Hi All,

I have started a little aquatic vehicle project that will be used to do depth mapping of the various ponds, lakes, and canals where I live in southern Florida. The mapping will allow the owners to determine their silt levels and silting rates.

My RSV is based on a similar RSV, only smaller, that appeared in the July/August 2010 issue of Robot Magazine and can be seen here:  eTrac RSV 

I chose to use fiberglass pontoons for a .60 size R/C plane and can be seen here:

The pontoons are manufactured by Great Planes and can be found at Tower Hobbies.

For propulsion I was originally going to build a couple of small outboard electric motors using Johnson-Mayfair 750GPM bait pump cartridges and 50mm Robbe three bladed propellers.

The housing for the bait pump cartridges was going to take a little bit of machining and the jaws in my Tag lathe still needed to be machined to allow me to chuck up plastic pipe couplers that are bigger than 1" in diameter.

Since I like Traxxas products, I found that the geared propulsion system for the discontinued Villain R/C racing boat might fill the bill as there are quite a few of the legacy Villain parts to be had on eBay for cheap:-).

So I downloaded the Villain exploded hull and drive train views and the parts list and proceeded to buy what I needed to put together two of the Villain geared propulsion drive trains.

At this time, while searching for Villain parts on Amazon, I found one last Villain built hull for sale and proceeded to order it so that I can build up a competition autonomous boat for competitions like the Sparkfun AVC only on the reservoir.

I began the installation of the Villain drive trains by cutting two sections out of the right pontoon just aft of the wire connecting bridge mounting points. I reinforced the sides and ribs of the pontoon, where I removed the fiberglass glass sections, with thin strips of poplar wood.

The toughest part of mounting the drive train was spotting the hole for the stuffing tube in the pontoon stern plate and getting clearance for the motor under one of the pontoon ribs. Pictures of the installation are below:

550 motor_reduction gears_and stuffing tube

Stuffing tube exit on stern plate

The propeller drive shaft is attached to a universal joint that is coupled to a short propeller shaft that is supported by an outdrive housing that is attached to a hinged trim support that allows the pitch of the propeller to be varied up and down vertically. I plan to epoxy the motor mount to the bottom of the hull once I have installed the rest of the propulsion hardware beyond the stern plate.

Right and Left Pontoons with Bridge

More build details and pictures to come.

Regards,

TCIII ArduBoat Developer

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Replies to This Discussion

Subbed. I'm looking into doing something similar.

@Mike,

If I had to do it again, I would use two small outboard thrusters like the bluerobotics.com 3" thrusters, as putting the propulsion drive train inside the pontoons has been time consuming and I have had to be very careful about moving the pontoons around so as not to damage them as the fiberglass is very thin.

I think that I will give the pontoons several coats of yellow epoxy paint to help beef up the thin fiberglass as I do not want to lay on more glass.

Due to the weight of the drive train in the stern area of the pontoon, it looks like I will have to keep the battery fairly close to the bow to help trim the pontoon without adding non-functional ballast.

Also, it is hard to find inexpensive water cooled ESC, with reverse throttle, that are not on backorder, so I am using Traxxas XL-5 R/C car ESCs that are waterproof, have a reverse throttle, and a large heat sink and I plan to mount them top side.

Regards,

TCIII ArduBoat Developer 

What sort of sensor will you use for measuring depth?

Hi M C,

I will probably use the NMEA 0183 Garmin Intelliducer through hull transducer since the transom version is no longer available. It produces easily decoded NMEA depth and water temperature sentences.

I will make a small hull to mount the transducer to and attach it to the pontoon bridge.

Regards,

TCIII ArduBoat Developer

I have bought a pair of pontoons a few months back for the same purpose. This was the once I bought, quite thin these also, but I guess every ounce counts on a rc plane. China Post have post rates that are quite low compared to usps, when you live in Europe. Seems the one TCIII found had a better form.

Anyway, my plan was to use two small bilge pump mounted so i could use a servo to turn it for steering.

