|Jun 17, 2014, 03:54 PM|
Joined Jul 2013
Micro Barges for Micro Tugs
When it comes to hobby projects, I enjoy using a variation of the KISS principle, "Keep It Small and Simple." While the micro category satisfies the first part, the second requires coming up with easier ways to do things. Ways that are, quite often, on the fringe of the status-quo.
Back in 2007 a thread named "Cheap fun barges" introduced the idea of converting plastic drawer organizers that are made by Rubbermaid into very simple barges for use with large scale model tugs.
By using the drawer organizers as one-piece hulls, the barges were a compromise between being easy to build and reproducing prototype design. That compromise remains in effect for this enhanced project that uses the same Rubbermaid plastic drawer organizers to make micro barges that are both "cheap" and "fun."
The largest drawer organizer that fits the micro category (Rubbermaid stock no. 2918) is 15 inches long by 6 inches wide. It makes a generic deck barge that can be used with available tugboat kits that are also easy to build.
Two of the kits are made by Lindberg: the 1:82 scale Diesel Tug, modeled after a former U.S. Army tug and the 1:72 scale Coast Guard Tug, a Disneyesque interpretation of an older steam tug. While it may look real, it is mostly make believe. A third kit is the much smaller 1:108 scale Revell Harbour Tug, another diesel boat.
These are not modern tugs with twin engines, Kort Nozzles and all kinds of bells and whistles. They are models of classic tugs that were in service when the kits were introduced some fifty years ago.
Although the two Lindberg kits are now being sold as simple shelf models, at sometime in their past they were sold as operating tugs with a battery powered prop and a manually set rudder. Even with this legacy, successfully converting these tugboat kits to powered RC operation is a rather daunting task and here is where this project offers an operating compromise.
The prototypes for all three kits are rather small and were used as harbor tugs. In their day, they kept busy hauling barges, usually one at a time, in confined and sheltered waters. To keep their barges under control, the tugs were securely attached "on the hip" of the barge, to use a standard tugboat term.
In modeling this prototype practice, a much easier to build powered RC micro barge can be used to maneuver an unpowered micro tug. If this heretical idea is found to be acceptable, then dig out the tugboat kits and have fun building them as simple shelf models.
As they are being assembled the lightweight plastic kits need only minor modifications to mate them with what is, essentially, an unsinkable powered barge. Unlike the rounded and tapered hulls of the tugboat kits, the drawer organizer barge will be about two inches deep, with square ends, a flat bottom and a sealed deck that is easily removable. This will provide a suitable space for installing the components needed for powered RC operation.
Continuing the heresy, instead of using propellers and rudders, the barge is powered by water jets using small, low voltage pumps, the kind that are used for miniature fountains. By using port and starboard pumps as a form of differential steering, the barge/tug combination can be remotely navigated around a pool or pond.
While each unpowered tugboat model can be permanently attached to its own powered barge, by choosing a different attachment method, all three tugs can be used with just one powered barge. Furthermore, by swapping out additional decks, the one powered barge can easily be converted into specific types of barges for the steam or diesel tugs.
For example, by adding coaming to an extra deck, the former deck barge then becomes a bulk cargo carrier. Add some piping and a small hut for a valve house and it becomes an oil barge. Spuds and a crawler crane will make a modern construction barge. In this way, the scope of the project can be expanded while overall cost is minimized.
Whenever working in small scales, there are always caveats. Any deck modifications should be reasonably well balanced and relatively light in weight. Depending on the total weight of the propulsion equipment that is installed on the barge, about eight ounces is the practical maximum.
For "on the hip" towing, prototype tugs should meet the sides of their barges at a twenty to thirty degree angle, not an easy thing to model. However, inexpensive ceramic magnets provide a strong, yet flexible connection between the rounded bows of the individual model tugs and the flat side of the powered barge.
In order to follow prototype practice, the tug needs to be positioned so its rudder and propeller is at or beyond the stern of the barge. Although they are made to different scales, the two Lindberg tugs can share the same attachment point on the barge. The small size of the Revell Harbour Tug will require an attachment point that is further aft.
Attached are photos of the generic deck barge with a "shelf model" Lindberg Diesel Tug. They were taken on Lake Kiddiepool, a convenient local source of confined and sheltered waters. Two of the photos show the interior of the barge with its pumps and controls mounted on the bottom and the tug attachment magnet mounted on the side.
