One engine or two - further question

[mriley]

The interesting debate over one engine or two has prompted another issue for me. Because of work, I have recently moved my boat from the Solent to the Thames, where it will be for a couple of years. It has twin V8 petrols which are revving very slowly to keep inside the river speed limit. I read about hazards of slow running, issues of oil contaminants not burning off, oil losing lubricicity, glazing of cylinders, stuck rings etc, damage to engines?? Enough to keep me awake at night. Should I worry, what can I do to reduce risks? Has anyone tried oil flushing or similar, is it recommended, or would it do more harm than good (given age of engines - 30 years or so but running OK). Thanks in advance for any replies.

 

[Chris_d]

I wouldn't worry about it, just about all the problems you refer to only effect Diesels, petrol engines are quite happy to run for extended periods slowly, in fact it probably extends their life. Its just about the one big advantage a petrol engine boat has, the lack of all these problems for river use.

 

[Medskipper]

The best thing for you to do is every now and again take the boat into the tideway and give the engines a good run, this should keep them in good condition!

I don't recommend a flushing agent when changing oil, as this tends to be very thin and if you don't get it all drained out, when new oil is put in the engine it is always going to mix with this flushing oil and be that much thinner, thus having a damaging effect.

Try running the boat on only one engine so you can at least keep the revs a bit higher when on the upper reaches, this will also save petrol, say one hour per engine running time.

Glazing of the bore or rings becoming stuck is unlikely to happen if you service the engines correctly and run them up in the tideway a few times a year.

Good luck

Barry

 

[tcm]

yep, i wd flush no prob - provided that you really flush the engine, several times, and the last times with some cheap cack tesco oil of the correctish viscosity. But regulat use is probluy the best thing for engines - hanging about for ages in damp air isn't good for any machine.

 

[boatone]

I run a single diesel boat on the thames now but until a year or two ago had a twin diesel.
One simple routine is to run alternate engines between locks. The offset effect is really not that big a deal as far as steering is concerned.
As Barry says, get down below Teddington occasionally and give them a run....St Kats or Limehouse makes a good weekend if the tides are right.

Where on the Thames are you based now? I'm near Chertsey and will keep an eye out for you....not many peeps on here with the same surname /forums/images/graemlins/grin.gif

 

[miket]

If you are really concerned and can't get to the tideway that easily you could acquire some "river" prop's.
Go for a finer pitch so they rev' faster for the same speed. If you can pick up some 2nd hand ones it may be beneficial on the river as you are bound to ding them sooner or later.

 

[Callisto]

Beat me to it Mike.

Some finer pitch props would probably be a good idea as if the boat is anything like mine, you get nearly 6knots at about 1500rpm which is not far above tickover!!.

Regards

JH /forums/images/graemlins/cool.gif

 

[MadMat]

I disagree - finer pitch props will let it rev, but not really put the engine under any extra load - doesn't really seem to be much point. V8 petrols will fairly happily run at fast idle all day. I also DEFINATELY would not using any flushing oils - there's quite a lot of residual oil left in - so unless the oil you are draining is in a very poor state, or the engines have an excessive amount of sludge, I wouldn't - even then I'd probably just do 2 or 3 consecutive oil changes with whatever your favourite brand is.

If you're going from salt to fresh, don't forget to change the anodes though.

 

[Callisto]

Hi Matt

Not suggesting that finer pitch would load the engine more better, i was thinking more along the lines of making the boat more controllable at low speed. A finer pitch prop gives a lower speed for a given RPM. Might make close quarters handling at river speeds a bit easier.

Agree on the anodes too.

Cheers

JH /forums/images/graemlins/cool.gif

Agree that the V8 can run well at just above tickover.

 

[MadMat]

Fair enough - I (incorrectly) assumed the finer pitch was intended as an attempt to rev the motors to give them a bit more work to do - I agree on the 'controllability' aspect.