Dry exhaust

I have dry stacks and fin type coolers for the main, gen. And a/c. The only issue I have Is in slow/no moving warm water. Heat saturation occurs.

I assume your talking about running the generator and AC at the dock?

Modern diesels are very efficient and have very little lost energy in the form of heat while they are idling. In Montreal in the winter, if I got caught in traffic driving my diesel, I could watch the water temp drop to the bottom of the scale and the cabin heater stopped working until I got moving again. The cooling system was great for hard driving but the diesel did not have enough extra energy to keep itself warm. VW puts "glow plugs" (their term) in the water jacket to heat the coolant electrically so you can have cabin heat.

I have no trouble keeping the Cummins running at the correct temperature when the water temperature is 5 degrees or so in the winter or 22 degrees in the summer. I think you are over analyzing the cooling issue. To add a little fuel to the fire, the oil cooler and trans oil cooler have coolant, not salt water, running through them.

Those of you regulars will recognise a pet theory of mine, for those of you raw-water cooled, why not run coolant instead of salt water through your expensive heat exchangers?

A home-made keel cooler might have different issues than a manufactured one.

I have a mechanical gearbox with no provision or need for coolant.

Xsbank said:

Those of you regulars will recognise a pet theory of mine, for those of you raw-water cooled, why not run coolant instead of salt water through your expensive heat exchangers?
.

Click to expand...

I for one do not ascribe to your theory as it increases the size and cost of the TX and main coolers. Secondly running the gears at temperatures 50 degrees or so below coolant temperatures makes for a cooler ER and happier clutch packs and other internals.

I totally agree on engine oil cooler being coolant cooled. This results in acceptable oil temperatures (plus 180) for those of us who run under light loads.

I've been in 40-50F water with a keel cooler for the past few months and the engine temp holds right where it should, regulated by the thermostat. Only as much coolant as necessary diverts through the cooler to regulate engine temp, just like with a radiator. And a keel cooler actually sees much less temp swing than a truck's radiator which can see anything from 110F down to -20F.

I prefer a well engineered wet exhaust system with bulletproof back flood prevention. It's the quietest and the cleanest and absolutely as safe as any keel cooled dry stack system, if its done right.

No doubt a good wet system can be quiet and clean. I guess it all comes down to how the boat is used and what an owners preference and experience is. I happen to be more familiar with dry from my commercial fishing experience and like to leave my boat in over winter (yes I go boating in the Maine winter). As long as it's safe I think it doesn't matter.

Fish53. Only an issue with the a/c. I may increase coolant capacity but I don't expect a cure.

Not an expert on transmissions, so I will just addd that American Diesel strongly advised about running the BW tranny cooler with coolant versus raw water.

They do have a kit or components and advice how to convert the engine oil cooler to coolant.

I would wrap the pipe and muffler ( but not bellows) with 5" exhaust wrap and cover with "Chill Seal".

Hamiltonmarine shows the 100' roll, 4" wide for $35. Good to 1000 degrees. They also sell the clear sealer for it. I have used "chill seal" on mine in the past. It is basically boiler lagging compound and makes a nice coating over the wrap. Roses machine shop in Gloucester sells it. Easy peasey for $50.
Was that Boston Beam trawler Whipples boat?

I unfortunately don't know much about her war or prewar history. She apparently went back to fishing after the war in the North Sea and then was eventually sold to Norwegian owners. At some point after that she was repowered with a 1700hp Bergen diesel and a Hunsted CP propeller and the wheelhouse rebuilt. The work done when I was there was a set of sweep winches installed up under the whaleback and a curved bulwark around the aft end of the wheelhouse to pull bobbins up against, the net was then strapped in. She also had the hold modified to process and carry salt cod.

psneeld said:

Not an expert on transmissions, so I will just addd that American Diesel strongly advised about running the BW tranny cooler with coolant versus raw water.

They do have a kit or components and advice how to convert the engine oil cooler to coolant.

Click to expand...

I have set up a few BW trannies on small detroits that actually have a cooler built in for the gear, using coolant. Sort of a necessity when keel cooling. This makes the tranny run hot, case gets to around 190F with IR gun. Not sure what the specs are for the gear, but these were commercial boats and run hard and had no issues with tranny at all.

The guts of a BW are really the same stuff as the guts of a car auto tranny, those get real hot in comparison.

I like gears cooled with coolant, the higher temps keep condensation out and oil stays nice and clean. And we know how many gears have been killed by sea water coolers leaking.

I suspect gear temp specs are often set considering SW cooling was being used, and there 190F is indeed hot. I can't see any reason the guts themselves are sensitive to 190F, and experience has backed that up.

The OP has a little gear with no cooling, probably a Hurth/ZF mechanical box. Those can be fitted with a "patch" cooler, but probably not necessary.

Actually it's a Newage PRM 120, I've had and rebuilt a number of ZF/Hurth gears (I have four now) and I believe they're over rated. I've had better luck with Newage and Twin Disc /Technodrive.

Agreed, those little ZF/Hurth mechanical boxes SUCK. But they are cheap and not much else available for low hp.

Not familiar with the PRM 120. Is it hydraulic?

The PRM 120 is mechanical as are the Twin Disc/Technodrive, they both use a cone type clutch instead of the ZF disc setup, much simpler and more reliable.