I'm an engineer that specialized in fluid mechanics and heat transfer. You did a great job. Some keywords for the topics you're working on are: counter current flow, approach temperature, tubing equivalent length, individual and overall heat transfer coefficients, NPSH available vs required, suction lift.
Thank you Art for your compliments and input, great food for thought! I will certainly look into these key words you have given me in an effort to improve the cooling, especially with the 3kw air-cooled motor I am striving to cool. Definitely using a fan to blow air out of the engine housing for the 10kw set-up would help.
The position of the external seawater pick up on the hull is vital to cooling as youve found. Look at how electric rc models position their pic ups to avoid cavitation. You may need a small scoop or tube projecting beyond the hull boundry layer.
Yes, I suppose a bit like one of those water pick up thru-hulls would be ideal. We must be content with getting our water through the saildrive though as we are so guarded against any drag. At least now we don't have to run the engine while sailing to make power like we used to.
It's so exciting to see your setup. I hope my aircooled gm 10kW will run cool enough. I'll mostly sail in Sweden and try to get to the med in the winter. So on average the air temp is about 15C maybe. 😅
Unfortunately you cannot rely on predictable air temperatures given climate shifts. So you may have to duct blown air over your motor or controller. If that fails model boats have used DIY contact coils wrapped round your motor case. See how it goes.👍🏻🧙🏻♂️🇬🇧
The video is very helpful with operating limits. If you can feel the air moving in the motor bay, estimate 15-30C colder air than motor limit required. Besides in and out fans, plan for engine bay fan. Use the video info ~1.5kW of waste heat to estimate air flow necessary. 0.25 BTU/lb-F, 28.8 lbs/359 standard cubic feet. Then delta T with 25-40F approach temperature. Maybe more air than you can move, I didn't do the calculation yet. Sorry about mixed units....those are the ones I know :-) Edit: I did quick calc, shoot for 100-200 cfm through engine bay plus circulation in the engine bay.
@@MoseLaura Lots of good advice for you Mose. Yes, I think you'll be OK with short runs for hoisting sail etc and for extended running you may need to blow air over it equivalent to the wind a motorbike would produce. Am keen to see your install!
@@AndrewStransky-cc2dr Yes cool! I ordered some fans so I'll install them in the motor compartment. At least to get fresh air through. I mostly sail but of course the motor is good for safety some times so then it's good to be able to somewhat rely a bit on it. :)
Interesting video Andrew. Have you considered using your cooling system to heat some of your freshwater supply? On Mind the Gap, one of the diesel engines supplied hot seawater to heat up the fresh water in our hot water cylinder. It was the only source for our hot water. Warm showers and hot water was pretty much taken for granted courtesy as a by-product of the system. Presume you have a similar setup from your remaining diesel engine and you could convert your electric cooling system to do this job as well, if necessary.
Thank you James! Our hot water heater was actually on the side of the motor we removed. We have been using the tanks 240v element to make hot water but when its overcast we do fall short of power. I don't have the coolant running through the tank yet but have heard others saying it is a good idea so may have to plumb that in although I'd thought it was a good weight saving not having that extra pipe, fittings and coolant , haha!
