About IPS system

[JLL]

Hi everyone,
I´m dealing with the installation of IPS system in a new 37' powerboat. The hull bottom, structure and weights were modified to match the Volvo requirements for the system.
When sailing beam reach (wind perpendicular to heading), the skipper must correct the heading continuously, and when doing so, the IPS boat suffer a list angle of about 5º (too much for a powerboat!).
Other bigger boats (about 43') with IPS sails very fine and don´t make the above.
Our trim angle at 0 Kn is 0º, at 20 Kn -6,3º and at 32kn-3,5º in shaft drive as well in IPS boat.The problem I have is not the trim angle but the list angle that occurs when we want to correct the heading running beam reach that doesn´t occurs with shaft drive.

Any idea to help?
Jaime

[gonzo]

Is it a powerboat or a sailboat? You say beam reach, which indicates sail power.

[JLL]

I´m sorry for the term used. Is a powerboat of 37' with 2x 310 HP, and I wanted to say: running with the wind perpendicular to heading.

I enclosed a sketch with both of the new engine room fitted with IPS and the old one shaft drive engine room (more about this system in www.volvo.com/VolvoPenta/Global/en-gb ).

Jaime

[gonzo]

I believe the problem may be the hull design. Because of its large lateral area, IPS acts like a rudder/keel. It is probably creating enough lateral resistance to make the boat list or heel over. The boat may not have sufficient beam. Maybe it is possible to correct the problem with stabilizers of some kind. They could be a water system or moveable fins.

[Deering]

Jaime,

A few questions:

1. Would a similar amount of course correction be required under the same circumstances with a shaft drive?

2. Do the larger boats have a similar hull design?

3. Twin engines or single?

I'm thinking there might be someting you can do to minimize the necessary course correction in the first place - something to improve tracking (keel extension or fins perhaps?).

I've looked at the IPS but haven't seen any boats with it. Aside from this problem you're having, what is your impression of the system? In particular I'm interested in the large seal around the rotating hull penetration.

[JLL]

Hi, everyone
I had been travelling last week and I couldn´t see the web page


Maybe it is possible to correct the problem with stabilizers of some kind. They could be a water system or moveable fins
Maybe, but it will be very expensive for a 37' boat.


1.Would a similar amount of course correction be required under the same circumstances with a shaft drive?.
NO, with shaft drives a course correction isn´t needed.

2. Do the larger boats have a similar hull design? ?
Well , the larger boat (a 43') as well the 37´have similar hull design (i.e little keel in high and similar keel extension related to WL, but different beams 13'9'' vs. 12'10", different maximum loaded displacements 13,7 T. vs. 11,2 T., different waterline lengths 34'6" vs 31'2") BUT both boats suffered a hull transformation: IPS requires a V of 17º

3. Twin engines or single?
IPS system is only for twin engines boats

I'm thinking there might be someting you can do to minimize the necessary course correction in the first place - something to improve tracking (keel extension or fins perhaps?).
Keel extension is not allowed by IPS developers: the system needs clear water in front of IPS. Fins are a possibility not yet tested: one aft at each chine

I've looked at the IPS but haven't seen any boats with it. Aside from this problem you're having, what is your impression of the system? In particular I'm interested in the large seal around the rotating hull penetration.
Up to my notice, other boats with that systems are some model of TIARA, FAIRLINE, BENETEAU,...You could find more in www.volvo.com/VolvoPenta/Global/en-gb.

The system has advantages for both shipyards and customers .To the first one, more simplicity and lower man hours, to the customers: more quiet running, lower vibrations, more speed, more aceleration, more manoeuvrability,fuel savings,..
Nevertheless I need the point of view of fishermens too

[Gilbert]

I didn't notice that anyone asked which way the boat listed under the beam wind condition. My intutition would say it perhaps might list away from the wind or that is to say to the leeward side. Is this correct?
If so, could it be corrected by keeping the units pointed straight ahead and increasing the speed of the leeward engine slightly as opposed to having the units turned into the wind as I am assuming they are doing?
I may be showing my ignorance here as I am unfamiliar with these units and how they are controlled.

[FAST FRED]

"The system has advantages for both shipyards and customers .To the first one, more simplicity and lower man hours, to the customers: more quiet running, lower vibrations, more speed, more aceleration, more manoeuvrability,fuel savings,.."

And with ZERO prop protection far more damage and $$$ repair bucks for the repair yards . The "Builders Choice $$$$$$$" Cheap to install and EXPENSIVE to maintain!

FAST FRED