Information Overload - Where do I start?:)

[Skypower]

Ha Ha - I see a clear link between Cats and crazy boat projects..... I have two cats myself and convinced that I 'speak' cat (from the outside I probably just look a crazy cat-man) If I understand it correctly the Digital Mermaid also gets allot of help in her build by her cat/s. Before I decided on building in Aluminum I did allot of research and all other materials scared me in one way or another (either from a maintenance effort point of view, or just unknowns I could not 100% control such as osmosis etc.). The curves and soft lines you can achieve with wood/glass is obviously a huge advantage but luckily I have personally always favored practicality over aesthetics so no loss on my side in that area Wow - A 65’x14’ or 70’x16’ house boat of that style, that is what I call a house boat!! And as you say, no lack of space to put your solar panels!! Go for it!!

At one point I had 3 cats(in the boat) and one harbor cat. The harbor cat was my guard cat and kept the males away from marking my boat when I was gone. She was well rewarded. She didn’t keep one female from having kittens in my flybridge! One of my 3 convinced me that she’d rather stay home and not go boating. That left Alex(orange) and Bob. Bob made it to 24 and Alex 13. Bob was super chill with anything and Alex was more like my shadow, very much with a personality of a smart dog. When we got to the islands he had free rein as long as no one had dogs.

 

[Modular Hippo]

At one point I had 3 cats(in the boat) and one harbor cat. The harbor cat was my guard cat and kept the males away from marking my boat when I was gone. She was well rewarded. She didn’t keep one female from having kittens in my flybridge! One of my 3 convinced me that she’d rather stay home and not go boating. That left Alex(orange) and Bob. Bob made it to 24 and Alex 13. Bob was super chill with anything and Alex was more like my shadow, very much with a personality of a smart dog. When we got to the islands he had free rein as long as no one had dogs.
View attachment 162726

Fantastic!! Cat's are such good company, we are of course only there humble servants (we all know that) but still the best!! Alex looks well cool, amazing how they always manage to jump up on the stool you are about to sit down on only seconds before you intend to use it (as if they know in advance, ha ha). Had cat's since I was born and the last two are called 'Black' and 'Brown'. Live in the country side and they were accidentally born in our attic without us knowing. Two weeks later the neighbor moved and took the mother cat with her (also not knowing about the litter). Watched TV one night and heard some strange noises, found the two hidden in the rafters and after 2 days of offering them water and some food I managed to get them down. The basic names of 'Brown' and 'Black' temporary as the first intention was to find a good home for them. We are now 5 years down the line and they have kept their names and rule the house They are both out and about at the moment or I would send a photo (one is a male black & white 'tuxedo' cat, very James bond!!) the other brown with a beautiful pattern and longer hair (female). Who knows, maybe they will travel the seas with me one day if all goes to plan

 

[Skypower]

Fantastic!! Cat's are such good company, we are of course only their humble servants (we all know that) but still the best!! Alex looks well cool, amazing how they always manage to jump up on the stool you are about to sit down on only seconds before you intend to use it (as if they know in advance, ha ha).

Exactly lol! He’d jump in the chair and look so satisfied with his eyes saying “Nice chair, where are you gonna sit?” So the next day I went to COSTCO and bought a second one (because they never carry anything you like very long). Next weekend I put both chairs down. He hopped in one and then the other. Funny to see the look of confusion and frustration as I wrecked his game.

 

[Skypower]

Cooling the speed controller with a raw water cooled heat sink may be a good idea but materials with copper or brass(zinc alloy) involved could be bad. You could make one from 6061-T6 aluminum with your own dimensions. The hose fittings should be Marelon fittings and the cross hole plugs should also be plastic to avoid galvanic corrosion. A “plastic safe” pipe sealant should be used, many are not. I would stay away from Teflon tape because of the extreme pressure it can exert on the plastic before it gets tight and it can loosen. I wouldn’t use anything permanent like 3M 5200 or Stikaflex. The idea is that there are two plenums that connect the cross holes and if the entrance and exit are on opposite corners that no path is different in length. For this to work the water must fill from the lowest and exit from the highest. It can be inclined to still work. If the flow was reversed the water could simply take the first cross hole and not reach the others. This could be made in a machine shop or “gun drilled” a competent person in a home shop could do it as long as they get the holes started straight.
The sketch is purely an example and probably not the size you need.

