Trying to understand skin tank cooling

[Ricco1]

My newly bought boat has skin tank cooling. I'm casting my mind forward to the winter, if we have a cold spell.

 

First thought was that the skin tank is below the level of the canal so shouldn't freeze up.

 

I then considered the water around the engine, which is possibly above the level of the canal. And the header tank, which certainly is.

 

Do I need to use anti-freeze? If so, how much? The skin tank looks like it holds dozens of gallons of water. I don't have to add gallon after gallon of anti-freeze, surely?

 

 

[Ray T]

Definitely use anti freeze, a 50 - 50 mixture will suffice. Just treat as you would your car's engine.

 

If you have central heating radiators in your boat that system will need anti freeze as well. Again I use a 50 - 50 mix in our boat.

Anti freeze will have corrosion inhibitors as well.

 

Unless you want to drain the entire system every winter.

Edited September 8, 2013 by Ray T

[nicknorman]

Definitely use antifreeze. I would say 30% antifreeze to 70% water is fine, because as you say the canal is unlikely to get very cold, although the pipe work in the engine room will probably get colder. But importantly, the antifreeze contains a corrosion inhibitor which will stop the innards of your engine dissolving into the coolant.

[Guest]

50/50 in mine. I change it every three years (ish). I am not 100% on this but seem to recall the system held 8 gallons. It will vary of course from boat to boat. easily tested with cheapo hydrometer from Halfords.

Edited September 8, 2013 by Guest

[Ricco1]

50/50 in mine. I change it every three years (ish). I am not 100% on this but seem to recall the system held 8 gallons. It will vary of course from boat to boat. easily tested with cheapo hydrometer from Halfords.

 

Sorry, is it the percentage of anti-freeze that you check with a hydrometer?

[Guest]

 

Sorry, is it the percentage of anti-freeze that you check with a hydrometer?

The one Ihave just has three balls in it. If they all float it is a certain strength, but TBH can't remember properly. It explains it with the gadget which is only a couple if quid or so. It displays the strength of the coolant mix. An expensive hydrometer will give the SG.

Edited September 8, 2013 by Guest

[nebulae]

As has been said,definately use an antifreeze in the cooling system.Blue anti freeze lasts for 2 years,green for 3 and red for 5 years.It is the inhibitor that degrades rather than the antifreeze.

[dmr]

My newly bought boat has skin tank cooling. I'm casting my mind forward to the winter, if we have a cold spell.

 

First thought was that the skin tank is below the level of the canal so shouldn't freeze up.

 

I then considered the water around the engine, which is possibly above the level of the canal. And the header tank, which certainly is.

 

Do I need to use anti-freeze? If so, how much? The skin tank looks like it holds dozens of gallons of water. I don't have to add gallon after gallon of anti-freeze, surely?

 

 

 

Has no one told you...boating is an expensive business! That whole cooling system needs antifreeze and the more expensive pink one is preferable.

With a bit of luck you will get change out of £100

Note that you should really drain the system, mix the antifreeze with water (50:50 as said above), then refill your system with the pre-mixed antifreeze.

Just pouring neat antifreeze into a part drained system is not ideal.

 

..............Dave

[bigste]

I live in Spain so no frost. We all use anti freeze because it is a rust preventer so you must use it for sure.

[Ricco1]

Thanks for the replies. I've no idea how much water my system holds. The boat was made by Hallmark, who have ceased trading. A google search for the specifications has drawn a blank. Any ideas where I might find out?

[RLWP]

Measure it! The tanks are rectangles, the pipes are cylinders and the engine will have a published capacity

 

Richard

[Guest]

I just drained mine into gallon containers, then when I knew how many gallons, I went and bought some antifreeze.

[Ricco1]

Measure it! The tanks are rectangles, the pipes are cylinders and the engine will have a published capacity

 

Richard

 

Tough one that! As for the engine capacity, how do you work it out from that? Is the engine capacity not the cubic capacity of the engine cylinders where (hopefully) no water should enter?

I just drained mine into gallon containers, then when I knew how many gallons, I went and bought some antifreeze.

 

Right. Next job (after checking with hydrometer I'll buy) will be how do drain the system. I'd imagine there should be a drain plug on the skin tank rather than the engine, the former being lower than the latter.

[Guest]

I got all the coolant that I could out of the engine with a lift pump (loads on Amazon for a few quid; handy on boat for other jobs) then took the vent out of the top of the skin tank and got out of that what I could with the pump. I took the hose off the engine that goes to lower skin tank and drained that inot containers with a funnel. suppose it should be flushed with clean water but I didn't bother. I filled the skin tank through the top breather then the engine last. Maybe I was lucky, but no airlocks were noted.

[Canalwatcher]

Cooling system on Zodiak (Isuzu 42hp) takes 26 litres including engine, skin tank and calorifirer.

