Old Diesels

[Northwindii]

I am looking at a classic yacht with 1948 vintage diesel V12s. These type of motors were used by the British Admiralty during WWII. They were recently rebuilt and the seller has a bunch of spare parts.

They are V12s developing only 360HP at 1,000RPM and cruise at 600 RPM. Aside from these figures and some historical info about the engine make and model, this is about all I know. No manuals or tuning advice from the manufacturer.

The question is: how best to use them in a refit? They are fairly efficient in terms of pushing the boat from here to there on a certain amount of fuel (CAT could not promise better fuel economy with a repower). And, they seem reliable despite their age. They are fairly simple. No EPA or electronics.

What changes would you consider? New controls and monitoring packages to get them to fit in a more modern system (throttles are hydraulic)? Better filters? How would you go about ensuring the motors were operating at peak efficiency with no manuals or specs?

On a somewhat related matter, the transfer cases are presumably from the same era. They are very heavy gears for the little HP produced. The shift of mechanical. Would you consider a modern reduction gear/clutch arrangement to make shifting easier on the entire system I.e. Introduce a little slip into the propulsion system.

I'm not to needlessly blow money. But, I would like to make smart changes to make the engines fit into a general upgrade of the boat and protect them going forward.

 

[Northwindii]

To clarify, by new controls and electronics, I only meant updating the throttle linkage to something controllable by a modern head and converting the analogue signals to digital for reporting the the helm. I am not suggesting the addition of computer controlled flow. Though if someone has a suggestion that direction, I am open to thinking about it.

 

[FAST FRED]

Why bother?

Industrial maring gradev items that have lasted for 1/2 a century mostly only need a bitb of love to carry on .

I would locate the engine builders plate and find out what type of V 12 they are.

If they are 12-71 Detroits , parts are readily aviliable world wide as they use mostly DD 6-71 parts. Books too are EZ to find.

Same for tranny and all shift items , find out the maker and do whatever preventive maint. is normal , and just use the vessel.

1000 rpm might suggest a larger engine ,than a 12-71 but in a yacht I doubt it could stand the weight. The 12-71 is already 2 tons.

"converting the analogue signals to digital for reporting the the helm."

Bad move as the analog gauges are probably mechanical , and will continue to work with no electric.

A mechanical up grade might be Murphy Switch gauges so the gauges will alarm if whatever setting you have set is exceeded.

Like having an attentive engineer on station 24/7.

"Introduce a little slip into the propulsion system."

Slip is heat & inefficiency , not desired .

 

[powerabout]

Love to know what engines they are?
Other than a Gardiner I cant think of any old pommy diesel worth putting in a boat

 

[Northwindii]

Paxman Ricardo V12 about 1948 vintage.

Not putting it in a boat -- it is already in a boat and given a recent overhaul there seems no good reason to replace it.

In light of what has been said, I am inclined to install a new control head that will send the mechanical signal to the throttle, clutch, gearbox but offers some modern advances in terms of preventing some abusive shifting and engine synchronization. Also, seems that there are plenty of aftermarket kits where I can get the signal off the analogue gauges to drive a second set of electronic gear. Suggestions and brand recommendations would be welcomed.

While I am at it, I am interested to know if there is a device that can calculate and adjust the throttle for the best cruising position. In other words, take engine load (maybe measured by exhaust temperature), fuel consumption, and ground speed to find the best throttle position for the prevailing conditions.

Thank you.

 

[stone beach]

