Thank you James for your incite and experience. I afraid I'm stuck with the motor but will change the prop during the haul out next year so maybe I can reduce the speed.
The coupling- I thought about getting one of those double chain couplings but not sure. I like the coupling you sell.
Doug
--- In electricboats@yahoogroups.com, James Lambden <james@...> wrote:
>
> 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
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > ------------------------------------
> > > > > > > > >
> > > > > > > > > Yahoo! Groups Links
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> >
>
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