 

Mick

[RLWP]

 

Tough one that! As for the engine capacity, how do you work it out from that? Is the engine capacity not the cubic capacity of the engine cylinders where (hopefully) no water should enter?

 

Not that tough - you are just trying to work out to the nearest 4.5 litre bottle how much anti-freeze you need

 

What engine do you have?

 

Richard

[Ricco1]

 

Not that tough - you are just trying to work out to the nearest 4.5 litre bottle how much anti-freeze you need

 

What engine do you have?

 

Richard

 

It's a Vetus M2, 11hp. I'm not certain of the engine size, but I think it's 1000cc

[RLWP]

The engine is 635 cc according to this: http://www.vetus-shop.com/vetus-m206-mitsubishi-engine-16hp-fwc-tmc40-21-p-2392.html

 

That's the cylinder capacity, not the coolant capacity

 

Richard

Edited September 9, 2013 by RLWP

[Ricco1]

The engine is 635 cc according to this: http://www.vetus-shop.com/vetus-m206-mitsubishi-engine-16hp-fwc-tmc40-21-p-2392.html

 

That's the cylinder capacity, not the coolant capacity

 

Richard

 

Thanks. Mine is a different one, the 11hp version, out of production now, I believe.

[trackman]

My 3 litre tug engine, ie large, with correspondingly large skin tank, needed less than 3 of the 4.5 litre containers of anti-freeze. That was to give a 50% mix.

The system includes a circuit to a calorifier coil and long hoses to/from the skin tank, since the engine is in a trad style engine room and the tank is under the back cabin some way away.

Your system isn't likely to need as much coolant as this, I would think.

Mix the water and anti-freeze before pouring them into your system, they don't mix easily once in the pipework. Engine cooling is probably not so sensitive as heating systems, but certainly in the latter unmixed stuff can cause fluuid locks that stop the flow totally. Rather like an airlock, but with the less dense anti-freeze rather than air being the culprit.

Edited September 13, 2013 by trackman

[RLWP]

Mix the water and anti-freeze before pouring them into your system, they don't mix easily once in the pipework. Engine cooling is probably not so sensitive as heating systems, but certainly in the latter unmixed stuff can cause fluuid locks that stop the flow totally. Rather like an airlock, but with the less dense anti-freeze rather than air being the culprit.

 

I'm pretty sure that advice relates to gravity feed systems, where the density of the liquid makes the system work.

 

If you have a pump, I can't see there being any problem

 

Richard

[blackrose]

A bloke who moored near me on the Thames told me his Liverpool boat didn't have a skin tank. I said that would be very unusual and had a look. Sure enough it had a skin tank but after 3 or 4 years on the boat the owner had never put any antifreeze/coolant into the system, just water!

 

I took the cap off the header tank to have a look if it was a coloured fluid and a drop of water fell off the cap onto his engine. He immediately grabbed a cloth and wiped it off. His boat was certainly very clean but I should think his engine must be in a terrible state. I couldn't help thinking that an aluminium engine block with rusty water from a steel skin tank running through it must be a good recipe for galvanic corrosion.

 

Funny how some people who clean and polish have absolutely no mechanical sympathy.

Edited September 13, 2013 by blackrose

[Guest]

I have often wondered if this stuff lives up to its claims:

http://www.ebay.co.uk/itm/Red-Line-Water-Wetter-Super-Coolant-355ml-Reduces-Temps-15C-/370872163729

 

Seemingly it can lower cooling temps by 15C, decrease warm up time, inhibit corrosion and lube the water pump. I have heard of something similar being used in liquid cooled racing engines.

[Tobymonster]

The skin tank will hold most of the coolant by volume. Buy enough coolant to fill up that tank. Don't go to Halfords unless you have their trade card, instead visit PartCo, Euro Car Parts or GSF where they sell antifreeze in 25ltr containers. Much cheaper, probably around £60. Pre mix the coolant with water and fill up the drained down system. As said previously, aim for 50%, but it doesn't need to be spot on, +/-20% will be fine.

 

Not only does coolant prevent corrosion and freezing, it will also help in keeping the engine and it's surrounds cool in the summer, (if the skin tank is in good condition and not too small)

Edited September 24, 2013 by Tobymonster

[Iain_S]

Thanks for the replies. I've no idea how much water my system holds. The boat was made by Hallmark, who have ceased trading. A google search for the specifications has drawn a blank. Any ideas where I might find out?

 

If it's a Vetus M2, the actual engine holds 2.2 litres coolant, or 3 litres if set up up for keel cooling (according to the manual). If the latter, you have to add the capacity of the skin tank and connecting hoses, which can be calculated. ( for the tank, L x W x H in cm, divided by 1000 : for the pipes : (half pipe diameter squared) x 3 x length (all in cm again), divided by 1000 will give the capacity in litres (near enough).

 

Iain