heavy displacement repower dilemma

[Salmoneyes]

[QUOTE=FlightPlan;2794321]I am surprised Cummins did not suggest their Re-man program for the 6BTA5.9 210. (/QUOTE)

Once I mentioned that the project was a boat, Cummins refused to talk to me about anything but a Marine motor. They would not entertain anything but their complete motor package.

(QUOTE) Enormous fines accumulate on a daily basis and even jail time is a penalty if they sell to a US documented boat. I did discover that because I was re-powering that maybe I could get a waiver after jumping every hurdle the EPA could throw at me. Since I like to use my boat, and my Perkins 6.34 was unusable, I moved on to the Cummins. (/QUOTE)


Amazing how we have time to punish folks who do not follow EPA regulations on re-power when we can not address "real" crime... (we do not want to get into a political debate here)

[FlightPlan]

I wasn't trying to go there. But you made my point. The engine guys spook.
This link comes from their webpage: https://www.cummins.com/engines/recon-marine
This is a marine engine.



You can get the 6BTA 5.9M 210 Intermittent duty engine. They call it a recon, not re-man. In any case, I had to buy mine from a warranty service dealer in St. Petersburg, Fl. You won't get there through their webpage. Try a warranty dealer for Cummins in your area.

[CSY Man]

. In Yanmar’s owner’s manual for their turbo-equipped yacht engines, it states that prior to shutdown, the engine(s) should be revved to Wide Open Throttle and back to low idle five times (in neutral, of course). Their intention is to clean out any carbon that might have formed on the turbo.

Wow, never seen that in my Yanmar 6LP-STE Engine Manual.
Didn’t read every word, but will look again)
(300 HP 4.2 liter, Turbo diesel, 1.5” shaft, 19X18 four blade wheel)

[MarAzul]

Originally Posted by Salmoneyes

I am in the process of "rebuilding a new boat" for long term cruising and long passages. One of the many hurdles is choosing the best option for repower.

Originally this 40 footer steel Pilot House tipped the scales at 42,000 pounds (loaded) and had a 130hp Mercedes OM352 with 2:1 and 23 inch screw. She burned roughly 7gph.

Hull is rated to 85hp (12m and 27000 lbs dry weight)

Here are my concerns

1. WEIGHT. the whole boat is undergoing major refit and mods to get her weight down closer to 30000 lbs. The Mercedes and box runs 1500 pounds. All the running gear is heavy to handle that kind of power.



2. HEIGHT of motor. The Mercedes is 32 inch tall. A lower motor will allow lowering floor in pilot house, allowing to lower pilot house roof, which makes windows smaller all adding benefits to the overall project requirements.

3. FUEL CONSUMPTION. Being it is a motor sailer, it will motor often and lower consumption means less fuel, less weight etc. I heard an argument made that more power allows you to use a smaller percentage of the motors capacity therefore using less fuel. I think using 80 hp of a 200 hp engine will use the same fuel as a 80 hp motor..

4.SIMPLICITY. This is the one that is really causing loss of sleep. I can McGiver a naturally aspirated diesel together in an emergency. The new common rail turbos could solve all these other concerns, but at the cost of simplicity. If the motor quit, I could be in trouble.

I would love to hear what folks who cruise long term with a heavy boat think about engine choice. Fuel concerns, weight concern, available parts around the globe, ability to service and repair, etc. etc.

That is a lot of fuel to burn!
My current Ketch is not really "heavy" at 60' and 30000# but I burn no where near that amount of fuel. She cruises on about .8 gal/hour.

The engine is a Cat 3034 (Perkins 704-30) direct injection, 63 hp.

It think the big difference is in using 3-1 reduction over the 2-1. which allows use of a much more efficient prop, 25 x 19" three blade folder.

Top end is 11.3 knots which I never do but for the test. In a 40' boat, noway you do this, and there is no way to power the boat to exceed the waterline length limit in speed either. So drop your hp and increase the efficiency with a target of running the boat under maximum WL hull speed. 7+ is easily done.

[Salmoneyes]

Originally Posted by MarAzul

So drop your hp and increase the efficiency with a target of running the boat under maximum WL hull speed. 7+ is easily done.

Exactly what we are looking at... I just sent sent off some numbers Michigan wheel, because when I run the numbers, we are way over proped.
That could have been part of the problem.

Im trying to run the math on different combos but its a pain... Ive had to teach my self calculus at 54 on a 10th grade education. Like reading Chinese, in Braille.

[MarAzul]

Originally Posted by Simi 60

I do wish I had the T and the A missing from out NTA 855 Cummins.
As she rarely gets run above 1200rpm (100hp) I doubt the T ever comes into play.

They certainly don't belong on any engine driving a boat at or below displacement speed.

[lifeofreilly57]

Originally Posted by Salmoneyes

Just looked... I really do not know how all that stuff on Alibaba works. I saw some 14 foot aluminum boats on there a few weeks back. After looking much closer, they were exactly the same as a Lund model that is very popular around here. I started thinking that maybe a lot of the stuff we buy here is coming from China, and rebranded.
Maybe that is why all the hub bub about tariffs and such. The boat in question was 1400 and when you buy from Lund its 8500.. I get tax, and import and all that, but why can't we crank out boats for 1400?

