So back to boats... as you go through the build you need to consider more than just some conjecture from behind the keyboard. Some factors to consider for most decisions: How complex is this system? If a part breaks, will I be able to replace it pondside? Is access to the component easy? How many joints/connections are there that could fail? What’s the reliability of this part compared to alternatives? Does this part require a lot of up-keep between battles? Some of those questions can be hard to tell if you are new, but things like ease of replaceability, access, overall complexity can be figured out. I used to use the gearboxes that mount on the face of the motor similar to the multi motor/single output units but there are several unnecessary complexities You can either use an elevated mount to attach the motor to the hull, or goop the gearbox to the hull itself. Gooping the gearbox might look good at first, but as soon as you need to tweak or replace a gear it is a royal PITA You need a coupling between the gearbox output and the shaft. It’s possible to run the shaft directly into the gearbox, but trying to get those little washers into a gearbox while it’s in the hull is also a PITA. BC has a good flex coupling, could also use dogbones. Overall it’s another thing to break, and extends the drivetrain length with no benefit Gearbox has 48p gear teeth which as OK for smaller ships, but not good for boats in the 25ish pound and up range. 32p is much better the simplicity of a basic Traxxas villain /BC in hull / homemade aluminum gearbox with the larger gear mounted directly to the shaft which ties directly to the motor pinion is leaps and bounds better. I’ve used them on my last 7 ship builds and would never consider going back to the other style. I’d recommend going with a 5mm shaft for ease of prop and gear selection. 1/8” would be no good for a boat that big
Another vote on the direct shaft -> Villain gearbox. It works. It works so well. Fewer set screws to come loose, overall stronger setup. Another vote on 32p gears and 5mm shafts. 5mm shafts are larger than most use currently, but you get the added benefit of easy to find RC car/truck gears and most current model ship propeller providers stock props sized correctly for your Scharnhorst in m5 metric thread. Also, on the topic of the single vs dual motor to single shaft. Its really a non issue. There are plenty (dare I say, the vast majority?) of single prop ships out there running single motors, you don't need the "reliability" of being able to drive it in on 1 motor. Just more $, more complexity, more stuff to go wrong. The single 775 to a big honkin 2.25" prop with gear reduction in between will work well.
I haven’t used a 5mm shaft setup but it sounds nice and beefy. So let’s help him (and me) find all the parts needed for this sweet setup. I know you can get 5mm shafts from servocity.com. Perhaps the stuffing tubes too. A 775 motor is easy, Amazon or wherever else. Who has a source for a gear box? I think the villain mounting plate is 25mm spacing for a 500 series motor but the 775 is 29mm. What about 5mm ID bushings? 5mm propeller source?
3/16 inch shafts are just a couple of thousands smaller. I use music wire and shim the shaft with .003 shim stock.
5mm shaft: https://www.mcmaster.com/1272t35 Stuffing tube bushing: https://www.mcmaster.com/6659k671 Stuffing tube material: https://www.mcmaster.com/8457k55 something like that would work McMaster is your friend. Learn to love it. The villain aluminum mounting plate will require some modification. From the 775's I have on my bench compared to the villain mounting plate also on the bench, looks like you have to hog out the center hole a bit and re-drill one of the mounting holes. All in all, minor. Or just build your own aluminum gearbox out of some aluminum angle. M5 metric threaded props you can get from https://www.model-dockyard.com/acatalog/Brass_Propellers.html, Protean Design on Facebook, and others. With the villain gearbox run the stuffing tube right up and in, like Kevin did here in this pic: I did the same on Jean Bart and it works wonderful.
