Keel-cooled outboard - PART 1

In this video I look at where the cooling water travels in an Tohatsu 9.8 HP two stroke outboard in order to start investigating how to convert an outboard to fresh water keel cooling.
For outboard repair information, checkout my website: outboard.danga...
If you are enjoying this channel, please consider making a donation to www.paypal.me/... or become a Patreon of Dangar Marine at / dangarmarine
T-shirts and other merchandise available at teespring.com/...
Common items used in these videos are available from my Amazon store at www.amazon.com...
Dangar Marine is proudly sponsored by MarineEngine.com. MarineEngine.com supplies a wide variety of spare parts for many brands of outboard motors. If you are in the US, be sure to check out their online store www.marineengin...
All music available at soundscloud.com...

[@onurson4000]

I love that hand-held bridgeport milling machine.

[@tyronerautahi9705]

Yeah I was thinking great I’ve never actually seen a head block milling machine I’m in for a treat. Then the disc grinder shows up. Got me good stu. Lol

[@DangarMarine]

Thanks mate. It wasn't their top-of-the-line model but I'm still very fortunate to have it. ;)

[@ripperace]

I’m very interested to see the completed project. It’s an interesting idea. Especially for the salt water bound folks.

[@DangarMarine]

Thanks mate. I think it will be a good upgrate for island boats where flushing them isn't really possible.

[@MrMccurley]

Got to admire a man who talks to his birds...

[@wissembannour3578]

I like what you do mate I m following you from Tunisia Great idea I did learn a lot from Ur videos Thank u so much

[@Jack-tx2ve]

Wanted to do this for years.

[@DangarMarine]

Me too!

[@Jack-tx2ve]

Looking forward to the results. Nice one Stu. Keel cooled hydrofoil wings?

[@stumphole8217]

the beard suits you, kind of like a boat motor jesus, i dig it!

[@vladavladic4070]

I like the project. I recommend that you leave the original pump in operation to cool the exhaust gases.

[@jaywalker549]

Stu, Treat it as if it were a motorcycle, using the motorcycle radiator, you could mount it on the lower outside of the transom, a couple inches separating the tramsom from the radiator will insure adequate cooling.,just a thought! Love the idea.... Keep up the great work. I wait in anticipation for the the next great video.

[@DangarMarine]

Yes, have been considering that, not totally sold on the keel cooling idea yet. I actually have a wrecked motorcycle that I could pinch the radiator off too so that may well be the way to go!

[@kimkeam2094]

Hi Stu, I hope you don’t mind, I referred you to a friend who has built a coaxial helicopter with an outboard engine as a power plant. He is suffering some cooling issues and this episode is just what the doctor ordered. Hope you don’t mind, but I think you are the best person with all the knowledge that I certainly am not up to date with this subject. Thanks

[@DangarMarine]

Sounds like an interesting project he's doing!

[@alan-sk7ky]

BTD 1982 ?

[@kimkeam2094]

@@alan-sk7ky 100% correct! He’s doing well but the nagging overheating is still an issue. Stu is the best one to understand the problem.

[@russellclement2058]

Hahaha love your portable milling machine Stu,,, hahaha,,, how many coopers did you find,,, 6 pack????

[@Fasteddyfishing]

Love the milling machine

[@jgsmith1624]

Surprised to see just how small the engine water passages are. I can see how easy it would be to plug one. Thanks Stu for showing this.

[@DangarMarine]

They aren't big, that's for sure. It isn't hard to see how they get blocked.

[@tallywhacker75]

this is basically how my friends boat air conditioner works, dosen't get "ice-cold" in the cabin and sleeping berths but keeps it all at a constant low temp (compared to the tropical temp outside) and use's very little power to achieve it (very low noise too :)

[@kiwiwifi]

