Ballast Systems

The Proʼs and Conʼs of Ballast SystemsBy Mike CaswellThere are many systems available for ballasting a submarine, and for someone new to this hobby, it must be very difficult to determine the best course of action. This article attempts to explain each system logically,Depending on the level of skills in electronics, plumbing and engineering, each system will press different demands on the modeler.What exactly does a ballast system do? It simply removes and replaces water to change the weight of the model, making it surface or submerge. This procedure is not complicated, but many of these ballast systems are fangled, expensive and difficult to maintain, and they lose this main objective.Also worthy of note is the fact that most model submarines do not operate at depths much below periscope depth. In fact, it can be extremely dangerous to dive greater than a few feet, as some ballast systems cannot overcome the water pressure, making their failsafe recovery system useless.Assuming there are minimal skills, we propose the following approach.The simplest system to operate is a Snort (Schnorkel) system, bringing fresh air into the ballast tank at periscope depth. The boat is trimmed so that when the ballast tank is full of water, only the periscope is out of the water. Therefore, if all the systems fail for whatever reason, the boat will float to the surface. When the ballast tank is blown (with fresh air from the Snort pump), the boat will surface to its correct waterline position. The ballast tank is either full or empty of water, there is no ʻin-betweenʼ. This makes operation of the ballast tank a very simple process for the novice.To dive, the boat is ballasted to ʻventʼ or flood the ballast tank, and the rear planes set to the dive position. As the boat moves forward, the planes will push the boat underwater. If the engines are stopped, the boat will assume periscope depth. The faster the engines are run, the deeper the boat will go, but it will always revert to periscope depth.Assuming there is some sort of catastrophe, and the boat dives to 15 feet or more, then the on board Gas Reserve will be activated by the failsafe system and it will blow the ballast tank. This is where gas systems excel over bladders and pumps, as the latter cannot overcome the water pressure.Once the basics of operating and maintaining a Gas/Snort Sub-driver have been mastered, a novice submariner may wish to try different systems. RCABS is in voguecurrently and is a good second choice, as it is a fairly simple operation to convert a Subdriver to this system, if required.The basic principal of RCABS-R (Recirculating Compressed Air Ballast System- Reversed) is that a bladder is placed into the wet hull of the submarine and is inflated prior to operation. To submerge the vessel, the pump deflates the bladder, passing the air into the Pressure Tank. When the vent valve is opened, the compressed air in the Pressure Tank escapes into the bladder, so the bladder inflates and the boat surfaces.Here is a typical Clippard valve, available for approx $25 from-Clippard Instrument Laboratory, Inc.7390 Colerain Avenue Cincinnati, OH 45239(877) 245-6247 Another solenoid valve from-/models/bhm.htmlAir Vacuum Pumps come in different sizes from-/models/pumps.htmlHere is a typical Clippard valve, available for approx $25 from-Clippard Instrument Laboratory, Inc.7390 Colerain Avenue Cincinnati, OH 45239(877) 245-6247 Bladders come in four sizes from-/models/bladders.htmlDrawing kindly provided by George Protchenko, who invented the RCABS-R system.The major advantage of RCABS-R over the standard RCABS system is that no air is taken from the pressure hull. This reduces the potential of leaks caused by a vacuum in the cylinder as the air is pumped into the bladder.If the system loses power etc. then the normally pressurised bladder is re-inflated as the pressure in the compressed air tank slowly leaks back into it. It will not do so at depth as the water pressure will be too great.This system needs an extra space in the hull to accommodate the compressed air tank. On the larger models, this may not be so much of an issue, but on smaller models, it could potentially create problems if additional ʻextrasʼ like cameras or torpedo launching systems are envisaged.RCABSThe RCABS System uses the air within the WTC to inflate a bladder laying within the boats hull. As the bladder inflates, the boat surfaces. To dive, a solenoid valve is opened and the air in the bladder is released back into the WTC.The RCABS system uses the same valves, pumps and bladders as depicted in the RCABS-R system.In