Excellent! I'll try to keep the solenoids away from the other components, especially the rudder servo and servo extension cord, whenever possible. I'm not certain how to phrase this question, but for weight and trim, does the port to starboard location matter much? Assume, of course, that everything is balanced so as not to introduce a propensity to capsize. But you stated that everything should be kept low with the majority of the weight midships, by length. Is it advantageous to keep everything in the center from port to starboard as well or can/should it be moved toward the edges? Thanks, John
I didn't realize that dual motors provided extra torque. I thought it was merely for redundancy. I know I have an old BC dual motor to single shaft gearbox in my basement. Perhaps I'll update my plans to use it. Out of curiousity, though, does anybody have an idea of how that will affect the power consumption? I assume two motors will use more energy than one, though based on my meager understanding of the physics involved, it probably won't be anywhere near 2X. The real question, I guess, is should I still be okay with a 6V 20Ah battery powering the ship? I assume so, since most of the ships seem to have 4 shafts and they would run, in turn, two drive motors. You mentioned the Titan pump. I've been away for a while but, before I left, everyone talked about the Stinger pump. Is the Titan the new 'pump to have'? Thanks! John
20ah of LiFe batteries is plenty. If you need more than that you had a really long battle and everyone else will be hurting for batteries as well. I really doubt you need worry there. Twin motors will use more power than a single motor at all times but its less than 2x power draw as well. Figuring out the difference is beyond a forum discussion. I run mine with a single brushless motor but it has a ridiculous amount of torque. Basically, the titan is just an even more powerful stinger.
Dual motors - share the load and as a result are more efficient... and unless one of the motors locks-up.. you get some redundancy but be prepared to run significantly slower. I made my gearbox as I like 32Pitch gears.. they chew up anything in their path with-out lockup. I did make a cover to keep out bb's and so far have not had a problem. Pumps - Much more complicated to figure out. I think it depends more on your battling style. At 28 seconds its hard to be a run and gun ship. However if your intention is to sit outside the battle and occasionally make a foray into the battle to drop some stern guns then you probably wont take much damage and you could use a stinger. Depending on your final weight, a stinger should be able to handle up to about 20-30 'below' shots (depending on quality of grouping of the shots, quality of sheeting job) before sinking. It will draw much less power so you will be more within the 20ah that you have in the ship. A single Titan pump (in the same conditions of the Stinger) will pump faster and will take 25-40 bellows depending on the conditions I listed above. Two Titan pumps can handle up to 45 - 50 bellows with less settling than the other pump setups, once again depending on quality of holes and sheeting. The other issue you have with just 2 of those cells is current capacity. I went to 4 cells to increase current capacity, not jut for overall storage capacity. 2 cells would not supply enough current for a single Titan pump AND dual motors, guns, and other stuff. If you want to use a titan pump it will draw the voltage down too low and your ship will suffer in performance. Those Lifepo4 cells are only rated at 2C or 3C, which is not a great deal of current. So with 20ah (2 cells) go with a stinger and 2 motors (very efficient). I would estimate that with the 2 motors (6amps) and the Stinger (12amps) you could run about 1 hour with a full pump stream. . If you add 2 more cells like I did then you can use 1 titan pump with no problems, and could run about 1/2 hour with no issues but I would try to get off the water before then. Rule of thumb. ... full pump stream.. call five. Keep in mind you have to measure amps before and after every battle.. a motor that is failing will draw more amps and drastically affect the estimated run-time. Stinger and Titan pump motors that start to fail can push 50% more amps .. so test test measure measure before EVERY battle. I now check amps on every motor on the bench after I install them and on occasion I will get one motor that measure .5 amp on the bench and the other is running 4.0 amp on the bench... uh..new motors please! Same for pump motors, I measure their current draw new, on the bench, and after a battle. Once it gets a bit high (bench measurement) I would replace it. I don't trust brushless yet.. too many issues. I run brushed and it all works and its easy to troubleshoot. I think all rookies should stick to brushed motors until they get their first boat finished. Its better to battle than to spend a year or two on the bench experimenting. Trust me its way more fun on the water. Hope this helps you out. Johnny
Thanks Hovey and Johnny! This helps a lot! For now, I'll plan on using the Stinger. As I progress, though, I'll see if I have the extra weight/money to run with 4 batteries and the Titan. Though, I'm guessing that would equate to 8-12 batteries and chargers for an entire day of battle. Otherwise, it may wait for a refit... Ditto for the brushless motors. I'll be sure to measure the current draw on the bench. Thanks, John
Two motors are only more efficient if the one is overloaded. A properly sized motor will be be more efficient than two due internal friction and other inefficiences being doubled. Thats another issue, but more torque does equate to better acceration and stopping (always a good thing). With a large 2" prop you willl need a beefy motor or two to get the best performance out of your ship. I agree that brushless are more work to maintain but better efficiency as well. Its a trade off that is not for everyone and this is my first boat that uses them so I cant say if I will stick with them yet. What I do have works, but its not for everyone. For a first build just keep it simple and go with brushed as they are easier to understand. IF you have any plans to ever upgrade to four batteries then you should plan to add them in now. Having 40 ah and not needing it isnt a bad thing, but having to reorganize and rebalance your ship at a later date is a lot more work than just planning on it now. Do it right the first time and then you dont have to redo it later. Saves money and time in the long run. Four of those on edge (two a side) with a bottle in between makes a nice layout.
