Engines for my 42' Hatteras LRC

[sunchaser]

Muriel
Is there a proven and reliable DD rebuild shop near you? If so, have you obtained a firm estimate for a total, not partial, rebuild?

 

[mvweebles]

I'm neutral on DDs (Lepke's continued praise is persuasive though- strikes me as a very knowledgeable wrench).

Cost aside, the DDs being mirrored with inboard service points would likely get me over the line on rebuilding them.

As a guy who is just finishing the grandaddy of over-improvement projects, i wish you the best of luck. Financially, it's a really bad idea - apart from marrying the wrong person, might be the worst financial decision you will make in your life.

Peter

 

[PierreR]

If I had to repower my 42 LRC I would consider engines around 75-80 HP each. Running the 42 LRC on one Detroit engine drives the boat above the theoretical hull speed at full throttle. I would go for the fuel savings as the Detroit's are not run high enough in my boat to really keep them in tip top shape.
In the long run, if your boat is a cream puff I would repower, if your boat is average, I would rebuild.

 

[Jmarsh203]

Being that the 42lrc is a semi displacement hull and not a full displacement slightly more power than stock wouldn’t hurt it at all, I definitely wouldn’t repower with less. If you are doing a repower and you only repower with enough power to reach hull speed you essentially hobble the boat’s capabilities, and anybody who knows about boats wouldn’t buy it or would only buy it at a massive discount, I see a few insufficient hp repowers like that a year for sale and they usually sit for sale for years because nobody wants them. You are on the right track with the JD 4045 if a repower is required, they would actually increase the value of the boat as long as you don’t do some ugly interior remodel with paint and wallpaper over some of the most beautiful woods ever put into boats lol. The JD engines are also extremely reliable and in generator applications run at 1800 rpm I’ve seen them break 60,000 hours without ever having the heads off so they are very very reliable. JD probobly makes the only new engines I would consider putting in any sort of expedition vessel, also the worldwide support is second to none, they beat out CAT years ago on service and parts availability internationally. I’m not a fan of the newer Cummins engines I’ve replaced too many front and rear main seals on the BT line both the 12 and 24 valves, also odd computer issues on the smaller qsm series. C series and 855 big cams are probably my favorite of the last generation mechanical injector engines. Now I am a diesel mechanic and have worked on many marine diesels and there are some very large advantages to a DD that are not available in any other engines. If I were building a single engine full displacement boat for extended world travel in exotic places I would go with a DD. The lack of an injector pump and the use of unit injectors essentially rules out one of the main issues that will put you dead In the water without a time consuming and costly professional rebuild. The ability to Cary a few spare injectors gives you the ability to easily swap them out if one goes down. One or two going down also won’t stop the boat from running. She will also easily run dirty fuel which is an important ability to have when traveling to exotic places. None of the newer engines are capable of running on dirty fuel. Now if I have twins the JDs would be a very good option. The 4045s are essentially the perfect match for the hatteras LRC line up until you go larger than the 48lrc. Then it’s the 6068 JD.

 

[folivier]

Those DD's aren't loud. You wanna hear loud? Take a ride on an oilfield crew boat with NO insulation and they're run wide open. That's loud!

 

[garbler]

Those DD's aren't loud. You wanna hear loud? Take a ride on an oilfield crew boat with NO insulation and they're run wide open. That's loud!

Beyond loud. I ran a couple of 60’ alum Breaux’s and Camcrafts for Tidewater back in the 70’s back and forth to the patch. We had like ten pairs of ear muffs hanging on the bulkhead so the experienced guys would actually run for them and grab seats as far forward as possible. The other guys just suffered if they didn’t have muffs or plugs. We ran those 8V71’s at 2250 all the time day and night every day including Christmas. Tidewater had a warehouse in Morgan City full of replacement engines and two men could swap them out in a single shift. Those engines never knew cool water and they were straight exhaust. What’s a muffler anyway ?

Rick

 

[SIBERNUT]

I second the 6BTA or even the 4BTA. But a friend repowered a 43 Vike with Iveco's & loved it.

