Highfield 310 CL with ePropulsion Navy 6?

[aybabtme]

Hello!
I'm planning to put a 6kW electric outboard on a 3.1m rigid inflatable dinghy, specifically these two things:

• ePropulsion Navy 6.0 is a 6kW (9.9hp equivalent), 48V outboard.
• Highfield 310 Classic is a 3.1m RIB (10'2") with an aluminum double floor and a front compartment that can "fit a 24L fuel tank". I already own the dinghy and my quick measurements of that compartment gives me a rough box of L:34cm (13.5") W:40cm (16") H:19cm (7.5"). I started building a cardboard prototype to get a better idea of how big of a box I can fit in there.

I think that front compartment can hold a 6kWh battery (and more), so that'd give me 1h of range at full throttle.

I'm been hesitating a lot, because the dinghy is rated for 20hp, recommending 15hp. And the outboard is ~3000$, plus about 2000$ worth of battery (I'm DIYing it) - vs ~3000$ for a Tohatsu/Mercury 20hp.

We don't need long distance dinghy rides for the foreseeable future and I'd like to avoid the trouble of dealing with gasoline and maintenance, so the electric is pretty attractive to me. It also seems to end up a bit lighter and easier to handle, the outboard itself is 68 lbs and the battery would be another 68 lbs. I'd only have to remove 1 at a time, instead of wrangling a 110 lbs engine.

Has anyone done this? We're in the San Francisco Bay and the surroundings for the next 2y. We're about 300lbs worth of human meat, 95% of the time.

[aybabtme]

BTW: the only 20hp equivalent I could find is this ridiculously heavy and expensive Torqueedo Cruise 10T, which only recently became available to purchase directly by consumers (as far as I can tell, since I noticed today that you can now "Add to cart" that model - it used to be redirecting consumers to contact dealers).

[Pete7]

So its 6kw, weighs 32kgs costs $3000 plus batteries and is water cooled. That's quite interesting for a smaller yacht.

Be good to hear how you get on

[Sailmonkey]

You’re asking for opinions regarding an electric outboard that you’ll use for two years?

Imho, at $2500 minimum per year for two years, your nuts.

But that’s just me.

[valhalla360]

1) Why are you comparing a 6kw...8hp motor to a 20hp motor? Wouldn't it make more sense to compare to a 8hp outboard (9.9 at most)?
2) If you don't need to go long distance, do you need to get on plane? A $200 trolling motor with a couple of deep cycle batteries is viable for under $500.

[fred4936]

We have friends of ours with a smaller inflatable, I think it is a Highfield with and inflatable floor, with a Torqueedo on it. It works really well for them. I have been on it and I liked it. Where they use it, planing would be dangerous (crowded anchorages). I saw the epropulsion unit at the Newport boat show, and was intrigued by it. Easy to handle, no gas, quiet. A good solution for the right application, like anything else.

[sail4677]

We have the 12.5’ Highfield dual floor and forward Locker 6 gal tank running with 15hp 2 stroke. 6 adults and gear plenty of power

[aybabtme]

Originally Posted by valhalla360

1) Why are you comparing a 6kw...8hp motor to a 20hp motor? Wouldn't it make more sense to compare to a 8hp outboard (9.9 at most)?
2) If you don't need to go long distance, do you need to get on plane? A $200 trolling motor with a couple of deep cycle batteries is viable for under $500.

I'd get a 20HP electric outboard if there was one that wasn't so heavy and expensive. But the only reasonable electric outboard I could find topped at 9.9hp. So that's why my indecisiveness is between a 20HP gasoline outboard or a 9.9hp electric. If the 9.9hp electric is enough to get on a plane, then that solves my question. If it's not enough and I'll be sloughing around, then I'm not interested and will get the gasoline outboard. Consequently, I'm not interested in trolling motors. I can get one as extra, given how cheap they are, but I want a main outboard that gets on plane.

[aybabtme]

Originally Posted by Sailmonkey

You’re asking for opinions regarding an electric outboard that you’ll use for two years?

Imho, at $2500 minimum per year for two years, your nuts.

But that’s just me.

We'll use it past 2y, I just provided our expected location for the foreseeable to frame the question.

[roverhi]

How are you going to charge the batteries if not hooked to shore power?? Someone else pointed out you're comparing apples and oranges, an 8hp electric to a 20hp gas engine. If engine weight is the issue get a 8hp gas outboard. You'll only be limited by the amount of gas you carry and weight of outboard may be similar.

[alansmith]

Aybab, please see if you can find the posts about fellas who talk about what the “real conversion” of going from gas to electric really ends up at. I totally understand where you are coming from with a hundred lbs outboard.

Just a thought. Sometimes the choice of a dingy will make a huge difference in how much power you need to plane it. For example a porta-bote at 10 foot could plane very nicely with a 6 hp outboard. You can pick up used Porta bote for under 1k and stores quite nicely.

I just seem to remember e motors being compared to gas outboards and fellas saying it ain’t what you think.

[Steve_C]

Or get two of the electric outboards

Then you could get on a plane You would need a bigger battery tho!

[valhalla360]

Originally Posted by aybabtme

I'd get a 20HP electric outboard if there was one that wasn't so heavy and expensive. But the only reasonable electric outboard I could find topped at 9.9hp. So that's why my indecisiveness is between a 20HP gasoline outboard or a 9.9hp electric. If the 9.9hp electric is enough to get on a plane, then that solves my question. If it's not enough and I'll be sloughing around, then I'm not interested and will get the gasoline outboard. Consequently, I'm not interested in trolling motors. I can get one as extra, given how cheap they are, but I want a main outboard that gets on plane.

Just because it can handle a 20hp, doesn't mean you need 20hp. Unless you are heavily loaded, I would expect a 9.9 to get that dingy on plane.

Even a 15hp doesn't add much over a 9.9...for Merc it goes from 84lb to 99lb and you can pick one up for $2700...Plus if it's only for a couple years, if you take care of it, you can probably sell it for better than 75% of the original price...I wouldn't count on that with an oddball electric system.

If you just want to an electric motor...get one but comparing to a 20hp is apples & oranges.

[joelhemington]

Originally Posted by aybabtme

BTW: the only 20hp equivalent I could find is this ridiculously heavy and expensive Torqueedo Cruise 10T, which only recently became available to purchase directly by consumers (as far as I can tell, since I noticed today that you can now "Add to cart" that model - it used to be redirecting consumers to contact dealers).

Those E propulsion units are very highly rated. Should be fine for just casual dingy rides especially in marinas where you don't want too much wake. That said, I'd also have a 15hp outboard locked on the rail just in case you need something serious outside the marina.

[aybabtme]

Originally Posted by roverhi

How are you going to charge the batteries if not hooked to shore power?? Someone else pointed out you're comparing apples and oranges, an 8hp electric to a 20hp gas engine. If engine weight is the issue get a 8hp gas outboard. You'll only be limited by the amount of gas you carry and weight of outboard may be similar.

With the inverter. The mothership has enough installed power generation and power capacity to replenish, and there's space for more.