The new product from blue robotics seems nice. But they might be a bit big for my pontoon boat? almost 10cm (4") in both length and diameter gives quite bit of trust, but for a RSV you don't need all that speed.

will order a pair on the kickstarter campaign anyway, are they to big a drinks to many amps, they will be used on a larger boat in the future :) 

Regards

Carl

Looks good Tom! Cant wait to see it on the water :)

Hi Linus,

Thanks, much appreciated.

The rest of the propulsion fittings came in today and the Villain built hull will be here tomorrow so I can complete the pontoon propulsion drive train this weekend and start on the boat hull which will be much easier than the pontoons:-)

Regards,

TCIII ArduBoat Developer

TC3, looking good. The chaps from BR seems to doing a good job with the thruster. Have you looked at alternatives to this?

Do you intend to use a skid steer control on steering?

Would hull weight really be an issue, as long as it is buoyant enough. Adding some more layers of glass on the transom would not upset the apple cart, would it?

This is a great idea, Tom. Keep us posted, thanks for sharing.

Antonie 

@Antonie,

Thanks for the input, much appreciated.

I originally was going to make my own thrusters out of Johnson-Mayfair 750GPM bait pump cartridges and 50mm Robbe three bladed propellers, but the work involved to build the cartridge mounts was going to take a fair amount of time. I would have considered the bluerobotics thrusters, but even they are somewhat bigger than necessary for the pontoons as they are only 38" long to begin with.

Yes, I plan to use skid (differential) steering and have two Traxxas XL-5 R/C car ESCs that are waterproof, have a large heat sink so water cooling will not be necessary though I am water cooling the motors, and are designed for the Traxxas brushed 550 motors that I am using.

Instead of adding an extra fiberglass layer I am thinking about paint the pontoons with several or more coats of epoxy paint to help add additional protection to the original fiberglass layer. Presently the pontoon are rated for an approximately 10 lb (4.5kg) load and I do not want to marginalize the pontoon freeboard. The battery for each motor weighs about 1 lb, each ESC weighs .25 lb, and the motor/drive trains add about another 1 lb each. So I am already about 1/2 way to 10 lb and I still have to add the Pixhawk navigation board, the Garmin Intelliducer depth finder, and an auxiliary battery for the Pixhawk.

More build details and pictures at the end of this weekend.

Regards,

TCIII ArduBoat Developer

Hi All,

This weekend I was able to move ahead with my dual pontoon RSV by completing the cutouts in the left pontoon and adding the second motor/drive train to that pontoon.

Additionally I have added the propeller/trim adjust outdrives to both pontoons.

The next step will be to add the two Traxxas XL-5 brushed waterproof ESCs and the battery for each motor to see what the pontoon trim looks like. I can move the battery for each motor fore and aft on each pontoon to adjust for a hull trim where the top of the props will be below the surface of the water at all times.

The motor compartments will have waterproof covers since the motors will be water cooled and do not need external air for cooling. The ESCs will be mounted forward of the motor compartment on the top surface of the pontoon since they are waterproof and require air cooling.

Since the Pixhawk navigation board and the Garmin Intelliducer depth finder are near the center of buoyancy of the pontoons I do not expect them to have much of an effect on the trim as the motor batteries.

More to come:-)

Regards,

TCIII ArduBoat Developer

Hi All,

This weekend I proceeded to add deck cutouts in the pontoons for the twin battery compartments and spotted and drilled the holes in the stern to attach the motor cooling water pickup and water supply tubing.

I also took measurements for the two watertight deck plates that I will construct and use to seal the motor/propulsion and battery compartments. The motor/propulsion deck plates will be screwed down to the pontoon deck while the battery compartment plate will have thumb screws for easy plate removal for battery access and charging.

Here are pictures of the additional work performed on the pontoons this weekend:

Third Deck Cutout for Battery Compartment

Stern View of Cooling Water Pickup and Cooling Water Supply Tube

This coming week I plan to cut and install the watertight deck plates, mount the ESCs on the motor/drivetrain watertight deck plate, finish installation of the motor cooling system, and complete the battery compartment.

Regards,

TCIII Autonomous Vehicle Developer 

Good Job Tom!

Can see it already doing surveys on the lake :)

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