I have lots of o&m experience of engines of this vintage (& older) and of this brand but a newer version (but not much!)
1. what kind of boat, you say "classic", do you want to preserve its nature? in which case change out seems unwise
2. how many engines & propulsion arrgt is ??
2. engine(s) already in the boat or out just now ? same question ref transmission(s)
3. "overhaul" means many things to different people. it seems you are not the owner (yet??), so do you know the history ? carefully overhauling an engine is not what most will do just before they sell a boat...clearly some caution is called for
4. old equipment typically needs more tlc but can be more robust than its modern counterpart. however dont expect these engine(s) to perform like a modern diesel. some internal components (particularly valves & pistons etc) are made of much less sophisticated materials than are available today and although all are probably well oversized from a mechanical load perspective their thermal capability will be much less...typically keeping all operating temperatures, (particularly exhaust temperatures) below the manufacturer's advised limit is critical. you will probably see the engine is equipped with either individual exhaust pyrometers or a switched dial arrangement to individual cylinder thermocouples for this reason.
5. changing the peripheral stuff like adding alarms & instruments is relatively simple to do, rearranging transmission controls may be less so. I can probably advise further when I know more details, if you dont want to broadcast everything you can send me an email
6. further consideration in whether to replace the major bits is their weight. modern equipment is typically lighter, so certainly you can "save" weight in the process but it will be in the wrong place and you will almost certainly have to add ballast negating any "saving". also modern stuff is operating in a totally different speed range so all the drive train will have to be changed, not just the engine.
7. if the propulsion set up has been correctly matched against max rpm and max continuous operating exhaust temp (may also be with a less than full loaded ship) your best cruising speed is probably about right now (600 rpm). I know of no device to do what you asked, but you can do it with some performance data simple maths. fuel consumption monitoring devices do exist, not sure how accurate or reliable they are.

 

[powerabout]

You can put torque meauring device on the propshaft and just measure fuel flow rpm and boat speed and you can generate all the data you need.

 

[FAST FRED]

Flowscan offers a unit that measures GPH of fuel use with an instant readout.

It can include a GPS , and give out MPG ,,but it does not do the math or adjust the throttle for you.

This is not done yet on modern air liners where million dollar systems are the norm.

Most folks figure out the fuel bill they can afford and use that as Long Range Cruise LRC.

I would suggest launching the boat and operating it for at least a season before the sledge or chain saw are used for "improvements".

They knew a lot about good reliable cruising vessels in 1950.

Today lighter and cheaper (with massive complexity and short service life) seems to be the norm, not why most folks purchase a classic.

" offers some modern advances in terms of preventing some abusive shifting and engine synchronization. "

All these are at your fingertips , no electric toys required.

Your ears will tell you when the engines are in sync.for free!

 

[powerabout]

Flight control computer certainly has control of the throttle.

 

[FAST FRED]

"Flight control computer certainly has control of the throttle."

It knows aircraft weight & CG so best speeds for the configuration.

And it has weather (winds aloft) info so a climb will be at varied speeds, and rate of climb to get to a fix on time , on altitude.

New big truck deisels have a GPS send route info and location , so the tranny brain decides weather to downshift before a grade for least fuel burn.

But so far there is nothing like the poster wants on anyones shelf,

 

[WestVanHan]

If they are fine,if it were me I'd leave them in.

BTW Ricardo still around and doing very well,they build the engines for McLaren, the driveline for the Bugatti Veyron, and tons of work for almost every auto maker,rail and marine company.

Love old engines and had a look,is yours the VEE RA/RB or the TP?

http://www.paxmanhistory.org.uk/paxeng34.htm

 

[powerabout]

Ricardo would do that project...

 

[Lepke]

Repairs and Parts for Old Diesels

http://striegelsupplyinc.com/
These guys in Mukilteo, WA specialize in repairs and parts for no longer made diesels. They specialize in American made, but can make parts for any diesel.
Probably much cheaper than replacing engines. They keep many historical boat/ship engines running.
Your older engines are probably less expensive to run than currently available engines. I live aboard a 83' boat with 2 Detroit Diesels of 1947 vintage. I burn 8.5 gallons/hr. @ 10 knots. For a boat this size, I think that is cheap.

 

[rayman]

northwindi, if the engines have been rebuilt then leave them in and use them. If you are only going to be running slow then don't be disappointed by the poor performance and clouds of smoke.They don't like running cold either. They are very noisy, rattle and clang like an old steam engine, develop piston knock early in life and leak oil from every joint. I have had long experience with them, mainly in the VRP from V4-V12 range in both propulsion and auxiliary instalations. One oceangoing dredger had 12-V16.s in the generator flat providing electric power, needless to say they did not all run at the same time.