T-Pain Is On A Boat: Re: [Electric Boats] Need Propeller Guru

Thursday, October 7, 2010

Re: [Electric Boats] Need Propeller Guru

I installed a Minn Kota 40 on my 18' canoe; I faired the round mounting shaft into a "rudder" to reduce turbulence and improve steering, and powered the whole thing with a pair of golf batteries. It' do nearly 5 mph with two persons aboard, and has a range of 20 mi or more.
[IMG]http://i71.photobucket.com/albums/i133/stmbtwle/MotorInstallation.jpg[/IMG]

--- On Thu, 10/7/10, David Brooks <avantiman@yahoo.ca> wrote:

From: David Brooks <avantiman@yahoo.ca>
Subject: Re: [Electric Boats] Need Propeller Guru
To: electricboats@yahoogroups.com
Date: Thursday, October 7, 2010, 8:28 AM

No, I ran one 101 at 60 amps. The 101 was however faired into the rudder blade to reduce drag, protect the prop and give directional control without the complication of seperate steering of the motor. A side benefit was that the 101 was virtually invisible in use unlike a seperate motor prone to theft. The MotorGuide 36 volt is 106 as I remember and far easier to rewire and has in my opinion a better prop. Dry weight of my boat was 2600 pounds without equipement load or batteries according to the manufacturer.
I went inboard electric on my present boat and get 4.5 mph at about 30-35 amps and 4 mph at 25 amps. Top speed is 6.2 mph at 115 amps with a 4500 pound boat.
Directional control and turning radius were far better with the rudder mounted trolling motor. Because of this it was possible to spin the boat in its own length. I need almost double the turning radius with the direct drive inboard. The Minn-Kota needed wot to cruise at 4.5, the inboard is loafing at that speed and has easily double the torque.
I may however get a 101 and rudder install for manouvering, , far cheaper than a bow thruster.
Dave

--- On Wed, 10/6/10, alex <alex04032@yahoo.com> wrote:

From: alex <alex04032@yahoo.com>
Subject: Re: [Electric Boats] Need Propeller Guru
To: electricboats@yahoogroups.com
Received: Wednesday, October 6, 2010, 9:38 PM

Dave, are you saying you ran two 101's at 30 amps each to get that 4.5 mph ? What is size and displacement of your boat ?

--- In electricboats@yahoogroups.com, David Brooks <avantiman@...> wrote:
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> I used Minn-Kota 101's on my British bilge keeler and the max speed was 4.5 mph at 60 amps.Â Stock pitch is about 4 inches. Be very careful re amp draw if you change the prop because of overheating.Â A 10x6 prop might give you the extra speed without overload.
> Also MotorGuide 3 blade props can be cut to fit and give a bit more speed and far better reverse thrust than the 2 blade Minn-Kota props. Please advise re vendor of used 101's as I have a possible use for one as a thruster motor.
> Thanks,
> Dave 613-798-3454
>
> --- On Tue, 10/5/10, alex <alex04032@...> wrote:
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> From: alex <alex04032@...>
> Subject: [Electric Boats] Need Propeller Guru
> To: electricboats@yahoogroups.com
> Received: Tuesday, October 5, 2010, 10:02 PM
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> Hey guys, my boat is almost done and pics to follow, but Im expecting the props will need adjusting and Id like to deal with that before launch.
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> I rebuilt an 18ft daysailor, 1200-lbs totally loaded, with six golf-cart batteries driving two 36v Minn Kota 101-lb-thrust motors rated 50 amps each. I estimate that is 3hp total at the props. My calc's estimate that a hull speed of 6mph can be reached with 2hp. Thats my goal.
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> Here is the tricky part. I dont know the rpm or pitch of the Minn Kota 101. Its 9"d, I hear its 4"pitch, but I dont know that or the RPM.
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> Rumor has it that at full RPM and small slip, the max boat speed for Minn Kota is 3.5 mph. If so, I want to increase the prop pitch and maybe diameter, too, so that I can reach hull speed. I have RMS amp meters on each motor and PWM controllers so I expect to be able to keep an eye on the motor amps/heating.
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> Can anyone analyse the Minn Kota RPM and prop ? Im preparing to buy a couple used 10x9 props and fix them to Minn Kota hubs. Any feed back on how this might result ?
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> p.s. I can buy used salt water Minn Kota 101's (1.5hp) anytime, including PWM controllers for about $450... thats a real watts/dollar bargain.
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> Thank you !
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