 

[Mako]

Speaking of noise, has anyone measured how many db the DD puts out?

 

[garbler]

Speaking of noise, has anyone measured how many db the DD puts out?

I can’t give you a quantitative answer but I can say these numbers have been tested almost everywhere people work with Diesel engines and since at one time there were more Detroit Diesels than any other this data is somewhere. OSHA tests db levels but probably not for public use. You have to consider db testing is only valid with ambient readings and engine rooms, installations, etc all affect sound wave and vibration transmission not to mention personnel’s distance from the sound source. Hard to nail down generally, so on-site testing is necessary

Rick

 

[Mako]

Rick, that’s a nice technical response, but it’s not so difficult for someone with a mobile phone to take measurements with a free app. I’m surprised no one’s posted these numbers on the TF

 

[garbler]

Wow Mako I had no idea you could do that. Very interesting I’ll have to check this out. Thanks

Rick

 

[Xlantic]

I have the BW 2,9:1 72C.
I have to check the reverse possibility and if yes which ratio. It may nit be the same ratio in reverse.

Muriel, I believe the 72C model, like my old 73C, cannot be used in reverse for extended periods of time.

My new Twin Disc Technodrive 170 boxes have 3:1 reductions.

As mentioned before, given the low cost of the gear boxes, now is a great time to get a new set.

If you keep the old BWs and later need to change them you will likely need to remove the engines again to accomplish it.

 

[rslifkin]

The Borg Warner Velvet Drives (71C, 72C, 73C) can handle an engine of either rotation (you reverse the pump and maybe another part or 2), but forward and reverse are very distinct and you can't just run the trans backwards (the reverse clutch pack isn't as strong as forward). Reverse is also a slightly lower reduction than forward on at least the 71C and 72C (forward is 1:1 through the main box and then into the reduction gear, reverse is 1.1:1 through the main box before the reduction gear).

Other than 1 ratio out of the whole set (which rotates the output opposite of input in forward), the output will always rotate the same as the input on these transmissions. So they're not suitable for counter rotating props unless you have counter rotating engines. The CR2 version of the 72C would work, but those are hard to get parts for at this point, handle less power, etc. So basically, a repower in a boat that previously had counter rotating engines (some old Detroits, old gassers, etc.) will need new transmissions.

 

[Keysdisease]

"In Europe, we consider silence as luxury."

Regarding your engine choices, they are all excellent. Regarding noise, some of the previous comments are right on.

Engine mount selection will be a very important decision towards structure borne noise underway. Whatever engines you choose will most probably come with a very generic mount that would fit a wide variety of vessels. A mount selection based on your vessel and installation will be he baseline for providing a quiet boat. Rubber Design and Trelleborg should be your first choices, and selection should be done after supplying the vendor or manufacturer with full driveline specs from engine drawings with C/G indicated, gear ratio, # blades on prop, etc. Only with complete information can the best mount be recommended.

As mentioned, engine room insulation is very important. A product with a 2lb noise barrier suspended in fiberglass or foam will provide the best performance. Anything "lightweight" that "works as well" is snake oil and somehow avoids the laws of physics. Very careful attention to details like air intake paths, cable runs and gasketed hatches can make a world of difference. Too often I have seen excellent insulation choice short circuited by an air path that shares a bulkhead with an accommodation space.

Lastly, a top shelf wet exhaust silencer installed correctly will provide the best performance for exhaust noise. A custom silencer can be "tuned" to your cruising RPM, the same way generator exhaust systems are "tuned" to 1500 or 1800 RPM. No part of the exhaust system, silencer or piping, should be hung from an overhead or hard mounted to a bulkhead. If possible the silencer should be "saddled' in a vibration isolated foam. These systems should also include a drain provision, sometimes called "waterdrop," that allows the exhaust to exit dry and cool with no splashing.

These same suggestions should also be considered for the generator, with the added suggestion to double isolate the generator.

