T-Pain Is On A Boat: Re: [Electric Boats] Two sheet skiff with inboard scooter motor.

Sunday, March 27, 2011

Re: [Electric Boats] Two sheet skiff with inboard scooter motor.

Well I already have the two motors, both 1/3rd HP. The Boat is only 7'6" long and I don't want to go more than a few MPH anyway! Another reply told me about the Thrust Bering(I should have guessed I would need such but that's why I asked). With my setup I don't need a rudder as I should be able to control by varying the speed of the motors or even reversing one. I'm in the 2/3 HP market. I'm looking for some examples of packing glands and from an old(1900's ) book I have some good examples that seem really simple(a chamber packed with grease and hemp rope)

Thanks for your comments. I have thought of buying a trolling motor but if I was the type to buy something I wouldn't have built the boat! The controller I made from stuff lying around my lab(I'm and EE so yeah I have Micro controllers etc lying around)

The main reason behind inboard control is that trying to turn my 220 pound 6'2" frame to hold onto the trolling motor is extremely uncomfortable. A steering wheel from an old game console does a really nice job connected to my motor controller. Plus the cost of a new trolling motor at wall-mart is more than I have invested in the Boat and motors(they were free). I'm at $75.00 mostly for paint and trim.

--- On Sun, 3/20/11, Dennis Wolfe <dwolfe@dropsheet.com> wrote:

From: Dennis Wolfe <dwolfe@dropsheet.com>
Subject: Re: [Electric Boats] Two sheet skiff with inboard scooter motor.
To: electricboats@yahoogroups.com
Date: Sunday, March 20, 2011, 6:10 PM

Displacement (as opposed to planing) boats are impractical to drive over 1.34 times the square root of the waterline length. That means you are unlikely to go any faster than about 4 mph. You could do this easily with a medium size trolling motor with a fairing and a better prop. This would avoid all the issues you are asking about. Two motor mounts, thrust bearings, packing glands, shafts, struts, etc will probably cost 5x one decent 50# thrust 24v trolling motor. Plus it will work perfectly after you take 20 minutes to clamp it on and connect two wires. Engineering an inboard installation is an expensive and complex job, there is a reason outboard power has 100% market share in the under 100 hp skiff market.

If you are really determined to build an inboard setup Glen-L has a good book about inboard installations. It's more aimed a the V-8 ICE crowd but you need most of the same parts they do, just smaller.

Also you would be much better off with a single prop and rudder. Half the cost and complexity and more efficient. One big prop is much better than two smaller ones. Dave Gerr's "Propeller Handbook" is the bible.

Good luck with your project.

Denny Wolfe
www.wolfEboats.com

On 3/19/2011 11:02 PM, stollte wrote:

Hi everyone!

I'm new here and this is my first boat build. I built a small (7' 6") two sheet boat(I'm surprised how well it turned out) and now I'm considering using two scooter motors to propel it. I figure with two props in the back I could steer by varying the speed of ether motor or even reverse one to turn tightly.

I'm good with the electronics so I'll have no trouble making a motor controller etc. I just need help on the boat part as I'm a total beginner.

My questions, to anyone who has any ideas or knowledge.

a) How do I run a shaft through the hull without leaking water?
b) How deep/what angle does the prop need to be for effective thrust?
c) How far from the back of the hull should the prop be positioned.
d) anything obvious that a beginner would miss.
e) What kind of torque is typical of a trolling motor, rpm, picking a prop etc?

Any links to DIY inboards for really small boats would be helpful and anyone using a scooter motor.

Comments suggestions are appreciated.

Thanks!