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That's a good solution but the volume of cooling water could be a bit of a problem when it expands, like the problem I had with mine.

Good fun at blacking time too!

 

A round pipe right up under the uxter plate will be a lot easier to do, say 1.25 bore iron steam pipe 6' long.

That will be 1.66 X PI X 72 / 144 square feet of cooling area= 2.6 ft sq, good for 10.4 extra HP

 

Or using 1.5" pipe, 1.9 X PI X 72 / 144 = nearly 3 ft sq good for 12  HP   and the extra volume is only around 2 ltrs.

Edited by Boater Sam
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7 hours ago, ditchcrawler said:

024.jpg

That surely has to have a far worse effect on water flows around the swim, prop and rudder than just adding a smooth  external skin tank that widens the swim over part of its length by no more than an inch.

And how the hell do you black around, (and presumably behind) that?


I can't see any advantage at all, and pleanty of disadvantages.

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Just ditch the skin tank and go for indirect cooling using a heat exchanger.  Over the last 16 years my last two boats have been like this as there was no way of getting a big enough skin tank(s) on the swims. My present boat has a skin tank but its about half the size needed for the Beta 2203 so its disconnected and not used.  I have very little problems with blockages and so long as the filter is above water level its an easy rinse out of any sediment that does collect.

If you also convert to a wet exhaust its also much quieter.....

Edited by Loddon
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By comparison this is what an external skin tank added on the outside of the swim can look like.

This was added to our former leisure boat "Chalice", and replaced the previous one, as it offered more than enough baffled area, with no need for the complication of two different tanks.....

 

IMG_0968.JPG

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35 minutes ago, Loddon said:

Just ditch the skin tank and go for indirect cooling using a heat exchanger.  Over the last 16 years my last two boats have been like this as there was no way of getting a big enough skin tank(s) on the swims. My present boat has a skin tank but its about half the size needed for the Beta 2203 so its disconnected and not used.  I have very little problems with blockages and so long as the filter is above water level its an easy rinse out of any sediment that does collect.

If you also convert to a wet exhaust its also much quieter.....

As a counter argument don't. far more to go wrong, more maintenance and potentially the need to drain down the raw water part to p[revet freezing in winter. You can't get a much simpler system that tank/keel cooling but each to their own.

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Far more to go wrong?

One extra pump and a tube stack, mind you I've just had to rebuild my pump, I believe its the first time in 24years.......

As for winter remove filter top, open seacock it self drains, close seacock fill filter with antifreeze run engine until AF comes out of exhaust into catch can whilst filling filter with AF. Takes longer to type it than to do it.

Edited by Loddon
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40 minutes ago, Loddon said:

Far more to go wrong?

One extra pump and a tube stack, mind you I've just had to rebuild my pump, I believe its the first time in 24years.......

As for winter remove filter top, open seacock it self drains, close seacock fill filter with antifreeze run engine until AF comes out of exhaust into catch can whilst filling filter with AF. Takes longer to type it than to do it.

What about the extra hoses and fittings, especially the suction side between sea cock and pump that tend to leak air into the system far more than the pressure hoses leak out? I have seen too many cooling system parts that deal with raw water split by frost to be 100% sure your method will work all the time. 95% sure I agree but there is room for damage.

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17 minutes ago, Robbo said:

Although there are benefits, such as works when stationary, reduced engine room heat, space requirements, cost.

I have never had any problem with cooling when running without the boat moving  but then I did make sure the skin tank was large enough when I bought the boat. I also don't see there is any practical space advantage when compared with a 20 to 25mm thick skin tank. Definitely an advantage when compared with the idiot 2  to 4" inch thick ones we some times see. I also think any practical advantage of a cooler engine bay is probably overstated as long as the engine bay venting is adequate and suitably located.