This project is brilliant. If the goal is to keep the characteristics of an outboard at the core of your solution, then my money says, it’s doomed to fail. Why? Because there are some major challenges that lie ahead. (Especially with a retrofit) The existing outboard cooling method is too efficient to improve upon. An enclosed system, by design, Introduces inefficiencies that will transform its tiny footprint into a donkey and cart. A current outboard is self contained, compact, almost portable (4 bolts); reliable, lightweight, efficient, and very cheap to manufacture, maintain, and operate. Flushing and impeller maintenance is all that is required to keep it functional. Fresh water use is best of course. May I be so bold as to say, there is no real problem to solve. ( or at least none to solve when operated correctly) The following features afforded by a raw water system, give us the outboard motor as we know it. An enclosed system cannot utilise them. 1- tiny coolant capillaries and low surface area requirements of coolant/.material tho be cooked. (This is only possible because of a low pressure, fast coolant flow, and a low coolant temperature environment) This environment is the plat opposite of an enclosed system. 2. Raw water cooling in an outboard has a coolant lifecycle that is way more efficient than enclosed. It uses the unlimited raw water efficiently. If fact, it is too efficient and needs to continually uses thermostats, and poppet valves throughout the engines run cycle to raise the temperature of the cylinders to maintain optimal combustion conditions. (Cars do this type of temp management on startup only). The raw water coolant lifecycle is as follows… Cold water in, water gets warmer through the power head, water becomes hot over the exhaust manifold then is expelled. The last stage of the coolant lifecycle (exhaust manifold )is where the outboard temperature is predominately managed. The coolant needs to be hot enough to not damage the manifold, therefore when it has passed through the manifold cooling stage, the coolant is too hot and the flow is now slow, free and lush. Then bye bye into the sea or lake it goes. Good luck managing the coolant from here to cool it efficiently enough to pass back through to the first stage of an enclosed recirculated system. Here comes the next stage of complexity and cost.

[@o0Hotiron0o]

Thank you Stu ;)

[@DangarMarine]

No worries!

[@rivercitycarcare1266]

Hey mate Doesn’t the exhaust need to be cooled by water or the leg would get hot

[@Drmcclung]

For what it's worth there's a guy in my area who's been experimenting with PEX tubing run in straight lines along the hull ever since that stuff came state-side. He swears by it since salt and water can't hurt it and holds up to insane amounts of heat. A single loop below the water line (a straight shot towards the bow, and a straight shot back towards the stern along the other side) seems to do the trick for all the 4cyl 4-strokers he's played with, up to about 80-100hp it's been pretty bulletproof

[@DangarMarine]

Thanks David, appreciate the info!

[@Drmcclung]

@@DangarMarine He did suggest anything 40ish horse or less, a whole motorcycle radiator, fan, inline filler & cap etc was the way to go if you have the space on your transom. Since the fan & shroud are already there already in a "puller" config and they're pretty robust and the fans off Honda bikes are surprisingly powerful and quiet. Just a nice pre-made ultra compact little setup that works well, a lot easier to rig up than bigger power keel cooling.. Over 80 horse won't work without a bigger radiator if you have the real estate, otherwise run your heat exchanger underwater. For tapping into the engine cooling circuit you're pretty on your own as they're all the same yet they're all completely different. He's got an older Evinrude he drilled & tapped for bungs.

[@scanadaze]

Thanks for the class.

[@DangarMarine]

You are welcome!

[@sfrrob]

The mulitple camera angles and pov shots are great. I know it's time consuming when editing, but it's well worth it.👍 Looking forward to see more of these kinds of videos in the future.

[@DangarMarine]

Thanks mate, glad you like it!

[@David-ji1vk]

Funny to see this video pop up, while flushing my motor couple if days ago was thinking of ways to do somethi g like this

[@joeyhummer]

🤣🤣🤣 love that mill Stu. That made my arvo.

[@davekimbler2308]

How about cooling the fresh water in the leg with a coiled copper tubing and using the lower unit pump to circulate around the tubing having a closed system on fresh but open on salt ? Maintaining the original look of the outboard . Use 2 impeller pumps , 1 for salt and 1 for fresh ran on the drive shaft of the outboard

[@DangarMarine]

Have been thinking about that, definitely still one option that is on the table.

[@user-tv5dt3nm9y]

Brilliant concept. I wonder if there exists some data on btu created for a given horsepower from which we could make an educated guess on the size of keel cooler needed. I’m gonna guess that coolant fluid capacity will be key. More capacity may substitute for slower moving coolant.

[@AndreasTornbrink]

Great vid as usuall!

[@Antipodean33]

Hasn't got an oxy torch there at the moment, but fortunately he has a cylinder block milling machine.

