Page 1 of 1

sEEgull conversion questions

Posted: Tue Dec 24, 2013 4:33 pm
by 1charan
Hello all,

One of my projects (besides re-doing my house) is converting a Seagull from gasoline to full electric. I have cannibalized an electric moped. First I manufactured an adapter plate from the electric motor onto the chrome shaft from the Seagull. I have also connected the outgoing shaft from the electric motor onto a piece of crankshaft from a Seagull (the square part). Both these parts took me a while on the lathe at my work. The next challenge is to find out which bottom parts I need from a Seagull.

My electric motor runs 8000 rpm max. Which means the square inner shaft has the same speed. Looking down from the motor towards the water, the shaft rotates clockwise. The electric motor can not turn the other way.

My present rowing boat is just 4 meters, I'm thinking about getting a slightly bigger one.

Which gear box do I need?
Which way does a gasoline seagull rotate?
Which propellor would be appropriate?
How far should the square shaft protrude (or not protrude) from the outer shaft, in order to connect a gearbox?

I hope you can help me, any information is welcome.



Re: sEEgull conversion questions

Posted: Tue Dec 24, 2013 10:15 pm
by Stelios_Rjk
Hello and welcome!

Well this modification must be the first time mentioned here.

I would suggest you use a gearbox and prop from a forty plus. In case your motor has a lot of power you could change the prop and use one 5 blade hydrofun type. This combination is used on centuries. It the same gearbox. 1:3.5 ratio.

Seagulls rotates ad your motor, clockwise.

Post some pictures if you like.

Re: sEEgull conversion questions

Posted: Wed Dec 25, 2013 12:54 am
by Charles uk
To tell you which gearbox might suit, it would help if we knew the power output of your motor.

To turn even the smallest Seagull gearbox pinion shaft at 8000 revs your motor will need to be at least 2.5 kilowatt.

I'm sure John has posted pictures of electric Seagulls on the main site.

Re: sEEgull conversion questions

Posted: Sun Jan 05, 2014 12:30 pm
by 1charan
Hello all and Best Wishes for 2014.

Thanks for the answers, this makes it easier to complete the project.
Here you can see two attempts at making an adapter plate. For the first two I made a round piece of aluminium and went from there. Later I found out that the two flanges on the chrome pipe are not centered. So for the final attempt I attached a blank piece of aluminium to the pipe with two M8 bolts, and put this in the lathe. This worked as you can see. The electric motor and the chrome pipe are firmly connected.

As you can see the motor is not even one horse power. Despite this, the original moped did about 55 kph. So I expect good performance from this.

The next part is the underwater section.
From Jan I got a tailpiece with 35:10 gears. I have cleaned most of the parts with a recipe from this forum (something to do with vinegar and soda). Works pretty well. The front end cap apparently needs a paper gasket. Is this still available?

Then the crownwheel. It is a bit loose, can move in and out about 1 mm. Probably more when the paper gasket is fitted. All the way to the front it rubs against the front end cap where a piece of alu sticks out. All the way to the back it makes too much noise when it is too close to the bevel pinion. Do I need to place washers in between? Stainless steel or copper or what?

Between the propellor and the housing there seems to be a rubber washer. The function seems to be to keep oil in and dirt out?

Nearly all the threads for the bolts are metric! M6 fits like a glove. Is this normal?



Re: sEEgull conversion questions

Posted: Sun Jan 05, 2014 12:50 pm
by Jan
Hi Charan,

I've found the missing parts for the gearbox, you need the steel thrust washer and some shims to adjust the end play of the prop shaft.

Maybe I can help you with a new paper gasket for the gear box.

I also found the transom bracket parts for your project.

Cheers, Jan

Re: sEEgull conversion questions

Posted: Mon Jan 06, 2014 9:18 pm
by kevinemery
Really sorry to put a dampener on your project but the 2.5kW quoted above is correct at 48 volts.
The most load you are going to draw is about 12 amps which will not produce the thrust you are going to need.
I am not saying that it will not work just the performance is going to be so poor its probably not worth the effort.
If you are building it just for the hell of it, go for it but it going to be very slow.


Re: sEEgull conversion questions

Posted: Mon Jan 06, 2014 10:06 pm
by Charles uk
Kevin it might work with a Featherweight prop on the 3.5 : 1 gearbox, that would require around 1.1 kilowatts, but this is only guessing the gearbox drag.

It might benefit from water cooling as it's going to get HOT!

Re: sEEgull conversion questions

Posted: Tue Jan 07, 2014 6:05 pm
by 1charan
Hello Kevin and Charles (and the others of course),

It seems strange, but I think it WILL work. A gasoline engine like a normal Seagull produces 2.5 kW at its peak. Most of the time it produces a lot less. Just take a look at a powercurve from a standard motorcycle. I own a Vectrix electric motorcycle. The powercurve is a straight horizontal line. This means it produces the full torque across the full range of rpm.

The same goes for the moped that I cannibalized. A normal moped has 5 horsepower and needs all of it to get up to 50 kph. I did it with this electric motor and 48 v. As for the cooling, it doesn't need it. I was aircooled on the moped, so I will aircool it on board (out board actually).

I think it is difficult to compare gasoline motors with electric motors. Anyway, it is a fun project and I will compare it with a Seagull 102 from Jan.

We shall see....

Re: sEEgull conversion questions

Posted: Wed Jan 08, 2014 2:10 pm
Interesting thread, look forward to seeing some results :D

Re: sEEgull conversion questions

Posted: Mon Feb 24, 2014 9:14 pm
by Niander101
Seagull 102 will own it big time :wink: