T-Pain Is On A Boat: Re: [Electric Boats] Catalina Conversion First Try

Doug,

The gearbox makes substantially more noise if you push it above 1750 rpm input speed, or above 1,000 rpm on the shaft.

We reduced almost all of our gearbox noise by changing to the new double stator motor with 28 turns, and new propeller with 14 inches of pitch. The new propeller at 6 knots is turning at only 860 rpm. Most of the time it is turning at 300 to 400 rpm.

Compare that to the Atomic 4 without a reduction gear which would turn the propeller at the speed of the engine, sometimes as high as 2500 rpm. But you don't hear the gears over the noise made by a gas or diesel engine.

Gears make noise when you run them fast.

The motors can make noise too if the controllers are not programmed correctly. That noise can transmit through the gearbox.

My guess is you are running at almost 3,000 rpm input with a 20 turn Mars Motor and 1500 output with 2:1 gears. If so, your gears will be noisy. The gearbox is rated at 1,750 rpm.

You can also get rid of noise by installing rubber mounts and a flexible coupling, thus isolating the system. Anything with a solid connection will act like a speaker for whatever is vibrating.

I also noticed that you have a solid coupling. Without a flexible insert, every time your propeller shaft goes around it will bind, because there is no such thing as a perfect alignment. That binding will also be amplified by the gearbox.

The best thing about a gearbox is the gears are 97% efficient. But you need to slow down your system with a bigger propeller and bigger motor to make it quiet.

James

Propulsion Marine

On Nov 8, 2010, at 4:14 PM, Doug wrote:

Ok so I took two videos, one showing the basic installation and the other operating at the slip. Here's the links
http://www.youtube.com/watch?v=RVztPV0Yxzk
http://www.youtube.com/watch?v=JIpHpoCZjjk
You might see the vibration I was talking about. I think I'll have to take things apart and use a dial indicator on the prop shaft.
Let me know if they work. I also took some stills which i'll put in the photo section under "Doug's C27 Conversion"
Doug

