Re: [electricboats] Maximum input voltage for outboard?

Hi all,

Apologies for not posting more about boating with my electric Eco 5, but life kinda got in the way as it often does.

So now it's time to sell my boat. It's been great, and works well, though I didn't get to use it as much as I hoped. Boating is still in my future, but we now want to move up to something more practical for months aboard. I.e.: more roomy. :)

"Galileo" is ready to go, with trailer. Asking price is $18,500, and she is located near Olympia, WA.

Basics:
It has 4 Renogy 100 watt solar panels, 4 LBP 24-volt lithium batteries (48-volt system) and a Karvin electric outboard motor. (Ultimate range still not exact, but for an example, I motored most of the afternoon near Anacortes and used about 25% of the battery capacity. Max speed about 7 knots.) Battery charger with shore power or generator hookup plug. It has a small galley, with sink and propane two-burner stove, and a plug for a 12-volt portable fridge (not included). It has a "C-Head" composting toilet (new, never used), full navigation lights and anchor light, interior lighting, deck lighting, interior fan. Berth space for a queen size camping mattress. Two small hanging lockers, and two general storage lockers. Large cockpit with four hull lockers. Includes anchor and rode in dedicated anchor locker with bow roller. Venture galvanized trailer with spare included.

Jim
jgjones252@gmail.com

Here are some recent photos:

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Re: [electricboats] Electric Motor for 40' Sailboat

Hi there,

This feed has helped me locate useful information. Thank you all.

I have finally found some youtube videos that answer most of my broader questions. Still to find a prop calculator that will give both trust and shaft torque for smaller props at 5 knots..

GRIN technologies have issued a range of videos over 6 years showing how a CAL 25 is using a hub drive bicycle motor.  

Here is the first video I saw and it links to the series 1-6. https://www.youtube.com/watch?v=JuIG5Uqk4_c

Here are GRINs current website: https://ebikes.ca/product-info/grin-kits/marine-kit.html

Grin also gave a motor away to two fellows with a 31 Keel boat (I think episode 4 or 5?) and it worked well for them with being able to cruise at 5knots with 2kw power and 2 knots at 500w power. Now GRIN also found a way to couple multiple hub motors in series to produce more thrust. So with their system you could start off small and add as needed. BTW they found 72v motors most efficient so moving up from 48v should make better "steam". By using large diameter open windings I can see how air cooling could work here- three 5kw hub motors could provide enough cooling for 15kw and give good redundancy. . Just need to make sure there is goodish airflow into and out of motor compartment. Controllers are still an issue with heat. Heatsinks are not very big and not usually oriented to get enough airflow. BTY fans are notoriously unreliable systems. They always block up if you add filters and they gum up if you dont. Low speed high volume work better.

GRIN also provide data.

Here is a fellow that installed a Thunderstruck in a CAL31. He spends goodly amount of time on all the tech needed to achieve an good outcome and references GRIN.

https://www.youtube.com/watch?v=aJW1I1iwR_c&list=PLLeegbeHhqqVZWBbyZZdI7omilt-DP99i

Here is a graph showing hull drag. It has been referred to several times.

I estimated boat drag force using this. And I used the expanded green line in the upper left. Then used online calculator for props to get defined hull speeds and then guessed shaft torque. GRIN mentions some numbers and they were in the ball park of my guesses.

Best Regards

Lee@vombatus.com.au
0427874796

On 11 Jun 2025, at 8:29 pm, Larry Brown via groups.io <elcapitanbrown=gmail.com@groups.io> wrote:

I wonder if there's a high temp solution for a clear cylinder with heat exchanging stainless components inside where the fresh water runs through the inner steel conduit and the saltwater runs around it but inside the clear sleeve.  You could see the state of the exchanger like you can see the state of a raw water intake filter.  Heat exchangers are normally all closed off and everyone avoids dismantling them for inspection.  The other problem with water cooling is the intake aperture.  Because it's as small as it is, with as much suction as it has, it's easy to suck plastic bags or floating grass into it to clog.  I wonder if you had a plate made that was say 12" x 12" with a lot of smaller holes that would spread the suction out, it might not clog so easily.  Another option might be to have an external hose above the water line connected to a stainless cylinder with holes around it like the strainer inside a raw water intake filter.  This could be held at the back of the boat out of the water from a davit or similar with an arm that drops it down under the water's surface when you need the motor.  It would be way easier to see if it has something fouling it.  It would be super easy to clear, and it would not leave a permanent hole in the bottom of the boat.  Downside would be that the hose would get eaten up by the sun if it was left out.  Maybe it could be made with a regular garden hose and when not in use it could coil into a cockpit locker.  IDK if that size hose would give sufficient flow etc but it would be fun to play with and see how well it works.  It would require a self priming pump which will probably have a shorter life cycle. 

