This isn't about Ship combat, but I'm building a large rc boat, that I want to use together with an gps and sounder to map the depths of small lakes, to make a depth charts for fishing. And this forum seems to be better suited that most rc boats forum because they are mostly for speedboats. I made a 2 fiberglass hull, bought some motors from ebay, shafts, propellers and was happy, well, until everything was mounted. And mounted it together as a catamaran with the sounder in the middle. The shafts I bought was 3" Propshaft M4/M4 and the motors 12V DC 1000RPM Mini Torque Gear Box Motor Hobby Everything fitted well, and seemed to work. But I have to main issues I have to much electric noise in the boat, so the receiver and gps systems are dying. I have filled the shaft with grease, but I still get water in trough the shaft. What kind of engines and speed of the engines do you use? Would a longer propshaft be easier to waterproof, or is there any other way to get the stuff waterproof. You are using pumps, but I guess you are trying to waterproof the boat as much as possible before going to combat? I hope I don't break a rule by asking for help with something else. Regards Carl Stiegler
yeah, it would be nice to use them ... I even got a few of those on my desk. However; the shape of my hulls wants me to use something else. There is room for a 60mm 3 blade, but the T100 will not fit, ofcorse, it is just fiberglass, so I could make it fit...
If you're getting to much electrical "noise" in your electronics, I'd suggest a separate battery system powering just those items. (You could also put in capacitors on your motors to act as filters, but for this application the separate power source works.) Leakage around the prop shafts.. you're going to get some, all ships do. Grease in the stuffing tube will reduce the amount. Depending on rpm (if low enough), you might even be able to put a rubber o-ring around shaft at both ends of stuffing tube (just grease them to reduce friction)
If most of your bits and pieces are going on the platform, you might be able to pack those pontoons with enough foam that a slow leak through the stuffing tubes wont matter much. A few questions for you.. Could you give us a better idea of dimensions and mass involved? How many amps are those little motors pulling to spin a 60mm prop in the water? What are you using for batteries? Are you sure the motors aren't causing a large voltage drop that is in turn causing the RX and GPS to drop out? Most of my stuff I target to run 1.5inch props 4000-6000rpm. Your application though I suspect your aim to go with larger slower prop to be a sound plan.
Very cool application. For the electrical noise issue: Run the receiver and sounder off of a different battery than what you're running the motors from, that electrical isolation can cut out a fair amount of noise. Try twisting the wires for each circuit or even replacing them with shielded twisted pair wiring if you can that might help cut down on them picking up the EMI from the motors. Twist together the wires going to the motor too while you're at it. Do you have capacitors on your motors? On Brushed motors the constant making and breaking of the connection internally as the commutator makes/breaks connection with the brushes can cause ALOT of electrical noise. Putting a small ceramic cap (~0.1uF) from each terminal to the can of the motor (or across the terminals, try both and see what works better) can go a long way in reducing that electrical noise. As for the shafts leaking: If you grease the shafts and have a decent tolerance between the shaft and the stuffing tube you shouldn't get much water in that way, longer shafts probably wont make it worse but I'm not sure it's really worth it. Really I'd just say run it wet as much as you can. Our boats typically leak a bit, well atleast those of us that actually battle with any regularity. In my experience most boats in general (not just models) leak a bit, accept it, deal with it (pump/waterproofing), and move on. A small bilge pump is is pretty easy to get (or even make, for your use it doesnt have to pump that much), and then a simple float switch will take care of it. The motors dont really care too much about getting wet and you can either attempt to build a water tight box for the electronics or just waterproof them. Lots of ways to waterproof electronics, epoxy, scotchkote, conformal coatings, nail polish, super glue, the list goes on.. The motors that people use in this hobby are as varied as the people in this hobby. You see a lot of 550s but that's just a physical size so not really descriptive about the motor performance. Also a number of us use brushless motors. Main drive RPM also varies widely depending on ship/propeller/gears/direct/etc. 2000RPM - 5000RPM seems to be roughly around where a lot of people fall out but I'm sure there are people on both sides of that and very few people actually measure the RPM they end up spinning at so even those numbers are a bit sketchy. (Our higher end pumps use much faster motors, ~20k+ RPM, I've seen over 40k RPM but the current draw at those levels is high enough to render them not really combat capable without significant planning and effort, also the small increase in performance really isnt worth it.) What are you using for the sounder?
