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Old 07-18-2014, 12:23 PM   #1
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Old Engine for New Trawler

As I am in planning stages for building myself a steel trawler I now need to consider the main engine. Based on my past experience I keep coming back to the idea of picking up an old GM 6-71 block and rebuilding it, which I've done before. The only thing I hated about them was the noise. Oil drip was manageable. Self contained fuel injectors are far superior to the racks and pumps required on 4 strokes (my opinion).

I was amazed at how reliable my old WW2 engines were. Real old school.

As a personal craft to be documented in the US, I'm unaware of any requirements for environmental or pollution emissions limits.

Any thoughts on the merits of such?
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Old 07-18-2014, 12:37 PM   #2
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If you put a good truck or excavator type air filter assembly on the intake, that gets rid of most of the noise. That blower is extremely loud, and that box type silencer is a joke. Don't use too much hose to couple as the hose transmits the blower noise, pipe not so much.

Exhaust, if using dry stack use a VERY GOOD muffler. If wet exhaust, use a VERY GOOD muffler (like a water lift).

Most of the noise comes from the air intake and the exhaust. Handle those, and it can be made (sorta) polite.

Noise from the block is not really high til you get up there in rpm (1600 or so, up). Down at trawler speed, they just purr.

Another option is the Cummins 855. Also old skool, but much easier to make quiet. Also unit injected (P/T), but not as simple as the DD. Cat 3406 in same category. These are a bit bigger physically than the 671.

I think technically a new build needs to meet certain epa regs, but I know of several one off builds with old engines that got documented with no issue. I don't think this ranks high on the EPA or CG radar.
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Old 07-18-2014, 12:37 PM   #3
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When building a custom boat always consider the day you want to sell. You are comfortable with 1939 technology, will the next buyer be? How much will you save as a total percentage of your cost to build?
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Old 07-18-2014, 12:54 PM   #4
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I'll second what yachtbroker guy said. And to top that off with an illegal engine.....

But you will have a very unconventional boat with a self built steel trawler. Maybe it doesn't matter. Anyone interested in your boat when you ultimately try to sell it probably isn't interested in a Nordhavn, etc.

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Old 07-18-2014, 01:00 PM   #5
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I don't like broker links on the forum but broker guy has a very very good point. It could be easy to say it dosn't matter much now but down the road it very likely will carry much more weight.

But the advantages of the old DD diesels could be even greater in the future. Can't make a case for it but power choice can be a completely objective or an act predicated mostly on likes and warm fuzzy feelings. Lots of people have warm fuzzy feelings for the DD and the shortcomings are .. well short. They burn more fuel but not much and noise can be isolated and insulated into near nonexistence.

To expose oneself completely one could build a new wood boat w DD power. That's what I'd probably do if I had the money. And the OP is only talking about spending his money and/or loosing same in the future. But the future is a long way off and the songs of Detroit Diesel power is near now. I agree w the OP that it is worth considering. And DD parts in his part of the world may be easier to come by than the latest stuff.
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Old 07-18-2014, 01:01 PM   #6
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Dave- You wet blanket!!!

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Old 07-18-2014, 01:05 PM   #7
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Agree with resale but as it is going to be a niche market looking at this boat on the secondary market(basically guys like me to be honest) why not put a Gardener in her? Old school and more universally popular than the DD in my opinion.

What size boat MB?
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Old 07-18-2014, 01:08 PM   #8
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Love that Gardner. But parts will be available for the 71, Cummins and Cat for the next 100yrs. Gardner parts may be difficult in the future.
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Old 07-18-2014, 01:39 PM   #9
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Quote:
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Agree with resale but as it is going to be a niche market looking at this boat on the secondary market(basically guys like me to be honest) why not put a Gardener in her? Old school and more universally popular than the DD in my opinion.

What size boat MB?
RESALE
Broker makes a good point, but I have no hope for any sorta resale value on a homebuilt, simple-outfitted, steel motor vessel. That relieves a lot of pressure!

GARDNERS
When I was living in New Zealand I often saw old Gardner engines advertised in TradeMe and in the papers. They weren't marinized but that wasn't much of an issue, so it was extremely tempting to pick one up and just hold onto it for the future project.

However, since I'll eventually be returning to the US it would not be a practical engine, unlike a DD, Cat or Cummings, which parts can be found anywhere in the western hemisphere. Actually here in the Middle East, engine availability is based on what's used in the heavy equipment in the construction industry. Lots of Cats and Hyundai and Isuzu blocks. Mercedes trucks. Also, tons of Ashok Leylands, a fantastic Indian motor. About double the displacement per hp of the American brands.

SIZE
Boat size is tending towards 45ft at about 25 long tons displacement. Actually a 4-71 would be better sized, but that's besides the point.
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Old 07-18-2014, 01:54 PM   #10
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Love my 6-71's. Many of my marina mates have all sorts of the new diesels from various manufacturers and my buddy who is a diesel mechanic loves all the work he gets from these owners. Parts are cheap and available and simple hand tools are all I need. If I ever get another boat, Detroits or Lehmans for me. Simplicity at its best.
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Old 07-18-2014, 02:00 PM   #11
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RESALE
Broker makes a good point, but I have no hope for any sorta resale value on a homebuilt, simple-outfitted, steel motor vessel. That relieves a lot of pressure!
There is that, you and I are pretty simpatico in that regard. I can care less about it too however many folks it's atop their list. Install the DD in that case and enjoy your boat.