[@MrLargePig]

Your idea for an adapter plate with as many of the connections inside as possible is a good one. A bit of machining, for sure, but neat solution, and it gets to the heart of the problem: It can be done, but is it sensible to do? Too many modifications and external fittings means too many places to fail. An adapter that contains all the various junctions and external fittings limits points of failure, and simplifies installation. Still wondering about the attachment to the heat exchanger- flex hose?

[@DangarMarine]

Yes, flex hose for the attachment to the heat exchanged. Thinking it would be best to group the with the fuel hose as a loom of three.

[@scottbeattie6645]

Educational and entertaining. Laughed easily as much as I learnt. The concept of an adapter plate to return to normal makes me think of all the effort put into other adapters and kits on the market, particularly with engine conversions etc. With all your engineering knowledge and skill you should be up for an Engineering Doctorate at Sydney Uni. Thanks for the effort for filming, editing, teaching and entertaining us all.

[@DangarMarine]

Thanks Scott. There are definitely challenges to the plate arrangement but I do like the idea of the installation being non-desctructive.

[@paulb1034]

An interesting vlog Stu, I'm puzzled why the outboard manufacturers don't use a sealed cooling system that circulates through the lower unit to dissipate the heat, fins could be added to the lower unit below the water line to achieve the required heat transfer.

[@mytube001]

Far too little surface area, I imagine.

[@DangarMarine]

Thanks Paul, it will be interesting to see how much cooling is required for this outboard and how compact it can be made.

[@ayl18]

Can't wait to see the project! what exactly do you do in IT?

[@DangarMarine]

Software development.

[@richardgatchell2523]

And also I have the same specialty surface milling mashean it uses all types of grinding disc's its a Dewalt hand held. Haha

[@richardwernst]

How are you going to cool the exhaust/area with water diverted? Perhaps utilize the regular water pump's output pipe to just flow water there?

[@nickscanlan1792]

What about cooling the exhaust in the leg so you don’t burn up the mid section or seals in the top of the gearbox

[@timjohnun4297]

Very good point

[@markk4285]

Thanks Stu. Very informative and entertaining. BTW I must have missed it. What happened to Peg Leg?

[@davidedwards6117]

where is the pump go that moves the coolant that works when the thermostat opens other than that look great

[@DangarMarine]

In the line between the header tank and the inlet on the block (see diagram at end of video)

[@mrleeal]

ok so block off both outlets. find the largest water jacket area block it off half way. drill and tap in and out flow each side of blocked area. run no thermostat

[@Phillv8]

I like the idea, however you will need to run the original raw pump to at least spray water up into the leg to cool the exhaust gasses. They will melt the plastic pump housing and seals very quickly if not cooled. That's why they have the outlets in the base housing poor straight back into the leg unrestricted. If you see a driveway hose come off and fry a pump in a couple mins you see all the damage the hot gasses do even under no load! They would melt the alloy under power with no water to cool and destroy all the seals.....

[@DangarMarine]

On the driveway the leg is completely out of the water, a huge amount of cooling is provided from the gearbox being submerged. Also, when running in the driveway without a hose the friction of the impeller running dry in the pump generates a huge amount of extra heat.

[@krissfemmpaws1029]

There is something you will need to do that is set the raw water pump up to cool the exhaust and gear leg.

[@caseyleonard6025]

How about utilising the raw water pump to inject into the exhaust gasses as high as possible to keep the midsection cool ???

[@DangarMarine]

Yes, have been thinking something similar. Just run it up to the top of the leg and let it flow back down. Having said that, I really can't see the exhaust getting that hot on a little outboard like this.

[@caseyleonard6025]

@@DangarMarine it will get hot enough to torch the paint off the leg , that little outboard will be working hard , near hot enough to melt the inner exhaust tube, be interesting to see the egt at the midsection after it exits the cooled manifold

[@CaptDavesSportfishing]

Im observing a phenomenon. Post china-plague, many KZbinrs look as if they've just given up. Given up on barber shops and razors, I mean.

[@boatbeard7767]

I wouldn't call the exhaust tube on a two stroke outboard a muffler, it's a tuned pipe so does have some effect - probably a quarter wave to work at 5000 odd rpm. The sound is only muffled by the water - as we all know from that guy at the ramp who insists on flushing their outboard and giving it a great handful of revs a few times... Earsplitting.

