Topics

Bow Thruster Amps rating.


Chris Doucette
 


Hi- maybe someone can help me understand... The Super Maramu 2k Manual shows that the bow thruster draws 7000W and 510A at 24V.  Is this correct?  If so, how does the math work out?  W=VxA is violated AND no reasonable wire size is rated for that 24v DC..\

 I am trying to properly fuse my battery bank and this beast is the crux.

Chris 
SV Amarok 285


Philippe Belloir
 

It s forbidden to violat W=VxA, :-) so you have to make a deal with 7000 and/or 510. I guess 24 is right.
Possible you can see W on the motor ?



Philippe Belloir  
+33 781 709 791


-------- Message d'origine --------
De : Chris Doucette <amaroksailing@...>
Date : 29/10/2020 19:23 (GMT+01:00)
À : "main@AmelYachtOwners.groups.io Group Moderators" <main@amelyachtowners.groups.io>
Objet : [AmelYachtOwners] Bow Thruster Amps rating.


Hi- maybe someone can help me understand... The Super Maramu 2k Manual shows that the bow thruster draws 7000W and 510A at 24V.  Is this correct?  If so, how does the math work out?  W=VxA is violated AND no reasonable wire size is rated for that 24v DC..\

 I am trying to properly fuse my battery bank and this beast is the crux.

Chris 
SV Amarok 285


 

Chris,

We shouldn't get into a discussion of what is right or wrong, but rather work to help you. Maybe the math is French math or Texan math, but it will draw as much as around 500 amps. Additionally, the bow thruster wire from the battery switch to the bow thruster is connected to the battery side of the switch. 

You might consider a batter terminal fuse for each battery. That would be my suggestion. In addition, you might also consider a 500 amp time-delay fuse located near the bus bar located near the bow thruster at the termination of the wire from the battery switch.
image.png

CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Thu, Oct 29, 2020 at 1:23 PM Chris Doucette <amaroksailing@...> wrote:

Hi- maybe someone can help me understand... The Super Maramu 2k Manual shows that the bow thruster draws 7000W and 510A at 24V.  Is this correct?  If so, how does the math work out?  W=VxA is violated AND no reasonable wire size is rated for that 24v DC..\

 I am trying to properly fuse my battery bank and this beast is the crux.

Chris 
SV Amarok 285


eric freedman
 

The bow thruster is If I recall correctly is 10 HP. 10 hp x 746 watts is 7460 watts without any loss .I would add at east 10% for that, 8200 watts/24=342 amps.
That would be dismissing and loss in the feed to the motor. If you look at the motor you will see multiple heavy gauge wires going to the motor.
Fair Winds
Eric

On October 29, 2020 at 2:38 PM Philippe Belloir <pbelloir@...> wrote:

It s forbidden to violat W=VxA, :-) so you have to make a deal with 7000 and/or 510. I guess 24 is right.
Possible you can see W on the motor ?



Philippe Belloir  
+33 781 709 791


-------- Message d'origine --------
De : Chris Doucette <amaroksailing@...>
Date : 29/10/2020 19:23 (GMT+01:00)
À : "main@AmelYachtOwners.groups.io Group Moderators" <main@amelyachtowners.groups.io>
Objet : [AmelYachtOwners] Bow Thruster Amps rating.


Hi- maybe someone can help me understand... The Super Maramu 2k Manual shows that the bow thruster draws 7000W and 510A at 24V.  Is this correct?  If so, how does the math work out?  W=VxA is violated AND no reasonable wire size is rated for that 24v DC..\

 I am trying to properly fuse my battery bank and this beast is the crux.

Chris 
SV Amarok 285

 

 


Karen Smith
 

Our SM#160 bow thruster draws about 485 Amps when it is running.  The exact power calculation is complicated because the voltage is not steady at 24 volts, but drops quickly, and significantly, under this load.  The reason the wire looks undersized by standard calculations is that it operates on a very short duty cycle, so heating of the wire is minimal.  If you were to try to push 500 Amps through that wire for an hour, you'd have a real problem.  