I also seldom think about parts availability if starting fresh. Build and maintain it proper, don't drive it like it's a rental and it'll outlive any of us. "Crap" happens but seldom unless Murphy shows up. Case in point, I'm looking at re-powering my 50 year old boat with a modern tier 3 diesel and the top choice so far is a Volvo. If I started a thread asking if that was a good idea I'd get 3 pages regarding lack of available parts. True but the parts don't start getting scarce until 25-40 years out, I'll be dead by then and the new owner can power his 100 year old boat any way he wants.
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Old 07-18-2014, 02:08 PM   #12
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Maybe someone oughta' start a thread about the merits of "old school." When I bought my boat it was 35+ years old, had 50+ year old engines in her with aluminum blocks (pulled from a WW2 minesweeper) and had sailed from the Great Lakes to Hawaii, South Pacific, Australia, back and all over the western hemisphere again. All with systems not much more complicated than Robert Beebe's. No a/c, hydraulic stabilizers, etc. If it ain't onboard then it can't break!
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Old 07-18-2014, 02:56 PM   #13
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Electronic engines are great for the environment and are great in cars where, when they quit, you pull to the side of the road and you call the tow truck guy. In a boat, not so much. I remember a time in Campbell River where I watched a mechanic tune a pair of Yamaha 250 outboards. He used a computer and a screwdriver. In other words, despite the modern technology, there are no "user serviceable" aspects of that engine, except to flush and change oil. The old clam crushers that smoke (a bit 8^)) and have no electrics beyond the solenoid shut-off are all user friendly and can be field repaired by the average owner. The DD engines are very loud. There is a guy here with a 48 Tolly with a pair of 6-71s and you can hear him coming for miles. As others have mentioned, you will need to spend some time on that issue.

Resale: who buys a boat thinking of resale? A boat is a sunk cost and anything you can recover from it when you are done with it is gravy. You will never get anything back that you spend on it, why expect more?

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Old 07-18-2014, 03:12 PM   #14
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Other than the exhuast my engines are relatively quiet in the saloon and they get quieter at about 1800 rpms, besides who sits inside while boating? Excluding people with pilothouses of course. My last 2 boats have had lower helms that sat unused, always from the bidge.
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Old 07-18-2014, 06:37 PM   #15
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Do not Dick around, put a reman 5.9 Cummins in it. You will not be sorry.
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Old 07-18-2014, 09:16 PM   #16
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Do not Dick around, put a reman 5.9 Cummins in it. You will not be sorry.
If it were me, in america I'd go that route Naturally aperated, simple engines.
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Old 07-18-2014, 09:29 PM   #17
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Cummins 5.9 is a great engine, but if the OP wants 71 power, go for it. A properly built 71 will be an awesome engine. Talk about smooooth.. six fires per rev compared to three per rev for the four stroke. At low rpm it is noticed. Noise can be minimized by careful engineering, not easy.
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Old 07-18-2014, 09:50 PM   #18
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No disagreement at all Ski but would love to hear a quiet DD. Wife hasn't a clue what the difference between a Diesel engine and a gasser but she does know she'd "never own a boat that sounds like that", her exact words.
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Old 07-18-2014, 11:00 PM   #19
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Not to throw a monkey wrench in your thinking here, but if you'd consider a 471, why not a Kabota (Nanni)? There should be plenty of compressors, gens, and industrial pumps, tractors & machinery there with Kabota power. Simplicity, reliability and good world parts network. Same ole engines available now that the had 25 years ago.
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Old 08-10-2015, 02:11 PM   #20
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Hello again. I'm restarting this thread now a year later.

Have decided against a home build (I have a great job with little free time) and am fine-tuning specs and negotiations with a foreign builder for my steel trawler, single diesel. It will be USA documented so a Tier 3 engine is required, which means electronic controls and computer chips.

Although the engine will be new, I am not entirely comfortable with this reliance on electronics, especially cruising in parts of the world where TowBoatUSA doesn't exactly serve (sarcasm here). The first time I'm stranded in some atoll in the Pacific because a computer chip fries will most likely be when I cut a hole in the deck, yank out the high-tech engine and replace it with my favorite Gray Marine 6-71NA. So this nightmare playing through my head brings up some questions:

1) Am I being overly concerned about the reliability of today's modern high-techies?
2) Having reviewed all the forms needed for documenting a foreign built boat, where is the one where the engine needs to be described and certified, as I can't find any reference to this? What's to stop a guy from cheating?
3) What about installing a little 10hp Tier 3 engine, documenting the boat, then yanking it out (or keep for a future genset) and replace with a "man's" engine?

…. I have a feeling I'm about to be yelled at by you guys… oh well...
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