[@cjs3677]

Hi Stu, Prob covered this somewhere, but wondering where you did you trade, and whether you did marine or light/heavy vehicle

[@ianwilliams487]

G'Day Stu,,Mate been thinking about this for a while,,any way,,use the motor water pump to cool heat exchanger,,and run seperate pump for coolant, Make small bracket and mount it behind motor leg,?

[@DangarMarine]

That's definitely one option on the table.

[@BricoleurTV]

So glad you're doing this, especially adding the heater I've been thinking on for so long. Means I can relax, lean back and not having to experiment with my own engine.. Too bad there are no Coopers here in northern Europe 🙂

[@DangarMarine]

Hope we come up with a solution for you!

[@BricoleurTV]

@@DangarMarine Might be hard, at least expensive to get the Coopers through customs but I sure appreciate your effort!

[@colinmead8996]

What’s funny is I felt a little stressed out realizing the tiny waterways in my outboards hmmmm. We do flush them. I guess the momentum in the flow helps keeps them clean 😊 & cooling

[@DangarMarine]

Yes, it is interesting to see how easily they can become blocked with corrosion or debris.

[@troyrowy6709]

Could you put a tight multi coil hx inside the leg cavity and use the original pump to pass raw water over it, keep it all self contained

[@DangarMarine]

Possibly! That's a nice idea to keep it all very compact and self contained.

[@JohnSmith-yv6eq]

Whatever intake you have for raw water..is a weak point that can be blocked. A static run of copper tubing up to the bow on one side of the keel and back down the other side of the keel....uses "raw" water on the outside of the tubing to cool the engine coolant....but requires no inlet, strainer, grille or hole to plug up...and no pump..... But to cool the exhaust and the gearbox in the leg...that will require a pump or a scoop anyway......

[@ross82]

Isn’t the exhaust cooled by the raw water? I’m only a few minutes in so may have jumped the gun.

[@JohnSmith-yv6eq]

You couldn't be righterer...... plus the rubber hub if the exhaust exhausts through the prop hub, plus cools the top of the gearbox.... especially the seals on the water pump housing???

[@davidwindel8715]

Also we call them grid coolers. On the side's. I'm a Texas man so ? Think! You are great 👍

[@lesmansom7817]

I feel like a bit of a dill, I’ve been treating KZbin as a learning media, but It’s really just self inflicted entertainment isn’t it? You’ve got your chooks and Adrian, Damian has Jess and her various props, did I see a neck brace and a crutch in the one episode? 😎🤘👍🍺 I’m going to have to gave another coopers red and ponder on that brain fart. 🤘

[@iFixJunk]

I will never tire of Stu's subtle humor.

[@wadelintick9538]

I have started to skip the video and go right to the chickens, very rewarding. cheers

[@jamesread11]

This will be interesting to see how successful it works, just something to bear in mind, I assume you will need to bung the tell tale so you don’t dump the coolant out the back :-)

[@DangarMarine]

You'll see in the final diagram I have the tell tale plumbed back to the header tank.

[@stephendredge6077]

It might make the plumbing simpler if you don't pass the full flow though the header tank. All you need is a small swirl pot to separate any air and provide a small amount of expansion volume. Small tube from the high point in the cooling system to the top of the pot and one from the bottom of the pot to the pump inlet. Also the leg pump volume can be calculated fairly easily, difference in area between a folded and unfolded vane times speed.

[@jdoo2252]

clever idea

[@pearcebrown1043]

What an interesting concept! I look forward to seeing the results

[@DangarMarine]

Thanks Pearce.

[@assassinlexx1993]

Drill and tap the intake and output. Plug extra outputs . Drill two hole in the lower cowling for the two hoses. You can test with a electric pump in a pail of water . Making it possible to check for flow and temperature. Will you be able to use copper pipe on a aluminum boat. With the inner action between the two metals. This looks like a great idea. Yes beer helps in planning.

[@finscreenname]

I'm a little afraid the "radiator" that will be needed to hold enough water is going to be too big and create drag to be useful. You also will not be able to "plane" the motor being the skeg will rise up to the surface of the water when the motor is working the hardest. One long pipe up and back along the hull, attached to the motor with rubber hoses may be an idea for a less drag radiator.

[@DangarMarine]

Apparently not. I've spoken to a few people now who have done this up to about 40HP. A smaller outboard shouldn't be too much trouble to make work.