Cheap, fun, easy to build and on the fringe of the status-quo -- this powered micro barge, made from a plastic Rubbermaid drawer organizer, meets the requirements that were set for this diminutive RC project.
|Jun 18, 2014, 09:02 PM|
As a witness to Dan's open water sea trials last weekend with this model, I can say without reserve that the concept works VERY well, and the execution is first rate!
|Jul 02, 2014, 12:10 PM|
Joined Jul 2013
The same variation of the KISS principle also applies to assembling the micro barge. For example, because of its unique construction, a drawer organizer barge needs to be built on a smooth, hard, flat plate that is about two feet long by one foot wide. The plate should be quite rigid, yet thin enough to allow clamps to slip over the edges. it also needs to be impervious to glues, solvents, abrasives and razor sharp objects.
Instead of some space age material, the plate is actually a 12" by 24" ceramic floor tile available at most DIY stores for about five bucks. Check it for flatness in the store using a ruler or other straight edge borrowed from the tool department. A couple of wooden blocks (cheap one by three furring strips) will provide adequate support while raising it up sufficiently from the workbench so the edges are accessible for using hobby clamps. The usual model building tools and supplies should be adequate for the micro barge project.
Here is a list of basic materials needed to build an unpowered, generic deck barge (source codes: DIY -- Lowes, Home Depot, etc; LHS -- local hobby shop; EBY -- eBay; LOC -- should be available locally):
1. Rubbermaid Drawer Organizer (EBY), Stock no. 2918; size 15" by 6" by 2" (also try the Rubbermaid web site for additional dealers)
2. Evergreen Scale Models strip styrene (LHS, EBY), Stock no. 199; 0.025" x 0.025 " square solid rod; 2 pkgs needed
3. Evergreen Scale Models sheet styrene (LHS, EBY), Stock no. 9030; 0.030" plain sheet; 2 pkgs needed (This is for the barge deck and two more packs will be needed for each additional deck.)
4. Stainless steel or brass bolts (EBY); 2-56 by 5/8" pan head, Phillips; approximately 18 needed
5. 2-56 Brass Threaded Inserts (EBY); buy two pkgs (This is a special item, so do an eBay search on this exact title. If no longer available, stainless or brass 2-56 nuts can be used, but they will increase the difficulty in assembling the barge.)
6. Aluminum bar stock (DIY); 1/8" by 1" by 36" (Get one that is flat and straight.)
7. Scotch Permanent Outdoor Mounting Tape (DIY, EBY) Product no. 4011 (This is a 1" by 60" roll of a super sticky version of double sided foam tape.)
8. Scotch Transparent Tape (LOC -- This is the old fashioned clear tape in the red plaid package.)
9. Binder Clamps -- Medium (LOC); need about a dozen (These are available at most office supply stores or go on line.)
The specified 2-56 bolts and threaded inserts serve two functions. While making credible bollards, they also secure the barge deck to the hull. If you prefer cleats over bollards, some modifications will be needed.
Styrene made by Evergreen Scale Models was specified as it comes in very convenient sizes for building the drawer organizer barge. Plastruct brand styrene can also be used, but it will require more work.
If you want a powered barge, here is an additional list of basic materials:
1. Thin wall brass tube (LHS, EBY); 1/4" inside diameter; need about a foot (K-S engineering or equivalent.)
2. Latex tubing (EBY); 1/4" inside diameter; need about two feet (This is the soft, tan pliable tubing often seen in chemistry labs.)
3. Evergreen Scale Models strip styrene (LHS, EBY), Stock no 189; 0.125" by 0.250" solid bar; 1 pkg needed
4. Ultra Quiet Mini DC 12 V Pump (EBY); 4 needed per barge (This is another special item that is currently available from multiple eBay dealers. Search on the exact title.)
5. Micro-servos (LHS, EBY); need 2 (TowerPro SG-90 or equivalent.)
6. SPDT Micro switches (EBY); lever arm type; need 4 (Most any of the small, 5 amp capacity micro-switches will do.)
7 RC gear and 12 V batteries of your choice
With the exception of the plastic hose barbs glued onto them, the Ultra Quiet Mini Pumps appear to be high quality, with brushless motors and a magnetic drive. Designed to run on solar cells, they have a low current drain. As they are cheap in price, sometimes with free shipping, you may want to order extras to have as spares.
I continuing to comply with the KISS principle, the operating controls are vary basic, just two micro-servos actuating micro switches for Port and Starboard steering and Fwd/Stop/Rev. It should operate using almost any two channel RC equipment. If the controls are not to your liking, then upgrade to ESCs. As the powered barge uses a form of differential steering, this may increase the complexity of the upgraded controls.
|Jul 11, 2014, 05:03 PM|
Joined Jul 2013
While waiting for the barge parts to arrive, the tugboat kits can be started. In the case of the Lindberg Diesel Tug, there are a number of threads describing its construction as a powered RC model. In contrast, when the Diesel Tug model is being built for this micro barge project, only a few, very simple modifications will be needed.