 

The fact remains a heat exchanger boat needs two water pumps, one of which usually uses an impeller (not on some trad engines ) that is recommended for a yearly change or at least every few years to prevent the wings falling off and locking the pipes/hoses.. The said impellers do not take kindle to being run dry as may happen if the inlet becomes blocked.

 

It was no accident that  e gradually converted all the hire boats from heat exchanger cooling to keel cooling. Saved a lot in breakdowns and maintenance.

 

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6 minutes ago, Tony Brooks said:

I have never had any problem with cooling when running without the boat moving  but then I did make sure the skin tank was large enough when I bought the boat. I also don't see there is any practical space advantage when compared with a 20 to 25mm thick skin tank. Definitely an advantage when compared with the idiot 2  to 4" inch thick ones we some times see. I also think any practical advantage of a cooler engine bay is probably overstated as long as the engine bay venting is adequate and suitably located.

 

The fact remains a heat exchanger boat needs two water pumps, one of which usually uses an impeller (not on some trad engines ) that is recommended for a yearly change or at least every few years to prevent the wings falling off and locking the pipes/hoses.. The said impellers do not take kindle to being run dry as may happen if the inlet becomes blocked.

 

It was no accident that  e gradually converted all the hire boats from heat exchanger cooling to keel cooling. Saved a lot in breakdowns and maintenance.

 

Our skin tank is forward of the engine bay, behind the wardrobe and bed. The boat-side is sprayfoamed so I don’t notice much heat leaking into the boat, and none into the engine bay except from the pipes (and the engine itself, of course).

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The raw water inlet through the side of the boat was constantly getting blocked on my boat when it was raw water cooled. Plastic bags, leaves, all manner of stuff. The immediate symptom was the engine overheating as the cooling water flow degraded towards zero.

 

It has now been changed to skin tank cooling, a vast improvement in reliability.

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59 minutes ago, Tony Brooks said:

recommended for a yearly change or at least every few years to prevent the wings falling off...

As opposed to the front falling off...

 

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When we changed from a PD2 to a PJW3 on a big Northwich we decided to have keel cooling and had a pipe right round under the counter, it went out and back under the side bed. Think it was made of scaffold tube and worked a treat even though no calcs made.

changed the engine on my barge which already had external keel cooling and the temp gauge showed around 90 degrees all the time so at the next docking had a bit more volume added and it still runs at 90 so think gauge faulty.

CA8E159A-88AD-4114-B6C6-94FDE2AC8F11.jpeg

Edited by Dav and Pen
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2 minutes ago, Dav and Pen said:

When we changed from a PD2 to a PJW3 on a big Northwich we decided to have keel cooling and had a pipe right round under the counter, it went out and back under the side bed. Think it was made of scaffold tube and worked a treat even though no calls made.

changed the engine on my barge which already had external keel cooling and the temp gauge showed around 90 degrees all the time so at the next docking had a bit more volume added and it still runs at 90 so think gauge faulty.

Maybe the thermostat is set to 90? Not high for a pressurised system but I guess rather high for an unpressurised system.

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On 01/08/2018 at 18:38, wergie said:

OK you lot, pay attention please..

I'm about to replace my rather knackered old engine with something a little more powerful.

My current engine is rated at 16 hp, and has a vertical skin tank has been sized accordingly.  It's replacement will be 30hp, hence the need for some additional cooling.

Now, my cunning plan is to build a horizontal keel tank in the drip tray under the engine. The tray is about 6' x 2', so there's plenty of area, but what I need to know is Will It Work.

Opinions so far seem to be divided...

If anyone has any experience of horizontal cooling tanks, if they work and how they are baffled internally I would be delighted to hear from you.

 

Steve

I think horizontal skin tanks tend to be less efficient than equivalent vertical tanks because the heat rises to the top surface of the horizontal tank which has air on the other side, rather than the bottom of the tank against the river or canal water where you want it for max heat exchange. But I guess if its thin enough it will work. 

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  • 8 months later...