[@finscreenname]

@@DangarMarine Good luck! I'll be watching.😎

[@kurtkujawa3880]

DESIGN AND BUILD IT SELL THE KIT. COPYRIGHT

[@dennisbailey4296]

Great to see you exploring a better cooling solution!! Just got back from Brupeg to remove the old engine. That was quite a job!! All the best from Surrey BC Canada

[@DangarMarine]

Thanks Dennis. I’m looking forward to seeing how it turns out!

[@_bodgie]

Head surfacing accuracy to a thousandth (or two) of a meter😂

[@DangarMarine]

Not guaranteed though. ;)

[@_bodgie]

@@DangarMarine Fixed or it's *ucked guarantee, perhaps.

[@glenb3682]

Stu, any thought as to melting the lower engine crank shaft seal with out water jet cooling? That now dry exhaust is going to burn it all up along with the paint work on the leg , and the pivot grease, under a running heated load. looking forward to the progress. Or are you saving the original internal pump to dedicate towards the exhaust cooling inside the leg?

[@DangarMarine]

Yes, thinking coolant through the engine and raw water for the exhaust.

[@JamesDriver40]

I've done mechanical engineering on oil and gas equipment. From what I remember of the process engineers (aka wizards) saying (aka greek), heat transfer is increased with higher velocities of both hot and cold streams. It also matters whether fluids are flowing same, opposite or cross directionally, even when separated by a tube wall. Didn't seem right to me but I never passed any classes in the dark arts. Anyway, when optimising a heat transfer system, there's a pretty fine balance between heat transfer capacity, pump size, tube diameter and tube length. I'm hoping for the non-optimal duct tape and WD-40 prototype though. If you've only got one outboard to risk melting, maybe you should start running some experiments with hot water flowing through copper tubes. Take an inlet and outlet temp reading and calculate how many joules of heat energy you can dissipate with different flow rates or velocities. Pump some river water through an esky as the water bath to keep it a steady temperature. Another problem with a single tube heat exchanger is that after some initial length, additional length isn't very efficient because the coolant is cooler so there's less temperature differential driving heat transfer which is why heat exchangers are typically a tube-bundle design - keeps the length to surface area ratio down. All depends on how much heat you have to dissipate and the good news is water on the ambient side will absorb heat faster than air would. Bootleggers don't need too much copper pipe or water flow to condense ethanol vapour into moonshine.

[@DangarMarine]

Great point about multiple short pipes being more effective that one long. Makes perfect sense.

[@JamesDriver40]

@@DangarMarine the more I think about it, some sort of labrynth milled into a pair of plates would be a reasonable design for the keel cooler. Copper would be anti-fouling but galvanic against an aluminium hull without proper consideration. I like a plate design because it has a large mounting surface if you want to be brave and essentially glue (maybe a phenolic resin) it to the hull, and the leading edge might be shape-able to reduce drag/ eliminate cavitation if you're going faster than 2 kt. The outer plate could be milled with a shallow fin design for surface area to make up for not having all around contact with the cool water like a tube would. Extending the plate aft of the transom could keep any tube connections from the engine and expansion tank out of the turbulent water. The commercial units appear to be a through-hull fitting which I assume you're avoiding as it's an outboard engine so there are no other reasons to have holes in the hull.

[@davidwindel8715]

A block emd's 12/ 16 turbo and blown. Detroit 3/6/8/12/16 the stay clear! Done all this Fun stuff if I can pass knowledge I will smile! And my fun one was a cat 3512 a very fun learning experience. If we can think? We can!!

[@DangarMarine]

Thanks David!

[@whatsupshittafabraans1926]

The very first drawing, it’s a beautiful tell-tale, a short stroke of genius,very good, but seriously I always wanted to imagine a way capture free heat for my storage shower hot water from outboard, steering kills my ideas- chow

[@birdfeeding]

This is an interesting project. Looking forward to watching it progress.

[@DangarMarine]

Thanks!

[@normdawe6830]

That sounds just like Brupegs engine coolant system.

[@normdawe6830]

The water was run bow to aft outside of the boat to keep the engine cool.

[@shalnks]

Plastic radiator in a shroud for protection. Due to the heat transfer it wouldn't have to be that big. An electric pump would not last that long and the power it would depend on what size you need. Why not utilize the inbuilt pump. it is pumping the required amount of water to cool the motor so you know the size required. Adapter plates on the inlets to make a closed system.