First, the sorry excuse for a propeller can be left off to reduce drag and the propeller shaft hole can be filled with modeler's putty. In addition, that inexplicable gap between the deck and the stern grating is plugged with silicone caulk. Make sure that the caulk does not interfere with the movement of the rudder.
The rudder was assembled so it would easily swing, but the rudder post crank arm was left off. The space between the rudder post cap and the hull was then packed with waxed dental floss, which allows the rudder to hold a set position, usually centered, yet deflect if it is hit.
Curiously, although it is not noted in the kit assembly instructions, there is a way for the combined deck/superstructure assembly to be easily attached and removed from the basic hull. While the deck and hull joint is not watertight, it is water resistent and that is all that is needed for an unpowered tug.
To accomplish this assembly, the folks at Lindberg molded a hole in the hull, just aft of the rudder post. To use this hole, the rudder must be moved out of the way. A corresponding hollow boss was molded into the after part of the deck assembly.
There is also a hole molded into the far forward part of the deck which mates with one of the extra black pieces that comes with the Diesel Tug kit. It is the one that looks like a small trapezoid with a hole through it. It has two ribs on one side and a hollow boss molded onto the other. The ribs need to be filed off, but leave the boss as is. This part fits on the two small ridges molded onto the inside of the far forward part of the hull, with the boss side down.
The size of the molded bosses indicates that small sheet metal screws were initially intended to secure the deck to the hull. Instead, the same 2-56 bolts and threaded inserts ordered for the barge can be used on the tug. The aft deck boss and the trapezoid part boss will need to be slightly drilled out to accommodate the threaded inserts and a tiny drop of ACC will hold the inserts in place. By screwing one bolt upward through the aft hull hole and another downward through the forward deck hole, the deck and hull can be accurately lined up and secured.
Apart from filling the big gap between the deck and the stern grating, no other measures were taken to make the kit watertight. To keep the tug from sinking if things go bad, a block of lightweight ridged foam from a local craft store was roughly shaped to fill the insides of the main cabin, while protruding about a half inch into the hull. The upper part of the block was painted black as it makes a good background for the open portholes.
If, for whatever reason, the tug begins to fill with water, it will settle stern first. When completely filled, the waterline then becomes the front of the main cabin. In this way, the barge attaching magnets will remain in position for towing and the hulk can be brought back to shore, albeit slowly, by the powered barge. On arrival, carefully pick up the waterlogged tug and just let the water drain from between the deck and hull. Barring any physical damage, the tug should be ready for action again in just a minute or two. At the end of the operating session, separate the deck from the hull and blot up any remaining moisture.
The barge attaching magnets are common ceramic ring magnets easily found at craft stores and on line. They are 3/4" in diameter and 1/8" thick and come six to a package. In this barge/tug setup the tug is attached to the left side of the barge, so the ring magnets are attached to the right side of the tugboat hull.
There is a shallow raised boss molded onto the forward part of the hull which serves as a locating landmark and the magnets are glued to the hull just in front of this boss. Three of these lightweight magnets are stacked together for increased power and they are counterbalanced by a quarter ounce weight form the LHS. There is no landmark on the left side of the hull, so just eyeball the location.
Finally, when operating, the tug and barge rub against each other with some force and the simulated side fenders included with the kit are too delicate to survive. Instead, install a length od D shaped EPDM rubber weather stripping on the magnet side of the tugboat hull along the line where the deck and hull meet. The weather stripping should be available from your local DIY store or online. I used Frost King brand V25W, which is self sticking. A dab of caulk on the open ends of the weather stripping will keep out any water.
When properly ballasted the tug weighs about a pound. There is a "step" molded onto the bow of the tug, just below the front fender and a notch on top of the rudder which can be used to establish an operating waterline. I bought several lead ingots on eBay, weighing a half pound each, and these were used to ballast both the barge and tug. The ingots were cut to an approximate weight and then trimmed to be slightly light using a bench belt sander.
The ability to place the weight in the hull and then to easily and accurately position the deck/superstructure assembly to check the effects (no bolting is necessary -- just line up the holes) makes the ballasting easier. When the weight is in about right, then glue it to the hull. Final trimming of the tug was done with half ounce weights from the local LHS.
|Aug 12, 2014, 10:53 AM|
Joined Jul 2013
If building a simple, one-size-fits-all, generic barge is not enough of a challenge, here is something to think about. As Rubbermaid plastic drawer organizers come in a variety of sizes, this project also offers a more creative option. Dedicated companion barges, based on specific prototypes, can be built for the micro tugs.
