Hey everyone, my names James and I’m brand new to to RC warship combat and luckily I’m located in SoCal near a pretty active club. I hope to use this thread to document my build process and solicit information from those of you who are much more experienced than I am. Why the DKM Scharnhorst: So why the Scharnhorst, honestly when I was starting to look at the various warships it was just a question of scrolling through Battlers Conmnection to see which ships there were that had more than just a hull. Being my first ship I wanted to get a bit more than just a hull to get the process started. I was actually leaning towards a VDT or an Italian cruiser because I liked how they looked, however I found the used Scharnhorst kit I picked up. You guys may recognize it from the sale page on here. I inadvertanily picked it up on eBay with a ‘best offer price’ that seemed like a great deal (at least to a newbie like me). What I got so far: So I purchased the kit and it came with a hull, sub deck installed (sort of), all the turrets, a old style battlers connection bilge pump, prop, prop shaft (installed), and drive motor. Just getting the ship and unwrapping it it I have a couple of concerns. The current motor mount appears to be just a PVC pipe, while not a problem, I haven’t seen a lot of people using that. Instead I have 3D printed a motor mount and think that it might be a better solution. Plan of Action Just like everyone else here, I want to try and get the ship up and battling as soon as possible. SCRAP (the local club) meets monthly for a battle so hopefully I can join soon. Ive outlined my anticipated steps below..... let me know if something doesn’t seem right or you have a suggestion that could make like less difficult for me! Float hull at max weight to mark waterline Clean up currently installed prop shaft.... (its pretty ugly) Install/drill rudder post holes in proper location Clean up sub deck (some edges have come unglued, etc) Install 2 dummy prop shafts Cut Windows in the hull? Water Channel (balsa and fiberglass or should I go with a pourable material?) Build top deck Try and figure out gun fitment dual stern & 2 bow side mounts) TBD
Again, welcome! It’s great to see another boat to shoot a....ahem, I mean another boat soon to be on the water at Prado. While I’m no expert, one question I have for you is about your 3D printed motor mount. What material is it? The motor itself can become very hot, especially if you get a fouled prop (which happens not infrequently in Prado due to fishing line, moss, and other debris). A PLA mount will mostly melt or warp. A higher temp material may suffice. Also it looks like the original builder set up a direct drive system. This probably won’t cut it at 6 or even 12v. You’ll probably want to do gears. There is a source on the forum here I believe for a 3D printed gearbox (again assuming you have a high temp material to work with). That’s all I got for now, looking forward to seeing you at a battle. But also they do build sessions after every battle so you could get some great advice there as well. -Will
Thanks Will, Yeah I was interested in the direct drive set up... It looks to have a typical 550 motor direct drive to a 2 inch prop. Ive searched on this forum but haven’t had much luck finding info on motor/prop size/director or geared for this ship. I was hoping that the 1st builder had some info and hence the decision to go direct drive. And regarding the 3D printing. Ive been using ABS which has much better temp resistance vs PLA, but heat may be an issue. Will have to look into printing with alternative material.
Regarding how to set up your drive system, I'm sure someone on here has some recommendations. If not, send an email out to our group which I think I saw you were now subscribed to. Several guys have experience with 3 screw boats that could probably share what they would recommend for a setup.
@jim13csulb My Scharnhorst uses a 550 driving the center shaft. It uses a BC gearbox for reduction though, very similar to the 3d printed one you have. I think the reduction ratio was around 1.5:1 or 2:1, but I haven't done anything with the ship in a couple years. The offensive arrangement also sounds similar to yours, with twin sterns and two forward sidemounts. I tried the triple stern/single sidemount, but wasn't thrilled with the result. That said, modern 3d-printed cannons may offer a solution. If you're willing to put in the effort, 3d-printed cannons are much easier to rotate than older brass-and-copper cannons. You could toggle that forward turret from one broadside to the other, and pivot the stern triples 15 degrees to either side.
Stem to Stern has some good examples of center prop drive ships you can crib off of. https://rcwarshipcombat.com/threads/sms-nassau.444643/ https://rcwarshipcombat.com/threads/dkm-bismarck.444634/ and others I'd plan to rip out the existing motor mount/prop shaft (maybe leave the prop shaft in, or consider upgrading it to 5/32 or 5 mm, probably not necessary but a little extra doesnt hurt), and those plastic dog bones have a habit of breaking leaving you SOL, deep six those pronto. Big Prop, big torquey motor (doesnt HAVE to be brushless, there are brushed motors that can do the job, for my money brushless is easier/better but YMMV), gears. A 2" prop may be enough, but if you can go 2.25" (? or more??) that would likely be better. You're asking one motor/prop to push around a 30-ish lb boat while most of the ships you'll be fighting get two motors/props to do the same work, that means you need a more powerful motor/prop combo than in a dual drive shaft boat. It needs to be robust since if you lose drive for whatever reason you cant limp around on the other shaft, going dead in the water means lots of patching. It's easy to build poorly and get not so great performance, however the upside is that if you get it dialed in...it's really fun. 3D printing is great and there are alot of good uses for it in the hobby, but don't let it blind you to conventional methods. A piece of angle AL is a damn simple/cheap and effective motor mount that isn't going anywhere on a hot day.
