Electric RIB project.

Hi all,
I became disabled about 10 years ago and for the last 5 years have been building off-road mobility scooters.it is

As such, I have a fairly good knowledge of electric motor control.
I dived for nearly 30 years and so have a reasonable knowledge of RIBS.
I want to get back on water but my days of thrashing around on high power RIBS are over. I live in Cornwall (UK) and we have some fantastic estuaries, the Fal, the Helford and some nice inland water not too far away.

What I want is a small boat, to act like my mobility scooter on land.
Which will allow me to explore the shallow tidal inlets.

The main problem I can foresee is getting snagged in weed fishing lines or moorings as I will not be able to untangle the prop.

For this reason and the need for a shallow draft I think the best way to go would be to use a 3m RIB and a small electric jet unit.
This would leave the transom completely free for me to add either a spare trolling motor (for safety) or may be a 10 to 15HP 4 stroke motor on remote for getting around at higher speed. A complete redundant system.

I would be happy to use the rib in displacement mode with the electric motor, 4 to 6 kn.


Initially I would like to use 36V (3 x 12V AGM) batteries as I have several controllers, cutouts etc. that I am familiar with.

Could anybody please help with the choice and location of a suitable motor and jet unit.

Thanks,

Steve

 

I'm curious about why you decided on a RIB rather than a boat with a hard hull.

 

Electric RIB

hi David,
I guess it goes back to all my years of diving. Always felt safe in an inflatable or a RIB.

safety, stability, good low-speed performance, good high-speed performance, manoeuvrable, light and so less to push around, so should be economical. Easy to transport. Shallow draft. room for 2 independent motors.
.seems to fit my requirements the best.

I wouldn't know where to start on a ridged hull.

having said that, I am in the very early stages and open to suggestions.

Regards,

Steve

 

Nice idea Steve, but I'm afraid there is no jet pump on the market that fits your purpose.

In principle any water pump can be used to propel a boat, although the efficiency will be a bit disappointing because most pumps are centrifugal ones. You could experiment with one or two large bilge pumps or an AC submersible pump in an enclosure. That is not a large investment.
Another option would be a bow thruster, running at a reduced voltage. They are not designed for continuous operation and most are quite noisy.

4-6 knots is a bit too fast for a 3 m. RIB, displacement speed will be slightly under 4 knots.

 

Outboard jets are centrifugal, not sure what size they start at, but do you really solve the problem of fouling with weed etc, you could just as easily clog the inlet.

 

thanks for your reply,
would it not be possible for me to use a standard jet unit at lower speeds?
I wondered about bow thrusters, but I want the bottom of the hullto be completely smooth, to avoid entanglement and allow access to very shallow water.

 

Mr efficiency

thanks for your reply, I actually want the jet motor unit be internal.
As for as clogging is concerned, I was thinking of that I could put a grid over the intake and if that got clogged, simply reverse the jet, would that not be possible?

 

Wouldn't a small jet ski pump work for this?

 

thanks for your reply. Yes, this is what I need help finding, do you know of one?

 

I have a small sailing dingy, Walker Bay 275. We use a Minn Kota Traxxis 55 lb thrust trolling motor on 12 volt deep cycle batt.



We're not small people and cruising speed is 4 kts. Don't know how long the batt will hold out with two adults but the kids run it around the marina all weekend on one charge.

The prop is a new supposedly 'weedless' one from Minn Kota.



Don't know if that would fill your needs or something like it.

 

thanks for your reply. being disabled, I am looking for something with complete redundancy and very low draft 6 inches Max, also I want the ability to do a reasonable speed as well, 10-12 kn' hence the need for 2 power sources, electric jet inboard for low-speed and conventional motor for planning speed.

thanks again,
Steve

 

Steve. Jets are the last thing you want around weed. They block up the intake and you can't tilt them up for cleaning like an outboard. You can get weedless props on small outboards.

 

Not personally, but there are a few jet skis being broken on ebay

Is weed a big problem in the Fal? I thought the Carrick Roads are mostly mud? I'm planning on taking my 16ft jet around there next summer (probably from Mylor), but previously I've only ever been in the shallows in that area when things have gone awry!

 

Hi,

like you I haven't spent much time in the shallows in fact not at all in the last 10 years so I don't really know but in my situation I have to assume the worst lines weeds etc. plan for the worst, hope the best.

Steve

 

Not what you envisioned, but these are weed-less.
Maybe an air motor could be fitted on a rib.