some models, locating the bladder in a convenient place may cause problems, due to cramped cylinder/hull conditions.Many RCABS/-R bladders will not inflate at depths of 10ʼ or more, due to water pressure.Once set-up, the RCABS & RCABS-R system is fairly easy to maintain and operate, however, there are no ready made systems available commercially, meaning a beginner has to spend time experimenting, tweaking and building a WTC.THE GAS SYSTEMThe Gas System uses a liquid compressed gas to expel water from the ballast tank. Gas is supplied from a can into the Gas Reservoir using a special valve that screws onto the can. Other types of gas are available, but none of them have the threaded exhaust port and need major modifications to fit the tire valve fill port.The benefits of a Gas Ballast System.Immediate BLOW-VENT operation. Realistic and scale like - No wait for bladder or piston pumps. Does not require a vent above the water-line as does a pump-type ballast system.Low Maintenance - No wires, pipes, motors, pumps or bladders. One servo operates blow and vent valves.Minimal space requirement which leaves room for torpedoes and cameras etc.Gas Empty Indicator - Boat assumes slightly positive trim, changes position in the water when GAS charge is low, telling Commander to return to port.Unique 'Gas Saver' mechanism meters out exact amount of gas to 'blow' ballast tank. (N/a to 1/144 Seawolf & Kilo due to limited space.)Deep Dive Blow Feature. Ballast tank will fail-safe BLOW at depths of up to 100'. Air pumps only work up to 15-20 feet.Fail Safe. Any gas leaks (unlikely) automatically fill ballast tank and surface the boat. Low Battery Drain. Occasional split second servo use to operate blow-vent- no pumps or motors to operate.For the new person in this hobby, a D&E Sub-driver is definitely the easier way to start out, as the units are sold assembled and virtually ready to run. Ballast tank size, waterline trim and other constraints are already calculated, so expensive experimentation is not needed. Even the motor/s and gear reduction drives are installed. In most models, the Snort system can be incorporated at a later date. This allows the submarine to use fresh air at periscope depth to blow the ballast tank, giving a realistic feel and look to the submarine. Gas becomes the safety back-up fail-safe system, and as this operates at depths of 100 feet or more, the chances of losing your boat in a deep pond are minimized.THE SNORT SYSTEMThe Snort System uses fresh air to blow the ballast tank. This concept is ideal in extremely small boats, where space in a major consideration.Here are two types of Air Vacuum Pumps, the smaller beingideal for 1/144 scale Revell & Trumpeter models etc.The larger pump has 17psi and 14 “ vacuum, drawing .2 ampThe smaller pump has 17psi and 12” vacuum, drawing .1 amp By installing a miniature solenoid valve the ballast tank is vented. Controlled by a switch such as a SubES1 which is plugged into the receiver and wired to the solenoid valve.see /models/bhm.htmlThis ʻSnort onlyʼ miniature Sub-driver is only 10” long by 1.5” diameter and is able to fit into the smallest Revell models. It is the ideal ʻPool Toyʼ system, as it incorporates a ballast system with dynamic diving, making the best use of an extremely crampedspace. The boat is trimmed to be at periscope depth with a full ballast tank, so ʻblowingʼthe tank will bring the boat to its correct waterline position. To dive, the ballast tank isʻventedʼ and the forward planes positioned downwards. With the engines running, the boat is dynamically driven to the required depth. If the engines are cut, then the boat will return to periscope depth. A final ʻblowʼ to the ballast tank, will return the boat to the surface. Two servos are installed, one for the rudder, and another for the forward planes. Although this doesnʼt give the degree of control larger boats with pitch controllers etc.The Snort system is extremely realistic, giving the operator the chance to drive the boat the way it was really done. Bubbles abound!THE SNORT SYSTEM - WITH GAS FAIL-SAFEA D&E Sub-driver or gas WTC can usually be modified slightly to accommodate a Snort system. All that is required is that the appropriate low pressure pump and SUB ES1 switch controller are installed. The pump sucks surface air into the ballast tank, blowing the water out. To vent, the normal vent valve is used. Gas is on board, only in the case of an emergency, or when deep diving.Custom built WTCs can be constructed around this simple concept, and may even have a much smaller gas reservoir to conserve space and weight. The vent valve can