I am partial to gearboxes that support the shaft on both sides of a gear. A reason I have seen for a lot of gearbox woes is the input or output shafts being inadequately supported. It then allows flex which allow smaller gear teeth (like 48p) to jump and strip. A more rigid gearbox is a good gearbox. I have always wanted to design and build my own but haven’t had the time to learn CAD. I would like to make a sealed oil filled pinion/spur gear box (32p). 3mm or so motor and output plates with oilite bushings. A 3D printed spacer/body with an o-ring groove for sealing. Also the ability to run the propshaft straight into the box. I have a Bismarck hull that I need a gearbox for and I figure it will be a great application.
exactly. from looking at the 1 motor to 2 shaft in person, and pictures of the dual motor single output, it looks like the output gear is supported on both sides. and it's not a super complex series of gears. it's just the output gear with the 2 pinions for the 2 motors. And cost isn't a whole lot more for the setup, and if it really came down to not wanting to deal with a driveline difference, I'd get a steel center driveshaft for an emaxx. I hope those that are 100% against a gearbox domt drive, those damn multi geared transmissions in most cars are going to fail so hard. Even the Tesla S with its 10:1 gearbox. and driveshafts with u joints. oh my, those will never work. I guess to each their own. Just seems some will always disagree and not think about other ways to do things, because it's not how they do it.
automotive drivetrains have extensive engineering, design, and testing. Most model boat drivetrains get a only few hours worth of thought before they're put together. We're basically building ships with a WWI aircraft designer's level of experience - still disagreeing over the number of wings to use, what type of construction to use, etc.
I'm just saying that seems a lot of people around here have the "My way or the highway" mentality, but worse as if you don't do it their way, you're an idiot, and you're opinion means nothing. I'm pretty sure too a lot of people use the Traxxas Villian motor mount, which from looking at a parts diagram, uses the same kind of pinion and spur type of gearbox/motor mount as the Batter's Connection, expect BC takes it a step further and does what an Emaxx Transmission mount does, allows for 2 motors to power the singe shaft. I'd also hope that a company trying to sell something for profit would at least put some R&D into their product. And if it didn't work, it wouldn't sell, and they would eventually quit offering it..... that's usually what happens with garbage products last I knew I added some pictures in case anyone wants to actually look at the things I'm talking about. And for the record, I'm not looking for a "you're right, that's the best idea" I'm just looking for some acknowledgement from the elitists that it is an option that will work. Instead of just "that's stupid" and "you're an idiot" especially when some of the arguments against the BC gearbox can also apply to the precious Villain gearbox as well....
Everyone is a special butterfly whose input is valuable It’s more like ‘been there, done that.’ My first single motor, dual output gearbox was in 2003. You can make it work sure, but I’d rather not see new people have to relearn the issues that experienced captains learned long ago. Shaft deflection is a non issue if the gearbox isn’t janky, especially with 3/16 or similar shaft and 32 p gears. I know sharing experience from actually building boats, attending battles, looking at others boats that work, and those that don’t work can be a foreign concept on this forum, but don’t be offended if someone points out issues you didn’t consider
Having used a 2 motor to 1 shaft gearbox to drive a Bismarck, I wouldn't recommend it. (It was BCs version but I don't think a different version would be significantly better) Can it work? Sure. Still based on my experience with it I wasn't a huge fan of that setup and wouldn't recommend it. The performance just wasn't there how I had it setup, I probably could have made it work if I really tried to but brushless just worked better in my testing so I went that direction instead. A 2:1 also takes up a good about of additional space in the stern which I'd rather have free to use for other stuff. A big 775, if your doing the brushed thing, has produced the best brushed performance that I've seen. Of course it's your boat, do it however you want, you can always change it later if you don't like it. I've had at least 3 or 4 different motor mounts in the Bismarck over the years. Some people like to build new boats, some like to tweak and tinker with what they have, there isn't a wrong way to do it. Contrary to what seems to be popular opinion these days even discussing ideas and recommendations online can be helpful.
At the end of the day we want to see you on the water. More boats=more fun, so there is always a desire to see you get to a battle and have fun. The best way (yeah, its not the only way) to get into the hobby is to meet and listen to the captains who ships usually work on the water. Then copy their style to get you on the water, and tweak away on a second hull.