On Wed, Jun 11, 2025 at 3:54 AM Lee Eldridge via groups.io <lee=vombatus.com.au@groups.io> wrote:

Having designed electronic equipment for half a century, I have some experience in reliability. Powers needed for effective propulsion need water cooling. Losses in copper and iron are significant and removing this heat out of the motor area is difficult but made considerably easier with liquid cooling. Also lower operating temperatures means performance does not to be derated for hot weather. The controller, even with the very latest design will be dissipating closer to 1kw - think of that nice electric heater keeping you warm. It glows red hot . Electronic systems are most reliable around 25c and above 50c things start to get difficult to design in reliability.

Liquid cooling is a highly mature field of engineering. Salt water heat exchangers work exceptionally well if regularly maintained. However it might prove more reliable to run a heat exchanger like used on diesel engines with a radiator to transfer heat to air . Maybe both?

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 10:24, Matt Foley <matt@sunlightconversions.com> wrote:

 Air cooled is possible at 10-15kw as long as it's designed for it. Can even push it to 20kw with a lot of air exchange. Also keep in mind, I wouldn't do an air cooled 20kw, if you planned on actually using the full 20kw for hours on end. 

Matt Foley 

Sunlight Conversions

Perpetual Energy, LLC

201-914-0466

sunlightconversions.com

instagram.com/sunlightconversions/

youtube/sunlightconversions

ABYC Certified Marine 

Electrical Technician 

On Tuesday, June 10, 2025, 8:30 PM, Lee Eldridge <lee@vombatus.com.au> wrote:

have a look at freerchobby.

seems dodgy name but people I see on youtube are using their motors etc. outspinnermotors are highertorque lower speed

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 04:41, cammcnally10@outlook.com via groups.io <cammcnally10=outlook.com@groups.io> wrote:



Thanks Peter,

 

I would prefer an air-cooled system but did not see any engines listed on Thunderstruck that also met all my other requirements. I am still trying to figure out what specifications of an engine to value above others. I will definitely reach out to them as they have only received good reviews from this group.

 

