The perfect Passagemaker III, propulsion

Read this. It is redundant and Bureaucratspeak but basically says no matter what precautions one takes, incompetence will prevail: http://www.pwsrcac.org/docs/d0028900.pdf
"The Inadequate Implementation of Planned Maintenance Program and Failure to ensure planned maintenance program were followed" are reasons that the Selendang Ayu failed (that, and the fact that so much time was wasted calling for help, saving money by hiring too small a tug, CG errors, tug errors, waiting too long to evacuate, the list is long...come on - calling by VHF ninety miles? One might get 36. Waiting a day before using the phone? Sounds like they were trying to avoid fines associated with a host of safety violations. Not one of the faults was "not having enough engines")
You spent a little time on a cruise boat and had failures every year. You stated "...lost both Zs due to a hydraulic failure." "...ate a mooring line and lost the sacrificial gear in it's transmission." This is FAR more likely to happen with twins - sorry. It is my contention, and the same with a majority of professionals worldwide, that two engines are more likely to cause failure than one (More complicated systems, for example, were a factor in the hydraulic failure you mentioned. There is no doubt. Only those that do not know insist on redundancy in propulsion. Fire systems are already required.
One last thing. Are the engines you propose truly redundant? That means that the vessel could perform related manuevers on one if the other were to fail. Otherwise, a twin engine boat, but of the size of the Selendang Ayu wud not have been able to turn the bow into the weather anyway and if the damned engine wudn't run because of insufficient compression (one cylinder happening to fail was just a symptom of a poorly maintained engine and not the cause of the accident), then two wud simply have twice as many cylinders with insufficient compression.
All of this being said, you are not going to change the mind of a professional mariner by citing an example where third-world maintenance was the first link in a tragedy. Not only THAT, the matter is settled. Richard is not building a sportfishing battlewagon or such and this thread is not the place for that discussion (I think that was already covered - it might take five minutes). Double hulls, quad engines, dual everything, are the realm of the ignoramus and the politician (and to be generous, the naive) and are no substitute for doing one's job.

 

I'm convinced.

 

You should have read the thread/s before you contributed. (contradicted)***

When your engine failures were so regular, you either worked for a stingy company buying cheap crap, or your engineers were far away from being highly skilled pro´s. (I assume the latter, having met some Navy "pro´s". Most are from the "Parts Replacement Division")

As Mark mentioned, the chance to catch a rope are far better with a twin set, than with a single engine, and almost always you have your catch in both props.
But it is moot to discuss twin or single engines for these vessel here. The votes and my decision are clear (and according to our professional experience), single!

The graphs will not tell you anything, because when the engine is derated, they change dramatically. And of course you loose torque, as you loose power. But when done right, you have most likely much higher torque with a derated engine, than with a smaller displacement of the same power.

Good question Mark.

The answer is simple. Yes the Grenaa is happy with car Diesel or any other medium destillate, as long as it is below 5,5 centistoke (without preheating). Being a European design of the late 60ies (relatively modern) it was already thought for low sulfur fuel.
The other engines in question have been never designed for MDO bunkers, so nothing changes.
The Grenaa will have a bit less power with ordinary car Diesel than with MGO/MDO though, due to the lower energy content. But I doubt one will notice any difference with these monsters.

Regards
Richard
***
http://www.boatdesign.net/forums/boat-design/perfect-passagemaker-style-within-genre-34092.html
http://www.boatdesign.net/forums/boat-design/perfect-passagemaker-ii-building-material-34265.html
http://www.boatdesign.net/forums/boat-design/perfect-passagemaker-iv-equipment-34464.html

 

It's like you said above, an unused Westerbeke 71C.. Bought it from a local distributor with a bargain price a couple of years ago (they were not anymore passing the new "green" regs). Anyway the (Westerbeke) has used the same blog both in gensets and in their 50 and 60hp models. Isuzu made engine and originally designed by the-best-known-english-diesel-manufacture-which-I-just-dont-recall-right-now And this lowsy mobile broadband isn't working properly... so I'm sitting frustrated in Vadsø right now
Anyway.. just had a thought if Jeff should move this side track of modifying smaller engines to a new thread..
BR Teddy

 

Teddy,

a Westerbeke was thought to be operated at 1500 or even 1200 rpm in gensets. So, no prob to derate that fossile!
The "green" question is another animal though.

 

I take that "fossile" as a compliment The "green" doesn't concern me, as a self builder I'm not under any legislation (boat directive,environment etc) anyway so long as everything "hazardous" (me included) stays onboard and I'm not selling it..

 

What else.

If I don´t like them, who does? The choosen Grenaa is the best proof.