Hull Cooling Closed System

[Moab]

I have been searching and cant find anything about this but I was wondering about using the hull surface to cool the engine.  Basically run a closed system where the engine coolant runs through something like a strake to cool it and then back to the engine.  I was actually thinking about something on the inside of the hull but it would be the same idea.

I am sure this has been done before but I dont know what to search for and havn't found anything yet.  I am sure if it was brilliant it would be done more but I would still like to learn more.  Water from the jet can be used to cool the exhaust.

Matt.

[johnmead]

The easiest and most trouble free, as in not easy to block, in my opinion, is the 40ml/20ml copper pipe that has been covered here in the past. I would be worried about having it as part of the hull, as it would be susceptible to damage, well in my boat anyway  . It would need to be in contact with the water at all times, which means that part of the bottom of the boat which gets the most hits.  Cheers John

[johnmead]

The water from the jet goes through the 20 ml pipe, inside the 40ml pipe which is the "radiator" and then out through the exhausts. 

[JR]

The water from the jet goes through the 20 ml pipe, inside the 40ml pipe which is the "radiator" and then out through the exhausts. 

I agree with what John has said... Copper xchanger is the way to go ....Dont try to re invent the wheel.... Cheers JR

[Moab]

I know about the copper heat exchanger.  It is actually how I first learned about this site, some one linked a thread about how to build them.  I really think the copper tubing exchanger is brilliant and the way to go.  I am running raw water throught a sand trap in my boat because of the simplicity and it is working great.  I was just curious if people used hull cooling in small boats and if it was effective.  And if they did how much surface area would it take?  I know there is a tremendouts amount of cooling potential through the hull I just wanted to know if anyone had tried it and how effective it is.

Matt.

[mof]

Matt, small boats are usually used to pound the living daylights out of, in remote water of no passers by. Less things to go wrong means easier conclusion to your day's boating. Did you see Cookie's thread the other day with the heli ride out? Stuff happens to your hull, and having a sandwich plate cooling system just adds to the risk with every impact. At least with the copper tube HX, you can bend the hull, even split it a bit, and still get home with your engine still running. Keep it simple, tried and true.

[Paul]

Matt, small boats are usually used to pound the living daylights out of, in remote water of no passers by. Less things to go wrong means easier conclusion to your day's boating. Did you see Cookie's thread the other day with the heli ride out? Stuff happens to your hull, and having a sandwich plate cooling system just adds to the risk with every impact. At least with the copper tube HX, you can bend the hull, even split it a bit, and still get home with your engine still running. Keep it simple, tried and true.

 

There's too many things to go wrong on these things already (been there many times), keep it simple, tried and true, and you might get back to the ramp under power....

[powerwill]

I have made 3 alloy boats [only one was a jet] and used the planing strakes for cooling all worked great. Im about to start on a small JET BOAT and am thinking of using 20 mm alloy and 40mm pipe inside the boat any thoughts, [much cheaper than copper]

[Jeff B]

Using aluminium tube instead of copper works fine. I have made full aluminium heat exchangers and they work excellent.
Aluminium is not quite as good heat conductor as copper so will need to be a bit bigger than the equivalent copper one.
Also corrosion resistance is not as good as copper and in salt water it will eventually corrode.
The thinner you make the material, the better it will transfer heat

[Jimmy Jet]

The old man cools his 400hp Chev with the set-up you are thinking of. It's works very well and the system is quite short due to increased cooling capacity through the hull. I did warn him that if he taps the bottom he'll probably lose his cooling if it cracks.
I'd go the 40/20 copper tube way for reliability. Approx 1 mtr of length will cool 100hp.

[johnmead]

The strakes on the old boat are almost flat  , none of them are without at least one damage spot and definitely cracked, going by the amount of water that drains out of them on the way up the road  They sure wouldn't have lasted long as a cooling system 

[powerwill]

So if I went with  2x 1.5 meter lengths of alloy piping it should cool a 3.9 rover v8?