Good engines on Appollo Duck little used

[Psycloud]

19 hours ago, Tony Brooks said:

I suspect a bit hard to fit a second alternator though.

Is that because they only have one pulley on the flywheel or some other reason?  Someone has previously fitted a triple pulley onto ours so would that mean we could (if we wished) fit a 2nd alternator?

[Tony Brooks]

8 minutes ago, Psycloud said:

Is that because they only have one pulley on the flywheel or some other reason?  Someone has previously fitted a triple pulley onto ours so would that mean we could (if we wished) fit a 2nd alternator?

Its more to do with finding mounting points for the brackets in my view. Unless Bukh supply a triple pulley I suspect the amount of dish on it would require one to be turned specially. The other option would be to get the flywheel machined or if you used a wide belt you may get enough drive just from sitting the belt on the flywheel because you would have well over 60% wrap.

However we come back to it being a competitively small engine by today's standards so getting it to drive a large alternator without an excessive loss of power may be difficult. It comes down to would it be cost effective and would doing so cause other problems. In any case as the engine alternator on a twin alternator engine in a boat with a well maintained electrical system spends maybe the first 20 minutes doing any work, after that is just sits there spinning you have to ask what the point of twin alternators are apart from redundancy and marketing - especially as in your case you have a triple pulley so could drive a single large alternator.

[David Mack]

1 hour ago, Tony Brooks said:

I have carefully inspected the photos and they were never direct raw water cooled.

Agreed these particular engines were never raw water cooled. But wasn't the base engine originally designed for raw water  cooling and hence a low temperature thermostat?

[cereal tiller]

15 minutes ago, David Mack said:

Agreed these particular engines were never raw water cooled. But wasn't the base engine originally designed for raw water  cooling and hence a low temperature thermostat?

Bukh Engines were originally designed for Fishing boats which are mainly used in Salt Water so a 50 Degree Thermostat was used to reduce Crystallisation and Salt blockages in the Pipework.

For Fresh water use a 60 or 70 Degree Stat would be OK.

[Mitchellmoxo]

20 hours ago, Athy said:

Not sure about the paint job - but then you can't judge a Bukh by the cover.

Brilliant. 

[Neil2]

12 hours ago, Tony Brooks said:

Pity no one told me that before I fitted one to mine! The domestic water gets close to dangerously hot.

Yes you can have a calorifier but piped slightly different to the normal way. You need a calorifier with a minimum of 22mm coils and just pass the coolant from the engine outlet through the calorifier and back to the skin tank. Admittedly no water heating will occur when the thermostat is closed but it works as well as a more conventionally piped system. 

In general it is difficult to fit a calorifier to any direct RAW water cooled engines because the thermostat housing incorporates an internal bypass that supplies water to the exhaust system when the engine thermostat is closed but on marinised engines like the BMCs the bypass was by external spring loaded valve so suitable modification to the pipework from the thermostat housing would allow the fitting of a calorifier (if you were happy to run with a  thermostat, 60C is plenty hot enough for domestic water.

These engines are tank/keel cooled, not direct raw water cooled like many of the smaller Bukhs

Edited to add - if they had been direct raw water cooled then great care would need to be taken in respect of internal corrosion. They are wet liner engines and corrosion around the bottom of the liner area would be very expensive to fix.

Interesting comments Tony but I wonder if there's a significant difference between the DV24 and the DV36.  There is no way my engine would heat domestic water through a calorifier even with large bore piping.  In canal use I suspect the thermostat is closed most of the time.  I've had this discussion with Nick Alsop, - I recall him telling me they test run these engines with just a bucket of water for cooling and it would run all day like that.  

My boat did actually have a calorifier originally but the original owners (who also fitted out the boat) removed it.  

[RLWP]

15 minutes ago, Neil2 said:

I wonder if there's a significant difference between the DV24 and the DV36

12!

[system 4-50]

40 minutes ago, RLWP said:

I wonder if there's a significant difference between the DV24 and the DV36

Is there time to work out dv/dt?

[RLWP]

26 minutes ago, system 4-50 said:

Is there time to work out dv/dt?

If you are quick

[Tony Brooks]

11 hours ago, Neil2 said:

Interesting comments Tony but I wonder if there's a significant difference between the DV24 and the DV36.  There is no way my engine would heat domestic water through a calorifier even with large bore piping.  In canal use I suspect the thermostat is closed most of the time.  I've had this discussion with Nick Alsop, - I recall him telling me they test run these engines with just a bucket of water for cooling and it would run all day like that.  

My boat did actually have a calorifier originally but the original owners (who also fitted out the boat) removed it.  

As I explained the smaller Bukhs are usually direct raw water cooled designed for a wet exhaust so they have a bypass arrangement in the thermostat housing blending cold and warm water to maintain water flow to the exhaust when the engine is cold. This means the outlet water is always cold or cool.

On my engine Viking Afloat (I assume) modified the thermostat housing so there is no bypass and then fitted a small bore permanent bypass closer to the skin tank side of  the cooling circuit. Thus I can pick up coolant straight from the engine. As the engine is tank cooled I doubt it even needs the bypass because the Jabsco pump vanes would just fold down if the water flow was impeded until the thermostat opened. The engines originally linked to are designed for keel/tank cooling so as far as I can see would not require a bypass.

In the case of a smaller Bukh with a dry exhaust you could make a new thermostat housing without a bypass for the exhaust water that is not needed or possibly modify the one you have. It may be just a case of blocking a drilling/gallery so as a trial a blob of body filler may do the job, its easy enough to chip away if necessary.

NOTE - the bypass I am talking about is ONLY to provide exhaust water, not for internal circulation during warm up. I very much doubt Bukh needs such circulation and have seen no evidence of it in the drawings I have found.

Now to Nick's statement. I don't like to contradict Nick but think about it. We are back to the steel fabricators' arguments that an over large skin tank will over-cool the engine. This has been debunked for years. The temperature of the cooling water is controlled by the thermostat. The thermostat will open just enough to allow sufficient flow through the skin tank to cool the engine just enough to maintain the thermostat temperature. You may not get much flow but what flow you get will be at whatever the thermostat is rated at.  In reality I think that you will get plenty enough flow as a whole range of engines all consume assimilate amounts of fuel in canal work so produce similar amounts of heat. The difference in efficiency between engines is comparatively minor fuel and waste heat wise. In fact I would suggest the DV24 would have to work harder than a DV36 so once you get the bypass situation sorted may produce MORE hot water than a DV36.

All I can say is if you do not believe me any member is welcome to visit my boat and see.

 

 

11 hours ago, RLWP said:

12!

Yes - probably BHP

[lpp2]

according to the bukh dv24 rme handbook there is a hot water take off plug.

Regards lpp2

[steamraiser2]

My money is on they are from the Alang and Bangladeshi ship breaking yards. We get emails from the yards every now and then trying to sell us a container full of ex-lifeboat engines. cheap enough if you buy 20 tons of them.