At least on our boat, the "bow thruster" cable carries all the 24V power to everything forward of the forward saloon bulkhead.  Mast and genoa furlers, cabin lights, nav lights, windlass...

We have fused our battery bank in two different ways, and both worked well. Keep in mind we have a bank of 4 pairs of batteries, smaller than yours which I believe is 6 pairs.  

Our batteries were first fused with four 125 Amp rated battery terminal fuses, one on each 24V positive, for a total of 500 Amps.  With 6 pairs of batteries you'd end up in the about same place with 80 or 90 Amp rated fuses.  When we changed battery brands, the terminal fuse holders no longer fit under the battery box lid, so we switched to a singe 500 AMP ANL-style fuse.  Never have any of these tripped.

We have also reworked the whole 24 volt distribution system so EACH of the wires leaving the battery box has a fuse appropriate to its ampacity, and the switches now interrupt current to everything except the bilge pump circuit.  To me this is a really basic safety issue.  If there was ever to be an electrical fire on the boat, or a piece of runaway equipment, I need to know I can shut off the power to everything without delay.

On the boats I have seen, Amel was very inconsistent about what wires they connected to which side of the main switches. On our boat, only the battery charger, bilge pump, and "always on 12V converter" were connected to the unswitched side. I think on later boats they just ran out of space on the stud on the switched side, so were forced to move wires to the unswitched post. 

Bill Kinney
SM#160, Harmonie
Annapolis, MD


jlm@jlmertz.fr
 

On CottonBay I messured in the past the bow thruster curent :

https://amelyachtowners.groups.io/g/main/photo/84720/1?p=Created,,,20,2,0,0

Jean Luc

CottonBay



Le 29/10/2020 à 21:46, Karen Smith via groups.io a écrit :
Our SM#160 bow thruster draws about 485 Amps when it is running.  The exact power calculation is complicated because the voltage is not steady at 24 volts, but drops quickly, and significantly, under this load.  The reason the wire looks undersized by standard calculations is that it operates on a very short duty cycle, so heating of the wire is minimal.  If you were to try to push 500 Amps through that wire for an hour, you'd have a real problem.  

At least on our boat, the "bow thruster" cable carries all the 24V power to everything forward of the forward saloon bulkhead.  Mast and genoa furlers, cabin lights, nav lights, windlass...

We have fused our battery bank in two different ways, and both worked well. Keep in mind we have a bank of 4 pairs of batteries, smaller than yours which I believe is 6 pairs.  

Our batteries were first fused with four 125 Amp rated battery terminal fuses, one on each 24V positive, for a total of 500 Amps.  With 6 pairs of batteries you'd end up in the about same place with 80 or 90 Amp rated fuses.  When we changed battery brands, the terminal fuse holders no longer fit under the battery box lid, so we switched to a singe 500 AMP ANL-style fuse.  Never have any of these tripped.

We have also reworked the whole 24 volt distribution system so EACH of the wires leaving the battery box has a fuse appropriate to its ampacity, and the switches now interrupt current to everything except the bilge pump circuit.  To me this is a really basic safety issue.  If there was ever to be an electrical fire on the boat, or a piece of runaway equipment, I need to know I can shut off the power to everything without delay.

On the boats I have seen, Amel was very inconsistent about what wires they connected to which side of the main switches. On our boat, only the battery charger, bilge pump, and "always on 12V converter" were connected to the unswitched side. I think on later boats they just ran out of space on the stud on the switched side, so were forced to move wires to the unswitched post. 

