heat exchanging radiator

[mattoc]

I have a LD 20 diesel and am researching alternative cooling systems rather than the common keel (copper piping running along the side of the keel) and raw water (in through the hull skin into engine and out muffler) systems.

Why not mount the radiator to the external transom wall under the waterline surely this would provide adequate cooling to the motor, being that water temperature is always greatly cooler than air temperature (which the motor was designed for) and there is always a constant flow of cold water.

Wouldn’t this be very similar to a heat exchanger were raw water is brought up through the hull skin and circulates around the internals of the heat exchanger and out through the muffler.

ANY help would be Great help
Thanks Matt

[StianM]

I don't think the heat flow will be big enough. what kind off hull is it? steel?

[mattoc]

its a 21ft hartley launch, glass over ply

[mattoc]

what do you mean by heat flow, do you mean this might cool the engine down to much ?

[StianM]

I'm not shure if I understand, but do you intend to use a comon radator?
You think that the cold seawater will cool down the hull enough so you can cool the radiator by cool'd air circulating the hull?

I mean that the heat flow trough the hull is not big enough for this.

If you had a steel or luminium hull it could be posible to weld circulating pipes directly to the hull and cool it that way, but it would nead to be smal pipes to get big enough area.

Would like a bether explanation or a drawing to tell

[stonebreaker]

What kind of radiator are you thinking about? One that normally operates in air? I wouldn't think a normal air to engine coolant type of radiator would stand up very well to high velocity water over it - the cooling fins are pretty thin and easily bent. Of course, you could maybe cut the fins out of the radiator. The radiator tubes are, after all, optimized for heat exchange.

Does your boat get up on plane?

[Frosty]

I think he means put the radiator in the sloshing water outside of the boat just below the water line on the transom. At 20Hp it cant be a planing boat!!!.
However I think it would work but not for long, I mean if this was in sea water it would crud up in days,-- let alone rot away. But if you made it so it folded up out of the water and maybe --yeah cut the cooling fins out.

[mattoc]

The Ld 20 is a 2 ltr diesel, I was thinking off mounting the radiator to the outside of the transom, just under the water line were the water is not violent, the launch was designed for planning but to accomplish this I would need over 180hp the Ld 20 puts out around 75hp I just want to potter around.

But I got word today that because the radiator is made of two types of steel usually copper and iron this may create a chemical reaction which will corrode the radiator rapidly

Ps how do I post drawings

[StianM]

You nead to find a host for the pictures.
I use photobucket http://s43.photobucket.com

Then you paste the image url in your post.

I would not put the radiator in the water.
Then using large wents on the engine bay and electric fan's for aircoling be a far bether option.

I don't think you will nead to pay a arm and a leg for a propper heat exchanger. I gues you can find one on a junkyard, shipyard or a place where they dismantle old old boats for scrap.

[FAST FRED]

"am researching alternative cooling systems rather than the common keel (copper piping running along the side of the keel) "

No need for expensive copper , we keel cool a DD 6-71 with 2 - 20ft pieces of 1 1/2 common water pipe and a couple of elbows. Anti rust painted of course.

FAST FRED

[Frosty]

Here in Thailand where truck motors are put in boats, You can buy huge iron heat exchangers with a brass tubed core that can be easily dismantled for cleaning, repair or replacement and the two plates at each end have just 4 bolts holding the end plates that are also reversable. there is but 2 x O rings and thats it. They cool engines up to the size of Hino E 700 ,-- wiegh a ton though but even have feet to screw to the bulk head and a filler cap on the top. They are CHEAP and come in various sizes.