Back up electric motor

[Rick Fisher]

Hello.



I have a 7.7m Rib which has an Evinrude 200 HO. The motor is a 2014 and has always worked great.



I use the boat out in the ocean, this particular boat is heavy. Its a Sealegs which has a heavily reinforced aluminum hull. Im guessing its 2200KG to 2400KG with the outboard, fuel and me onboard.



I would like a small kicker but don't have a spot to mount one. The purpose would be for very shallow water and in case of the 2014 motor giving me some trouble. I wondered would a Torqueedo 1103 .. rated at 3hp Gas move this boat ? Its heavy but its still a Rib with a narrow alum hull and a 20 degree deadrise ? I also thought of an electric bow mounted outboard. Anyone had any experience with this ?

[Peter_C]

Nice ride! I miss being able to launch across beaches, and even thought about building a hydraulic self driven wheel set.

Usually the "rule" is 1HP per meter of boat. Ideally you also want a separate source of fuel for which electric is definitely one. Electric has come a really long way, but it still has a little bit left to go. On that note I bought a used Honda 5hp from a guy with a 27ft sailboat that "upgraded" to a Torqueedo.

Are you sure there isn't room? A custom sliding bracket or something could be fabricated.

Looks like you've been looking for a solution for awhile. https://www.rib.net/forum/f8/sealegs...ion-81598.html

Have you googled? Curious what happens if you engage the tires to push you forward?

[Limecc]

It will move it but slowly and not for long.

I have a 70lb Watersnake for aux on a 4.5m boat. Torqueedo is likewise rated 70lb although they say to add 50% to compare to trolling motors so is more powerful at 105lbs.

1hp = 745.7 watts. Torqueedo's 520 propulsive watts equals 0.7hp.

The Watersnake draws 50A thanks to it's brushless motor so that's 600 watts. Using a 100Ah Lithium battery to 0% gives a 2 hr runtime.

Torqueedo battery is 915 wh equiv to a 80Ah 12v Lithium. The motor is rated 1100w (915÷1100) giving 0.83hr runtime to 0%. Calculation in line with their claimed 50 mins.

Sidenote: do you know always running Lithium below 20% charge until BMS kicks in greatly reduces longevity?

The Watersnake cost me £270, battery box £70 (both Ebay) and 100Ah Lithium cost £249 (currently on Amazon for £280) Total £589 vs £1900 for Torqueedo. Weight is split into two making it easier to transport.

Happy to be corrected if I made any mistakes above. Thanks.

[spartacus]

Nice set-up.

As mentioned, I can't see an electric auxiliary shifting, let's face it, 2.5 tonnes of boat in anything other than millpond conditions. Auxilliary engine brackets can be fabricated. I'd have thought you'd be looking for 8hp minimum.

You also want something ready to deploy. I've seen auxilliary engines mounted in front of a console, but you just know if your main engine fails for any reason, then its invariably blowing a gale and speed is of the essence if you need to switch.

Also think about how the auxilliary will be secured underway. The auxilliary engine saddle is rated for its own hp, not on the back of an 8m Rib with 200hp main engine in the Pacific or Atlantic. Tethered in the up position. There's always a way.

[Peter_C]

Post a few pictures of your boat from behind and above. A model number would be good too as we have no idea what you are working with. Gotta think outside the box on this one.