For example, historically, a typical railroad car float was some 40 feet wide by 300 feet long, which is too big to be interpreted as a micro barge. A companion car float for the 1:108 scale Revell Harbour Tug would be nearly three feet long. Nevertheless, by doing a little research, a prototype was found that can make a car float for the much larger, 1:82 scale Lindberg Diesel Tug.
Starting around 1900, the B&O Railroad in Baltimore established a tug and car float "bridge" across the Northwest Branch of the Patapsco River as a way for oversize loads to bypass some local tunnels. It was abandoned, along with the rest of the B&O marine operations, in the nineteen seventies.
The following web site documents this rather unique service while it was actually being used. The site includes several rare photos of a special railroad car, carrying a huge load, sitting on a car float, along with some nice views of classic B&O tug. Somewhat surprisingly, to handle such massive shipments, single track car floats were employed.
In the real railroad world, loads that are oversize are often overweight. Although the mini-floats carried one car at a time, as opposed to seventeen for the bigger car floats, they were designed to support heavy, concentrated loads.
While the average loaded freight car weighed about sixty tons, these barges could handle a car weighing nearly three hundred tons. With just one track running up the middle of the barge, any tipping or balancing problems during loading and unloading would be minimized.
Two of the mini-floats were built by Bethlehem Steel at its Staten Island yard in 1954 to replace wooden barges that were built in 1910. B&O records list them as being 24 feet wide by 125 feet long.
Unfortunately, an exact scale model of this mini-float will exceed fifteen inches, the maximum length allowed for the micro category. Furthermore, compared to the graceful B&O tugs, which were 110 feet long, the Lindberg Diesel Tug, which is about a 90 footer, is noticeably undersized. Fortuitously, by building a model of the mini-float out of a drawer organizer which is 15 inches long, but only 3 inches wide (Rubbermaid stock no. 2917), the size problems can be resolved.
In complying with the maximum length restriction, the drawer organizer mini-float is 21 feet wide by 103 feet long, using the same 1:82 scale of the Diesel Tug. When compared to the prototypes, the compromised mini-float and the undersized model tug are both about twenty scale feet short, making them, proportionally, a suitable micro companion pair.
As the scale of 1:82 is very close to the model railroad scale of 1:87, detail parts and "ready-to-float" barge loads are available. One such load is plastic model of a period, heavy-duty railroad car with an electric transformer load. As the model is a bit shorter than the super-heavy-duty generator carrying car, it is also, proportionally, a good match for the micro tug and barge. The model is made by Bachmann as part of their Silver Series and the stock number is 18348.
One of the smallest drawer organizers, 9 inches long by 3 inches wide (Rubbermaid stock no. 2915), forms the core of a companion barge for the Lingberg Coast Guard Tug. Unlike the Lindberg Diesel Tug, which is modeled after an actual Army tug, the Coast Guard kit is mostly make believe.
For example, despite being made to the larger scale of 1:72, the assembled kit, at 12 inches long, is actually smaller then the Lindberg Diesel Tug. The diminutive nature of the Coast Guard kit becomes even more apparent when it is compared to another 1:72 scale model tug. It is the Carol Moran, made by Dumas, which is eighteen inches long.
To complement its Disneyesque design, a equally unusual barge was chosen as a companion for the Coast Guard tug. The apparently derelict prototype was documented in 2002. It can be seen in its natural habitat at the following web site. Photos of it are at the bottom of page two and at the top of page three.
The barge consists of improvised floats that started out as railroad cars. Although old and obsolete, their tanks were originally designed to survive train wrecks and they are quite sturdy. When welded to steel beams they make a rigid framework that supports a heavy timber deck, which extends beyond the floats by several feet at each end. The deck, in turn, is used to support a small crawler crane.
With no known dimensions, interpreting this exotic, one-of-a-kind prototype as a micro barge is considerably more of a challenge than a generic deck barge or even the mini-float. In mimicking the proportions of the prototype, a model barge hull, made from the small drawer organizer will fit beneath the deck and in between the side tanks.
When in the water, by running it nearly submerged, the added hull can be effectively hidden by the extended wooden deck and the four side tanks, preserving the unique look of the prototype. The overall dimensions of the resulting micro barge will be about 12 inches long by some 6 inches wide, making it a good match for the smallish Coast Guard tug.
A somewhat vexing problem is finding a suitable crawler crane in a scale that is close to 1:72 as most of the models sold today tend to be modern and quite large. Although it represents an older and smaller prototype with a shorter boom, the 1:76 scale model of the 1940s era Ruston-Bucyrus 19 made by Corgi is an available compromise. Like many Corgi models, it is mostly made from cast metal parts and it come fully assembled. Its stock number is DG225005.
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