--- In electricboats@yahoogroups.com, "tartan27hull157" <tartan27hull157@...> wrote:
>
> Hi Doug,
>
> Yes, very interested in that video if you do get a chance. I am not much of a physicist, more of a linguist, but we do a fair amount of sound stuff, at least in the vocal tract. I am curious whether the pitch of the whine varied with rpm, or was it constant?
>
> And, since you're talking about taking video, you mean you can actually see the vibration?
>
> Does the Cycle Analyst not give you shaft rpm? I thought it had a programmable speed mode that converted motor rpm to bike speed, and I assumed you could tell it your number was 2:1 (or whatever is in your gearbox) and get shaft rpm.
>
> Thanks again, Paul
>
> --- In electricboats@yahoogroups.com, "Doug" <dj2210@> wrote:
> >
> > Paul
> > I will take some video the next time i'm down at the boat and post it so you can hear the noise and see the vibration. I was using a 36lb thrust Minnkota trolling motor for a month while engine-less, hung off the stern. That was quiet! Boat didn't go fast either. I wish this inboard was as quiet. Definitely a high frequency whine on mine but definitely within hearing range.
> > I stuck the Cycle Analyst in a plastic enclosure and made it swing-able mounting inside the companion way. That way it can be out of the way when not needed and doesn't get hammered all the time from the sun. Eventually I'll mount the speed sensor down on the shaft coupling to get RPM.
> >
> > I bought the Mars motor from Mars and months later the Kelly.
> >
> >
> > --- In electricboats@yahoogroups.com, "tartan27hull157" <tartan27hull157@> wrote:
> > >
> > > Hi Doug, thanks for the notes. After I posted I noticed that the title of your photo is "gearbox installation" so I should have figured that out. As for the noise issue, that was what I was really interested in, you think it was the PMAC itself? Not the controller (I have heard that they generate a high-frequency whine, though it's supposed to be out of human hearing range?), or the gearbox?
> > >
> > > Silence is a strong motivation for me so I balk a little at any noise issue.
> > >
> > > I did like the Cycle Analyst, building an enclosure I this is a good trade-off since you can find the best place it with minimum new holes and such. I assume you like to see it from the helm?
> > >
> > > Did you get the Mars 3001/KBL48301 combo from Kelly?
> > >
> > > Thanks, Paul
> > >
> > > --- In electricboats@yahoogroups.com, "Doug" <dj2210@> wrote:
> > > >
> > > > Hey Paul
> > > > I do have a 2:1 gear reducer and it reverses rotation but that worked out great for the Mars PMAC. The mount is aluminum and made up of 2 pieces of angle and U channel bolted together.
> > > > I also was planning on doing a belt/pulley reducer and still might just to see the difference. The advantage of the that is easier to change reduction ratio and the (for my install) placing the motor closer to the aft of the boat allowing for more space in my engine compartment. I can just fit 2 group 31 batteries between motor and compartment door. The other 2 batteries go where the fuel tank was.
> > > > Yup i did my conversion in the water but the bottom needs redoing so maybe I'll change the prop when that happens next year.
> > > > Every thing takes more time than anticipated. I thought I would have had this done last month.
> > > > P.S. I really like the large Cycle Analyst although you do have to provide your owe enclosure.
> > > > P.P.S. Did I mention that the Mars PMAC is noisy?
> > > > Doug
> > > >
> > > > --- In electricboats@yahoogroups.com, "tartan27hull157" <tartan27hull157@> wrote:
> > > > >
> > > > > Doug -- thanks much! This is very similar to what I am thinking of putting in my T27, the pictures are a great help!
> > > > >
> > > > > I can't quite see, is there reduction? From the angle of the motor it looks like it is bolted directly to what looks like a sort of bellhousing integrated with the pillow block...so, is it direct-drive? Or perhaps there are gears or a belt I can't see.
> > > > >
> > > > > I have a longer shaft alley, so my plan was to put the motor aft of the forward end of the prop shaft (above the prop shaft). The prop shaft and drive shaft would penetrate a plate which supports both the thrust bearing (below) and the motor (above), with a toothed belt running about 2:1 between them. Like you, I was going to mount this whole "sled" on rubber engine mounts, though I wasn't sure how much need there would be for dampening. My A4 didn't seem to vibrate much, and I have the shaft out to get it checked by a prop shop...I may replace it, as well as the prop (obviously, I am out of the water...if memory serves, you did your conversion in the water?).
> > > > >
> > > > > Anyway, thanks again for the detailed info and appreciate any thoughts you have on the design of the mounts. I looked into "drop-in" replacements and even helped another guy in the yard "drop in" his SolidNav Explorer...it didn't exactly "drop in," so I am still pretty interested in fabricating a solution specific to the space available.
> > > > >
> > > > > Take care and happy sailing, Paul
> > > > >
> > > > > --- In electricboats@yahoogroups.com, "Doug" <dj2210@> wrote:
> > > > > >
> > > > > > Thanks and yes I have 4 rubber mounts which you should be able to see under my photos. I didn't spend too much time in the alignment stages just made it connect to the coupler. My atomic four also had a vibration (although not as bad) so I'm wondering if the prop shaft is bent or not balanced.
> > > > > >
> > > > > > --- In electricboats@yahoogroups.com, tartan27hull157@ wrote:
> > > > > > >
> > > > > > > Doug-congrats on your first e-sail! Curious about your vibration issue. Do you have any dampening installed? I am looking at the same motor/controller combo and am trying to figure out best way to mount it.
> > > > > > > Sent via BlackBerry from T-Mobile
> > > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: "Doug" <dj2210@>
> > > > > > > Sender: electricboats@yahoogroups.com
> > > > > > > Date: Sun, 07 Nov 2010 02:17:24
> > > > > > > To: <electricboats@yahoogroups.com>
> > > > > > > Reply-To: electricboats@yahoogroups.com
> > > > > > > Subject: [Electric Boats] Catalina Conversion First Try
> > > > > > >
> > > > > > > Installed the Cycle Analyst this afternoon and since the wind was up decided I needed to sail. This is the first time that I've had a chance to try out what I spent time and money on. This is what I observed with my iPhone gps 5.4mph(4.6knts) @70amps. 50amps produced 4.5 mph. Battery consumption for the time the motor was on used 22ah.
> > > > > > > The controller (Kelly) temperature was slightly warm and the motor (Mars PMAC) was very warm. I didn't have a temp gauge but I could put my hand on the motor for a few seconds until I needed to let go.
> > > > > > > I do have some issues with vibration which I'll have to correct and it is louder than I expected producing a loud whine.
> > > > > > > Whats nice is just flipping a switch to run it- no water, fuel or smell.
> > > > > > > Doug
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > ------------------------------------
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> > > > > > > Yahoo! Groups Links
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