Bill Kinney
SM#160, Harmonie
Annapolis, MD


eric freedman
 

Hi Jean Luc,
What model Amel do you have?
Fair Winds,
Eric
Sm 376 Kimberite

On October 30, 2020 at 1:21 AM "jlm@..." <jlm@...> wrote:

On CottonBay I messured in the past the bow thruster curent :

https://amelyachtowners.groups.io/g/main/photo/84720/1?p=Created,,,20,2,0,0

Jean Luc

CottonBay



Le 29/10/2020 à 21:46, Karen Smith via groups.io a écrit :
Our SM#160 bow thruster draws about 485 Amps when it is running.  The exact power calculation is complicated because the voltage is not steady at 24 volts, but drops quickly, and significantly, under this load.  The reason the wire looks undersized by standard calculations is that it operates on a very short duty cycle, so heating of the wire is minimal.  If you were to try to push 500 Amps through that wire for an hour, you'd have a real problem.  

At least on our boat, the "bow thruster" cable carries all the 24V power to everything forward of the forward saloon bulkhead.  Mast and genoa furlers, cabin lights, nav lights, windlass...

We have fused our battery bank in two different ways, and both worked well. Keep in mind we have a bank of 4 pairs of batteries, smaller than yours which I believe is 6 pairs.  

Our batteries were first fused with four 125 Amp rated battery terminal fuses, one on each 24V positive, for a total of 500 Amps.  With 6 pairs of batteries you'd end up in the about same place with 80 or 90 Amp rated fuses.  When we changed battery brands, the terminal fuse holders no longer fit under the battery box lid, so we switched to a singe 500 AMP ANL-style fuse.  Never have any of these tripped.

We have also reworked the whole 24 volt distribution system so EACH of the wires leaving the battery box has a fuse appropriate to its ampacity, and the switches now interrupt current to everything except the bilge pump circuit.  To me this is a really basic safety issue.  If there was ever to be an electrical fire on the boat, or a piece of runaway equipment, I need to know I can shut off the power to everything without delay.

On the boats I have seen, Amel was very inconsistent about what wires they connected to which side of the main switches. On our boat, only the battery charger, bilge pump, and "always on 12V converter" were connected to the unswitched side. I think on later boats they just ran out of space on the stud on the switched side, so were forced to move wires to the unswitched post. 

Bill Kinney
SM#160, Harmonie
Annapolis, MD

 

 


jlm@jlmertz.fr
 

SM 316 with 8 100Ah battery ...

JLM


Le 30/10/2020 à 06:42, eric freedman a écrit :

Hi Jean Luc,
What model Amel do you have?
Fair Winds,
Eric
Sm 376 Kimberite

On October 30, 2020 at 1:21 AM "jlm@..." <jlm@...> wrote:

On CottonBay I messured in the past the bow thruster curent :

https://amelyachtowners.groups.io/g/main/photo/84720/1?p=Created,,,20,2,0,0

Jean Luc

CottonBay



Le 29/10/2020 à 21:46, Karen Smith via groups.io a écrit :
Our SM#160 bow thruster draws about 485 Amps when it is running.  The exact power calculation is complicated because the voltage is not steady at 24 volts, but drops quickly, and significantly, under this load.  The reason the wire looks undersized by standard calculations is that it operates on a very short duty cycle, so heating of the wire is minimal.  If you were to try to push 500 Amps through that wire for an hour, you'd have a real problem.  

At least on our boat, the "bow thruster" cable carries all the 24V power to everything forward of the forward saloon bulkhead.  Mast and genoa furlers, cabin lights, nav lights, windlass...

We have fused our battery bank in two different ways, and both worked well. Keep in mind we have a bank of 4 pairs of batteries, smaller than yours which I believe is 6 pairs.  

Our batteries were first fused with four 125 Amp rated battery terminal fuses, one on each 24V positive, for a total of 500 Amps.  With 6 pairs of batteries you'd end up in the about same place with 80 or 90 Amp rated fuses.  When we changed battery brands, the terminal fuse holders no longer fit under the battery box lid, so we switched to a singe 500 AMP ANL-style fuse.  Never have any of these tripped.

We have also reworked the whole 24 volt distribution system so EACH of the wires leaving the battery box has a fuse appropriate to its ampacity, and the switches now interrupt current to everything except the bilge pump circuit.  To me this is a really basic safety issue.  If there was ever to be an electrical fire on the boat, or a piece of runaway equipment, I need to know I can shut off the power to everything without delay.

