Monday, July 29, 2019

RE: [Electric Boats] Sevcon Gen4 regen

 

I have a Sevcon Gen4 controller and seeing this posts about regen I tried this on mine yesterday and got my meter to show regen of 1 amp at 5.2 knots and 2 amps at 6 knots after putting the throttle on very low.  I have a 48volt system...

 

Rgds  Peter

 

From: electricboats@yahoogroups.com <electricboats@yahoogroups.com>
Sent: Wednesday, July 24, 2019 10:10 AM
To: ELECTRIC BOAT GROUP <electricboats@yahoogroups.com>
Subject: Re: [Electric Boats] Sevcon Gen4 regen

 

 

Interesting I replaced the dead original controller with a Sevcon recently. I am not sure of the model but, did notice I started to see regenerative at much lower speed than the original Navonics 400 controller.

 

On Jul 22, 2019 10:11 PM, "lightdoesnotage@yahoo.com [electricboats]" <electricboats@yahoogroups.com> wrote:

 

I discovered something weird/interesting on the Thunderstruck 10kW kit with a Sevcon Gen4 controller.  Our reduction is a 3:1 belt fyi.   

 

We were out doing a bit of sailing today and were moving at about 5.2 knots.  I pushed the throttle forward a bit and we started regen at about 60 watts.   I then pushed the throttle MORE forward and the regen went UP to about 120 watts.   Pushing it even farther and it dropped off and then started to consume a small amount of power.   On some gusts when we were going 5.8 knots I saw a max of around 170 watts of regen when playing around with the throttle.

 

Just interesting.   I am not sure if you guys already knew this.  I had first assumed that once you pushed the throttle out of neutral that was all you had to do to get regen but it seems like you can fine tune to get more regen by adjusting the throttle a little further.

 

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Posted by: "Peter Beckett" <pcbeckett@gmail.com>
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Saturday, July 27, 2019

Re: [Electric Boats] recent haulout electric drive observations

 

Pacific Seacraft great boat. You are lucky to have such a big aperture. Yes definitely a 20'' prop would be more efficient. Less blades rather than more blades is recommended. Four blades props are used to reduce prop diameter generally and a compromise. 20'' x 3 blade with more pitch will reduce the shaft RPM. I do not like those chain couplers personally I suspect they are limited in the amount of misalignment tolerance. You could try replacing it with a Polyflex coupling or similar.

On Sun, Jul 28, 2019 at 2:52 AM lightdoesnotage@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
 

We hauled our boat out a couple of days ago to replace the zincs and clean the hull.   We tried to measure the prop size.  It looks like about 8.5 to 9 inches radius, so maybe a 17 or 18 inch prop?   There is a bit more than 3 inches of clearance between the top and bottom.


We have a 3:1 reduction with a Thunderstruck 10kW drive.   Our boat is a 1989 34 foot Pacific Seacraft sailboat with about a 14,000 pound displacement.  Currently we are able to go about 3 knots with 1100 to 1400 watts and 4 knots with 2000 to 2300 watts.  5 knots requires a vibrating 4000 watts and we have never tried to go full bore 10,000 watts.   I do not like the vibration and am still trying to figure it out.  The prop shaft did not seem to have any side play so I am kind of ruling out the cutlass bearing.  I think the problem is that the double sprocket chain coupler allows too much movement such that you are trying to handle 200 to 400 pounds of thrust through two flexible couplings (the cutlass bearing and this double sprocket).   I really think that if we lock down the prop shaft with another thrust bearing in some sort of pillow block BEFORE the chain coupler that the vibration would go away.   I haven't found that bearing and mount  yet.   The other idea is to abandon the Thunderstruck reduction and go with a 3:1 gear reduction that has a rigid coupling to the prop shaft.   That would be harder/more expensive.


On the prop side of things, I am thinking we could upsize our prop maybe 2 inches?  This would still give us 2 inches of clearance on the top and bottom.   Perhaps going to 4 or 5 blades as well?   This would mean we get more thrust for a lower speed (thus reducing vibration perhaps) AND we would get significantly more regen with the larger surface area.   Sailing performance hit could be minimized by running the motor at a few amps to maintain max speed if we didn't want to regen.  I don't really know where to start on the prop sizing thing though.




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Kind regards Mick 0414 264 312

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Re: [Electric Boats] Re: recent haulout electric drive observations

 

Yes, the pillow block bearing would definitely help. 
And getting a new prop could help.

Have you spoke with thunderstruck? They might have experience with correcting your problem, that would be my first step.

Yes, you could get a bigger prop. The rule of thumb is 2 inches of clearance. You will want to do calculations to get the correct prop. "The propeller handbook" by Gerr, will teach you how to calculate the best fit for your needs. Props have many variables, and his book will explain how to find the best prop for your boat. The prop is extremely important when trying to gain efficiency. So it is well worth putting time into figuring out the best one.

