RC barge for water sampling.

[sporter]

I'm not sure if this the proper forum, I normally hang out in the RC sailplanes area, but, I have a question.

I need to build an RC boat that will carry a water sampler and sample container out into a lagoon or estuary to collect water quality samples. Normally, we would use an inflatable boat, row out, and fill the sample container by hand. Company safety policy is making this almost impossible. I propose using an RC boat to collect the sample. I can remotely initiate the sampling routine from shore.

I'd like to fabricate a white foam hull, maybe a barge style. It needs to be stable. I was thinking about 24" wide, 50-60" long, and about 6" thick. The load will be about 25 pounds including sampler, sample container, and 12V battery. What motor/motors should I use? Rudder?

I have servos, radio gear, etc. I just need help with the hull shape and drive components. It will need torque and stability in gentle currents, speed does not matter.

Thanks
Sean

[toesup]

I'd like to fabricate a white foam hull, maybe a barge style. It needs to be stable. I was thinking about 24" wide, 50-60" long, and about 6" thick. The load will be about 25 pounds including sampler, sample container, and 12V battery. What motor/motors should I use? Rudder?

I have servos, radio gear, etc. I just need help with the hull shape and drive components. It will need torque and stability in gentle currents, speed does not matter.

How about something along the lines of a 3x Springer?...
http://www.rcgroups.com/forums/showthread.php?t=522762
I would think a Springer hull should be able to cope with the 'load' you are looking at carrying..

You will probably need a motor with some 'grunt', possibly a Pittman and consider possibly a twin.. Yes, 'rudder'.. and again possibly a twin rudder system.

[boatman]

Just a idea a big airboat maybe eletric

[sporter]

Thanks. I will probably scale it up, so, the total length is about 4ft, probably shaped from white foam, then glassed. Do you have a link for Pitman motors?

Thanks again

Sean

[toesup]

Do you have a link for Pitman motors?

http://www.ametektip.com/index.php?option=content&task=view&id=116

Although some good buys in Pittman's can be had from ebay.. as well as some of the big electrical surplus stores on the net.

[Dorsal]

Styrofoan will float 55 pounds per cubic foot, so the barge doesn't need to be that large.
(ref http://www.marinefoam.com/styrofoam.html ) At 60" long, your design would float 275 pounds, so it's going to bobble on the slightest ripple like a cork.

[towboatjoe]

Here's a rough idea.
For use in areas that are weedy an airboat system would be best for all the propulsion is above water.
Pontoons are the most stable hull configuration.
I would cut a 1/2" sheet of plywood 40" long and 22" or 24" wide for a deck platform.
Build foam pontoons and cover the foam and plywood with thin mat and epoxy finishing resin.

[sporter]

Thanks, that looks like it will work. So, you recommend using an air motor instead of a submerged prop? Does any company make an airboat fan and housing and motor/prop that will fit this?

Sean

[johnmca72]

I built a similar vessel for recovering dead-in-the-water boats. I used a pair of automotive dashboard fans (about 8" dia., 12V) from an auto parts store. They cost about $10, & already came with a plastic "cage" (clip, lighter plug, etc. discarded). I replaced the motors with RS-550s, powered by 6V, & they blow plenty of air to propel the thing at a good clip.

JM

[Aerominded]

To move a 25# barge, with adequate control, I would not reccomend an "airboat" setup- you would need to get into some serious money in motor(s) and batteries to make that work-

Better to go with a conventional submerged prop here- in my opinion...

[towboatjoe]

How about using a pair of fan motors.

Sporter said some of the water areas have debris and other things that could foul a prop. If it wasn't for that I would put motors in each pontoon with no rudder and steer the vessel with seperate speed controls using a four channel radio.

[sporter]

Yeah, there could be situations where the boat needs to manuever through shallow water with reeds, debris, etc. I like the fan boat idea for this reason. I'm going to build it with one fan to start. If this is not adequate, I'll add another fan and use a mix on my RX to control the individual fan speeds in turns. Again, speed is not important, control and stability are paramount.

I start shaping the pontoons this weekend.

Sean

[mfr02]

For weedy water, paddles work well, especially feathering types.
You say you have the radio gear. I assume that what you have is legal for surface use?

[sporter]

My RC stuff is all for air (JR 9303 TX 72mhz). Once this pilot project is complete, I'll need to get a surface legal TX and RX.

Sean

[sporter]

Some progress...

Towboatjoe offered the plans in post #7. I decided to use his dimensions, as no other plans were offered. The top portion will be this thick foam, which will aid in recessing some of the gear it will carry. The pontoons need further shaping and glassing.

I still need to add the sampler, bottle, and gel battery (shown in the left of picture 1). I'm starting with a single brushless outrunner, on 12V, and using a 10" X 4.7 prop. The rudders are in the curing box now. They are glass over blue foam, from an old handlaunch glider wing.

Sean

[Aerominded]

Looking good, Sean! Are those tools for sailplane fuses I see in the background? :)

[sporter]

Yeah, DLG pod fuses.

Sean

[boatman]

i'm glade my ideas work

Eletric airboat with reverse can be very handy i think for this build :cool:

[tugboater]

Looking good. Should serve your purpose right.

[toesup]

I'm starting with a single brushless outrunner, on 12V, and using a 10" X 4.7 prop.

Is that combination going to provide enough thrust for something that large / weight?...
I would of thought something of that size might need more 'grunt' than a 10" x 4.7... :confused:

[sporter]

I don't know if this will provide enough thrust. I thought I would start with one motor, then add an additional motor if more thrust is needed.

Do you have another suggestion?

Sean

[Prins Willem]

I built a similar vessel for recovering dead-in-the-water boats. I used a pair of automotive dashboard fans (about 8" dia., 12V) from an auto parts store. They cost about $10, & already came with a plastic "cage" (clip, lighter plug, etc. discarded). I replaced the motors with RS-550s, powered by 6V, & they blow plenty of air to propel the thing at a good clip.

JM

Sporter,

If you used something like this consider making the fan units rotate instead of using rudders. I'm picturing the Navy's LCAC maneuvering capabilities. Slave two or four units together and you should have good maneuverability forwards or reverse.

[toesup]

I don't know if this will provide enough thrust. I thought I would start with one motor, then add an additional motor if more thrust is needed.

Do you have another suggestion?

I dont have any experience with airboats Sean.. but to my 'eye', a 10 x 4.7 prop on an airboat of that size and weight just seems too small.
I think you should, if possible, overpower rather than underpower though.. something of that size is going to be pushed arround by wind and current quite a lot and would need considerable power to be manouverable.

Is that the biggest prop you can run on that motor?.. could you get a bigger motor and therefor a bigger prop?.. or as PW suggests, go with two motors linked together..

Its easier to add power now rather than retro fit... :o

[Ghost 2501]

handy use of a trashed glider, using its wings to make rudders :)

[sporter]

I did use an old wing to make rudders. But now, I may have the entire motor assembly turn like Prins Willem suggested.

Just picked up a cheap surface TX and RX, so I'm legal. I definitely don't want to shoot down any of my airplane buddies.

More progress will be made today.

Sean

[Ghost 2501]

you could have gone 2.4ghz then have one tx for surface and air and be legal at the same time

[sporter]

Initial wet testing had good results.

The fan system on a rotating shaft works great for stearing. The total weight is about 40+ pounds, so she draws about half the pontoon thickness. This is about 2.5" of draw, so the speed maxes out about 2 knots. The turn diameter is about 8 feet. I will re-shape and lengthen the pontoons to decrease the wetted surface and reduce the overall drag, they are pretty blount and "barge-ish". But, that's what I asked for.

Thanks for everyone's help
Sean

[boatman]

Great i'm glad it works
also like to see a few pics of it at work

[sporter]

Complete and "working".

Sean

[Aerominded]

Very cool, Sean! I have to say I am amazed by the "authority" with which the air prop drives the boat! :)

Nice job! (and it looks like there is plenty to sample in that pond! :eek: )

[green-boat]

Congradulations on getting it going.

I think you are the first one to actually get a purpose built boat up and running. There have been a lot of requests but we have yet to see the finished product. Don't be painting flames or stripes on it now, your boss will be thinking your having too much fun out there.

[toesup]

Looks good Sean!...

How does it handle wind and current with that prop?