 

[Modular Hippo]

Exactly lol! He’d jump in the chair and look so satisfied with his eyes saying “Nice chair, where are you gonna sit?” So the next day I went to COSTCO and bought a second one (because they never carry anything you like very long). Next weekend I put both chairs down. He hopped in one and then the other. Funny to see the look of confusion and frustration as I wrecked his game.

Ha Ha Ha

 

[Modular Hippo]

Cooling the speed controller with a raw water cooled heat sink may be a good idea but materials with copper or brass(zinc alloy) involved could be bad. You could make one from 6061-T6 aluminum with your own dimensions. The hose fittings should be Marelon fittings and the cross hole plugs should also be plastic to avoid galvanic corrosion. A “plastic safe” pipe sealant should be used, many are not. I would stay away from Teflon tape because of the extreme pressure it can exert on the plastic before it gets tight and it can loosen. I wouldn’t use anything permanent like 3M 5200 or Stikaflex. The idea is that there are two plenums that connect the cross holes and if the entrance and exit are on opposite corners that no path is different in length. For this to work the water must fill from the lowest and exit from the highest. It can be inclined to still work. If the flow was reversed the water could simply take the first cross hole and not reach the others. This could be made in a machine shop or “gun drilled” a competent person in a home shop could do it as long as they get the holes started straight.
The sketch is purely an example and probably not the size you need. View attachment 162879

I like your idea and very much doable even for a DIY person. Am I understanding it correctly that you would feed it cold raw water and pump it back in to lake/sea once it has passed through the heat sink,absorbed the heat and done it's job. Or are you thinking a closed circuit? I guess the first one as if not the temperature would just keep on rising. I guess you either use something like this where you use a pump to move the water through the system and keep feeding it cool raw water, or you use a closed system where you need a pump to move water plus fans to cool the water. I guess raw water cooled engines are standard so nothing new but as I never operated one myself I directly wonder how seaweed and other debris is stopped from clogging inlet, or if entering the system what other issues could occur? I like the idea!

 

[digimer]

"you mentioned aiming for 12-15 so what is your thoughts about that?"

The trip home made me realize (I think I mentioned earlier) about how much running under power I'll actually do. On top of that, it's entirely possible to push into an adverse current for hours on end. So given then, I decided I wanted to be able to push hard, so I went from thinking 10hp would be ok (1kw:3hp) to wanting to be closer to 1:2 instead. To get that in a 48v package, 10kw/motor seems to be max. 2x 10kw would for sure give me the oomph I need when I need it, and would be overkill really. However, the best motor option I've found so far is 5 or 10kw, so 2x 10kw is the top choice atm.

"Or are you worried that the heat in the motor/controller area will be so hot that it will only push hot air around"

Exactly. Knowing now that motoring for 8h straight is entirely possible, that's a lot of time for heat to build up in the engine bay. I know I can vent the engine bay, and maybe that would be enough to do it. However, I already have the 3/4" through-hull/seacock and heat exchanger, so might as well use it. Should be less noisy, not having a pair of squirrel cage fans running in the engine bay as often.

 

[Skypower]

I like your idea and very much doable even for a DIY person. Am I understanding it correctly that you would feed it cold raw water and pump it back in to lake/sea once it has passed through the heat sink,absorbed the heat and done it's job. Or are you thinking a closed circuit? I guess the first one as if not the temperature would just keep on rising. I guess you either use something like this where you use a pump to move the water through the system and keep feeding it cool raw water, or you use a closed system where you need a pump to move water plus fans to cool the water. I guess raw water cooled engines are standard so nothing new but as I never operated one myself I directly wonder how seaweed and other debris is stopped from clogging inlet, or if entering the system what other issues could occur? I like the idea!