On the boats I have seen, Amel was very inconsistent about what wires they connected to which side of the main switches. On our boat, only the battery charger, bilge pump, and "always on 12V converter" were connected to the unswitched side. I think on later boats they just ran out of space on the stud on the switched side, so were forced to move wires to the unswitched post. 

Bill Kinney
SM#160, Harmonie
Annapolis, MD

 

 


Chris Doucette
 


Thanks everyone!  My setup has me in 4 groups of 100AH 12V Battle Borns @24v (400AH).  I have each group's positives and negatives aggregating to corresponding bus bars that then lead to the battery box posts.  I have an AMP ANL-style fuse holder in-line on the positive bus bar.  Everything I touch on this boat is going to be fused / breakered out appropriately.  I'll start with the 500amp and move up to 600 if needed.  

Bill Kinney- basically doing what you have done with your 24v / 12v distribution. I am going to work backwards from distribution and  "Unstack" the main Amel switches and move all the cables to bus bars (4 of them Engine Pos, Engine Neg, House load Pos, House Neg.) proper fusing closest to distribution and breakered out for switching. Same goes with any of the 12v distributions. All with appropriate marine wire, fittings, and labeling. 

On the AC side I am removing the Amel Auto Priority Gen / Shore Power priority switch (yes it has severed her well so far) in favor of a manual rotary Gen-Off_Shore switch..  Just for my peace of mind. 

Chris 


Dan Carlson
 

Hi Chris,   Please share pictures of how things look after you “unstack” the main switches.  I have been considering that as well. 

 

Here are a few responses to your ideas: 

  1. I would prefer to leave the very heavy bow-thruster cables as is on the Main switch.  I don’t want to add anything in that heavy load circuit that I can avoid.  
  2. I read a few concerns about ANL fuses for heavy load circuits and recommendations to use Class T for those.  I have one 400A class T from Blue Sea on the positive battery cable.  The inverter/charger, solar MPPT etc are also fused separately (200A ANL on the Victron Multi-Plus 3000/70/16)

 

Would also be interested in more information on where you mount and how you wire your rotary switch when you get that installed.

 

Thanks and regards,  Daniel and Lori Carlson on sv BeBe, sm #387

 

 

 

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Chris Doucette
Sent: Friday, October 30, 2020 8:55 AM
To: main@AmelYachtOwners.groups.io Group Moderators <main@amelyachtowners.groups.io>
Subject: Re: [AmelYachtOwners] Bow Thruster Amps rating.

 

 

Thanks everyone!  My setup has me in 4 groups of 100AH 12V Battle Borns @24v (400AH).  I have each group's positives and negatives aggregating to corresponding bus bars that then lead to the battery box posts.  I have an AMP ANL-style fuse holder in-line on the positive bus bar.  Everything I touch on this boat is going to be fused / breakered out appropriately.  I'll start with the 500amp and move up to 600 if needed.  

 

Bill Kinney- basically doing what you have done with your 24v / 12v distribution. I am going to work backwards from distribution and  "Unstack" the main Amel switches and move all the cables to bus bars (4 of them Engine Pos, Engine Neg, House load Pos, House Neg.) proper fusing closest to distribution and breakered out for switching. Same goes with any of the 12v distributions. All with appropriate marine wire, fittings, and labeling. 

 

On the AC side I am removing the Amel Auto Priority Gen / Shore Power priority switch (yes it has severed her well so far) in favor of a manual rotary Gen-Off_Shore switch..  Just for my peace of mind. 