Hi All,

My 70ft Roger Fuller has a 2.0 litre marinised Mercedes engine (No, wouldn't have been my choice either). This is cooled by just the skin tank and it's not a pressurized system. It has a plastic header tank tee'd off the return from the skin tank. I suspect the thermostat must open at around 90C as that's where the temp gauge stops rising.  The marinising included water cooled manifold and oil cooler. I haven't gone very far in the boat (Ricky to Uxbridge Dry dock and a few trips Ricky to Harefield Marina. Longest trip 4-5 hours in the summer) and whilst the engine room does get pretty warm, the temperature of the engine loiters at 90C all the time. When I asked Roger about the skin tank, he said it was well baffled ensuring that a good cooling flow is ensured throughout its length. Water to the skin tank is very hot and comes back barely lukewarm. Can the skin tank really be cooling that well or is there perhaps a blockage restricting flow? 

 

Reading this thread has got me nervous and I'm wondering if the engine should be running cooler. It's never been connected to the calorifier but I intend to do that soon.

 

Thoughts anyone?

Stephen 

 

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If its unpressurised and doesn't boil, its OK.

If you know the horsepower, divide by 4 and that's the required skin tank area in square feet. assuming a side tank not a base plate tank.

The hotter you run a diesel within reason, the more efficient it is.

58 minutes ago, Stephen Jeavons said:

Water to the skin tank is very hot and comes back barely lukewarm. Can the skin tank really be cooling that well or is there perhaps a blockage restricting flow? 

 

 

So it is dumping heat into the canal as it should, perfectly OK.

If its unpressurised and doesn't boil, its OK.

If you know the horsepower, divide by 4 and that's the required skin tank area in square feet. assuming a side tank not a base plate tank.

The hotter you run a diesel within reason, the more efficient it is.

58 minutes ago, Stephen Jeavons said:

Water to the skin tank is very hot and comes back barely lukewarm. Can the skin tank really be cooling that well or is there perhaps a blockage restricting flow? 

 

 

So it is dumping heat into the canal as it should, perfectly OK.

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This thread and discussion is almost as varied and controversial as "marine sanitation". If anyone now (and those few actually researching later -

Just my penn'orth and actual experience.

 

Before I built my boat I hired from "the Squadron Leader"  and did the Thames ring. Lovely boat and great on the canals. However on the reach above Putney the engine (standard skin tank) overheated and we slowed down (folks treated their hired boats kindly in those days) we were not racing, nor punching the tide - just moving comfortably on a wide river. It made me wonder whether skin tanks were a good idea for anything more than pottering around the  Brum canals..

In later years we always hired from Teddesley, and Peter M was an advocate of heat exchanger cooling. Quiet running, no smokey exhausts and no overheating.  Seems good.

Thus 'our' hull was built with a girt big mud box which not only traqps the mud, but leaves and crayfish and even of partially blocked with leaves (!) still keeps the engine cool.

As with all things on a boat, if the facility is sensibly planned and designed - then it works. Just translating something land based designed - or not even designed at all (i.e. not practical) invariably ends in tears.

If adapting domestic equipment to a 'marine' environment you should look at the constraints that such an enviromnent puts on you For example:-

  • Butler sinks
  • Large screen TVs
  • domestic cookers
  • lots of high power interior lighting
  • Poor storage
  • Inadequate off-grid power capacity
  • Ditto power replenishment
  • Composting loos
  • loos with rubbish steel tanks under your bed...
  • et al....

Methinks too many folks coming on here with impossible and inpractical requierments trying to have what works in "bricks and mortar" situations into what is fundamentally a glorified water based environment.

 

Some have done it

 

A helluva lot of newbies on here haven't. A shame 'cos it can be done.... with care....

 

Enough (a Large Whisky already consumed with the promise of an aged beef joint (long dead cow )magiced by SWMBO awaits here on land and I have every confidence that She will replicate that when on board...