Raw water (seawater) is the most efficient because all you need is a small pump. But it does have its pros and cons. All thru hulls are a point of failure, water invasion. If you already have one or need to water cool the motor the issue is mute. Most marine thru hull intakes should have an exterior strainer (course) and an interior clean out filter/strainer to protect the pump and small passageways further down. A closed system needs some sort of heat exchanger(another pump) or radiator(fan in addition to circulating pump). Another option, but it depends on heat load, enclosed space and manufacturer’s requirements is simply an aluminum extrusion with a fan. I use this to cool a big rectifier you could use one or more side by side with a 12volt or 48volt fan. Just be sure you have a large flat surface and thermal paste between the surfaces. I bought both fan and extrusion from Amazon. Any system you go with should have a thermostat to control motors as needed and to save power and wear.

 

[Skypower]

Yes the fan is noisy

 

[Skypower]

For low power, low flow pumps (not powerful marine engine impellers pumps) I highly recommend using an exterior strainer with small holes not the type with slots used for engines. With a marine heatpumps that use a magnetically driven rigid impeller would clog up in the line between the thru hull and strainer. These small, efficient, quiet pumps have three drawbacks. Low suction, must be below water level(not self priming) and usually 115 volt AC. But I’ve never looked into a 12 volt unit. And you would probably need the smallest version.

 

[Modular Hippo]

"you mentioned aiming for 12-15 so what is your thoughts about that?"

The trip home made me realize (I think I mentioned earlier) about how much running under power I'll actually do. On top of that, it's entirely possible to push into an adverse current for hours on end. So given then, I decided I wanted to be able to push hard, so I went from thinking 10hp would be ok (1kw:3hp) to wanting to be closer to 1:2 instead. To get that in a 48v package, 10kw/motor seems to be max. 2x 10kw would for sure give me the oomph I need when I need it, and would be overkill really. However, the best motor option I've found so far is 5 or 10kw, so 2x 10kw is the top choice atm.

"Or are you worried that the heat in the motor/controller area will be so hot that it will only push hot air around"

Exactly. Knowing now that motoring for 8h straight is entirely possible, that's a lot of time for heat to build up in the engine bay. I know I can vent the engine bay, and maybe that would be enough to do it. However, I already have the 3/4" through-hull/seacock and heat exchanger, so might as well use it. Should be less noisy, not having a pair of squirrel cage fans running in the engine bay as often.

1kw:3hp, interesting as not seen that direct conversion before. That means that against a single 10kw motor I would be a quarter under my original recomended output from the Yanmar combustion engine which is 39hp. Hmmmm, definitely food for thought.... Both currents and wind can go wild in the UK so if I am unlucky I could go against both at times. 'Squirrel cage fans', ha ha - Yeah, if you got it then you might as well use it, being a well proven concept it should also hopefully be less of a risk and more plug and play

 

[Modular Hippo]

Raw water (seawater) is the most efficient because all you need is a small pump. But it does have its pros and cons. All thru hulls are a point of failure, water invasion. If you already have one or need to water cool the motor the issue is mute. Most marine thru hull intakes should have an exterior strainer (course) and an interior clean out filter/strainer to protect the pump and small passageways further down. A closed system needs some sort of heat exchanger(another pump) or radiator(fan in addition to circulating pump). Another option, but it depends on heat load, enclosed space and manufacturer’s requirements is simply an aluminum extrusion with a fan. I use this to cool a big rectifier you could use one or more side by side with a 12volt or 48volt fan. Just be sure you have a large flat surface and thermal paste between the surfaces. I bought both fan and extrusion from Amazon. Any system you go with should have a thermostat to control motors as needed and to save power and wear. View attachment 162933


View attachment 162935

Good ideas and some good components tips, thank you - As I currently do not have a thru-hull, and agree that any holes in a hull comes with a risk I probably lean more towards a closed system. Two of the heat sinks would be pretty much spot on as far as surface goes for the motor controller. The motor/s I have in mind have internal water cooling so as long as I can make sure the water during it's journey around the circuit is cooled I think that should be a winner. Will post some trials as and when I have the components Thanks.

