down a fish, Volvo Penta added a cool feature to the mix. With the press of a "Sportfish Mode" button, the drives will cant themselves outward which improves the steering dramatically when backing down.
Reverse speed didn't seem to be improved: Either with or without Sportfish Mode engaged I was getting a max of roughly 7-mph over the bottom, but steering responsiveness was improved. I had much more control over steering the stern, and certainly much better over inboards.
Dynamic Positioning System
Volvo Penta's DPS uses a dual GPS antenna on the hardtop, coupled with a digital compass. Activate the joystick with the "Docking" button, and then depress the button with the little "target" symbol on it and the DPS is engaged. Your boat will then hold her position, and heading, without you having to do anything.
I tried it while offshore and found it to work great against a light wind and tide, but I needed to show it on camera so I headed to a day-marker to try again. Now with a much closer visual reference I engaged the system again and found the same results. It nailed the location every time. But realistically, when would you use something like this? Well, I can think of several occasions, starting with holding position waiting for a bridge, when waiting for a fuel dock to open, a lock to drain, or bridge to open. Fishermen will love it when they are working an underwater wreck or sea mount. When in a fleet of boats watching an event, instead of anchoring you might be able to use the DPS.
When not to use it is when people are in the water. The pods and props are still turning so use caution. Don't use it to hold yourself over a wreck for divers. And I wouldn't use it at the dock as a method of tying up the boat single-handed. I found it to have about a 2' (.6m) margin of error when testing it in a slip. Most of the time it was even more accurate, so it's a very useful tool in many applications.
When you use the joystick for docking, there are two modes, regular and high. The regular mode is accessed simply by pressing the "Docking" button. Now whatever direction you move the joystick, that's the direction the boat will move, and in case it hasn't been said to death… even sideways.
You may, however, find yourself docking against a high wind or fast current or both. In that case, press the "High Mode" button and you'll have more thrust to counter. In my experience, this "High Mode" is most useful for fighting your way up to the dock in adverse conditions. To lie against a dock, I'll always switch back to "Docking" mode as it gives a much gentler response.
The IPS joystick has three buttons. The top is for Dynamic Position System, the lower left activates the joystick for docking, and the lower right adds more power.
When you actually move into a slip, do not treat the joystick as if you were playing a video game. Use small pulses, let the boat respond, and then pulse additional corrections. I like to start the boat moving, and then steer that momentum with my pulses. Remember, you can rotate the joystick to rotate the boat.
Thankfully, IPS is here to stay. It's given a shot of adrenaline to an industry that was craving the next big thing. Now that it's here, more and more are taking advantage and rightfully so. From my experience, it's a pleasure to work with, and it makes every boat just that much cooler. Not only does that reflect the pride of ownership on your boat, but being able to get a larger boat than you thought you could handle is not without its benefits.
Finally, while it may still be a bit too soon to know for sure, I’ve got to believe on the used boat market, an IPS-powered boat will sell for much more money, and sell far faster, than the same type boat with conventional drives.