I will. I'll be getting a lot of help !
Thanks
--- In electricboats@yahoogroups.com, "fulldec2001" <fulldec2001@...> wrote:
>
> Please keep the details on the Sneakeasy project coming. I am very interested in a project of this scope and can't seem to find much in the way of specifics on-line.
>
> --- In electricboats@yahoogroups.com, "luv2bsailin" <luv2bsailin@> wrote:
> >
> > Looks like you've got a project ahead of you!
> > I've been messing around with hobby CNC for a few years, and it is definitely addictive and a lot of fun.
> > Are the Sneakeasy plans available in a CAD format, or will you have to digitize them yourself? Even if you do it shouldn't be too hard since it's such a simple boat.
> > I talked to my brother Scott about running some numbers for you, and he said he'll take a look at it when he gets a chance. He owns a company that makes inboard kits (www.electricyacht.com) and he has the numbers down pat, though I doubt if he's done anything quite like the Sneakeasy yet. I'm anxious to see what he comes up with.
> > Can you tell me the model numbers of your motor and controller? That would probably help too. He should have data on all the Mars motors. I was running a Mars brush motors with an Alltrax controller on a 225AH 48V bank of GC batteries in my Albin 25 last summer. Last fall I got hold of one of Scott's newer brushless systems that was used as a boat-show demo, and I'll probably be trying that out this summer. I posted the performance numbers for the Albin on this forum a while ago, so you should be able to find them by doing a search. If not let me know and I'll dig it up. As I remember the max speed was about 6.2 kt at 110A. That hull is obviously not a good comparison for the Sneakeasy, but may be somewhat useful if the motor/controller combination is similar to yours.
> > I'll e-mail you separately to talk about the CNC stuff.
> > Cheers,
> > Jim McMillan
> >
> > --- In electricboats@yahoogroups.com, "b504now" <b504now@> wrote:
> > >
> > > We ordered (and parts are arriving as we speak), the blacktoe (http://buildyourcnc.com). I agree, I've got some uncertainty.
> > >
> > > by all means send me email. I check it weekly so don't get surprised if I'm a bit laggard.
> > >
> > > Thanks
> > >
> > > --- In electricboats@yahoogroups.com, "luv2bsailin" <luv2bsailin@> wrote:
> > > >
> > > > There's one big unknown there, and that is how many amps will the motor actually draw at your chosen RPM. That is directly related to how much load is on the prop, which is not easy to calculate since it varies by boat speed and prop efficiency, and prop efficiency (or slippage factor) also varies with load.
> > > > Have you been able to find any drag test info, or did Mr. Bolger publish any estimates? That would be helpful.
> > > > I'm not that good at the math, but I think I understand the basic concepts pretty well. Basically my understanding is that, for this type of motor anyway, the motor will spin at a particular RPM for any given voltage, and as you load the shaft it will draw whatever amperage it needs to maintain that RPM. Thus amp draw is proportional to torque.
> > > > I need to chew on those numbers some more, but it's a start. I'll try and get my brother to look at it too. He has designed a lot of installations and is a whiz at this stuff.
> > > > So what kind of CNC router did you get, and what software are you using to lay out the cut files? A buddy of mine has a Shopbot which we used to cut out panels for one of my dinghies, and I've been fooling with Rhinocad to design some more. Cool stuff! Where are you located? I'd like to correspond off-line if you're willing.
> > > > Jim McMillan
> > > >
> > > >
> > > >
> > > >
> > > > > --- In electricboats@yahoogroups.com, "b504now" <b504now@> wrote:
> > > > > >
> > > > > > ok. Some better information. Now I am new to this game so any thoughts, help or fixes would be good.
> > > > > >
> > > > > > My prop is 10 1/2 dia with 13 pitch. I am not sure I want to go that way but lets start there. Oldish lower unit. My lower unit has a 7/4 ratio (drv Shaft to Prop) so my math works like this....
> > > > > >
> > > > > > If I want a cruising speed of 12 mph, 2 hr run time, at an efficiency of 50%, I'll need a prop speed of 1950 rpm. That translates to 3411 rpm at the drv shaft (allowing for gearing).
> > > > > >
> > > > > > If my battery bank produces 225 and operates to 40%, my run consumption needs to be about 1750rpm and based on the feedback, about 3.5hp, 67amps. (all 48v). So I will likely gear up 2/1 (emtr to drv shaft) which gets me to 3500. That seems close enough.
> > > > > >
> > > > > > everyone pick holes....I need all the help I can get.
> > > > > >
> > > > > > I also have built a few boats, both stitch and glue as well as traditional. But I just purchased a CNC machine capable of cutting 4X8 sheets. So my son's and my boat building is about to take a leap forward. The Sneakeasy will be the first one we do with CNC parts. (and also the first one my wife chose)
> > > > > >
> > > > > > Thanks
> > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
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