 

[digimer]

Raw water (seawater) is the most efficient because all you need is a small pump. But it does have its pros and cons. All thru hulls are a point of failure, water invasion. If you already have one or need to water cool the motor the issue is mute. Most marine thru hull intakes should have an exterior strainer (course) and an interior clean out filter/strainer to protect the pump and small passageways further down.

Another consideration is blockages of the through hull... I grounded a couple of times in the Erie canal, and the much stirred up by rocking / kedging off the bottom kicks up debris that can easily be ingested.

I've got a sea strainer of course, and will with the electric cooling, but it's still possible to cause a blockage that slows or stops water flow. I won't ever know for sure, but I am pretty sure this is why I lost my impeller on my trip home that caused me to overheat and, having lost power, hit the rip rap along the shore of the canal.

No option is best, but best to consider as many pros and cons as possible.

 

[digimer]

1kw:3hp, interesting as not seen that direct conversion before. That means that against a single 10kw motor I would be a quarter under my original recomended output from the Yanmar combustion engine which is 39hp. Hmmmm, definitely food for thought.... Both currents and wind can go wild in the UK so if I am unlucky I could go against both at times. 'Squirrel cage fans', ha ha - Yeah, if you got it then you might as well use it, being a well proven concept it should also hopefully be less of a risk and more plug and play

My Yanmar 3GM30 is 27hp continuous, 30hp peak / 1 hour.

If your boat is ~40hp, I'd want 15kw minimum, 20hp to be safe.

 

[digimer]

For low power, low flow pumps (not powerful marine engine impellers pumps) I highly recommend using an exterior strainer with small holes not the type with slots used for engines. With a marine heatpumps that use a magnetically driven rigid impeller would clog up in the line between the thru hull and strainer. These small, efficient, quiet pumps have three drawbacks. Low suction, must be below water level(not self priming) and usually 115 volt AC. But I’ve never looked into a 12 volt unit. And you would probably need the smallest version.


View attachment 162946

As with everything in marine, everything is a trade-off. So with that said, take what I"m going to say as the balance I prefer, not what's best.

I don't like external strainers, or if there is going to be one, one with more generous openings (like the tear-drop stile with slits pointing aft) are preferred. If craps gets sucked up, I'd personally rather it go into the sea strainer where I can clear it without going for a swim.

 

[Skypower]

As with everything in marine, everything is a trade-off. So with that said, take what I"m going to say as the balance I prefer, not what's best.

I don't like external strainers, or if there is going to be one, one with more generous openings (like the tear-drop stile with slits pointing aft) are preferred. If craps gets sucked up, I'd personally rather it go into the sea strainer where I can clear it without going for a swim.

Normally the slots are aimed forward but it may not be a problem if you are not moving fast and may help reduce some clogs, however I’d still be concerned.
The powerful rubber impeller pumps literally rips most plants matter to shreds at the intake and you may find the remnants in the internal strainer where given time much of that will decompose into smaller pieces and pass through harmlessly. The electric centrifugal impeller pumps simply don’t have that much suction. If you have any long stringy aquatic plant matter, it will slurp it in like spaghetti and clog. You will find small holes in the intakes on all marine heat pumps. I installed a heat pump to an existing thru hull and couldn’t fix it till my next haul out. Must have pulled that hose off the inside strainer 20 times and pulled as much of that long length of smelly weed out as I could, then I had a chance to blow it out with compressed air. A year later I put the outside strainer on I never had a problem.
Actually found the order of the one I bought
They make wedge shaped types with even smaller holes but they are expensive and I’d think that they’d clog easily if there’s not a lot of flow blast it clear.

 

[Modular Hippo]

My Yanmar 3GM30 is 27hp continuous, 30hp peak / 1 hour.

If your boat is ~40hp, I'd want 15kw minimum, 20hp to be safe.

