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Bertram31.com General Bulletin Board
Re: Mercruiser Gets it righter?
Posted By: vic Roy In Response To: Re: Mercruiser Gets it righter? (CMP)
Date: Thursday, 16 March 2006, at 8:51 a.m.
Well, I'll stick to stupid and here's why: it's just a baby version of the Z drive used on cruise ships and large tugs. However, the Z drives use very substantial steel housings vs. aluminum on the IPS. An industrial strength system vs. a fairly flimsy one. The advantages are obvious - flat shaft angle, the ability to swivel the prop, but that's about it. The major disadvantage is having aluminum in the water constantly with seals to leak seawater into the gearcase. Fishing line and seals don't mix too good.
I subscribe to Workboat magazine and have for years, and the advantages and disadvantages of the Z drive have been debated there for a long time by the folks that make their livings running boats. At this point most Z drive applications in the commercial marine industry are limited to harbor tugs and cruise ships. The harbor tugs love them for the ability to exert the same bollard pull in any direction. The cruise ships use them for one simple reason only - to save space so they can cram more paying mullets aboard.
The system has its place, but in my view not in high speed power boats. It will be impossible to keep the drive from eating up without constant hauling. The conventional shaft, sturt and rudder system is near foolproof and I see the cost of the IPS and the certain maintaince nightmare as not worth it.
There is a system called the Saildrive that is used on many larger sailing cats that is an outdrive through the bottom that does not swivel, the cat uses its rudders to steer. Its used mostly in low hp applications, such as Yanmar 40 hp. My friend Buddy Stockwell (the guy that quit the law practice and is sailing his cat all over) says they are ok, but require constant maintaince to keep them from just eating up before your eyes.
Perusing the newbuild section of Workboat over the past few years I'd guess in commercial applications conventional drives outnumber Z drives about 100 to 1.
UV
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