Advantages- Handling

Great news for devotees of outdrive legs, the handling of the IPS will delight you. And excellent news for shaft drive junkies, the handling of the IPS will charm you too. Low speed manoeuvrability is excellent. In practice, IPS provides all the
"outdrive" advantages of vectored thrust so you can push or pull the stern around and turn extremely tightly using just one engine, or both if you need more haste. But unlike most outdrive setups, IPS also works okay when you leave the wheel centred and use ahead and astern commands as you do with shaft drives. The response is slower but still distinctly shaft-like.

The drive units also have plenty of keel area so they provide remarkably good directional stability. Pottering out of the marina on just one engine required only the slightest deflection of the wheel, and like shafts and rudders, side winds have less effect than on outdrive leg boats. The great thing is that you can pick and choose depending on what you are trying to achieve. Centre the IPS and turn in your own length. Or vector the IPS, tap the bowthruster, and see yourself pulling smartly sideways and backwards or fowards out of a tricky cross tide marina berth. Master the IPS fully and you will be giving those implausibly manoeuvrable twin jet-drive boats a run for their money.At high speed, the good directional stability remains. Rudders work well at medium to high speed but IPS permits a tighter turning radius and better speed through the turns because, like outdrive legs, there is nothing blocking the prop wash.

Advantages- Efficiency

Significantly increased propulsive efficiency is one of the key benefits of IPS, but that increase has been made possible only by a fundamental rethink of propulsion principles. About the only thing IPS has in common with conventional shaftdrive is that it uses fully submerged propellers rather than jets or surface-piercing propellers.
IPS uses two forward-facing contra-rotating propellers per unit. The superior efficiency of twin contra-rotating propellers over a single larger diameter one was appreciated many years ago, and Volvo's Duoprop outdrive is the established manifestation of that theory. Because they operate in clear water, propellers work better in tractor (pulling) form than in pusher mode but shaftdrive installation naturally ensured that the pusher principle has remained dominant in the marine world.

Introduction To The New IPS System

Volvo Penta rewritten the rules with regard motorboat propulsion systems. In a stroke they may have consigned stern-drives and shaft drives to history, and in the process revolutionised the way motorboats are designed and built. Inboard Performance System, or IPS, is an innocuous title for the most important development in propulsion since the invention of the outdrive, and something that may render the conventional shaftdrive obsolete.
IPS is a combined engine and propulsion system, sold as a package in the same way that an outdrive can be. You can't buy the propulsion unit on its own, and currently IPS is only approved for twin installation. There are two models, both employing the same propulsion/transmissi on unit. Combining this unit with the 310hp D6-310 gives the IPS-400, attach the 370hp D6-370 and you have the IPS-500. The engines are the same as used in sterndrive and conventional shaftdrive applications.