Thanks for all the info everyone. I got the ship in the water this evening to try and figure out the waterline to mark out the windows..... I may have run into a problem or essentially not sure how to proceed. On the ship list, my ship has a max weight of 32 pounds.... Should I use the max weight to try and find the waterline? Here are a few pictures of the hull loaded up with 30 pounds of weight.... seems like it sits rather low? Actually fully loaded it sits just about at the armor belt on the hull, which I believe is too low. Comparing the pics below to the fully constructed Scharnhorst on the Battlers connection site has me wondering if I’m doing something wrong...... Here is a picture of a completed scharnhorst from the battlers connection site:
I'd use a Hobbywing 880 ESC with a BC Dual motor single output gearbox, with the 550 motors. the 880 is fully programmable and can be ran up to a 4S Lipo.
I’d go up to a 775 size motor, I would not want just a 550 on a ship that big. The pictures at 30 lbs look good. Marking the waterline at a weight you think you want the boat to be, and then mark the bottom of the windows about 1.25” below that. Marking at max weight can be risky if you want to remove weight later, since the bottom of the windows might not be 1” below waterline. You can also wait until the end of the build to cut the windows
Thanks Kevin, would you recommend a single 775 motor? Based on the previous comments I was looking at running dual 550s geared to the single prop shaft.
A big 35mm diameter by 35-50mm long brushless outrunner will have all the power you need. There are cheap ESCs on Hobbyking. I like to get ESCs that greatly exceed the motor specs and don’t have to work as hard/get as hot. That setup I just spec’d will spin 7500rpm on a 2:1 gearbox (which of course can be slowed down). Combine that with a big 2” prop and that Scharnhorst should be able to dig. https://hobbyking.com/en_us/turnigy-aerodrive-sk3-3542-1185kv-brushless-outrunner-motor.html https://hobbyking.com/en_us/turnigy-rc-boat-esc-120a.html
A thing to think about for your gun layout, depending on what rule set you are building the boat for (IRCWCC?) and how they allow your units, Scharnhorst in IRC is a 5.5 unit boat. You could run a triple stern, a bow 1 unit sidemount, a bow .5 unit sidemount, and a full 1 unit pump. That gives you the power of the triple stern, something that is rare among axis boats, while not sacrificing your sidemount on one side. If you are thinking of Brushless, there are many solutions to your drive system. Personally for a first boat and for simplicity's sake, I'd run the brushed motor direct drive to the prop with the 60A Hobbywing ESC from Battler's Connection. No need for anything super fancy. The PVC pipe motor mount is something I've seen done in a few brushed motor boats. It works fine. There are a ton of solutions to mounting the motor. Some people just epoxy a hose clamp into the boat. So long as the motor is lined up to the shaft properly and secured in place in a way that still allows it to be serviced, it'll be fine.
Speaking of rule sets, did you get the SCRAP rules yet? If not I can send them to you. It might seem like gibberish now but at least you’ll have them.
Single. Use a piece of aluminum 90 degree to hold the motor as a gearbox (see pictures Chris pointed out earlier in thread).
I do not have the scrap rules... I would love to get a copy of them. My email is james@dinwiddieland.com Thanks
I'd still go for the dual 550s if you dont go brushless. The 550s are cheap, and if one goes out, you still have another to limp on in. A single 775 vs the dual 550s is about the same performance, the 550s will have a small amount of speed, but the 775 will have a touch more torque. I've been playing with Emaxx trucks for quite a few years, my dad bought me one as a kid when they first released, and I've always had one since. They came with a dual 550 21t "Titan" setup, and there has been a lot of dewalt drill motor conversions and such, and when the Summit came out with the single 775, a lot of people went that route, but didn't really notice a difference in performance. tje Kershaw designs dual 700HO motor setup was the best before going brushless. Brushless on the other hand can get pretty crazy in one of those trucks. I have 2 currently (one true emaxx and one an electric converted Tmaxx) and the Emaxx will do standing backflips and front flips with a 4s brushless setup. The Tmaxx will pull a wheelie straight up and go a few feet before it flips itself over. I'm planning on toning that one down and getting a wheelie bar for both, and new bodies for them.
Not sure yet... I like the idea of it and how it looks, but my priority is to get the deck to fit right first... then perhaps Ill make the cuts.