That's a good point (i.e. get it right the first time). I'm going to have to think about my design choices. Luckily, I have some time before I have to make a decision. Thanks! John
Holes (1/8") drilled at the corners of the penetrable windows: SMS Bayern hull with windows cut: On a side note, I seem to enjoy the smell of ground fiberglass. That's all for now... thanks! John
Looks good. Make sure the hull hasn't "hogged" (bowed out in the middle) when you're laying out your subdeck & deck. Fiberglass hulls, especially one you've cut the windows, will tend to sag in the middle unless you glue in some supports.
Thanks! I think it's already doing that a bit. I cut the rear subdeck today from 1/4" model aircraft plywood and noticed the top caprails are sagging a bit out and down and the center is bulging upwards. However, when I pinch everything together (i.e. subdeck and hull) to the proper width, everything seems to return to normal. I still have a lot of shaping to do on the subdeck and have to cut/install the reinforcements for the ribs, so it may be a while before everything is glued in place. I'll keep an eye on it as the build progresses. Thanks again, John
Back in 2008, Bob in Minnesota gave me the idea for a shot counter to keep track of the amount of ammunition remaining in each cannon during a sortie. This past week, I found the parts in my basement which I purchased back then and was planning to use on the project. I figured if I'm going to open up my radio for the button modification, I may as well resurrect the shot counter. This evening, I build a prototype as proof of concept. Sorry about the cleanliness of the build: Basically, the two DIP switches allow you to preset the initial value into the counters (0111 0101 for a 75 round cannon, 0101 0000 for a 50 round cannon, 0000 0001 for a spurt gun ). Then, each press of the SPDT switch (which will be replaced by a DPDT switch in the radio) will subtract one from the counter. Assuming I can get my cannons to fire only a single shot when activated, the value indicated on the counter should be a good estimate of the amount of ammunition left in the cannon. A SPDT switch (not shown since I just grounded the corresponding pins manually during a reset) will reset the counter back to the initial value. Obviously, something like this (or, more precisely, something like 4 of these) will have to be mounted on some kind of supplementary board and perhaps bolted to the radio... I haven't quite figured out how I'll do that yet. Parts list: 1x LDD C812RI (dual 7 segment display) 2x CD74HCT4511E (7 segment display driver) 2x CD40192BE (Presettable up/down counter) 2x DIP Switch (4 pds) 1x SPDT Switch (for reset) 1x DPDT Switch (in radio) I may also add an optoisolator between the circuit in the radio and the shot counter, but we'll get to that once I get the courage to take apart my radio. Thanks, John
errrm.... Usually we just keep "pulling the trigger" until we hear "pshh" instead of "phut!" sounds. Lots easier.
Lol! I swear someone explained it to me once and it made sense It's not necessarily to determine when you're out of ammo. As you said, that's easy. It's more to gauge the amount of ammo left and use that information to plan your tactics. Would you willingly enter a furball if you knew you only had a couple shots left in your sidemount? In other words, it's for those situations when you were expecting a 'phut' and got a 'pshh' Thanks, John
While the geek in me sees a shot counter as a cool thing to have and I do like the idea. I think the real point that Jeff was trying to make was that you should get the boat running before worrying about other cool gadgets like a shot counter. You goal should be to close with, and engage the enemy. Everything else should either help you to do so, or it is a distraction at this stage. After you are on the water see if you need it. Also on the water is where the real fun is.
I see your point. I know having a boat on the water is fun. In my humble opinion, so is circuit design. Perhaps that makes me an uber geek... Thanks! John
LOL, Jeff is ALWAYS reminding me of just that! I am always getting sidetracked from my main project for some project or another....
I know the feeling McSpuds... I played around with a preliminary PCB design at lunch today. I still have to check my footprints, double-check everything is pinned correctly, etc.. Right now, the 4 circuits are approximately 9" x 3": Don't worry about it taking time away from working on the boat... I'm at work. Cutting plywood would be frowned upon. Thanks, John
Having a shot counter on your radio is a big help in a lot of situations, I highly recommend using one. I think it is awesome to see someone else finally building one! If you run into an issue, ask, I may have run into that or something similar myself. However you are taking a significantly different approach so a lot of mine won't be too applicable. Still seeing someone else's design is really interesting to me, thanks for sharing! If you're interested I can post some pics of what I ended up building when I get home.
Please do. I like to see other people's designs; it usually makes me realize how strange and overly complex mine are. I'd especially like to see how you mounted it to the radio. Thanks! John