I owned an Orion for 15 years, but recently sold her. PS makes awesome boats. I was thinking of converting her to electric too.

Good luck
Kev


On Sat, Jul 27, 2019, 12:53 PM lightdoesnotage@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
 

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Posted by: Kev <captainyoung@gmail.com>
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[Electric Boats] Re: recent haulout electric drive observations

 
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[Electric Boats] recent haulout electric drive observations

 

We hauled our boat out a couple of days ago to replace the zincs and clean the hull.   We tried to measure the prop size.  It looks like about 8.5 to 9 inches radius, so maybe a 17 or 18 inch prop?   There is a bit more than 3 inches of clearance between the top and bottom.


We have a 3:1 reduction with a Thunderstruck 10kW drive.   Our boat is a 1989 34 foot Pacific Seacraft sailboat with about a 14,000 pound displacement.  Currently we are able to go about 3 knots with 1100 to 1400 watts and 4 knots with 2000 to 2300 watts.  5 knots requires a vibrating 4000 watts and we have never tried to go full bore 10,000 watts.   I do not like the vibration and am still trying to figure it out.  The prop shaft did not seem to have any side play so I am kind of ruling out the cutlass bearing.  I think the problem is that the double sprocket chain coupler allows too much movement such that you are trying to handle 200 to 400 pounds of thrust through two flexible couplings (the cutlass bearing and this double sprocket).   I really think that if we lock down the prop shaft with another thrust bearing in some sort of pillow block BEFORE the chain coupler that the vibration would go away.   I haven't found that bearing and mount  yet.   The other idea is to abandon the Thunderstruck reduction and go with a 3:1 gear reduction that has a rigid coupling to the prop shaft.   That would be harder/more expensive.


On the prop side of things, I am thinking we could upsize our prop maybe 2 inches?  This would still give us 2 inches of clearance on the top and bottom.   Perhaps going to 4 or 5 blades as well?   This would mean we get more thrust for a lower speed (thus reducing vibration perhaps) AND we would get significantly more regen with the larger surface area.   Sailing performance hit could be minimized by running the motor at a few amps to maintain max speed if we didn't want to regen.  I don't really know where to start on the prop sizing thing though.


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Re: [Electric Boats] Pactorq Motors replacment options

 

We have a similar size/ weight boat, so interested in what speeds you get with the old motors and new. 

We are thinking of thunderstruck 10kW's at 48V, or even the motenergy me1002 to allow some short distance speed/power. The Oceanvolt quote was...interesting!

Rob


On Sat, 27 Jul. 2019, 4:05 pm Michael Ryan mryanqld@gmail.com [electricboats], <electricboats@yahoogroups.com> wrote:
 

Hi The most obvious choice for value is 2 x 5kw Sailboat Kits from Thunderstruck. That will give you a lot more power then the Pactorq set up. If you have a 144 volt battery bank connect in series and parallel to drop it down to a much safer 48 volt system. I assume it is shaft drive with a gearbox or some other type of reduction. You may be able to use the existing shafts and props. We need to know the prop diameters and pitch to suggest a suitable reduction to the prop shaft.

On Sat, Jul 27, 2019 at 2:33 PM sailorboy55577@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
 

Bought an older Sail Craft catamaran powered with Pactorq servo brushless dc motors, 144volt, I lost commutation in one motor and through the process found out their obsolete.  I'm looking to replace the set, I see there are many options available, just thought I'd put it out there if someone has the wisdom to recommend a suitable replacement. 14000lbs displacement, 44 ft long, 3.5 ft draft. 



--
Kind regards Mick 0414 264 312

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Posted by: Robert McArthur <rjmcarthur@gmail.com>
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Friday, July 26, 2019

Re: [Electric Boats] Pactorq Motors replacment options

 

Hi The most obvious choice for value is 2 x 5kw Sailboat Kits from Thunderstruck. That will give you a lot more power then the Pactorq set up. If you have a 144 volt battery bank connect in series and parallel to drop it down to a much safer 48 volt system. I assume it is shaft drive with a gearbox or some other type of reduction. You may be able to use the existing shafts and props. We need to know the prop diameters and pitch to suggest a suitable reduction to the prop shaft.

On Sat, Jul 27, 2019 at 2:33 PM sailorboy55577@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
 

Bought an older Sail Craft catamaran powered with Pactorq servo brushless dc motors, 144volt, I lost commutation in one motor and through the process found out their obsolete.  I'm looking to replace the set, I see there are many options available, just thought I'd put it out there if someone has the wisdom to recommend a suitable replacement. 14000lbs displacement, 44 ft long, 3.5 ft draft. 



--
Kind regards Mick 0414 264 312

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Posted by: Michael Ryan <mryanqld@gmail.com>
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[Electric Boats] Re: Sevcon Gen4 regen

 

I meant to say shifter in forward

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