 

Edited by OldGoat
'we' need a spell checker...
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On 07/08/2018 at 04:07, blackrose said:

I think horizontal skin tanks tend to be less efficient than equivalent vertical tanks because the heat rises to the top surface of the horizontal tank which has air on the other side, rather than the bottom of the tank against the river or canal water where you want it for max heat exchange. But I guess if its thin enough it will work. 

+1 for this?

We had just such a problem with a large volume horizontal tank - just a box with the base plate as it’s bottom and with no baffles.

Replaced it with a much smaller vertical one on the outside of the swim which was baffled and much thinner, probably about an inch compared with the 3” or 4” depth of the horizontal one.

I was amazed at how efficient the relatively small new one was - hot inlet at the top, zig zagging down to the cool outlet at the bottom.

Physics wins the day?

 

 

 

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16 hours ago, Boater Sam said:

If its unpressurised and doesn't boil, its OK.

If you know the horsepower, divide by 4 and that's the required skin tank area in square feet. assuming a side tank not a base plate tank.

The hotter you run a diesel within reason, the more efficient it is.

So it is dumping heat into the canal as it should, perfectly OK.

If its unpressurised and doesn't boil, its OK.

 

In general I agree with Sam but much depends upon the engine design. Engines are pressurised nowadays because certain parts can run very hot indeed and the pressurising raises the boiling point of the coolant and thus prevents the coolant boiling n these hot spots. Typically around the exhaust valve seats and the injector holes. Even allowing for the antifreeze to increase the coolant boiling point my gut feeling is that there is a danger on an unpressurised system running at 90C on a canal of it suffering localised boiling when  used on rivers at higher powers and speeds. I think I would change the thermostat for a cooler one. I think the one in there is probably 88C so an 82C or something around 75C may be a long term safer option. NOTE: the temperature gauge will not register localised boiling until sufficient coolant has been expelled to allow the engine to actually boil.

 

Agree it should be fine for canal use.

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Tony and others,

Thanks for the comments and suggestions. The location of the thermostat is not obvious as the engine is mounted to the side (we have hydraulic drive) but I'll certainly find it and look for a lower temperature one with a view to swapping it when I drain the system down to pipe in the calorifier. I've also worked out, based on its dimensions that the skin tank capacity is just over 15 litres. The baffles will likely reduce this but assuming they're welded to the outer skin rather than the inner wall, these should also aid cooling (must quiz Roger on this point).

 

I'll let you know how I get on.

Thanks again folks

 

Stephen

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33 minutes ago, Stephen Jeavons said:

Tony and others,

Thanks for the comments and suggestions. The location of the thermostat is not obvious as the engine is mounted to the side (we have hydraulic drive) but I'll certainly find it and look for a lower temperature one with a view to swapping it when I drain the system down to pipe in the calorifier. I've also worked out, based on its dimensions that the skin tank capacity is just over 15 litres. The baffles will likely reduce this but assuming they're welded to the outer skin rather than the inner wall, these should also aid cooling (must quiz Roger on this point).

 

I'll let you know how I get on.

Thanks again folks

 

Stephen

Its not the VOLUME  that determines how it cools but the surface AREA in contact with the canal water. How many square feet? How many horses in the engine? Maximum 4 times the area.

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56 minutes ago, Stephen Jeavons said:

Tony and others,

Thanks for the comments and suggestions. The location of the thermostat is not obvious as the engine is mounted to the side (we have hydraulic drive) but I'll certainly find it and look for a lower temperature one with a view to swapping it when I drain the system down to pipe in the calorifier. I've also worked out, based on its dimensions that the skin tank capacity is just over 15 litres. The baffles will likely reduce this but assuming they're welded to the outer skin rather than the inner wall, these should also aid cooling (must quiz Roger on this point).

 

I'll let you know how I get on.

Thanks again folks

 

Stephen

I also suspect you have an oil cooler for the hydraulic oil 

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