Argy Bargy Rescue Vessel Page

ARGY BARGY - VIDEO CAMERA AND MODEL BOAT RECOVERY VESSEL
Introduction, Jaws, Sub Catcher, Crane, Winch, Hull, Propulsion, Video Camera, Top Deck, Pump, Electronics, Parts List, Summary

	Figure 1a: Jaws Recovery System. Photo courtesy of John P. Figure 1b: 5.8GHz Wireless and Canon compact camera. Photo courtesy of John B. Figure 1a : Jaws recovery system and Figure 1b: 5.8GHz wireless and Canon compact Cameras.		75 Rescues since June 2008
Introduction	My interest in radio controlled boats started in 2007 after browsing various RC hobby categories on the internet. After attending a few meetings and sailing days run by Broadmeadows Model Boat Group (BMBG), I was convinced to launch into scale model boating. However, after a few mishaps on the lake it soon became obvious to me that everyone focused on scale model detail, less so on reliability and no thought of recovery when things go wrong. BMBG do not have a dingy, instead we rely upon hook and line or other model boats to affect a recovery. Boat recovery it seems rarely enters the mind of a marine modeller. Pride and faith in the vessel completely block out any thought of trouble. So I suggested to BMBG that my first boat would be a scratch built recovery vessel. They probably thought I was crazy, but I went ahead and built Argy Bargy.		Top of page
Jaws	I wanted to design a vessel that would recover stranded boats from surface water, weed beds, reeds and islands. I had seen Pusher Tugs, but they could only push boats, never pull them backwards out of reeds, etc. This got me thinking about a jaws system (Figure 1) that could clamp onto boats and then use a life line attached to the recovery vessel to retrieve both boats. This strategy does not rely on the power of the propulsion system to extract the stranded boat. The jaws were made parallel to and as low as possible to the water to maximise the effectiveness of clamping different hulls. They are made from “I” shaped Aluminium curtain track material. Vertically they are stiff, but horizontally they can flex enough to moderate clamping forces on fragile boats. Two plastic packaging straps interconnected between the jaws prevent the two hulls colliding. One strap is partly below the waterline to help recover semi-submerged boats. A Barge design was chosen because it allows such low horizontal jaw movements. What do you name a barge that pushes other boats around? Argy Bargy of course. Kite line from a radio controlled winch passes through a pulley on top of the crane and is tied to a fishing snap swivel. A line from each jaw passes through a pulley on the front deck and connects to the swivel. When the winch retrieves line both jaws pull inward. Letting line out causes the jaws to open assis ed by some hat elastic connected between the jaws on the opposite side of the fulcrum. This strategy works well for stranded boats. I have even used to lay buoys. But it’s not good for boats or submarines that barely float.		Top of page
Sub Catcher	This led me to design the Sub-Catcher system (Figure 2). It operates like a fork lift.
	Figure 2a: Sub Catcher up position. Figure 2b: Sub Catcher down position. Figure 2c: Rescued submarine. Photo courtesy of John Parker. Figure 2: Sub Catcher Up/down positions and Rescued Submarine.
	The crane is moved to vertical and slid along its moving tracks to over hang the bow. A plastic coated wire mesh rack hinged onto an aluminium frame slides into internal tracks on the crane. Small plastic step height adjustment blocks manually control the racks angle of attack. Line from the winch is attached to the rack enabling it to move up or down under radio control. The rack presents very little resistance to motion. It can reach a depth of about 200mm. I have used it in boat dozer mode to push submarines back to shore. It’s also great for removing plastic bags, bottles and other floating rubbish from lakes. Fork lift mode is used for lifting lighter subs or supporting sinking vessels if I can get to them in time. Changing between jaws and sub catcher takes about 2 minutes once ashore.		Top of page
Crane	What would a recovery vessel be without a crane? Argy Bargy’s crane is characterised by its versatility. I have already shown it in two positions, but it can also be angled at several positions up to a maximum of 45° over the bow and a treble hook attached (Figure 3).
	Figure 3: Crane with Treble Hook. Figure 3: Crane with Treble Hook.