Chris 

 


Chris Doucette
 

Hi Dan,

I certainly will share what I land on here..  Also In the Class-T vs ANL. The Class-T max out at 400A  (what you have and seems to be working).    
I chose ANL due that I can put one on at the the Amp rating that will match the bow thruster (thus my original question of this thread).  I guess I will find out if it blows!  It seems here there is not a write or wrong- but it is good to see others being safe as well.  
Here is a good guide I found to fuses, use, and sizes.
http://assets.bluesea.com/files/resources/reference/Quick_Guide_to_Blue_Sea_Systems_Fuses_and_Fuse_Holders.pdf


Philippe Belloir
 

Hi,
On my maramu I have a Leroy Sommer motor 12v 500A 6000w



Philippe Belloir  
+33 781 709 791


-------- Message d'origine --------
De : Chris Doucette <amaroksailing@...>
Date : 30/10/2020 18:25 (GMT+01:00)
À : main@AmelYachtOwners.groups.io
Objet : Re: [AmelYachtOwners] Bow Thruster Amps rating.

Hi Dan,

I certainly will share what I land on here..  Also In the Class-T vs ANL. The Class-T max out at 400A  (what you have and seems to be working).    
I chose ANL due that I can put one on at the the Amp rating that will match the bow thruster (thus my original question of this thread).  I guess I will find out if it blows!  It seems here there is not a write or wrong- but it is good to see others being safe as well.  
Here is a good guide I found to fuses, use, and sizes.
http://assets.bluesea.com/files/resources/reference/Quick_Guide_to_Blue_Sea_Systems_Fuses_and_Fuse_Holders.pdf


Bob Chapman
 

My belief, from many years in both aerospace and industrial electrical engineering, is that one should only put one terminal under a fastener (screw or bolt or nut). When there are more than one, it significantly increases the chance that a wire will wiggle, particularly where there is any vibration, thus loosening the whole “stack”.  Then the added resistance due to the looseness will quickly lead to a red-hot stack If there’s much current flowing in the stack.  I clearly remember ordering silver bars drilled and tapped to use as common bars. Wasn’t so very expensive. 

On Oct 30, 2020, at 3:58 PM, Dan Carlson <carlsdan61@...> wrote:



Hi Chris,   Please share pictures of how things look after you “unstack” the main switches.  I have been considering that as well. 

 

Here are a few responses to your ideas: 

  1. I would prefer to leave the very heavy bow-thruster cables as is on the Main switch.  I don’t want to add anything in that heavy load circuit that I can avoid.  
  2. I read a few concerns about ANL fuses for heavy load circuits and recommendations to use Class T for those.  I have one 400A class T from Blue Sea on the positive battery cable.  The inverter/charger, solar MPPT etc are also fused separately (200A ANL on the Victron Multi-Plus 3000/70/16)

 

Would also be interested in more information on where you mount and how you wire your rotary switch when you get that installed.

 

Thanks and regards,  Daniel and Lori Carlson on sv BeBe, sm #387

 

 

 

From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Chris Doucette
Sent: Friday, October 30, 2020 8:55 AM
To: main@AmelYachtOwners.groups.io Group Moderators <main@amelyachtowners.groups.io>
Subject: Re: [AmelYachtOwners] Bow Thruster Amps rating.

 

 

Thanks everyone!  My setup has me in 4 groups of 100AH 12V Battle Borns @24v (400AH).  I have each group's positives and negatives aggregating to corresponding bus bars that then lead to the battery box posts.  I have an AMP ANL-style fuse holder in-line on the positive bus bar.  Everything I touch on this boat is going to be fused / breakered out appropriately.  I'll start with the 500amp and move up to 600 if needed.  

 

Bill Kinney- basically doing what you have done with your 24v / 12v distribution. I am going to work backwards from distribution and  "Unstack" the main Amel switches and move all the cables to bus bars (4 of them Engine Pos, Engine Neg, House load Pos, House Neg.) proper fusing closest to distribution and breakered out for switching. Same goes with any of the 12v distributions. All with appropriate marine wire, fittings, and labeling. 

 

On the AC side I am removing the Amel Auto Priority Gen / Shore Power priority switch (yes it has severed her well so far) in favor of a manual rotary Gen-Off_Shore switch..  Just for my peace of mind. 

Chris