Hi Digimer,

I agree with your estimations but what throws me a bit is The Neds configuration as his boat is not far from mine in foot/displacement and he seems to be able to get to 4-5 knots fairly easy without pushing is 10Kw motor. Had hoped to be more confident by now in relation to the calculations but still pretty much a foreign language to me

 

[digimer]

Hi Digimer,

I agree with your estimations but what throws me a bit is The Neds configuration as his boat is not far from mine in foot/displacement and he seems to be able to get to 4-5 knots fairly easy without pushing is 10Kw motor. Had hoped to be more confident by now in relation to the calculations but still pretty much a foreign language to me

The thing that changed for me on my trip home was really understanding the difference between "what do I normally need" and "what might I need in a pinch". Most of the time, I fully expect that a single 10kw would be just fine, but there will be times when I need to push harder, and I'd run out of breath with just 10kw. In my opinion, you need to design/plan for those worst case times, to be safe.

Now, as I say that, I must also remind that I am designing for live-aboard and for crossings. If you plan to weekend sail, as the vast majority of sailors do, then you could well argue that you just won't go out in adverse conditions, and so you can safely not worry about that. I'd absolutely agree in such a case that you don't need as much punching ability.

 

[Modular Hippo]

The thing that changed for me on my trip home was really understanding the difference between "what do I normally need" and "what might I need in a pinch". Most of the time, I fully expect that a single 10kw would be just fine, but there will be times when I need to push harder, and I'd run out of breath with just 10kw. In my opinion, you need to design/plan for those worst case times, to be safe.

Now, as I say that, I must also remind that I am designing for live-aboard and for crossings. If you plan to weekend sail, as the vast majority of sailors do, then you could well argue that you just won't go out in adverse conditions, and so you can safely not worry about that. I'd absolutely agree in such a case that you don't need as much punching ability.

Just like yourself I am building for live aboard and crossings hence wanting to get this bit right. I tend to always 'over-design' everything (structural) to make sure that I can feel safe - as you say, guess I need to apply the same for the motor. problem so far is not knowing where 10 kw motor sits in the range of output. Been looking at the below 2:

Motenergy ME1302 (DLC-28) Brushless 15 kW - 38 kW Liquid-Cooled PMAC Motor 48-120V

<p><span style="color: #ff0000;"><span style="color: #2f2f2f;">These patented axial flux motors are designed to work with sinusoidal (sine wave) controllers such as the Sevcon Gen4.</span><strong></strong></span></p> <p><br /> <strong>Features</strong><b

www.electricmotorsport.com

HPM 20 KW Liquid Cooled BLDC Motor - Golden Motor North America - Canada and USA

Model: HPM-20KW -- High Power BLDC Motor. Voltage: 72V/96V/120V. Rated power: 20-25KW. Peak power: 50KW. Speed: 3200-6000rpm.

goldenmotor.bike

 

[digimer]

Just like yourself I am building for live aboard and crossings hence wanting to get this bit right. I tend to always 'over-design' everything (structural) to make sure that I can feel safe - as you say, guess I need to apply the same for the motor. problem so far is not knowing where 10 kw motor sits in the range of output. Been looking at the below 2:

Motenergy ME1302 (DLC-28) Brushless 15 kW - 38 kW Liquid-Cooled PMAC Motor 48-120V

<p><span style="color: #ff0000;"><span style="color: #2f2f2f;">These patented axial flux motors are designed to work with sinusoidal (sine wave) controllers such as the Sevcon Gen4.</span><strong></strong></span></p> <p><br /> <strong>Features</strong><b

www.electricmotorsport.com

HPM 20 KW Liquid Cooled BLDC Motor - Golden Motor North America - Canada and USA

Model: HPM-20KW -- High Power BLDC Motor. Voltage: 72V/96V/120V. Rated power: 20-25KW. Peak power: 50KW. Speed: 3200-6000rpm.

goldenmotor.bike

The Golden motor 20kw would require almost 400A continuous at 51v. I'm not sure there is a single motor controller that can provide that continuously. Most of the controllers I was looking at advertised their peak current, with sustainable current being 40% of that (ie: "500A" controller can do 200A continuous).

Is one of the reasons I decided to go to a dual motor/controller setup. The redundancy is a huge benefit, but sustainable power is the real driver.

Note also where the motors get their peak efficiency. The Golden motor 10kw has peak efficiency of 87% at around 5kw. Something important to factor when calculating range.