Marinising New Holland Tractor Diesel

[Bradley]

Has anyone got any thoughts or experience of using pipe 1 -1/4" fitted external to the hull to cool the engine. I am thinking of 2 lengths 20 feet long and the water circulated by the engine's own water pump.

[Dutch Peter]

Has been used, is still used, but I believe the general opinion now is that you can better make a cooler on the inside of the hull. Because of the problems of repairs/corrosion/growth/conservation with the outside pipe.
With the internal cooler you make a labyrint on, let's say 1m^2, of the hull. Works really wel!

[Bradley]

Thanks for your comments Dutch Peter, however I am committed to using tube on the outside. My engine is 7.5L 150kw @ 2000 rpm, my real concern is will 40 feet of 1-1/4" tube be sufficient to cool the engine ?

[FAST FRED]

I have a 50 ft Navy Launch with a 235HP DD that has what you describe.

Although we seldome burn over 5gph ( 90HP) there has been no problems , even in warm Florida water.

The pipe is slightly curved to match the hull and has 2 elbows and a short nipple at the 180 turn .

Works great , lasts a long time if painted .

A commercial keel cooler might have less drag , but in an 8-12k boat , who would notice?

FAST FRED

[Bradley]

Thanks for you comments Fast Fred. Could you tell me what size pipe you have and what length is exposed outside the hull. Do you use the standard engine water circulation pump to move the water around. Does the water flow need to be slowed down or will the thermostat control the flow and temperature.

[FAST FRED]

The pipe is 1 1/4 as you sugested and itt simply was threaded on either end of the std pipe , 21 ft long.

Folks HAVE used copper tubing (the heavy stiff stuff , not the refrigeration stuff in rolls) , but it doesnt seem to last any longer than iron pipe.

The DD stock circ pump moves the water , and although trechinacily overcooled the engine runs fine in the stock 180F thermostats.A radiator system usulally only drops the circ water 20 deg or so , the keel cooler does far more! But is is used in many fish boats for decades with no harm.

Its a seamless system that only needs the distilled water and antifreez changed out every 3 years to maintain SCA levels.

Try it , you will never go back, to handle the exhaust there are silencers (Hospital Critical grade) that make the exhaust almost un noticable , but there heavy and expensive.

FAST FRED

[Bradley]

Thanks Fast Fred. This has helped me confirm my ideas. It is so easy and simple I keep thinking there must be a problem somewhere !
Following on from this can you see any reason not to have smaller tubes to cool the engine and gearbox oil.
Regarding Exhaust I have attached a drawing (.DXF) of an exhaust stack/silencer/air exraction. I once saw a detailed drawing for this type of exhaust with dimensions dependent upon engine size/ type etc. have you seen, or do you know anything about this idea.

Regards Bradley

[gonzo]

To reduce drag, you can put a plate welded to the pipe. It will also increase the cooling surface.

[FAST FRED]

Following on from this can you see any reason not to have smaller tubes to cool the engine and gearbox oil

SURE , fewer holes in the boat.
With relativly cool water returning to the engine , the oil and gear box lube could be cooled with a heat exchanger in the engine coolant circ line.

It would require a heat exchanger large enough to flow the engine coolant with little loss of head pressure , but thats only a cost item.

Most cooling with keel coolers havs NO seacock in the circuit , two holes might be ON but 6?

FAST FRED