-CM

--

Larry Brown

S/V Felicity

Placida, FL

~~~~~~~~~~~~~~~~~_/)~~~~~~~~

    ~     ~          ~~           ~

~           ~~_/)    ~      ~ ~        ~

     ~                  _/)          ~

Re: [electricboats] Electric Motor for 40' Sailboat

Sounds interesting and having it clear sounds really good idea so seeing blocks is easiest. Certainly a heat exchanger for an electric drive system does not need to be nearly as large as one for a diesel engine as there is no burning at the heart of the machine. 

Would a wide inlet with screen filter for low flow work better? Where is the spot that delivers lowest potential for blocking and highest potential for clearing blocks easily? In the transom maybe where a wider screen could be placed over the inlet. Possibly having outlet next to inlet would be self clearing and rely on water mixing to keep cool enough water coming in? Would hull side be better where velocity of water might tend to clear blockages and or minimise them - potentially having smaller outlet would create higher velocity water to push away debris and wider inlet to get better mixing.

Best Regards

Lee@vombatus.com.au
0427874796

On 11 Jun 2025, at 8:29 pm, Larry Brown via groups.io <elcapitanbrown=gmail.com@groups.io> wrote:

I wonder if there's a high temp solution for a clear cylinder with heat exchanging stainless components inside where the fresh water runs through the inner steel conduit and the saltwater runs around it but inside the clear sleeve.  You could see the state of the exchanger like you can see the state of a raw water intake filter.  Heat exchangers are normally all closed off and everyone avoids dismantling them for inspection.  The other problem with water cooling is the intake aperture.  Because it's as small as it is, with as much suction as it has, it's easy to suck plastic bags or floating grass into it to clog.  I wonder if you had a plate made that was say 12" x 12" with a lot of smaller holes that would spread the suction out, it might not clog so easily.  Another option might be to have an external hose above the water line connected to a stainless cylinder with holes around it like the strainer inside a raw water intake filter.  This could be held at the back of the boat out of the water from a davit or similar with an arm that drops it down under the water's surface when you need the motor.  It would be way easier to see if it has something fouling it.  It would be super easy to clear, and it would not leave a permanent hole in the bottom of the boat.  Downside would be that the hose would get eaten up by the sun if it was left out.  Maybe it could be made with a regular garden hose and when not in use it could coil into a cockpit locker.  IDK if that size hose would give sufficient flow etc but it would be fun to play with and see how well it works.  It would require a self priming pump which will probably have a shorter life cycle. 

On Wed, Jun 11, 2025 at 3:54 AM Lee Eldridge via groups.io <lee=vombatus.com.au@groups.io> wrote:

Having designed electronic equipment for half a century, I have some experience in reliability. Powers needed for effective propulsion need water cooling. Losses in copper and iron are significant and removing this heat out of the motor area is difficult but made considerably easier with liquid cooling. Also lower operating temperatures means performance does not to be derated for hot weather. The controller, even with the very latest design will be dissipating closer to 1kw - think of that nice electric heater keeping you warm. It glows red hot . Electronic systems are most reliable around 25c and above 50c things start to get difficult to design in reliability.

Liquid cooling is a highly mature field of engineering. Salt water heat exchangers work exceptionally well if regularly maintained. However it might prove more reliable to run a heat exchanger like used on diesel engines with a radiator to transfer heat to air . Maybe both?

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 10:24, Matt Foley <matt@sunlightconversions.com> wrote:

 Air cooled is possible at 10-15kw as long as it's designed for it. Can even push it to 20kw with a lot of air exchange. Also keep in mind, I wouldn't do an air cooled 20kw, if you planned on actually using the full 20kw for hours on end. 

Matt Foley 

Sunlight Conversions

Perpetual Energy, LLC

201-914-0466

sunlightconversions.com

instagram.com/sunlightconversions/

youtube/sunlightconversions

ABYC Certified Marine 

Electrical Technician 

On Tuesday, June 10, 2025, 8:30 PM, Lee Eldridge <lee@vombatus.com.au> wrote:

have a look at freerchobby.

seems dodgy name but people I see on youtube are using their motors etc. outspinnermotors are highertorque lower speed

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 04:41, cammcnally10@outlook.com via groups.io <cammcnally10=outlook.com@groups.io> wrote:



Thanks Peter,

 

I would prefer an air-cooled system but did not see any engines listed on Thunderstruck that also met all my other requirements. I am still trying to figure out what specifications of an engine to value above others. I will definitely reach out to them as they have only received good reviews from this group.

 

-CM

--

Larry Brown

S/V Felicity

Placida, FL

~~~~~~~~~~~~~~~~~_/)~~~~~~~~

    ~     ~          ~~           ~

~           ~~_/)    ~      ~ ~        ~

     ~                  _/)          ~

Re: [electricboats] Electric Motor for 40' Sailboat

I like the creative thinking but I agree with Lee that liquid cooling is a mature technology.  And your needs will be determined by the particular installation.  I have a ME1616 liquid cooled motor.  It is fine without cooling up to 140 amps (according to mfg).   At 48V that's 6700 watts.   For my installation in a 6 ton 10M boat (12,000 lb, 33 feet) that gets about 0.85 of hull speed or 6 kts.  So in normal operation (5 to 5.5 kts) I really don't even need cooling.   To get to my 7 knot hull speed (assuming the power reserves to sustain that) I would probably be fine with my air cooled heat exchanger which for me is a Ford Taurus heater core with a muffin fan.  I also have a sea water cooled heat exchanger but I suspect that was overkill.  And that is my preferred design philosophy for these systems.  Don't over-think it but do overbuild it.  And I prefer to keep below 70% of any limits including temperature. 

Info on my cooling system:
http://dan.pfeiffer.net/10m/electric_drive_cooling.htm

I'll see about adding some photos of my Ford Taurus heater core.  Basically a little radiator. Maybe 7x10"?  And fairly robust build. 

Dan Pfeiffer

On 2025-06-11 5:59 am, Larry Brown via groups.io wrote:

I wonder if there's a high temp solution for a clear cylinder with heat exchanging stainless components inside where the fresh water runs through the inner steel conduit and the saltwater runs around it but inside the clear sleeve.  You could see the state of the exchanger like you can see the state of a raw water intake filter.  Heat exchangers are normally all closed off and everyone avoids dismantling them for inspection.  The other problem with water cooling is the intake aperture.  Because it's as small as it is, with as much suction as it has, it's easy to suck plastic bags or floating grass into it to clog.  I wonder if you had a plate made that was say 12" x 12" with a lot of smaller holes that would spread the suction out, it might not clog so easily.  Another option might be to have an external hose above the water line connected to a stainless cylinder with holes around it like the strainer inside a raw water intake filter.  This could be held at the back of the boat out of the water from a davit or similar with an arm that drops it down under the water's surface when you need the motor.  It would be way easier to see if it has something fouling it.  It would be super easy to clear, and it would not leave a permanent hole in the bottom of the boat.  Downside would be that the hose would get eaten up by the sun if it was left out.  Maybe it could be made with a regular garden hose and when not in use it could coil into a cockpit locker.  IDK if that size hose would give sufficient flow etc but it would be fun to play with and see how well it works.  It would require a self priming pump which will probably have a shorter life cycle. 

