What mains do you find best

There is no answer to the question on the best main engine, since there is no best yacht. Depending on size, speed, propulsion and cruising grounds you will come up with different suggestions on engines.

But I made a quick look on existing charter yachts 150-200 feet and the dominating brand is Caterpillar.

Hi,

I have to say I am a Cat Fan, I won't go as far as to say I am one of those people who you would swear has yelow blood but I do like them.

They are like any manufacturer and have had their share of problems in trying different things from time to time.

The worst thing I remember with Cat in recent years was when they really upped the output of the 3306 Genset family. Ths is a now dis continued engine series much to the relief of many end users and dealers.

I have workedas an Engineer on boats with, each Main and gen pair is a different boat
Detroit D 353 ( Good piece of kit)
D 353 Mains and D 330 Gensets ( Older units all quite tired reliable though)
Duetz Mains and 3304 Gensets (Gens OK, Mains had bad rebuild kept us busy)
MTU 16V396TB94 Mains and Perkins Gensets ( not enough room to list all things that went on with these)
3512A Mains, 3306 and a 3304 Genset ( All very good, Gensets over 15k Hrs 1lt Lube Oil used in 250 Hrs)
3512A Mains 3306 Gensets ( Hi Output 3306's and nothing but trouble)
3512B Mains and 3306 Gensets ( Hi Output 3306's Hi Lube consumption sometimes 4 litres a day)
D399 Mains and 330 Gensets ( These were all pre combustions engines and the mains were just amazing pieces of kit, a previous Chief had named them after his ex wives)
3516Series2S Mains and C18 and 3056 Gensets ( All brand new)

The good old Detriot Diesel Two Stroke is unfortunately fast becoming a thing of the past, I worked on a lot of 53 and 71 series when doing my aprenticeship nearly 30 yrs ago and still love to hear an 8V53 or a 6- 71 getting a workout, especially in a non marine appliocation where it's just all gas and noise out the pipe with no water distortion.

In the past with quite a few different experiences, I have worked with the same engines but in two different boats. One boat with the same engine, I could find it to be some what problematic and tempermental. Then on another boat, the same engine can run like a fine tuned sewing machine with out a care. All boat have there personalities. I have often wondered if it is then there fore more of the installations by the builder that will make engines seem better or run better than others in different situations. Or then if maybe it's the effect of you recieving one engine that was built on a friday afternoon verse the same engine built right after the just gave pay raises to all the factory workers.

C4eng has a point. I was a diesel mechanic on trucks in my previous life, and even though we had the exact same engines in different tractors, some would just be different than other. Maybe more smoke that, if you changed air filters and leaned out fuel pumps all day, would never go away. Others would just purr, never hickup, and run forever.
I'm a Cat fan also. Real workhorses and if kept after will run forever. Also ran a yacht with 6-92's Detroits that ran well, just dirty engines. Others wouldn't go near them with a 10-foot pole. Recently the 61' sunseeker I ran had 10-cyl MAN's mechanical injection. At speed they were great, but at idle they were rough, due to half the cylinders shutting down at idle (they're built to do that). But other Sunseekers I was on didn't feel as bad. Yes, engines can be fickle, and they do need TLC. One aspect I always look at is not just the engines but available space around them. My thought is that if space is tight, then perhaps, and just perhaps, not all work done on them was done correctly, which could lead to problems later, maybe when you're on the boat. Just my $.02.
Capt Tom

Caterpillar used to finance the building of yachts which used their engines via Caterpillar Finance. I am not sure if they still do.

I have seen one where the engine overspeeded while the technician was servicing it and pieces of the gears made holes in the ceiling. The technician was injured not by a projectile but one hit a stool which spun and hit his leg.

Mercedes/MTU did the same, but I am not updated on how they do today.

Hi,

It looks like Cat Finance is still doing boat deals.

http://finance.cat.com/cda/layout?m=94307&x=7

I worked on a project once where Cat were going to finance the whole thing, their terms were a bit onerous for the client who went elsewhere for his finance.

I concur with C4ENG and CaptTom and nod my head reading K1W1's numerous examples.
A blanket statement is really in order here, to wit: Virtually every marine engine manufacturer has had a problem with at least one of it's products. What is truly amazing to me, however, is how these "opportunities" were resolved.

Roger Penske had just bought Detroit Diesel in 1987 and the first 8V-92s delivered had a severe mismatch in their air intake plumbing. We're talking 25 pairs of engines for one boatbuilder--some on the assembly line, some in the water-- and Roger ordered a fast fix, on his nickle entirely .

Those Cats mentioned by Dave? Heck, you'd have thought that they forgot how to build engines there for a minute. The new inline-sixes-- the sixteens mentioned, the 26-series, the 56-series, the 76-series, and the 96-series all had early production problems and, to the best of my knowledge, were addressed .

Way back in the early '80s, BMW came out with a marinized inline six which was soon withdrawn due to overheating problems ( in South Florida, anyway) .

When the late '80s 10-cylinder MAN debuted, it too, had it's woes. I recall airplanes carrying banners at the local boat shows saying bad things about MANs. Lawyers got involved. MAN ended up replacing an awful lot of pistons and helped yacht brokers polish their sales skills by needing to explain in great detail why this or that boat was not a risky bet .
On the plus side, they all learned that you could put a ton of hours on a 10 MAN engine .

Cummins used to own the truck engine ( from whence marine diesels come) business until they got careless. Then, with the new early '90s 6BT line, they were golden again... but for small boats .

MTU: great horsepower-to-weight ratio and a must-have if you wanted a fast 70-100-footer. Very expensive to maintain ( you got to be gut friends mit Dieter, ya!), however... not yer father's 6-71 .

Hi,

Up till now, my favorite is WARTSILA NSD., R32, V32, R46, L64...

I worked, repaired, overhauled, rebuilt engines from 15 kW - 12500 kW.

MTU is nice, but expensive. Reliable.
Not a fan of CATs.
CUMMINS is impressively simple. Only fuel adjusting of timing is a little bit tricky..
VOLVO PENTA is good, only too sensitive.
DEUTZ is ok.
MITSUBISHI is really, really nice. Reliable, simple.
MaK, depends on, what type to talk about. In general - very reliable.
HANSHIN is almost sensless to mistakes, made by service guys (it even works with broken rocker-arms....).
WICHMANN (old two-stroke norwegian) is one of a kind...

Actually, so compliceted. Different models of the same brand can be very different.

The best thing is, that engine is used at appx. 80-85 %.

Talk to it, listen to it, feel it, love it...

rgds,

Andrei

A wise man indeed!

Well, blow me down. Who knew that the old Jimmies had a Norwegian cousin?

I have worked on 1 or 2 engines. Must admit I do like MTU's and Cats both pretty easy to work on with just a hand full of tools. My next favorite is a big old 5 cylinder Ruston that was in a tug I worked on years ago built in 1932. Didn't enjoy the Deutz, couldn't do anything without getting covered in oil. Detroit's well you know the old saying " When they stop leaking oil you have a real problem ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,Your've run out !!!!!