Look back in the archives on this site. There was a gentleman who was using those Chinese built engines on some Pacific islands due to the low cost. He had some initial problems with them which turned out to be a minor factory assembly issue but did cause a major failure. Once he figured it out the engines ran fine. And he was still ahead if the game cost wise in comparison to Yanmar.
I've worked as a project manager putting in factories in China from the early 90s up until about 4 years ago. The manufacturing infrastructure has improved dramatically, but quality is a crapshoot from one entity to another and customer service is still not formed into their business dna. Warranties are rarely honored, and good luck taking them to court.
Of course, you can buy three engines for the price of one Yanmar.......
It would be worth looking up that past thread. I'd be curious to see what the end result was, wish I could remember the title.
Unfortunately I'm in my boat a thousand miles from home with limited connectivity.
By the way, I chose to rebuild my 4108 because it's a dependable mechanical engineer. I'm in a 40000lb 47 foot cutter. Could have used a 60 - 80 hp motor but I went for reliability and simplicity. Also this is a performance cruisers so it sails well.
I get 1.2 - 1.4 gph at 2800 tomorrow all day long.
Your needs would be more in the 60 -80 how range. Prop accordingly.

[Salmoneyes]

Originally Posted by lifeofreilly57

.

By the way, I chose to rebuild my 4108 because it's a dependable mechanical engineer. I'm in a 40000lb 47 foot cutter. Could have used a 60 - 80 hp motor but I went for reliability and simplicity. Also this is a performance cruisers so it sails well.
I get 1.2 - 1.4 gph at 2800 tomorrow all day long.
Your needs would be more in the 60 -80 how range. Prop accordingly.

Id be really curious to your LWL. Your boat is close enough to mine to compare HP range... What HP are you running currently?

[lifeofreilly57]

Originally Posted by Salmoneyes

Id be really curious to your LWL. Your boat is close enough to mine to compare HP range... What HP are you running currently?

I don't have that info readily available since I'm not on a wifi connection. But if you go to sailboat data.com look up a Cheoy Lee Pedrick 47CC. The displacement is listed as 37,000lbs but it weighed 40,000 lbs on the lift with full fuel tanks and empty water tanks. 125 gallons of diesel, 150 gallons of water capacity.
This boat would really be properly sized with an 80 hp motor based on my experience. Especially when fighting a foul tide and headwind. But then again it's a sailboat. I can do 7 knots under motor in benign conditions but get down to 4 - 5 in heading seas. Under sail I get 7 -. 8 heading to wind in 15 knots if wind, 9 - 10 knots on a beam reach in 15 - 17 knots if wind.

[mako]

Originally Posted by lifeofreilly57

Look back in the archives on this site. There was a gentleman who was using those Chinese built engines on some Pacific islands due to the low cost. He had some initial problems with them which turned out to be a minor factory assembly issue but did cause a major failure. Once he figured it out the engines ran fine. And he was still ahead if the game cost wise in comparison to Yanmar.

Yes I remember that thread and I recall the guy was in Papau New Guinea, but the thread ended with not much further followup. He was using Weichai engines?

[Jimmyhenry]

We are 46ft. 15 tonne. Have a Perkins 4-236. About 85 hp. More than adequate power. Good speed. Uses 4 litres per hour. Don’t know how much that is is US gallons. Jeez when are you guys going to join the rest of the world??? Haven’t even seen a “gallon” for over 50 years. I suppose you also still use feet and inches and miles!!!

[mako]

Jimmy, at that loading your engine is running at about 22% power. Not good for long term longevity. Do you regularly run it up or anything else?

BTW, I love the metric system but still absolutely hate Celsius. Fahrenheit has it all over you guys!

[Simi 60]

Originally Posted by MarAzul

They certainly don't belong on any engine driving a boat at or below displacement speed.

I'm sure working boats pulling a load yet still not exceeding displacement speed would disagree.

[mako]

Originally Posted by MarAzul

They certainly don't belong on any engine driving a boat at or below displacement speed.

I used to believe that also, and certainly common sense tells us that a naturally aspirated very simple engine is the best solution for a trawler yacht. However when you research engines and speak to knowledgeable persons you learn that turbo'd engines are more fuel efficient and quieter.

I still believe that a fire-breathing after cooled engine is not the ideal solution, but a simple turbo on a mechanical tier-0 old school engine is perfect, especially if you run it under some level of load (say 50%) and the turbo starts to spool up a bit.

[Salmoneyes]

Im currious about this.. Im being lead to believe the switch to the new stuff is running smaller and lighter since they can get more power, but at the cost of running higher RPM, which adds noise and a level of vibration.

It also looks like these newer diesels require the DEF and or DPF? After the experience we had with our truck, I would never do that..

2 winters in North Dakota letting the truck idle for days, caused some excessive build up of carbon (or ???) on one of the 3 sensors in the exhaust pipe. By 65000 miles, they wanted 9 grand to replace it all. The motor ran, but the economy was 1/3 what it was originally with a noticeable decrease in power..

One of the main reasons we are looking for simplicity for this repower.