Engines for my 42' Hatteras LRC

[MVDarlin]

Any thought to a Yanmar repower?

 

[Xlantic]

If I go to for the 6bs... I have no choice than having new panels compliant with the Cummins... No ?
Thank you G....

When I replaced my GM Toro-Flos with Cummins 6Bs I was able to re-use all the instruments except for the tachometers. I kept the temperature and oil pressure sensors from the old engines and installed them in the Cummins.

The tachometers for the original engines were Stewart Warner's 811531 and the senders were 811532. I believe the senders are not compatible with the Cummins as they are gear-driven so I was not able to reuse them nor the tachs.

But, if you are planning to sell your old engines, you may want to include the sensors/senders and instrumentation for a better price.

 

[Muriel 42LRC322]

Cummins 6B

Thank you Gilberto, You have been my best advisor for Cummins. I am in touch with your team and they are very quick in answering and recommendations. I may move before Christmas in my decision. I will let you know and may ask you again some points. Which gear boxes have you and are you satisfied ?

 

[Xlantic]

Thank you Gilberto, You have been my best advisor for Cummins. I am in touch with your team and they are very quick in answering and recommendations. I may move before Christmas in my decision. I will let you know and may ask you again some points. Which gear boxes have you and are you satisfied ?

Twin Disc Technodrive 170 with 2.94:1 reduction. I am happy with them. Twin Disc has a solid reputation.

They are a bit shorter than the Velvet Drives so the engines will move aft a few centimetres.

 

[Crux]

My 4-53 are supposed to be 1600 hrs approximately which is nothing... the boat spent before I purchased in 2019 3 years for sure without cruising... for good reasons from the previous owner. I purchased like this and I knew. This boat is going to be my last boat and I am willing to re do and re check everything and cruise in serenity. Yes before selling them I wish to overhaul them... better than selling like this with some corrosion and dusty points... It is my way of doing... compression test and big check. Anybody would be interested please come back to me in private. I have no idea of the price for the 2 engines. Thank you.

I hear you, but I disagree with the part about 'overhauling them before selling'.

When I buy such things, its a 'negative' to see the word 'overhauled' and have any confidence in what the extent of work, who did it, their qualifications, what they may have seen, etc etc.

Will the shop doing the work provide a detailed work order and warranty to the 2nd party purchaser?

I think much better, and more reassuring to a prospect to present the engines exactly as you have..... plus:

Provide all the records you have....
Buyer encouraged to inspect....under the supervision of your shop
No 'rattle can" paint job....leave them as is....just a good wipe down with wd-40
...sure, wipe away any loose rust/corrosion.

The provenance of the engines as being original equipment in a Hatt 42 LRC speaks volumes.

So, spend nothing, and apply those overhaul fund$ to the new project

 

[Jmarsh203]

Any thought to a Yanmar repower?

Great engines for certain applications but not for heavy boats, perfect for the newer lighter style semi displacement boats like mainships, ranger tugs and Downeaster style picnic boats just to name a few. But with older heavier built boats really heavy big iron still reigns supreme. Out of the older boats I wouldn’t consider putting them in anything over around 36 foot or 25-30,000lb boats. Yanmar asks allot out of their alloy blocks and aren’t known for lasting particularly long when trying to push something too heavy. Great engine option where weight is an issue like on faster boat but a slow heavy boat will quickly show its weakness. I mean they turn up an alloy block that is essentially same cubic displacement as a 6bt to over 440hp, it’s obviously not going to last as long.

 

[Muriel 42LRC322]

Thank you for your recommendation. I say "overhaul" as the translation of a French word actually. I just wanted to do a check to present the engines at her best....but I understand your point.
Thank you for the gear box recommendation also...

 

[rslifkin]

Great engines for certain applications but not for heavy boats, perfect for the newer lighter style semi displacement boats like mainships, ranger tugs and Downeaster style picnic boats just to name a few. But with older heavier built boats really heavy big iron still reigns supreme. Out of the older boats I wouldn’t consider putting them in anything over around 36 foot or 25-30,000lb boats. Yanmar asks allot out of their alloy blocks and aren’t known for lasting particularly long when trying to push something too heavy. Great engine option where weight is an issue like on faster boat but a slow heavy boat will quickly show its weakness. I mean they turn up an alloy block that is essentially same cubic displacement as a 6bt to over 440hp, it’s obviously not going to last as long.

