Gardner 6LW Fresh Water Cooling

[Steve.Sharratt]

Fisherman, The engine is near the stern and she has a vertical stem and the stern has a high sweep. Overall, a fairly flat bottom with rounded chines which is typical of the dutch Beurtschip. Below is some information that the manufacturer sent me:

The pipe, which should be connected from the highest point of the box to the side of the ship, is for venting (de-aeration) and for circulation of the seawater. Therefor the pipe must come through the side of the under the waterline. This pipe must be slightly raised for proper de-aeration of the box, and to allow a smooth flow of seawater.

Normally the heatexchanger that is mounted on the engine can be removed and replaced by the bottom type cooler.
The Jacketwater circulation pump should be used to circulate the cooling water through the cooling system.
The seawater pump is no longer necessary.

I suspect that I couldn't use the existing inlet for the raw water as it may be too low.

 

[duncan99210]

I've seen engine coolers on narrowboats which are essentially large water tanks built into the bottom of the hull, underneath the ballast and against the hull itself. The coolant circulates through the tank, loosing heat to the hull and surrounding water. No external pipes to be damaged, simply a tank in contact with the hull. The one on my brother's boat must have had a capacity of about 100 litres or more. It took some time for the coolant in the tank to warm through but it seems to be a common system on narrowboats.
I'm pretty sure that the engine used a heat exchanger so that the engine itself got to running temperature pretty quickly. The coolant in the keel cooler was circulated by a raw water pump and it only gradually got warm, never hot. Seemed like a sensible way to go when the quantity of crap in the canal water is taken into consideration.

 

[fisherman]

If you have to make new holes, could you put the cooling pipes on the stern, or at least under the upswept part of the hull out of the way of damage? If it were me I would try to install a large bore pipe inside, from the bottom to the stern and let the river flow though it, wrap a small copper pipe round it to run the engine water through. When stationary convection would cause a flow. Could be done with flanges and gaskets.

 

[Steve.Sharratt]

Duncan - That is exactly what I am trying to achieve and is where the subject item is confusing me. I simplistic terms, it is just a box that creates a large surface area in which hot water passing through is cooled. This, in conjuction with the system being attached to the hull, where it is coolest, is sufficient to cool the water before it is recirculated. I intend(ed) to keep the existing closed system on the engine, including the heat exchanger (although the manufacturer says this is not required) and just install this system in place of the raw water intake. My reading of the information is that the box needs some sort of breather but it also mentions sea (read 'raw'?) water circulation. Could an expansion tank achieve the same?

Fisherman - I think that could work although a lot of the upsweep is above the waterline. Certainly, if this system requires new holes, it means a much bigger undertaking. Not something I am keen on and as you say, there are simpler ways of modifying if this is the case.

 

[duncan99210]

Duncan - That is exactly what I am trying to achieve and is where the subject item is confusing me. I simplistic terms, it is just a box that creates a large surface area in which hot water passing through is cooled. This, in conjuction with the system being attached to the hull, where it is coolest, is sufficient to cool the water before it is recirculated. I intend(ed) to keep the existing closed system on the engine, including the heat exchanger (although the manufacturer says this is not required) and just install this system in place of the raw water intake. My reading of the information is that the box needs some sort of breather but it also mentions sea (read 'raw'?) water circulation. Could an expansion tank achieve the same?
.

On my brothers boat, the coolant flowed through the heat exchanger to the keel cooler, then from the cooler to a header tank located on a bulkhead above the level of the engine, before returning to the raw water pump. The header tank had was open, suggesting that the system wasn't under pressure and the vent was designed to cope with the expansion and contraction of a fairly large volume of coolant. You could use an expansion tank to do the job with a two way pressure relief valve to prevent any chance of the coolant slopping out of the vent if the boat were to encounter rough water or simply use a vented cap somewhat similar to an outboard motor fuel tank.

I'm pretty sure that the engine on the boat was also a Gardner.

The keel cooler is a common solution to the engine cooling problem on narrowboats. They are usually fitted at an early stage in the build of a narrowboat and are placed along the keel in direct contact with the hull. The coolant circulating in them has to be dosed with anti freeze both for frost protection and to guard against corrosion.

Final point. Your current exhaust is almost certainly a wet one, with the raw water injected into it to keep it cool. You will need to replace the exhaust pipe with a hot exhaust which will require adequate insulation along its length as well as some support and a flexible connection to the engine. Narrowboat exhausts are typically as short as possible for this reason.

 

[fisherman]

OK. There was a FV with a Gardner ex bus engine complete with radiator and fan, and it worked fine. To extend the concept you could go back to the domestic copper cylinder, fit a cabinet round it and ventilate it, maybe with a fan, and there are many off the shelf cooling units about for, eg, aircon/shop cabinets/cold rooms if it comes down to air/water cooling. In winter run radiators.
If you are prepared to make a new hull hole, how about an inspection trunk over the prop, square section steel to above WL with a bolt on flange to the hull, removable gauze in the bottom, then take the engine raw water off the side of it. The inlet is then accessible by hand, and less likely to pick up debris due to turbulence from the prop.