i've seen several posts with people saying that they don't use a water tight box. how do you do it and why do you not do it?
Watertight boxes seemed like a good idea to me. That is, till I considered that anything that keeps water out will, with the tinyest of leaks, prove very effective at keeping water IN. Now I just keep my receiver in a latex glove, and let the servos swim.
Pot the receiver in epoxy and cover all the other circuit boards with scotchkote. If you run with solenoids and team delta boards as well as an ESC, both of which are easy enough to waterproof with scotchkote, then you only have one servo for the rudder which needs waterproofing. I just waterproofed that with more scotchkote. Why do I do all this instead of just putting stuff in a watertight box? I think its easier and more effective at protecting stuff from water damage. Without a central box you can place things a little more freely in the hull but that also means more wires going all over the place so things dont look as neat.
A properly built water tight box will not leak. Even if it does leak, you should have taken steps to keep the water away from your stuff. like waterproofing your servos even in the box and keeping them off the bottom of the box. There is nothing worse then sinking in the first sortie, haveing your box leak and being out the rest of the day. I've run with water proofed rudder servos for years. They WILL fail at some point. Then you will sink. So don't put in a water tight box. When your stuff leaks and goes crazy someone will find you and make sure your ship is also leaking.
Evil, That is the way I have done my servo. After a day in the water it is working fine. The mineral oil keeps out the water, no mater how deep you sink. Go this extra step: Epoxy the outside of the servo case all the way to the top. This helps keep in the oil.
My Cadorna was made so that all the servos were on a single tray in the stern that came out with a single screw. When I sank, I removed the screw and flushed them out with rubbing alcohol and was good to go in half an hour. At the time, I didn't experiment with waterproofing the servos. In the transports, I have an even easier system with no screws. I can pull it out of the water and swap servos, or even the receiver, in less than five minutes and get back fighting again. This time I plan to experiment with scotchcoat on the RX and mineral oil in the servos. The idea is that my experience with water tight boxes has been less than satisfactory, and, as Darren said, they held water in and were difficult to access. Leaving everything open saves space and allows more freedom in placement, as well as making recovery easier when it hits the fan.
From my perspective, the better question is: "why bother with a WTB?" I have heard that WTBs are pretty popular, especially in Fast Gun clubs. I have never understood why. The best that I can figure is they are a relic of the past that most folks haven't figured out aren't necessary any more. I view WTBs as a dangerous element of uncertainty, because you never know if they will leak. On the other hand, a ship that DOESN'T have a WTB, and instead puts that effort into mounting unprotected electronics high above the bottom of the boat, is significantly more reliable. Think about it this way: which would you rather have, a 50% chance of a 5-minute sink recovery time plus a 50% chance of destroying your electronics completely, or a 100% chance of a 45-minute recovery time? That's a little bit of an exaggeration, but I hope it gets the point across. And now with Skotchkote for circuitboards, Mtroniks waterproof ESCs, and the new mineral-oil-filled servos, you can spend a little extra effort and turn that 100% chance of a 45-minute recovery time into a 100% chance of a 5-minute recovery time. A further benefit is, as Gascan pointed out, that you can use internal space more effectively without a WTB. To answer your question of "how do you do it", the trick is planning ahead of time. If you can skotchkote your receiver and circuitboards, use a reliable waterproof ESC, and use waterproof oil-filled servos, you effectively eliminate the only argument in favor of WTBs. Whether or not you do that, there is still a lot you can do that will improve your sink recovery. They are: 1) get a reliable recovery float. Having a reliable recovery float on your ship helps you locate it when sunk, whether in 2 feet of water or 20 feet. When you know where your ship is, it spends less time submerged and wet. Electronics aren't damaged by lots of short exposures to water, but a single long exposure (when you can't locate it) can destroy everything. 2) get a RELIABLE recovery float. I cannot stress enough the importance of having a recovery float that works. Too many people in my local club do not understand this concept, and spend most of the day sitting on their behinds because they got sunk in the first 15 minutes and spent an hour or two trying to find their ship when the float failed. When designing your float, you can either A) consider every possible way that your ship might sink, and ensure that the float will deploy despite that, or B) consider how to ensure that your ship will sink in only one way, and ensure that the float will deploy that way. 3) mount sensitive stuff in high places. It doesn't do you a whole lot of good for your receiver to get wet when the first few drops of water enter your ship, and the same applies to your servos, circuitboards, etc. Spend a little extra time putting them well above the bottom of the boat, so that by the time they get wet you know that you're already screwed. Also, keep your sensitive stuff away from bilge-pump priming holes. I've been sunk because of that before 4) Place your sensitive stuff with ease of access in mind. It doesn't do you a whole lot of good to recover your ship in 30 seconds if it takes you 20 minutes to unscrew the decks. Same thing with removing servos, accessing the receiver, etc. Heck, if you really want to protect your servos, drill a hole in the top of them and another in the bottom, so you can pour rubbing alcohol in the top and have it drain out the bottom without needing to remove it. The transports that I built use absolutely no screws to hold water-sensitive stuff. The deck is held
The new mineral-oil servos are servos that are filled with mineral oil, then sealed up with skotchkote and an o-ring. You can find more information about it here: http://www.societyofrobots.com/actuators_waterproof_servo.shtml
That's too much work. I have rudder servos that have lasted for YEARS using the following treatment: Drill holes in the bottom of the case to let the water out (I glue screen over the holes to keep out debris). coat the control board Soak the pot in Corrosion X (or similar). Done.