[@AquaMarine1000]

Davis Craig electric water pumps are option lasting thousands of hours. These pumps have a glass filled nylon housing with a magnetic drive. Unlike engine driven pumps these are non parasitic. Davis Craig pumps are widely used in motor sport for their reliability and increased engine performance.

[@julianmckinnon7615]

why do 2 strokes need a thermostat? Won't 3 seconds of running get everything thermally expanded like pistons etc. Nothing else to warm up I imagine.

[@JohnSmith-yv6eq]

The temperature of the water that an outboard runs in is not always California bathwater... sometimes it's Alaska Bering Sea, or glacier lakes. You need a thermostat otherwise the engine runs too cold...... plus the thermostat actually forces the coolant to flow through every part of the block... and not short-circuit causing steam pockets in the non-thermostat, non-pressurised head....

[@anthonygordon6403]

Hi Stu - how do I send work to Adrian and you if you want it - particularly heavy diesel work to Adrian

[@tamaralee4108]

This is really interesting! How big to make the water pump and the raw water "keel cooler" pipe loop will be the most interesting issues.

[@richardgatchell2523]

Stu that drill holder pised me off that much I gave them away the person was my brother he can now deal with the problem shame I lost out on the money but I was sick of them falling on the floor when I couldn't get them out.

[@DangarMarine]

Glad I'm not the only one!

[@bobuncle8704]

Very interesting project.

[@kodibassInsideoutboards]

I Have been playing around with this concept for a while, My design will use the standard waterpump to deliver raw water to a expansion tank that has inter coils inside the tank, the sealed coolent from the powerhead would go thru the coils " Heat exchanger to b cooled. Because of thr temperatue differences this should cause the water in the block to flow. kodibass

[@Fantic156]

Bugger the outboards, show us more cute snakes ... 😜 Seriously, you do great videos mate, thanks .. 👍

[@dvx216]

if you have to drill plastic get drill bits for plastic and they wont blow out or crack when close to the edge.

[@DangarMarine]

I'll keep my eye out for some.

[@ryszardrudnicki7548]

Fajnie wytłumaczone dla młodych mechaników

[@rxcalvosa]

Call a patent attorney

[@samwhitehead7695]

Love your milling machine, Great to see a sense of humour,

[@rc300xs]

Milling machine 😂

[@youdonthavetoreadthispost.5850]

🤔 A flat-plate counter-flow heat exchanger could take the heat from an outboard and use it to produce heat and/or hot water🤔 A hybrid pair of outboards - one gas, one electric 🤔 Could recharge its own batteries on the run 🤔 Heated handrails are a possibility 🙂 It's all in how you control the exchanges. Good stuff with lots of possibilities.

[@DangarMarine]

I like the idea of headed hand rails. :)

[@youdonthavetoreadthispost.5850]

@@DangarMarine They have them on the fishing boats up north. Everything freezes. We stood on gunny-sacks for traction. Baits froze on the hook. A heated handrail and a warm cabin was a blessing when fishing for cod in January 🙂off Montauk N.Y. which is a fishing mecca, in case you don't know. Now I have a propane heater for my Aluminum drift boat which cannot burn 🙂

[@bensmith4563]

That milling machine is tops

[@benrandomly2016]

Don't use a pressurized radiator cap. Outboards don't use pressurized cooling, they use flow. It may cause internal gasket failures.

[@simonilett998]

Adaptor plate method will also require a longer driveshaft to match the extra thickness of the adaptor plate. Also, don't overlook the need for exhaust cooling that would've been done by expelling the original raw water out through the prop👍🇦🇺

[@nielsdebakker3283]

exhaust/tail section cooling, I am 5 minuntes in and I am already missing that bit. The tail section of the outboard will get hot as hell caused by the exhaust gasses. Grease and oil in the tail will not like that.

[@DangarMarine]

Good point about the driveshaft (and gear selector) length. Looks like it might be easier just to tap in directly.

[@soggybottom3463]

"If you mark and pre-drill all of them, none of them will line up"....Hmmm. I believe that is a quote from the Bible. And if it isn't, it really really should be...😂😂😂

[@KevinPaulineNeal]

Hi. I’m trying to figure out what the shaft size and thread type is on my 1991 90HP 2 stroke flywheel is. The Nut is missing and I’m trying to find another. Any idea?

