Thursday, June 20, 2019

Re: [Electric Boats] Re: Albin Vega direct drive?

 

Regarding vibration. I have run my TS 10kw motor both directions alone on the bench with no load to around 3200 RPM. No vibration only a high frequency tingle felt on the aluminum motor mount.. Fitted in the hull with reduction gear but no prop on the shaft at maximum RPM it appeared to have dampened the high frequency tingle slightly but noise had increased.The maximum RPM dry tests in the hull were carried out for only about 10 seconds. I did not want to heat up or damage my new cutless bearing and shaft seal. As I have a dripless shaft seal I had a head of water in the tube for lubrication and cooling. At this point the noise is more concern than vibration, I had not planned on any sound deadening in the engine bay.The fibreglass hull and bilge area is amplifying the motor and belt noise I assume. I have not fitted the prop yet or done a sea trial. I had my prop scanned and it has slight variance of pitch in the three blades but within normal tolerances, I have been told that this will not be a problem or cause vibration. If it does I will take it back and get it re-pitched and balanced. I can not see that a cutless bearing could cause vibration. Check it for wear, it should be nice and tight, no movement, but turn freely. I hate to be the bearer of bad news but I suspect your alignment is out or your prop is causing the vibration..

On Fri, Jun 21, 2019 at 12:20 AM lightdoesnotage@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
 

Do you guys get any vibration with your Thunderstruck kit?   We get a pretty good vibration above 50 to 60 amps with our 3:1 reduction 10kW Thunderstruck kit and a prettty strong amount of vibration if you were to take it up to 140 amps or so.   I have worked with alignment and have it about the best I can, so I am stuck thinking either it is in the cutlass bearings or ??



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Kind regards Mick 0414 264 312

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Posted by: Michael Ryan <mryanqld@gmail.com>
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Re: [Electric Boats] Re: Albin Vega direct drive?

 

Sometimes I get a little vibration like sound with my thunderstruck, but it seems to be working properly. I installed a high speed corrosion ressistant bearing from McMaster Carr.

Also have some drive belts on board, I snapped one of mine because the lower portion was soaked in bildge water when my engine compartment didn't drain properly. 

I'd say the belt is the weakest link in the system. I'm also probably going to raise my sevcon higher and dryer in case things go bad.

On Thu, Jun 20, 2019, 7:19 AM lightdoesnotage@yahoo.com [electricboats] <electricboats@yahoogroups.com> wrote:
 

Do you guys get any vibration with your Thunderstruck kit?   We get a pretty good vibration above 50 to 60 amps with our 3:1 reduction 10kW Thunderstruck kit and a prettty strong amount of vibration if you were to take it up to 140 amps or so.   I have worked with alignment and have it about the best I can, so I am stuck thinking either it is in the cutlass bearings or ??

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Posted by: John McDonnell <jack21322@gmail.com>
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RE: [Electric Boats] Re: Albin Vega direct drive?

 

I do get vibration when the initial thrust is high and then it subsides as the boat accelerates.  At higher amperage (Above 40) I experience vibration, but I feel is still connected to the thrust force on the chain coupling that connects the shaft to the 2:1 reduction system.  I also experience vibration at certain RPMs, so I just tune the throttle accordingly.  Could be the bearings, but most likely is the chain coupling.

 

From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups..com]
Sent: Thursday, June 20, 2019 10:20 AM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Re: Albin Vega direct drive?

 

 

Do you guys get any vibration with your Thunderstruck kit?   We get a pretty good vibration above 50 to 60 amps with our 3:1 reduction 10kW Thunderstruck kit and a prettty strong amount of vibration if you were to take it up to 140 amps or so.   I have worked with alignment and have it about the best I can, so I am stuck thinking either it is in the cutlass bearings or ??

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Posted by: "Gennaro Fazio" <gfazio@rochester.rr.com>
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Re: [Electric Boats] Re: Albin Vega direct drive? [1 Attachment]

 
[Attachment(s) from Thomas Stein tom@tsteininc.com [electricboats] included below]

I have the same vibration problem with generous amounts of throttle.  I assumed it was a bent prop shaft since no amount of messing with the alignment seems to help.


Tom
 

   Thos. Stein Inc.
 850 259 8600 cell
   78-B Ricker Ave.
Santa Rosa Beach, FL 32459


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Attachment(s) from Thomas Stein tom@tsteininc.com [electricboats] | View attachments on the web

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Posted by: Thomas Stein <tom@tsteininc.com>
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Re: [Electric Boats] Re: Albin Vega direct drive?

 

Do you guys get any vibration with your Thunderstruck kit?   We get a pretty good vibration above 50 to 60 amps with our 3:1 reduction 10kW Thunderstruck kit and a prettty strong amount of vibration if you were to take it up to 140 amps or so.   I have worked with alignment and have it about the best I can, so I am stuck thinking either it is in the cutlass bearings or ??

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Posted by: lightdoesnotage@yahoo.com
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Re: [Electric Boats] Re: Albin Vega direct drive?

 

John R 
Direct V Reduction: Yes you have summarized it very well and we can put it to bed! The only point I would like to add is that personally I believe the raised height of the motor out of the bilge using a reduction plate motor mount is a big plus to keep the motor nice and dry.
My reduction with 72 tooth and 22 tooth gears is about 3:1 as well.
I looked at  LEM 200-127  Yellow Tail system as well. Very interesting and quality product no doubt. Unfortunately it was price the price of  the my Thunderstruck kit with reduction.

On Thu, Jun 20, 2019 at 12:57 AM 66b6dcd5b59507e7d751ea81382ea1f6 <no_reply@yahoogroups.com> wrote:
 

This Yellowtail system is in fact what I use and have done so successfully for seven years:


Now let's put this direct drive vs gear reduction discussion to bed once and for all. There is nothing wrong with direct drive, but like all engineering design there are pros and cons. I'll come to that in a moment, but suffice to say that for most leisure boats/yachts discussed on this list the most common system is a 48V DC motor with a reduction drive.

Here's some pros and cons of DC direct drive.

Pros
  • As long as the power requirement is not too high you get a quieter as efficient system and more cost effective system compared to a 48V geared one.
  • Depending on displacement/power and range required you can run at 24V, therefore needing less batteries if using typical large AGM ones or Lithium. If you need more you can run at 36V or 48V in series but will not be able to use the full voltage due to a higher shaft RPM, limited Prop choice, but you will get more power than 24V and naturally more range at cruise speed.
  • Less weight and more compact.


Cons
  • You are more restricted in prop choice and shaft RPM as to make a DC direct drive as efficient as possible (with just air cooling) you need to choose the lowest Torque/amp you can and consequently (as it's directly related) you get a lower RPM/Volt. The shaft RPM will then govern the prop choice, controller voltage to get the power required. Consequently peak shaft RPM will tend to be higher than geared with a more optimised prop.
  • If you don't have a hull attached Plummer Block/Thrust bearing you can't remove the drive with boat in the water..
  • Shaft alignment is trickier.
  • You have to match the prop and optimise it to get the right balance of motor voltage vs amps to maintain the best efficiency at cruise speed. That's much easier with 48V geared.

John R.






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Kind regards Mick 0414 264 312

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Posted by: Michael Ryan <mryanqld@gmail.com>
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