Of the above waterproofing techniques, do any or all help reduce the occurrence of "servo jitters" when wet??? Seems like filling with oil would keep water off of the pot, but does thr corrosion X have a similar effect?
Yes, Corrosion X is a water displacer. Occasionally I have jitters after a sink, but I just shoot more CX into the pot.
does a mag switch have to go in a WTB. can you post some Pictures of your stuff (Kotori87).Pictures from all would be helpful . ty
A mag switch can swim. For a while .(Till corrosion eats the insides). Encapsulated esc's are , IMHO, better at surviving submersion.
The whole point is to avoid servo jitters and other electric and electronic woes after a sink, and if possible, to avoid jitters from battle damage before sinking. There are two main schools of thought. One school says that everything is going to get wet anyways, so you should make it easy to access to fix or replace as quickly as possible. The second school says that you should prevent such equipment from getting wet and protect it, so you don't need to worry about it. I have mostly tried to follow the "easy access" school of thought. I drill holes in the side or bottom of my servos so I can pour rubbing alcohol in them without removing any screws. I use as few screws to hold down the deck as possible, using flip levers, tongues, and magnets instead. This allows me easier access to the inside for maintenance, work, or simply flipping a power switch. Servos are also held in place with as few screws as possible. In Cadorna, I needed to remove one 4-40 nut to remove the tray holding all three servos. In my transports, the servos are locked in by the deck, so I have instant access. Water tight boxes fall into the "protection" school of thought. They are intended to prevent water from getting to the components in the first place. Some people have sealed the seams of their servos with tool dip and sealed the output shaft with an o-ring. These methods suffer one problem at greater depths: water pressure compresses the air inside and increases the strain on any seal, such as a glue joint or o-ring. When the seal fails, the air inside gets compressed and the water floods the compartment. Deep sea ROVs reduce the strain on their seals by filling their compartments with oil, though this idea is still new to model warship combat. The oil doesn't get compressed as it gets deeper, and pushes back against the water pressure to reduce the pressure differential on the seal. Even if the seal fails, the oil is already inside the compartment to displace any water that tries to enter. Another option in the "protection" school is to coat electronics with epoxy, CA glue, Scotchkote, or some form of sealer. This is what the MTroniks ESC's use, and it works well for static, solid state electronics. I have heard that many members of the NTXBG and a few from the WWCC are using Scotchkote to protect their receivers and non-waterproof ESC's. The MTroniks waterproof ESC's have been growing in popularity, and every new ship I have seen has one. With quick access to wet servos and electronics and commercial waterproof ESC's, I thought that the benefits of a watertight box did not outweigh the drawbacks. Now with the ability to waterproof receivers and other electronics, including other ESC's, and especially waterproof servos, I see no reason to build watertight boxes anymore. Yamatoman, do you apply CX only to the pot, or do you apply it to the whole servo? What do you coat the board with? Evil Joker, a MAG switch is a servo that pushes two momentary switches. It would be treated like any other servo, either waterproofed, opened for access, or put in a box. Carl (kotori87) and I have photos of the transports in a thread about the SS Puma.
Just the pot. I use whatever conformal coating is handy on the board (thinned Shoe Goo, Scotchcoat, clear nail polish, etc.)
Does using Scotchkote on some of the electrical components, particuarly an ESC create a problem with heat build up??
I haven't had any problem running an ESC coated in scotchkote, I left the heatsink on coated and it just sits open in the hull so it gets wet. That and it doesn't get very warm to begin with. Its a Dimension Engineering Sabertooth, just pick the size that fits your needs they are all basically the same from what I can tell besides the current rating.
So the DE looks like its working good for you Snipe, I have had no issues either, except for the one that the props got locked into Rick's stuffing tube, and burned up, but then he just sent me a new one for free to replace it, so I'm a happy customer. My new Kumano is running the dual Sabertooth, covered with scotchcoat, and runs really nice, both forward or backwards.