On Wed, Jun 11, 2025 at 3:54 AM Lee Eldridge via groups.io <lee=vombatus.com.au@groups.io> wrote:

Having designed electronic equipment for half a century, I have some experience in reliability. Powers needed for effective propulsion need water cooling. Losses in copper and iron are significant and removing this heat out of the motor area is difficult but made considerably easier with liquid cooling. Also lower operating temperatures means performance does not to be derated for hot weather. The controller, even with the very latest design will be dissipating closer to 1kw - think of that nice electric heater keeping you warm. It glows red hot . Electronic systems are most reliable around 25c and above 50c things start to get difficult to design in reliability.

 

 

Liquid cooling is a highly mature field of engineering. Salt water heat exchangers work exceptionally well if regularly maintained. However it might prove more reliable to run a heat exchanger like used on diesel engines with a radiator to transfer heat to air . Maybe both?

 

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 10:24, Matt Foley <matt@sunlightconversions.com> wrote:

Air cooled is possible at 10-15kw as long as it's designed for it. Can even push it to 20kw with a lot of air exchange. Also keep in mind, I wouldn't do an air cooled 20kw, if you planned on actually using the full 20kw for hours on end. 

 

 

Matt Foley 

Sunlight Conversions

Perpetual Energy, LLC

201-914-0466

sunlightconversions.com

instagram.com/sunlightconversions/

youtube/sunlightconversions

ABYC Certified Marine 

Electrical Technician 

On Tuesday, June 10, 2025, 8:30 PM, Lee Eldridge <lee@vombatus.com.au> wrote:

have a look at freerchobby.

 

seems dodgy name but people I see on youtube are using their motors etc. outspinnermotors are highertorque lower speed

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 04:41, cammcnally10@outlook.com via groups.io <cammcnally10=outlook.com@groups.io> wrote:

Thanks Peter,

 

I would prefer an air-cooled system but did not see any engines listed on Thunderstruck that also met all my other requirements. I am still trying to figure out what specifications of an engine to value above others. I will definitely reach out to them as they have only received good reviews from this group.

 

-CM

 

 

 