Something that hasn’t been mentioned yet is also shaft material choice. I choose ground stainless steel shafts for every application. The diameter can vary though. Shaft deflection is indeed a moot point until a gearbox is overpowered and a prop get moss on it and the teeth jump past each other. Or someone decided on brass shafts. I remember Ron Hunt was showing me how he replaced the plastic spacers in his BC gearbox with aluminum to increase rigidity. All the little things add up to make something better. If you have something you want to try, do it. Everything we do now had to have been tried by someone looking to do something different or better. I ran a dunkerque on long can 400 size motors on planetary gearboxes 15 years ago. I got pretty skeptical looks. However, when I cranked it up to 11 and was zipping across the pond like a powerboat, blasting through weeds and moss, they were impressed. I torture tested its tiny 48p gears and it held up great. Why? I filled the gearbox with a light lithium grease and the actual surface area of the teeth engaged on a planetary design is better than a spur type of the same footprint. However, you might just need to take all my “keyboard warrior” knowledge with a grain of salt. To some I don’t battle frequently enough. Danged ol’ Navy and family always getting in the way.
Wanted to post a little update... my wife and I have gotten a new puppy so there has been significantly less time in my work shop. My focus was getting the two drag prop shafts mounted and the rudder post mocked up. The pics are just the mock up, as I now have the shafts epoxied in. I’m waiting to mount the rudder posts until I get the gearing and linkage all set between the servo and the rudders. Ive picked up a waterproof servo and have some gearing in transit to hopefully get the rudders turning. I figure I need to wait until I get all those parts to determine how high up the posts need to be and where to mount the gears on the rudder shafts. I also want to mention that I really appreciate all the insight! I have decided based upon the comments that the single 550 motor just wasn’t enough for this ship. With that being said I intend to run it with a brushed motor and I’m planning to sticking with 550s thus I think I’m going with a gear box dual drive single shaft system. I know some have said it isn’t the greatest, however given its my first ship I think it should work out and will give me reasons to tweak and modify in the future. I’m hoping that the system will be sufficient.
Just yesterday I fit my rudders and I've had trouble with fitting the gears and now I'm looking into just using push rods. I've seen it done before but there isnt alot of space, especially for you.
Using push-pull rods to link the servo to the rudder arms can work well. Setup the rudder arms toward each others post, essentially one underneath the other. Then cross your linkages (form an X) from the rudder servo to the arms. You will get different throw from your rudders. The inside rudder (in a turn) will kick over harder and get your rate of turn up. The outside rudder will be at a more shallow angle keeping up your speed (a smaller slower boat can find that handy). You can also parallel the rudder linkages to create equal throw. Both setup have their strong suites.
Time for a quick update.... I haven’t had much time out in the workshop, but trying to make the most of the time. As I mentioned in an earlier post, I decided to go with a dual motor to single output gearbox. With that in mind, my priority has been to figure that system out and get the rudders all situated. I installed the rudders posts and created a small servo mount out of some scrap ply.... didn’t like it so ended up scrapping it and building one out of a few pieces of ABS. I’m much happier with how it came out. There really isn’t much room in the aft for the rudder posts, so I ended up with a gear/chain set up. I’m liking it so far, but until I get it on the water.... who knows. I also focused on getting the top deck cut out and shaped to fit the hull. Also picked up the appropriate esc and some other parts. Over the weekend I went out to meet the local guys at the pond to watch a few shorties and take a look at their ships. That was extremely helpful and got to meet several awesome people. Next Steps: Figure out the dimensions needed for my water channel... and then build it... Start getting the cannons and figure out how to mount all of those Get a transmitter and receiver so I can actually get it on the water..... Speaking of transmitters, any good experiences with a FrSky X7s?
I'm running the X7. It's pretty good so far. There is a bunch of stuff you can do on FrSky's computer program, but I haven't done any of that witchcraft yet. Adjusting things pondside is pretty easy. what sucks is that there is no manual for it, so you have to trial and error everything. But the receivers are inexpensive, and easy to waterproof with E6000. I'm going to use my X7 with all of my boats, and likely buy a second transmitter for a friend to use when I get my second boat operational. Speaking of, storing different boats in the transmitter is pretty easy even for me.