	There is nothing ornamental about the crane or winch. Together they can lift 2.3 kg. It may even lift more, but I have not plucked up the courage to try for fear of stripping the reduction gear drive. Two spotlights are mounted on the underside of the crane. During night operations, one illuminates the jaws, the other the winch and fore deck. I have used the treble hook to recover buoys. You simply lower the hook fairly deep into the water and run over the buoy rope. Once hooked I retrieve as much line as possible, then pull on Argy Bargy’s life line to bring both back to shore.		Top of page
Winch	The winch consists of a plastic electrical wire spool fitted to a steel shaft mounted on roller bearings. A 96 tooth gear on the shaft connects to a worm drive which is in turn driven by a 3.75:1 geared reduction drive and 6V electrical motor (Figure 4). Overall reduction ratio is 360:1.
	Figure 4: Winch with Reduction Drive, Diaphragm Pump and Speaker. Figure 4: Winch with Reduction Drive, Diaphragm Pump and Speaker.
	100 metres of kite line is loaded onto the spool in case I hook something really big. I can back off all the line and reverse my way to shore. The winch travels at 2.5 metres per minute. I use this fact to measure lake depths by timing how long it takes a sinker to reach the bottom. In and out direction is controlled by two 5 Amp relays switched by a multiplexed 2 channel electromechanical system.		Top of page
Hull	Hull dimensions of 920 mm long x 315 mm wide were derived from the longest jaw length (~350 mm) needed to clamp a long boat and the maximum beam (~300 mm) of boats likely to be recovered. Hull height of 75 mm enabled enough space to stand two 12V batteries as well as provide approximately 20 kg of displacement. Now weighing 10.5 kg, that leaves about 9.5 kg spare for crane use or jaw carrying capacity. Box construction using 12 mm thick pine complimented by a 45° bow and under cut stern seemed to be appropriate. 3 mm ply was used to cover the bottom of the hull. Two solid bulkheads divided the hull into three water tight sections (Figure 5). A third bulkhead was placed in the bow to reinforce the 3mm ply joint.		Top of page
	Figure 5: Hull profile. Figure 5: Hull profile.
	A long brass propeller tube was run from above the water line in the centre compartment through to the lower stern edge and epoxied in place. A polymeric bushing was glued in place to act as a rudder tube. The top and bottom faces of the bushing were wide enough to seal O-rings on the rudder shaft against water ingress. A rudder with small integrated Kort nozzle swivels around the propeller (Figure 6). The outside of the hull was covered with two coats of fibre glass tissue. The inside only one coat. Polystyrene foam fills all vacant space inside the hull.
	Figure 6: Propeller and Kort nozzle. Figure 6: Propeller and Kort nozzle.
Propulsion	A 24V, Johnson motor recovered from an old DeskJet printer runs the single screw. A 10 tooth pulley on the motor drives a 20 tooth pulley on the 4 mm main shaft via a 2.5 mm pitch belt (Figure 7). A 60 mm, brass 4 blade D type propeller provides only slow speed but powerful thrust at about 4000 rpm. An Electronize VR43 24V speed controller with BEC provides forward and reverse control.
	Figure 7: Motor, Pulleys and belt drive. Figure 7: Motor, Pulleys and belt drive.		Top of page
Video Camera	It became apparent that long distance rescues needed an on-board camera to assist navigation. It was very difficult to judge approaches from so far away and this caused many drive-by misses of the stricken vessel. So I bought a 2.4GHz wireless camera and digital video recorder with LCD screen. The battery operated CCD camera transmits video and audio signals via 2.4GHz wireless protocol to a digital video recorder mounted on Argy Bargy’s transmitter. The camera is mounted on a radio controlled turn table mechanism allowing full 360° rotation (Figure 8). This feature is essential to keep moving boats in frame.
	Figure 8a: Video Camera and Turntable. Figure 8a: Video Camera and Turntable.	Figure 8b: Video Camera, Turntable and Digital Video Recorder. Figure 8b: Video Camera and Digital Video Recorder.
	A 2.5 inch LCD screen on the recorder shows live pictures from the camera up to 100 meters away. Recording at 25 frames per second and 640x480 resolution to an 8GB SD card allows about 5 hours of video to be captured. However with the introduction of 2.4GHz radios, video interference became a major problem so I switched to a 5.8GHz wireless night vision camera for navigation. Video clips are know recorded via a Canon compact digital camera mounted on the turntable (see photo a top of page).		Top of page
Top Deck	Three old packing crate lids formed the top deck. Their folded steel edge afforded an extra level of protection from errant high speed petrol boats. A rubber moulding was fixed around the outer edge for 360° bumper protection for delicate balsa species. 7 mm ply decking made fixing accessories and other bits easy. Simply drill and screw any where at all. No need to worry about reinforcing. Sealing between the top deck and hull was achieved by laying a 12 mm wide self-adhesive rubber tubing strip around the hull perimeter. 8 bolts fastened to the hull penetrate the deck evenly around the outer edges and are screwed down with nuts hidden inside bollards. A single coat of fibre glass tissue was applied for long term protection against waves breaking over the deck. And yes, as expected, waves do break over the deck. A cabin was constructed from 3mm ply using my own design. Three rotary thumb wheel counters on the side engine cowling record the number of rescues. Ten dollar toy pirates from a local store add some character and interest to this otherwise unconventional boat.		Top of page
	Figure 9: Cabin with Rescue Counter. Figure 9: Cabin with Rescue Counter.
