Full electric high speed RIB

Hey,

I would like to adapt a speed RIB with an electric motorization but can’t find literature.

Goal is to enjoy a silent speed boat (>30mph) during all seasons (no winterization required), for less than 10,000$ and more than 30 min at top speed with 1 or 2 pax.

Eventually, I would add a small quiet generator to charge the batteries and extend the range.

Rib could be a Zodiac Futura or equivalent, with a max hull speed around 30mph and a rigid floor.

A 10kw electric engine should do the job (Zodiac states their boat needs a minimum of 7hp to go planning with 1 passenger, and recommend a min of 15hp). About $3000.

As it seems there is no electric outboard at a reasonable price, I would have to convert a 15hp outboard with a EV electric car conversion kit. About $2500.

The battery seems to be the tricky part:
- Gel batteries are cheap but heavy: each 2kwh weigh as much as one passenger and seems to require as more additional power. And their capacity are ruins by high amps.
- Lithium (LIMA or LiFePO4) are 3 times lighter, deliver more amps, but cost so much! About $4000.

Is there any risk to increase the voltage on such a light boat (from 48V to 72V or even 120V)?

Does anyone already tried to make a planning electric RIB? Any bug?

Thanks!

 

Try the search function here for Electric or hybrid propulsion, to find this topic handled a hundred times. Not to propel a RIB but there is no difference.

 

I haven't done the math, so I believe you up front.
You estimate that you need a 10kW motor and require it to run full speed for at least half an hour.
Your other estimate is that each 2 kW of lead/gel storage weighs the same as a person. My guess is that you mean the capacity indicated on the battery label.
But the actual storage capacity is approx. half that, because you will want your battery bank to function more than once, so you should use only 50% of the total charge.

That means one person extra for each available kW, or 5 extra persons for your 30 minutes full speed.
Will the RIB plane with 6 persons on board? Probably not, it certainly won't reach 30 mph with just 10 kW.

Lithium reduces the payload to 4 instead of 6, you will severely exceed your 10 k$ budget and still not reach the 30 mph.

So is it feasible?

 

For the specifics you've given arn0, it can't be done.

Tom

 

Thanks all for your feedbacks,

to Apex1: I actually think there is a difference with RIBs: they weight less and need less energy to start planning. I am not an expert so I may be wrong...

I havent seen anyone on the forum reaching high planning speeds on a light boat with electric motorization ; does that mean this is impossible?

to CDK: I agree it cant work with Gel batteries, I came to the same conclusion.
Not sure to understand your point about 50%: aren't the LiFePO4 (for exemple) made to handle deep cycles?

5kwh of LiFePO4 weights 140lbs and cost $3000 (need to add another $1000 for the batteries management system + charger) = $4000.

So if i am alone in the boat, the payload is almost the same of a 2 pax classic oil-engine Zodiac, with about 15hp, wich is twice the power needed to plane according to Zodiac... am I missing something?

 

A 10 kWh lithium pack, in cutting-edge LiPo or similar, is going to be around 60-70 kg and cost well into the five figures. Double that weight and half the cost for LiFePO4 types.

But a 10 kW motor is not going to get you anywhere close to 30 mph, not on a 12-foot Zodiac Futura (which, btw, is an inflatable, not a RIB). Zodiac's own tests on that boat indicate 19 kW / 25 hp is needed to get it to 28 mph, and that's when lightly loaded. The 15' version of the Futura needs closer to 50 hp for 30 mph performance. And you won't find an inflatable that's significantly more efficient than these. Inflatables in general need more power than RIBs of the same size, which in turn usually need more power than comparable true rigid boats.

When Zodiac- or any other boatbuilder- says "Yeah, it'll plane with 7 hp", what they really mean is that if you put one 14-year-old kid in it and tell him to gun the throttle, he'll probably be able to get it just over the planing hump. Good performance, especially with a bit of a load, requires a lot more power.

You'd be looking at a minimum ~20-30 kW motor and controller, to get the performance you want from an inflatable or RIB this size. If you want a half-hour of run time at speed, you are now looking at a 20 kWh battery pack, which- in lithium- weighs as much as two crew, and costs as much as a nice sports car. In lead-acid, such a pack weighs just over half a tonne.

As you can probably see by now, there's a reason why most electric boats are slower types, and why the electric outboards you do see- Torqueedo, etc.- are marketed in terms of convenience, ease of use and quiet operation rather than raw performance.

 

The AC-20 here might do the job:
http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php
With controls and wiring you will need about USD6000 I expect if you do the work yourself to get it mounted on an outboard leg.

For half an hour of operation you will need something like 15 to 20 kWh. Best price is around USD1/Wh. These are a little cheaper than that:
http://www.electricmotorsport.com/store/ems_ev_parts_batteries_thunder_sky.php
However there have been quality issues in the past. Anyhow say USD15,000 for the battery.

It is doable but you need deep pockets. It will get cheaper as more electric cars go into production and the components are produced in greater quantity.

Rick W

 

Hi arno, quite the opposite is true!
The rest was handled already by others.

Richard

 

Check this out...

http://www.youtube.com/watch?v=76e19SxVzXE&feature=related


And a home built jetski...

http://www.youtube.com/watch?v=QYKE5hQnXbM

Keep the weight down and you can plane an electric boat. Battery technology is ready, for a cost. 100 AH cells go for $140 each...

http://cgi.ebay.com/Foxx-Power-100-...Cycling_Parts_Accessories?hash=item20ad921060

You can get a BMS for under $400...


http://cgi.ebay.com/ebaymotors/LiFe...itemZ120474620950QQptZOtherQ5fVehicleQ5fParts

Find a 20 HP outboard and convert it to electric with a lemco 200...

http://www.cloudelectric.com/product_p/mo-lemco200.htm


Expect no more than 20-25 mph for 30 minutes. You could step up to 72 volts but the weight and cost go up. Also, safety is a concern with higher voltages.

I'm not sure if the LIFEPO4 cells like a marine environment but they are supposed to be sealed.

 

I tried this. I modified a 7.5hp mercury 2 stroke to use separately excited golf cart motor running at a bit over 48V. With more than 10kw input at 240 A DC, and probably about 8kw of shaft power, it wouldn't quite plane a Sea Nymph 14 foot aluminum boat. the boat is probably less than 200 lb. I used aircraft starter NiCad batteries optimized for high power. The battery pile was about 200 lb and mounted well forward for what I hoped was a good CG placement. The boat would *just* plane with the 7.5 hp 2 stroke and 1 passenger (no extra 200 lb). I tried a bout 3 different props, but nothing scientific. I feel like it was very close to working, but not super practical. It was rather nice at displacement speed.

 

Thanks for the info on electric outboards fellas.....Very interesting......j....