be a small solenoid.As the Gas system is only used in emergencies, such as a deep dive which needs a failsafe to operate, the on board supply of gas can be dramatically reduced. A smaller tank, or just a quick shot of gas injected will be enough to operate the boat for hours. In fact, the batteries will be run down before you run out of gas.The D&E Sub-driver could also be modified to run as an RCABS/R system, installing a bladder into the ballast tank, or free hull space and using the Snort pump to inflate it.For the beginner, making a decision on which of the numerous systems to use is a somewhat daunting experience. There are so many proʼs and conʼs to each system, so how does one make an informed choice?I guess it depends on the degree of model making, engineering and electronics skills you possess. If you are of the fortunate few that are proficient in all these skills, you can try all the systems over a relatively short period of time, and tinker with each one. In my own case, I found I had enough problems building the model itself, and after several attempts at building a Water Tight Cylinder, I gave up in favor of purchasing a ready made unit.Determining the ballast tank size and overall WTC size needs experience that I do not possess. Figuring out which type of ballast system to use and actually getting it assembled and working, proved to be a major problem. I found that gleaning over the few model submarines forums available, that there was a small core of people who were more experienced, yet they seemed to be over complicating everything, and were obviously biased in their thinking. Not one set of decent, easy to follow instructions existed.I purchased parts to make my own cylinder, and initially went the gas route, but I had to make the gas reservoir myself, and install seals and motors in the end-caps. It was a difficult project, and the outcome was failure because of inadequate and explicit drawings. I tried to convert the system to a bladder operation, but this also was fraught with problems. So, after many weeks of tinkering in my basement, I quit and purchased a ready-made gas system. My time was now devoted to finishing the model, and unfortunately, I picked a fiberglass mold, which had very little in the way of instructions, no fittings kit, and it needed a ton of work. The combination of trying to build a WTC and a fiberglass model was too much for someone with few skills and just starting out in this hobby.Eventually, the boat was in the water and working, but it took me over eighteen months and much frustration.I should have stuck to a smaller model, an injection molded kit that had good build instructions, and had a ʻfittings kitʼ with all the parts ready to convert it to an R/C model.Having now completed my first model, I can safely say my experience was a trial by fire, and I now feel well informed to advise a newcomer on the fastest way to get a working model. After all, the real fun part of this game is to get the darned boat in the water and -play!So, here are my suggestions.1.Get a plastic injection molded model that has a Fittings Kit. Donʼt try to modify any injection molded model that does not have one of these kits, you will have no end of problems.2.Get a Gas Propel Cylinder, ready made, that can easily have the Snort system installed. Boats as small as the Trumpeter Kilo (15” long) can operate a Snort.3.Trim your boat so the Snort intake is just above the waterline when the ballast tank is flooded (vent). When the ballast tank is empty of water (blow) it should sit in the water at the correct waterline position.4.Operate the boat using the Snort to blow the ballast tank. There are only two positions for a ballast tank, full or empty. Do not try to trim the boat halfway.5.To dive, vent the ballast tank completely, so you should be submerged with the Snort tube out of the water, then use the rear planes and the force of the propeller to dive. So, if you have a problem, stop engines, and you will surface, even though your ballast tank is full of water. You should easily be able to dive one or two feet deep using this technique. Any deeper and you probably wonʼt be able to see where you are going and could easily lose your boat.6.Only in the case of an emergency will you need to blow the ballast tanks using the reserve tank of liquid gas. It is worthy of note that ONLY a gas system will recover a boat that is lost to depths of over approximately twenty feet. Bladder systems pumps are unable to produce sufficient pressure to inflate the bladder at these depths. A gas system used as the fail-safe will work at depths of 100 feet.。