At the same time, Cummins turns the current electronic version of the 6BT (the QSB 6.7) up to 550hp and they still have a reputation for good longevity. Same with the 480hp versions of the previous QSB 5.9.

I do agree that some of the high powered Yanmars haven't had the best reputations. But not all of their engines are pushed that hard. The sailboat engines are generally very well regarded. And they do make heavier duty stuff sold with commercial duty ratings as well. The 6CHE3 makes 115hp at 2550 RPM in a medium duty commerical rating, for example (and is naturally aspirated like the 120hp Cummins 6B you're looking at. The 6CHE3 is 6.5 liters, as a comparison point.

Realistically though, power vs displacement isn't a great indicator of lifespan, as seen by some engines (like the B series Cummins) being pushed much harder than conventional wisdom dictates and still giving a good lifespan. It's really about what a given engine was designed to handle power-wise while giving a good lifespan. That's why taking a light duty engine, turning up the power and working it hard tends to give a short lifespan. But a lower rating of the same engine may last well, and a different engine design at the same power level will last well.

Because of that last bit, I'd stay away from the higher ratings in any given engine model and stick to models that have a good reputation for longevity and/or are well liked by commercial operators. It also helps that you'll be technically a bit overpowered for displacement speeds, so you won't be running the boat like a well powered displacement hull where the engines are working hard and can benefit from being rated for nearly continuous WOT operation.

 

[Muriel 42LRC322]

Volume

Most engines like the Yanmar won't have the volume... at least of the DD which is 3.48 liters.... The Beta was perfectly online.... The JD is 4,5 and the 6B 5,9 liters....
Because of the weight of the boat... I am happy to have at least the same volume than the DD.

 

[twistedtree]

While we are spending your money, and since we have grown from a 4 cyl 4.5L Deere to a 6 cyl 5.7L Cummins, why not also consider the 6cyl Deere 6068? It's another incredibly well proven marine engine.

 

[Muriel 42LRC322]

You are right;... the reason is financial. The 6Bs are rebuilt the the 4045 are new...and more expensive. The 6 cylinders JD might be more expensive then the 4045...

 

[garbler]

A very timely article appeared in my mailbox today in Professional Boatbuilder. It’s written by Nigel Calder who I often question but never his math and rarely his methods. The article is titled Follwing the Curve it’s all about proper engine selection and optimization. Lots of graphs and technical breakdown which those in this thread, especially Muriel, will find relevant though perhaps a bit redundant in some respects.

This publication may be hard to find but I would guess your boatyard will have a copy laying around to copy.

Tell you what I’ll see if I can scan it for you and try to post it
Rick

 

[garbler]

Hopefully this article will post

Rick

 

[Muriel 42LRC322]

Thank you a lot Rick,
I am having it printed and carefully read it this evening.

 

[Wayne]

Cummins 6BT5.9M engines with Velvet Drive 71CR Transmissions

'Lo All! My old 43' Albin trawler had Cummins 6BT5.9M engines and Borg Warner Velvet Drive 10-17-00-012 AS14-71CR transmissions with 2.57:1 ratios in BOTH forward and reverse. The boat also had a Glendinning engine synchronizer which worked perfectly, as the boat tracked perfectly straight when it was on - also indicating that the engines were putting about the same power to the props. When going forward, the port engine ran in "forward" and the starboard engine ran in "reverse", as indicated by the marking on top of the transmissions. The shift cables were simply mounted in opposite orientations so as to achieve the results. Never had any problems with the engines or transmissions other than one internally shorted oil temp sensor. The entire salon floor was made up of a grid work of fixed frames and removable panels: 2"x2" frames with 1/4" (?) teak and holly flooring over 1/2" (?) sub-floor. The grid was filled with 2" fiberglass insulation and had ~1/16" sheet aluminum covering the bottom. The engines had Vernalift mufflers. We could talk at normal volume in the salon, on the fly-bridge and aft deck when cruising. Fortunately, the boat had 2 blowers blowing inwards and 2 blowing out, as after shutdown on a warm evening, those engines had a lot of heat to dissipate. Those fans did seem to make a lot of noise in a quiet anchorage. We always tried to anchor well away from everyone. Lost the boat to Hurricane Michael. Hmm - memories.