Pump	A 12V diaphragm pump was fitted with a view to pump air into recovery lifting bags lowered on the crane. But as reality set in, this seemed a bit ambitious on my first model. So it was used as a novelty to spurt water at unsuspecting by-standers on hot Australian summer days. Kids love it.		Top of page
Electronics	Two 12V batteries connected in series supply a 24V speed controller, motor and electrical system which includes 6 lights, a horn, water pump and video camera turntable. All motors were suppressed with capacitors. A four channel 27 MHz radio controls everything except for the lights. 24V, 12V, 5V and ground signals were distributed via terminal strips. 24V supplies both incandescent light circuits and the video camera turntable’s adjustable voltage power supply. 12V runs the Kemo™ Fog Horn kit and water pump. A regulated 5V, 4.5 Amp power supply built using 3 LM340T05 transistors, a few capacitors and Vero™ board supplies the 6V winch motor. The winch motor stall current rating of 5 Amps meant the regulators would shut down before damaging the motor. The adjustable supply used an LM317 transistor, a fixed resistor and a potentiometer to output voltages in the range 5 to 18V. I found the video camera turntable worked best at about 9V (Figure 10).
	Figure 9: Electronics. Figure 10: Electronics.
	The winch, horn, pump and video camera turntable were all controlled by a multiplexed 2 channel electromechanical system and relay board. Two standard servos were mechanically connected to the shafts of two rotary switches in such a way that full movement of a stick could activate three contacts. Both switches had there positioning ball and spring removed to make the servo’s work easier. The position of rotary switch #1 determines which deck of rotary switch #2 would be supplied with 24V. Refer to the wiring diagram PDF. The position of multi-deck rotary switch #2 determines which relays energise to supply power to a device. Two 24V, 5 Amp rated relays drive the winch motor back and forward. Two 24V, 2 Amp rated relays drive the horn and water pump. Another two 24V, 2 Amp rated relays drive the video camera turntable left or right.		Top of page
Parts List	Propeller motor: Johnson motor C6464 60002. Water pump: Thomas diaphragm liquid pump 5002F. Winch motor: Faulhaber 3357 006 C. Video camera turntable motor and mechanism: Old video player. ESC: Electronize 43VR. Servos: Hitec HS-311. Batteries: DiaMec 12V, 2.2 AH. Propeller: Raboesch 60mm 4 blade brass 174-14. ideo camera turntable Shaft: Raboesch 4mm Stainless Steel and brass tube. Timing belts and pulleys: RS Components Synchroflex. Horn: Kemo Fog Horn kit No B 015. Rotary switches: Grayhill. Radio: Awesome Products 4 Ch Rx and Tx by Model Engines. Note: Similar equipment from other suppliers would also work.		Top of page
Summary	Construction of my first model boat is complete. Argy Bargy was designed and built from scratch to recover model boats and submarines. Argy Bargy has successfully rescued 24 boats sinced about June 2008. Types recovered include a 1.1 metre petrol speed boat, a runaway steam battleship, a balsa run-about, an upturned airboat and several submarines. Argy Bargy has recovered them all without damage. As a bonus, I have even designed some buoy's Argy Bargy can drop and retrieve from a lake. The impact of Argy Bargy has been two fold. Some members have improved their boats reliability to avoid the embarrassment of being rescued. While others have endulged in more risky behaviour knowing they can be rescued if misadventure strikes. I like to think Argy Bargy’s stable, indestructible, unsinkable and reliable as gravity. For me, the project has been a good introduction into the mechanics of model boat building. Now that Argy Bargy stands ready for recoveries every sailing day, I can focus on my next project. A classic boat with curves, character and all that other stuff. Commenced building May 2007. Launched June 2008.		Top of page