Electric / Hybrid Drive Options

Hey everyone,

Seems to me that a hybrid electric drive would be a great option for a Hobie TI. Why not use a 2.5hp / 3hp electric motor / high density marine battery with a small marine-grade gas generator to kick in when the battery is low?

I hear that ePropulsion supports regeneration via the propeller when sailing, but wouldn't it also be possible to detect when the battery voltage is low and start up a quiet gas generator, just like PHEV vehicles do?

We have many current channels around here (Vancouver Island) that run around 6-7 knots, and I'd love to be able to safely navigate them if I had enough thrust. Range is always an issue. A gas motor is great, but often noisy, and I believe those brushless electric motors have much less to maintain and are generally more reliable than a gas motor... If the generator kicks out, at least you have a battery to get you through a tight spot.

Or just go with a Suzuki 2.5hp?

What about the weight distribution on the boat. I hear at higher speeds (7-9 knots) under power, the stern becomes heavy. Is this due to the motor weight at the rear or the planing characteristics of the TI hull?

What do you all think?

Thanks,
Mark

The problem with what you propose is that you would need to find a quality, kayak-appropriate, electric marine motor that would be able to be powered off of a 120 VAC gas-powered inverter generator. The Torqeedo, ePropulsion, and Bixpy marine electric motors were designed to be powered only via their respective lithium battery DC power packs. Unless you knew exactly what you were doing electrically, add a proper DC power supply, and then radically modify their wiring, you would not be able to power them via a 120 VAC generator.

You might be able to power a 12 VDC trolling motor off of a 120 VAC generator and a suitable 12 VDC power supply, if you get all of the amperage requirements correct, but trolling motors do not make very good kayak propulsion motors as that is not what they were designed for.

If you wanted to design your own marine motor using a brushless electric motor, you would need to resolve all the myriad engineering issues involved on your own. This is possible but requires more money, engineering talent, and R&D than the typical boat owner has or is willing to invest.

You would also need to deal with the extra weight of the gas generator, its noise and hot exhaust, its fuel, its potentially lethal 120 VAC output in a very wet environment, find an appropriate place to mount it, and be extremely careful about operating a gasoline-powered, high voltage, high heat-generating device directly on the deck of your plastic TI/AI while on the water in all weather conditions.

If you want the advantages of an electric motor, such as nearly silent operation, and need extra range, then simply buy a spare battery. Having two high-capacity batteries should give you all the range needed for a single day's outing. A spare battery would cost around the same price or less than a proper, well-made, small 2200-watt inverter generator and DC power supply, weigh significantly less, be a lot safer, more dependable, and far less complicated.

If you don't mind the noise and exhaust of a gas-powered motor, then a 2.5 HP Suzuki with about a gallon of extra fuel onboard should give you all the range you need for a day's outing. A 2.5 HP Suzuki would cost only around as much as or less than a proper 2200-watt inverter generator and DC power supply, would weigh less, and again be a lot safer, more dependable, and far less complicated.

Both of these options are far more practical than attempting to use a gas-powered generator.

I don't really like plug-in hybrid and hybrid automobiles because they merge all the complexity, moving parts, and maintenance of an internal combustion engine with all the complexity, parts, and battery replacement cost (eventually) of an EV. A hybrid kayak solution sounds the same. Seems it'd much simpler, cheaper and easier to either go all electric and carry a spare battery, or go ICE and carry spare gas, if needed to meet the travel distance/speeds you desire. If you have to add a gas engine, power conversion/management, battery, electric motor to a kayak - one that already pedals, paddles, and sails - maybe a kayak is the wrong choice for your intended use. Plus there are the inefficiency losses. A gas engine powering a generator powering an electric motor is nowhere near as efficient as a gas outboard.

On our Torqeedo-powered Oasis "hybrid" means we pedal while we run the motor.

All that said, I would really really like a kayak that is electric motor powered on the rudder (like the evolve v2 rudder mount but sturdier and more powerful) but where the pedal drives spin small built-in generators to recharge or augment the motor battery rather than power fins in the water. Much cleaner design and no Mirage drive holes in the hull. On something like a Tandem Island I would also want regen capability where the prop motor charges the battery under moderate sailing speeds like on some ePropulsion electric outboards. Bonus points if a 12VDC tap is available so I don't need a separate battery for chartplotter, bilge pump, lights... And, of course, I want the option for solar charging.

Hobie does have a patent for a pedal-driven cable or hydraulic transfer to a remote rudder drive that could merge human and electric power. It is interesting but I like my solution better.
https://patentimages.storage.googleapis.com/bb/52/53/2b6fbc067081e4/US8753156.pdf

Peter

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2016 Hobie Oasis with Evolve v2 rudder mount, Sidekick ama kit, Mirage sail kit, Garmin echoMAP CHIRP 42dv, bilge pump
2007 Hobie Outfitter x 2 with Mirage sail kits, large rudder blades