$0.02

 

[Muriel 42LRC322]

Db on 4-53

I did !!! I stopped at 90db on the fly and was not at full rpms... Again... For 30.000 Euros more than the rebuilt I'll have new engines... less noisy, reliable and under guarantee. Does it deserve ? I understand your point. But 90db is a lot. Maybe I can play with my old mufflers. Right. I know I can't do more.

 

[High Wire]

I’m a “run what you brung” kind of guy so first vote would be for rebuilding the Jimmies. 2nd would be John Deere and third the Betas. Consider what the loss of engine weight will do the the rough water handling. A guy in my marina repowered from Detroits to Cummins Bs twenty years ago. The boat sat several inches higher in the water and rolled like crazy. Loved the extra speed, hated the roll. The weight difference between Detroit and Beta will be significant.

 

[capngrumpy]

Its your money but i would definitely go for the Deeres. i have a 2005 200 hp 6 in a 53ft 26 ton boat and i have a 2.5 gph fuel burn a 7.5kn in moderate sea and wind. At 1500rpm with the engine room door shut the noise level in the wheelhouse is almost nil. i would agree with Greg qs, if you do serious hours you will pay for new gears very quickly

 

[Bradenvlp]

If you do repower, as mentioned, pay attention to the mounts. I repowered with JD two years ago and didn’t and re-mounted the engines last year. Other than that misstep, I couldn’t be happier with the engines.

 

[Nomad Willy]

You’re choices are too few.
The first step in re-powering is to know how much power you’ll need but you’ve basically got that covered.
I’m not going to say this is a good idea or not but it deserves mentioning .. I think. Since noise is so high on your list and I would think running 4-71’s at a lower power setting and rpm may be a simple solution as would be running different engine at lower load. In the 50’s the 62’ CC Motor Yacht had three 6cylinder gas engines. That boat was probably the quietest and smoothest boat around.

There are lots of attachments (boat to engine) that if matched to the engine can greatly simplify changing engines. When I repowered my 30’ Willard I had somewhere around 12-15 engines on my list. And I suspect there’s more choices in you’re power range. And I probably should’nt mention it but if noise really is you’re #1 issue a gasoline engine is considerably quieter than any diesel. But that’s a lot of bilge to blow and resale value would take a hit.

But in the real world rebuilding the old engines is probably the best choice.

 

[Comodave]

The Deeres would be my choice. Great engine.

 

[Muriel 42LRC322]

Repowering and other considerations

First thank you all and these forums are a fantastic source of information. Please excuse my english as it is not my first langage.
1 - Weight consideration : of course I analysed this point and know that in case of repower, except with 6BTs I will have to add weight in the engine room, below the engine for the difference in weight.
2 - Transmission : thank for this very qualitative details confirming that I will have to change the transmission. It is increaging the final price but nor choice and even if it is less risky in the future.
3 - I really know that the DD are good strong reliable engines, mirrored, counter rotative…. All this was so well done and they are working ! I would do a nice overhaul or rebuilt and yes they will survive me !
At this point having my engine room empty and ready to start a new page… I am thinking new mechanical engines, also a bit smaller… with the right power you are right… will cost more but will give so much satisfaction in noise, and tranquility for while… and guarantee… and…

That’s where I am. Betas 105 or 115… JD404550 or Cummins… So now In really have to add the gear boxes to my quotation. Ouffff. ANd I loose my counter rotative engine finally ??? And have to change then one propeller also !!! Right ?

I am quoting each situation. With covid all engines are more expensive today… I hope to have my final decision with 2 weeks.

Thank you again all of you !!!


Muriel

 

[Mako]

I did !!! I stopped at 90db on the fly and was not at full rpms... Again... For 30.000 Euros more than the rebuilt I'll have new engines... less noisy, reliable and under guarantee. Does it deserve ? I understand your point. But 90db is a lot. Maybe I can play with my old mufflers. Right. I know I can't do more.

Muriel, glad you have some numbers to judge from now. 90db leads to permanent hearing loss over long term exposure. I had twin Jimmies in an old boat with horrible (or no) sound insulation and I suffered noise fatigue over prolonged periods, cruising for days on end at sea.

