General Engine Questions & Opinions

Shopping for boats in the PNW-for 4 to 6 months of live aboard during the "Inside passage Season". Looking at a lot of nice boats with a lot of different engine packages.

Try to research the engines on the internet and here is some 'feelings" and questions I have come up with:

1-will a pair of DDEC 6-92's move a 61' Ocean Alexander at 10 kts burning 6 gph?
2-Are DDEC 6-92's producing 650 hp with 3,000 hrs running on "borrowed time?
3-Are 3176/96 Cats some of the less desirable Caterpillar engines?

1. No.
2. Yes.
3. Sorta.

10 kts on a 61 with 692 probably more like 6gph per engine.

692 at 650 is a way-high rating for that motor, not good for long life unless it was run at hull speed. Also, parts support is iffy, computer control is old generation with support iffy. I'd avoid these unless a super deal. And even then...

3176/96 not a bad engine, but aftercooler issues took many out early. Be very cautious, get it checked out well.

1 mmm no
2 yes
3 realy not sure

2-Are DDEC 6-92's producing 650 hp with 3,000 hrs running on "borrowed time?

If they were actually run at that HP/RPM they would be DEAD by now.

I would think they were run at far lower HP , 200 perhaps (12-14GPH per engine ) and will have another few decades left in them.

Actually, I was off a little-should have been 625 hp and I meant they were rated for that at max output not that they were run at that level for 3,000 hrs.

ktdtx said:

Actually, I was off a little-should have been 625 hp and I meant they were rated for that at max output not that they were run at that level for 3,000 hrs.

Click to expand...

The anaswer is still yes. Your mission to do ALASKA reliably will be elusive on any high hour "new to you" older boat. Not only should you buy the "best" you can but budget conservatively to get the engines totally brought up to date with the appropriate engine specific shop. You will be shocked at the cost to do this right on a 600+ HP engine.

Good luck, there are indeed some very nice older vessels out there. It just takes time to find them. You'll figure it out. Have you looked at Nordlunds? Often these vessels are owned by very savvy owners who care about maintenance.

The only way you'll get a good idea as to how much time they have left is via a complete survey done by someone who knows and works on DD 2 stroke engines. Count on two days and 2 grand for that. Yes, 6gph per engine is about right, maybe slightly low. Parts are not hard to get, the factory still supports these engines, though I am not fond of the DDEC element which gets pricey in and of itself. I ran a pair of non-DDEC 8v92ti's 650hp for a couple thousand hours virtually all at hull speed or below, was religious about maintenance; a thorough survey was done at just about the 3000hr mark and they were judged to have around a couple thousand more hours left.

Twice I've run into problems sourcing the 92 piston/liner kits for the DDEC engines. These are unique to the DDEC's with lower compression ratio, and the aftermarket guys did not make them. Factory lead time was in the months. Not sure if the DDEC computer stuff is still supported at this point.

No problem getting kits for mechanical 92's. I'd have no problem buying a boat with those.

Thanks, I "thought" these engines were living on borrowed time and now more sure about my "thought".

Ken