Midwest Boothbay Lobster Boat Power System

by Mike
(France)

Midwest Lobster Boat, Image courtesy of <i>Midwest Products</i>

Midwest Lobster Boat, Image courtesy of Midwest Products

Midwest suggest their MEPSIII elctric motor to power this craft 30 inches long x 10 inches wide).

Can you suggest a suitable alternative electric motor/ mount/ESC/wiring harness powered off NiMH batteries.

Any suggestion appreciated.

I wrote a page how to estimate what size motor boat motor to choose. If you have not read it already, it will hopefully give you a good over view.

I also went over to the Midwest website looking for the MEPSIII, but the information they provide is pretty much useless.

I can't tell by your question what performance you're after, so I have to assume a modest scale like appearance. These lobster boats should be able to plane, but at a relatively modest speed. Having said that, most modelers like to have a little extra power "just in case" (whatever that means).

Next, I went over to my trusted library and pulled the 100 Boat Designs Reviewed and found what they call "A Modern Maine Picnic Boat" - I would call it a daycruiser.

Some of her properties are (rounded):

  • Length: 28 feet

  • Displacement: 6670 lbs

  • Engine Power: 275 Hp (205,150 Watts)



So, comparing your Lobster Boat with the daycruiser, (given there are 12 inches to a foot), the relation is about 1:12.

Converting the 205,150 Watts at 1:12 scale we get:

205,150/(12^3) = 118 Watts.

Browsing through various motors, it seems you're in the realm of a good quality RS-550 or 600 motor. Graupner, Robbe, Great Planes, Traxxas and others offer them.

If you're running direct-drive (no gear reducer), you need to experiment with propeller size and pitch. I would recommend a scale type propeller rather than one for high performance. The propeller you want has a pitch in the 0.5 to 1.1 range.

This motor will get hot and will need cooling. The larger the diameter of the propeller and the more aggressive the pitch, the hotter the motor will run.

The best way is to use a cooling jacket. Those can be bought online or in certain hobby stores.

As for an ESC, you're squarely in the ProBoat territory. It has become very popular and economical.

Also, be sure to check out the following pages:


Here are some products you may be interested in:


Comments for Midwest Boothbay Lobster Boat Power System

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Correction
by: Mike in France

Hi Petter,

Just a minor detail, I don't want to take up you time - in fact, Cornwall Boats recommended me the 2.5:1 motor/gearbox as displayed at :
http://www.cornwallmodelboats.co.uk/acatalog/mfa_950d2_51.html

If you think this is OK please don't respond, you are bound to have better things to do.

Best

Mike
Very grateful
by: Mike from France

Dear Petter,

Again, my sincere thanks for your feedback - I will query the metal gears, however, they seem to be a good hobby shop with a very wide range of stock, I can always replace the motor if needs be.

I also saw on YouTube a Midway Lobster Boat demo with a figurine of Bob McKenzie sitting aft of the cockpit - looks very good so I'm busy trying to procure one now.

A Bientot!
Looks promising...
by: Petter

Mike,

Those options looks pretty good for a well tempered behavior. The motor is a RS-385, which runs about 35-50W, probably towards the lower end as shown with the gear box. I'm not familiar with the ESC, but have to trust the vendor who is providing it.

The good news is, you most likely won't need to cool that motor, so less headache installing water cooling intake and discharge.

One word of caution that may or may not be an issue: The gearbox has metal gears and may be noisy. A gearbox with a pinion of metal and main gear of plastic usually run quieter. I'm not saying it's a bad motor, sometimes you just have to test and make your own judgement.

Best of luck,

Petter
Powering my Midwest Lobster Boat
by: Mike in France

Dear Petter,

I have shopped for 'geared motors' amongst European companies; some are more helpful than others. Cornwall Model Boats came up with:

http://www.cornwallmodelboats.co.uk/acatalog/mfa_950d2_51.html for the motor/gearbox

and

http://www.cornwallmodelboats.co.uk/acatalog/mtroniks-viper15.html for the ESC

They also suggested one 7.2v Nimh battery.
When you have a spare minute, (no rush), please let me know what you think - it sounds rather larger than what you considered adequate. Incidentally, the price is OK for me.

Thanks again and take care.

Mike (in Corsica at the moment).
p.s. the closer I examine you website the more I appreciate what a labour of love it is.
Skilled advice
by: Mike in France

Once again I am indebted to you for your time and careful responses - it is all grist for the mill and is helping me to narrow the choices.

I will not have time to start building my boat until mid-May and will doubtless continue to reference your excellent website whenever I have a doubt!

Thank you - I'll keep you posted.
Powering the Lobster Boat
by: Petter

The calculation I used was pretty conservative. If the boat doesn't need to plane, you could probably half that number and still have plenty of speed. So, having 50 to 60 Watts is probably sufficient for what you're describing. The boat will probably still plane, but just barely.

The good news is, reducing the power you'll gain plenty of run time.

Another note, I'm not sure if geared motors are available to you where you live. A geared motor will be able to swing a bigger propeller more efficiently. This way you may not need to cool it and you'll gain even more run time. A gear ratio of 2:1 or somewhere in that neighborhood should do it.

Ultimately, there is always some trial & error involved at the stage you're at. It's also a great opportunity to learn and get your hands dirty. 8^)
Powering my Midwest Lobster Boat
by: Mike

Thanks so much for taking the time to respond to my query - very useful information and it helps me to narrow down the field. incidentally, I don't need it to plane, just a respectable scale model speed!!
Mike in France

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