No engine is totally quiet unless turned off, so definitely budget for enhanced sound treatment with either a technician, or yourself, checking every small cavity and opening.

BTW, the costs you're quoting seem very high. I hope you're not planning on executing this work in Southern France. Can you find more affordable labor rates in Portugal or Spain, or if you have the time, Poland? Also you may wish to call the guys at Abato in Netherlands (outside of Rotterdam) and speak to them about other engine options.

 

[Comodave]

If you get counter rotating transmissions you could keep the props if they are the correct size.

 

[Xlantic]

That’s where I am. Betas 105 or 115… JD404550 or Cummins… So now In really have to add the gear boxes to my quotation. Ouffff. ANd I loose my counter rotative engine finally ??? And have to change then one propeller also !!! Right ?

Muriel, no, you do not have to change the propeller on the currently counter-rotating engine. When you replace that engine with a "normally-rotating" one you need to invert the way you connect the control cable so the gear box runs in reverse when you want to go forward and vice-versa. So, that gear box, effectivlly running in reverse, will invert the rotation and the propeller will turn as before.

Before making the purchase you may want to check the various parameters (HP, RPM, gear reduction, prop pitch and diameter, and boat displacement ) in boatdiesel.com's calculator (you will need to pay their $50 annual membership fee).

 

[Muriel 42LRC322]

Work cost

Thank you… I m doing the works in Spain on purpose. New engines are very expensive, and more since covid.
I am probably at 19000 euros per engine with gear box … plus works…
But I save the overhaul of the DD and may resale them probably !

 

[twistedtree]

I’m a “run what you brung” kind of guy so first vote would be for rebuilding the Jimmies. 2nd would be John Deere and third the Betas. Consider what the loss of engine weight will do the the rough water handling. A guy in my marina repowered from Detroits to Cummins Bs twenty years ago. The boat sat several inches higher in the water and rolled like crazy. Loved the extra speed, hated the roll. The weight difference between Detroit and Beta will be significant.

From what I'm seeing in spec sheets, the Deere 4045 is the same weight as a 4-57, if not a little heavier.

 

[PierreR]

First thank you all and these forums are a fantastic source of information. Please excuse my english as it is not my first langage.
1 - Weight consideration : of course I analysed this point and know that in case of repower, except with 6BTs I will have to add weight in the engine room, below the engine for the difference in weight.
2 - Transmission : thank for this very qualitative details confirming that I will have to change the transmission. It is increaging the final price but nor choice and even if it is less risky in the future.
3 - I really know that the DD are good strong reliable engines, mirrored, counter rotative…. All this was so well done and they are working ! I would do a nice overhaul or rebuilt and yes they will survive me !
At this point having my engine room empty and ready to start a new page… I am thinking new mechanical engines, also a bit smaller… with the right power you are right… will cost more but will give so much satisfaction in noise, and tranquility for while… and guarantee… and…

That’s where I am. Betas 105 or 115… JD404550 or Cummins… So now In really have to add the gear boxes to my quotation. Ouffff. ANd I loose my counter rotative engine finally ??? And have to change then one propeller also !!! Right ?

I am quoting each situation. With covid all engines are more expensive today… I hope to have my final decision with 2 weeks.

Thank you again all of you !!!


Muriel

Thank you for this thread. Having the same boat, I played around with some of the power options you are contemplating. I pulled up the power curves for the Beta engines. I do not know how fast you intend to cruise. I plan on cruising in the 7.0-7.5 knot range or an S/L ratio of 1.2. As best I can figure the prismatic coefficient is somewhere around 0.61-0.62.
I was surprised by studying the power curves of the various Beta engines was a difference there is. It looks as if you can beat the fuel mileage with 40% to 50% savings.
Based on one poster's claim of diminished sale value for to small and engine I played around with the Beta 98T and the 90. The 98T should deliver that speed at around 1,300 rpm and the 90 around 1,400 rpm. I was surprised that the savings of the 90 over the 98T was substantial. Going lower to the 75 did not really produce additional savings and might increase noise. The 42 LRC has very good sound deadening, even with the DD 453's and would be better with the Beta engines. The 90's should drive the boat to 9.4 knots.
If you plan on traveling much the fuel $ savings should pay of the engines quicker than I would have initially thought.
You upset my apple cart of the DD 453's being golden. Even at current USA diesel prices I can pay for new engines in 5 years with my current plans. If my DD-453's suddenly need a lot of work, I am strongly considering a switch. I did not look at the power curves for the Deere's I am afraid to.
From what I am hearing here, you can keep your props depending on transmission gear ratios as the transmissions reverse the rotation of the prop.

 

[PierreR]

The difference between the 2 Detroit's and the 2 Beta engines total about 600 lbs. The engines are centered and low in the 42LRC and the weight difference should not be that significant on the roll rate. Fuel and water can vary by ten times that amount. Adding a 225 lb person on the fly bridge would have the same effect.

 

[fgarriso]

All DD two stroke have blower wine. If you rebuild them they will still wine. I have two 6V71-DD and they do. Sound-down panels help, but it is just the nature of the beast.

Just a short correction

The engines are not "6V71 DD: brain dead late at night.

The correct model is : DD 6-71N" sorry for the error.

 

[Jmarsh203]

Thank you for this thread. Having the same boat, I played around with some of the power options you are contemplating. I pulled up the power curves for the Beta engines. I do not know how fast you intend to cruise. I plan on cruising in the 7.0-7.5 knot range or an S/L ratio of 1.2. As best I can figure the prismatic coefficient is somewhere around 0.61-0.62.
I was surprised by studying the power curves of the various Beta engines was a difference there is. It looks as if you can beat the fuel mileage with 40% to 50% savings.
Based on one poster's claim of diminished sale value for to small and engine I played around with the Beta 98T and the 90. The 98T should deliver that speed at around 1,300 rpm and the 90 around 1,400 rpm. I was surprised that the savings of the 90 over the 98T was substantial. Going lower to the 75 did not really produce additional savings and might increase noise. The 42 LRC has very good sound deadening, even with the DD 453's and would be better with the Beta engines. The 90's should drive the boat to 9.4 knots.
If you plan on traveling much the fuel $ savings should pay of the engines quicker than I would have initially thought.
You upset my apple cart of the DD 453's being golden. Even at current USA diesel prices I can pay for new engines in 5 years with my current plans. If my DD-453's suddenly need a lot of work, I am strongly considering a switch. I did not look at the power curves for the Deere's I am afraid to.
From what I am hearing here, you can keep your props depending on transmission gear ratios as the transmissions reverse the rotation of the prop.

You own the hull at this point, no matter what engine you install it will not change the hull design so the decisions on what engines to put in should be greatly deminished without destroying the boat. you should have made the decision on what “cruise speed” you wanted before buying the boat not choosing engines to replace based off of that. Changing engines will not change a semi displacement hull into a full displacement hull, if you want a full displacement boat go buy one. If you own a semi displacement boat repower with something suitable for the hull not the speed you want to go . Also Any engine built in the last 40 years will pretty much take the same amount of power/ to push a boat that weighs X at any equivalent speed. Anything semi new ish diesel powered makes between 18-21 hp per gallon of fuel burned per hour. Diesels also self meter fuel based on load not rpm and load is directly correlated to weight, wetted surface, and speed. So two boats with all things being equal hull and weight wise with two different motors one with 50hp engines the other one with 150 hp engines will burn equivalent amounts of fuel at equal speeds or close enough it doesn’t matter maybe 1-2% difference or something small like that. Which also means that the difference between two 50hp engines or two 150 hp engines to pushing a boat at say hull speed will have no appreciable difference in fuel burn. and while doing that the higher hp engine will be making that power much easier which will last much much longer, while also being able to bump up rpm and go faster.. And on a boat like a hatteras 42 lrc which is a semi displacement hull not a full displacement hull if you hobble it with less power than factory you will loose the majority of your investment almost instantly.