[@peterfuchs4596]

Love the thinking but wonder on economics. Are well made marine alloys well able to take SW vs closed ID flushed or if not. Flushing difficult in many areas asvFW not available so I'm interested why big commercials haven't researched this for that market. Many use diesel outboard or mini prop . Slow as hell but durable and can run off coconut oil locally made and often sail supplement. Mainly interisland transport and fishing handline bottom or smaller tuna . It would be great if a way to help tens of thousands without FW dock access if they could double internals life. Example my Chevy pickup probably go 300k with reg maintenance but if SW run through it doubt it make it half way . Apply to small boat engine for subsidence fisherman and a huge potential savings . Eg you could run double time sharing a boat at same lifespan but feed two families. Well I enjoy all your work as obviously many do and you inspire more thinking. I often wonder about electric too and some sort ofvenergy recapture if drift fishing and solar. Again thinking of our less fortunate relying on slow but stable power to live in rough environments with more limited resources and a real need for local fuels like coconut oil and sun. A few miles offshore at 5bkts top gets you a boatload of fish in half a day when running. Salt and dry for bad weather. Sweet potato coconut pandanus breadfruit and poultry swine but nothing like fresh fish!

[@stephenstebbing9460]

Must have been quite a few Coopers on Renko I reckon.

[@user-Adam72]

With the 'telltale's lines - I would suggest having 'clear' bulb windows so that you can visually see the water is flowing - pressure sensors may not be reliable at the low pressure. I would then feed them back into the main line back to cooler locally at the engine - this would reduce the chances of springing a leak on those runs, and/or keep the leaks 'ouboard'.

[@leebatt7964]

Stu, some older snowmobiles used a very similar cooling system, coolant runs through heat exchangers that are positioned in the track tunnel so that snow is thrown up onto it. P.S. for those Aussies that may be reading this, snow is frozen water that falls from the sky in the form of a fluffy solid and covers the ground. Snowmobiles are what rednecks use to travel over snow, usually very drunk and way faster than is safe to do so. Think jetski minus the hot bikini clad sheila but instead with an obese man wearing a space suit.

[@tamaralee4108]

Doesn't some of the existing pumped water get injected into the exhaust gas flow to cool it? If so then will you still need some pumped raw water to retain that function?

[@DangarMarine]

This doesn't seem to have much cooling water going into exhaust but there are plenty of option to solve that problem if it gets too hot!

[@calvingreene90]

Open cycle water cooling to closed cycle water cooling.

[@nathansalway8015]

I've thought about doing this. 1 no more impeller changes and 2 I can run a cabin heater off it so many cheap 12v water pumps available now makes the idea very tempting

[@alan-sk7ky]

Neat project, Stu do outboard legs need water down the exhaust to prevent overheating damage? If they do perhaps retain original waterpump and divert that water up a pipe and back down in the exhaust gasses.

[@shirmworm]

Great vid!!! Thermodynamics = Fun Times!!!

[@AlisonFort]

They make themselves feel at home, these birds!

[@DangarMarine]

They do!

[@thething4763]

My thought would be to keep the raw water pump and weld covers over the raw water intakes on the leg. Inlet side and pump handled. Return side ??

[@nicksaunders8814]

Could you demonstrate how to set up the rollers on a boat trailer. I’ve been towing on gravel roads and mine are out of alignment. Would like to know how to reset. Or servicing a boat trailer?

[@JamesKlyng1twofish]

M dot X cp X delta t is the formula for a heat exchanger. M dot is mass flow rate of the fluid moving, cp is specific heat of the fluid, and delta t is the temperature difference that can be required. Equal both of these together for each side of the heat exchanger fluid.

[@michaelnelson912]

Put me down for one of the kits when they come out :) This is fun!

[@jacobpetersen9430]

So cool i aleays thought about this as well intresting to see how it goes :)

[@darrylmcleman6456]

Several of my boats had "BUSS HEATERS" in them running of the v-8 I/O. We had year round fishing here on Canadian Westcoast and once hands got wet and cold it was game over.The heater was a great hand warmer! CHEERS from HERE!

[@DangarMarine]

A heater does sound like a good thing to have for a winter fishing trip.