--

Larry Brown

S/V Felicity

Placida, FL

~~~~~~~~~~~~~~~~~_/)~~~~~~~~

    ~     ~          ~~           ~

~           ~~_/)    ~      ~ ~        ~

     ~                  _/)          ~

Re: [electricboats] Electric Motor for 40' Sailboat

There's no need for raw water heat exchanger and all that entails if you use a radiator and fan. This combination gives you the best of both: it extracts the heat away from the motor and it's controller out the air without needing the risk and maintenance of dealing with saltwater. Thunderstruck and others have them. 

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Re: [electricboats] Electric Motor for 40' Sailboat

I wonder if there's a high temp solution for a clear cylinder with heat exchanging stainless components inside where the fresh water runs through the inner steel conduit and the saltwater runs around it but inside the clear sleeve.  You could see the state of the exchanger like you can see the state of a raw water intake filter.  Heat exchangers are normally all closed off and everyone avoids dismantling them for inspection.  The other problem with water cooling is the intake aperture.  Because it's as small as it is, with as much suction as it has, it's easy to suck plastic bags or floating grass into it to clog.  I wonder if you had a plate made that was say 12" x 12" with a lot of smaller holes that would spread the suction out, it might not clog so easily.  Another option might be to have an external hose above the water line connected to a stainless cylinder with holes around it like the strainer inside a raw water intake filter.  This could be held at the back of the boat out of the water from a davit or similar with an arm that drops it down under the water's surface when you need the motor.  It would be way easier to see if it has something fouling it.  It would be super easy to clear, and it would not leave a permanent hole in the bottom of the boat.  Downside would be that the hose would get eaten up by the sun if it was left out.  Maybe it could be made with a regular garden hose and when not in use it could coil into a cockpit locker.  IDK if that size hose would give sufficient flow etc but it would be fun to play with and see how well it works.  It would require a self priming pump which will probably have a shorter life cycle. 

On Wed, Jun 11, 2025 at 3:54 AM Lee Eldridge via groups.io <lee=vombatus.com.au@groups.io> wrote:

Having designed electronic equipment for half a century, I have some experience in reliability. Powers needed for effective propulsion need water cooling. Losses in copper and iron are significant and removing this heat out of the motor area is difficult but made considerably easier with liquid cooling. Also lower operating temperatures means performance does not to be derated for hot weather. The controller, even with the very latest design will be dissipating closer to 1kw - think of that nice electric heater keeping you warm. It glows red hot . Electronic systems are most reliable around 25c and above 50c things start to get difficult to design in reliability.

Liquid cooling is a highly mature field of engineering. Salt water heat exchangers work exceptionally well if regularly maintained. However it might prove more reliable to run a heat exchanger like used on diesel engines with a radiator to transfer heat to air . Maybe both?

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 10:24, Matt Foley <matt@sunlightconversions.com> wrote:

 Air cooled is possible at 10-15kw as long as it's designed for it. Can even push it to 20kw with a lot of air exchange. Also keep in mind, I wouldn't do an air cooled 20kw, if you planned on actually using the full 20kw for hours on end. 

Matt Foley 

Sunlight Conversions

Perpetual Energy, LLC

201-914-0466

sunlightconversions.com

instagram.com/sunlightconversions/

youtube/sunlightconversions

ABYC Certified Marine 

Electrical Technician 

On Tuesday, June 10, 2025, 8:30 PM, Lee Eldridge <lee@vombatus.com.au> wrote:

have a look at freerchobby.

seems dodgy name but people I see on youtube are using their motors etc. outspinnermotors are highertorque lower speed

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 04:41, cammcnally10@outlook.com via groups.io <cammcnally10=outlook.com@groups.io> wrote:



Thanks Peter,

 

I would prefer an air-cooled system but did not see any engines listed on Thunderstruck that also met all my other requirements. I am still trying to figure out what specifications of an engine to value above others. I will definitely reach out to them as they have only received good reviews from this group.

 

-CM

--

Larry Brown

S/V Felicity

Placida, FL

~~~~~~~~~~~~~~~~~_/)~~~~~~~~

    ~     ~          ~~           ~

~           ~~_/)    ~      ~ ~        ~

     ~                  _/)          ~

_._,_._,_

---

Groups.io Links:

You receive all messages sent to this group.

View/Reply Online (#32881) | Reply to Group | Reply to Sender | Mute This Topic | New Topic
Your Subscription | Contact Group Owner | Unsubscribe [newarmyguitar24@gmail.com]

_._,_._,_

Re: [electricboats] Electric Motor for 40' Sailboat

Having designed electronic equipment for half a century, I have some experience in reliability. Powers needed for effective propulsion need water cooling. Losses in copper and iron are significant and removing this heat out of the motor area is difficult but made considerably easier with liquid cooling. Also lower operating temperatures means performance does not to be derated for hot weather. The controller, even with the very latest design will be dissipating closer to 1kw - think of that nice electric heater keeping you warm. It glows red hot . Electronic systems are most reliable around 25c and above 50c things start to get difficult to design in reliability.

Liquid cooling is a highly mature field of engineering. Salt water heat exchangers work exceptionally well if regularly maintained. However it might prove more reliable to run a heat exchanger like used on diesel engines with a radiator to transfer heat to air . Maybe both?

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 10:24, Matt Foley <matt@sunlightconversions.com> wrote:

 Air cooled is possible at 10-15kw as long as it's designed for it. Can even push it to 20kw with a lot of air exchange. Also keep in mind, I wouldn't do an air cooled 20kw, if you planned on actually using the full 20kw for hours on end. 

Matt Foley 

Sunlight Conversions

Perpetual Energy, LLC

201-914-0466

sunlightconversions.com

instagram.com/sunlightconversions/

youtube/sunlightconversions

ABYC Certified Marine 

Electrical Technician 

On Tuesday, June 10, 2025, 8:30 PM, Lee Eldridge <lee@vombatus.com.au> wrote:

have a look at freerchobby.

seems dodgy name but people I see on youtube are using their motors etc. outspinnermotors are highertorque lower speed

Best regards

Lee Eldridge

0427874796

On 11 Jun 2025, at 04:41, cammcnally10@outlook.com via groups.io <cammcnally10=outlook.com@groups.io> wrote:



Thanks Peter,

 

I would prefer an air-cooled system but did not see any engines listed on Thunderstruck that also met all my other requirements. I am still trying to figure out what specifications of an engine to value above others. I will definitely reach out to them as they have only received good reviews from this group.

 

-CM