Revealed at the last London Boat Show (January 2005), the IPS (Inboard Performance System) shows enthusiastic features: higher top speed, faster acceleration, reduced fuel consumption (improved cruising range), better handling, more room onboard…
What is the IPS ?
It is a combined engine and propulsion system, developped by Volvo Penta since 1998. It consists in two forward-facing (similar to a plane!) contra-rotating propellers.
According to the IPS Project Manager Lennart Davidson, the propellers are more efficient due to their operating in clear water. This point seems to be confirmed by the tests. The other benefit is that IPS makes things quieter (-7 dB compared to a classical system) and smoother because the propulsion unit feeds thrust loads directly into the hull, thus reducing vibrations and nasty exhausts fumes.
Volvo Penta says that the IPS offers « car-like manoeuvring ». The whole emmerged system rotates, providing all the advantages of vectored thrust.
Last, more room is available on board, due to the reduced space needed by the IPS.
This seducing system, sold as a package controlled by the EVC (Electronic Vessel Control) platform, also offers an auto pilot.
Which boats are concerned by the IPS ?
IPS has been desgined for twin powered (310 HP D6 Diesel for IPS 400 and 370 HP for IPS 500) units between 35 and 45 feet.
What are the IPS weaknesses ?
IPS could appear to be fragile if colliding the bottom or hitting rocks or floating objects. Actually, propellers are not protected and leg and pod will shear off flush with the hull. The lower bearing carrier has been engineered to break at predetermined points, avoiding water embarking on board, but then losing the bearing carrier, of course.
We asked Tiara Yachts the reasons of their choice and the criteria thatwere considered. Tests (including customer reactions) were ran for over a year on a 3800 Open unit. The result is that IPS seems to be a real step forward. To take advantages of this system, Tiara decided to design a completely new boat taking advantage of the new weight, prop, etc. as well as the improved handling and extra space that the integration of the IPS provides. This boat is the Sovran 4000.
The IPS in a nutshell :
Tests results provided by Volvo Penta are edifying: 20% faster, 15% greater acceleration, 30% lower fuel consumption. Tests were ran out with two Cranchi 41 Méditerranée (LOA : 12.2 m and 9.5 tons displacement), one equiped with the IPS 500 system, the other with TAMD 63P conventional shaftdrive, both powered by two 370 HP engines.
Max speed :
IPS 500 : 37 knots
Conventional shaftdrive: 31 knots
Difference: around 20%
Acceleration : (from 0 to 25 knots)
IPS 500 : 13.3 s
Conventional shaftdrive: 15.3 s
Difference: around 15%
Fuel consumption – Autonomy (at 30 knots cruising speed):
IPS 500 : 95 liters/hour
Conventional shaftdrive: 135 liters/hour
Difference: around 30%
– AlP –