 

[Muriel 42LRC322]

Thank you Wayne,
Veryinteresting to me ! I do thank you on the gear box info. Some gear boxes doesn’t have the same ratio on reverse. I have some 6BTs on another boat. Iam convinced of their reliability on 6B120 hp.
My current GBoxes actually… and after inpection… are Warner AS3-71C ratio 2.0:1.

 

[rslifkin]

It sounds like Wayne may have had the CR2 version of the Velvet Drives, which can be run in either direction.

 

[Muriel 42LRC322]

Contra rotation

Then... Another point on my contra rotation.

My engines are today Port anti clock and Starboard clock !

Any new engines will have the same rotation.

One of my propeller will still be fine... The other won't !!!

What if I move each propeller to the other side (port to starboard and versus).

Is it satisfactory to have propeller Port Clock and Starboard Anti Clock ???

 

[rslifkin]

Then... Another point on my contra rotation.

My engines are today Port anti clock and Starboard clock !

Any new engines will have the same rotation.

One of my propeller will still be fine... The other won't !!!

What if I move each propeller to the other side (port to starboard and versus).

Is it satisfactory to have propeller Port Clock and Starboard Anti Clock ???

Having the props rotate outward is more typical, although inward can work. Having them rotate inward (at the tops while moving forward) will give noticeably less prop walk when maneuvering, so the boat won't turn as readily with engine thrust.



Having both props spin the same direction will noticeably impact maneuvering and will also cause you to run with the rudders offset a little to go straight.

 

[Muriel 42LRC322]

Understood… and yes logical.
Thank you… I can then save the money of the new propeller that it would have involved. And I can keep my gear boxes as they are ! Without the reverse issue on ratio !

 

[rslifkin]

Understood… and yes logical.
Thank you… I can then save the money of the new propeller that it would have involved. And I can keep my gear boxes as they are ! Without the reverse issue on ratio !

No, I don't see any way to keep both your current props and transmissions with new engines that both spin the same way. You have standard Velvet Drives which cannot run in reverse, rather than the CR2 model.

 

[Muriel 42LRC322]

And you wouldn't recommend to change only one then...

 

[rslifkin]

And you wouldn't recommend to change only one then...

If you can get a new transmission for one side with the same gear ratio, you certainly could. I'd rather have 2 new transmissions and sell the old ones with the old engines, but as long as the ratios match, 2 different transmissions will work fine.

 

[Muriel 42LRC322]

Ok understood....and I agree. Thank you for all this !!!...

 

[PierreR]

Then... Another point on my contra rotation.

My engines are today Port anti clock and Starboard clock !

Any new engines will have the same rotation.

One of my propeller will still be fine... The other won't !!!

What if I move each propeller to the other side (port to starboard and versus).

Is it satisfactory to have propeller Port Clock and Starboard Anti Clock ???

I am confused. How do you make a LH propeller a RH propeller by swapping sides?

 

[Muriel 42LRC322]

….. mistake…. You are right….

 

[Crux]

Suggest....don't be 'penny wise and pound foolish' on this transmission biz lol!

 

[Muriel 42LRC322]

I am doing foolish on so much things ! lol..... Yes ok...

 

[sunchaser]

OK, now I'm confused. Aren't some transmissions reversing gears so engine turns same way but shafts don't.

 

[rslifkin]

OK, now I'm confused. Aren't some transmissions reversing gears so engine turns same way but shafts don't.

Yes. Some transmissions are directional, where there's a defined Forward and Reverse. In those, Forward may rotate the output the same as the engine or opposite, depending on the trans and ratio in question. For other transmissions, there's just an A and B position, either one can be used as forward.


Velvet Drives are in the first group. Unless it's a CR2 model, then output is always the same as input in Forward (excluding the 1.88:1 ratio where output is always opposite of input).