The purpose of this thread is to document my first warship build, the Iowa, as well as to hopefully get some advice from those of you that have more experience building ships. The hull is a ModelShipsAhoy hull which is projected to be here sometime next week. The current plan is to power it with two 400kv Turnigy brushless motors with BC gearboxes as I've already got those motors from another project. The pump is a BC one-unit pump powered by a 2700kv brushless motor. ESC's are going to be Hobbywing Quickrun 60A. Power will either be 12 or 12.8v depending on if I go with SLA or LiFe. The guns will be actuated by 12v solenoids. I'm currently planning on a 3 stern 4 sidemount setup with two cannons in each of the forward turrets. I won't have much else to post until the hull and other parts come in. Those of you with more experience feel free to point out any issues with my current plan that you notice. As I said earlier, I'm relatively new to this so I'll take all the advice you're willing to give.
Going ahead and looking at the cannon setup, I wanted to run my thoughts by you all as far as the plumbing goes. I'm looking at using a 1/8 NPT BC regulator with the following setup: 1/4 PTC Manifold w/ 1/8 NPT Male End 1/4 PTC Fitting w/ 10/32 Female Thread 1/4 PTC Y Fitting to Bow Cannons 1/4 PTC Manifold to Stern Trips 1/4 PTC to 1/4 NPT Check Valve to Accumulator Tanks 1/4 PTC to 1/4 NPT from Manifold to Solenoids I've attached a diagram outlining what I'm currently looking at doing.
Welcome - it would probably be good to link you up with Lee who lives around Louisville. You said you were relatively new, so have you built a ship already? If this will be your first RC warship, I would recommend shelving the Iowa hull for a few years and starting out with something more manageable in the class 4 to 5 range, something like a Maryland or Iron Duke. I think all experienced IRCWCC captains would agree with this - there's a lot to manage and get right on an a ship like an Iowa, and it needs to be pretty high performance to not get slaughtered - the main reasons being that it would be the longest ship on the water with the most target area and poor maneuverability, so it's much easier for other ships to get their guns on target in an area where the Iowa can't fight back. I believe I'm the only guy right now with a functional Iowa. Lugging the boat around at an event and getting everything tuned in is a lot more work than most boats If you decide to stick with the Iowa, please check out my build thread https://rcwarshipcombat.com/threads/uss-missouri-build-ircwcc.445059/. Also note that I refit it several times, so a lot of things were changed from the first build, so I would be sure to check the later posts to see how the boat ended up. There are still several things I would have built differently given what I know now, but they aren't worth the effort at this point. Generally I always recommend new people ask questions before purchasing items Feedback on the specific items you mentioned: For drive motors, 400kV at 13V geared will probably be too slow - I tested mine with 540kV I think and performance was terrible. Of course the gear ratio and prop size also play a role, but I wouldn't go larger than 2" prop given skeg spacing and rudder size. My current drive system is 775 brushed motors running at 20V and performance is great. 2700kV brushless for pump is a bit high, you can always just throttle it down to around 70 - 80%. 2700kV at 13V running at full throttle will pull around 45A which is excessive. Most very large boats (67"+) run 2 pumps. Brushless pumps require more maintenance than brushed, but they can be reliable too. My boat will end up with 2x brushless pumps For batteries, you'd want LiFe or LiPo. SLAs have fallen out of favor given their low discharge current capabilities (see note about the 45A pump above), slower charge rates The stern guns on Iowa are relatively useless based on the length of the aft deck (trajectory is too high to do damage to most), I started mine with the setup you mentioned and then swapped to using stern sidemounts Anyways, please keep asking questions as they come up - sorry if this is bad news, but I'm a "just rip the band aid off" kind of guy because I want new people to be successful in their first boats so they stick around - starting out with an Iowa is a much more difficult path to be successful relative to something like a class 4 or 5 ship
Thanks for the information Kevin. I'd much prefer to know ahead of time if something isn't going to work out before I put the time and energy into it. I've been lurking around the forum for a while and had read through your thread previously. I should clarify that while this is my first build post, I intend for this to be a long-term thread where I work on the Iowa over a longer period of time. I intend to pick up a 4-5 unit hull in the near future, I just haven't decided on which one I wanted to build yet. Regarding your feedback, I had seen several posts about these motors driving some of the other larger ships (Bismarck and NC) at decent speeds (9 sec. 100') with 2.5" props at 14v IIRC. Seeing as I had them on hand and with the size difference between the Iowa and those other ships it appeared worth trying to see if they would be able to meet the 24 sec. 100' standard. If this isn't the case I don't mind getting other motors that will meet that standard. For the pump would you have another recommended Kv to go with? I'd assume lower, around 2000-2100 would be more preferable in this situation? As far as the guns go I'm not set on any particular setup. If the plumbing layout I posted above passes muster I can switch out the manifold with another Y connector in order to make it 6 cannons and two pumps.
I sold mine many years back to ensure that I didn't go insane and pull it back off the shelf again and upset my back further. It was fun on the water, but hauling it back and forth pond side will wear on you, especially in the days I had mine. This was before ESCs became the norm and well before today's brushless and better battery tech were around. Speed was set by changing out the gears and some events it took lots of trips from bench to pond to get her dialed in to 24 seconds. Today it'd simply take a little dialing in with the throttle throws on the ESC. My CO2 system was fairly simple and only had 2 main lines - 1 from the Regulator to the Bow expansion Tanks and one from the Bow Tanks aft to the stern tanks. The bow tank setup was two copper pipes running fore & aft with a 1/4" copper tube soldered in as a cross connect. The solenoids attached at both ends of each tube with 1/8" ID gas feed from the bow going into a fitting soldered into the middle of the port tank and a similar fitting soldered into the starboard tank was where the 1/8" ID line aft to the sterns connected. That let me fire the A turret doubles from the front port & starboard solenoids and the B turret from the aft pair. If I were to do it again today, I'd keep the same tank setup but upgrade the feed lines to 1/4" nylon tube. The triple tank was just an enlarged version of what you will find in most NCs or other triple stern ships. With so many guns to feed, you want to keep the system as simple as possible to reduce possible leak points. Drive wise, mine ran off a pair of geared 550 motors (bit hotter than the stock johnsons) that I needed to watercool to keep temps down. 2" props got her plenty motivated. Kevin's 775s are a good option. I ran one in my Bismarck and probably should have refitted Iowa with them once I found them. 7 guns will keep you busy lakeside though even on the good days when they are rocking. It's about the same as trying to keep a trio of cruisers operational except that in the Iowa's case, if the guns are not working well, you'll be pulling a very heavy boat off the bottom and back to shore. And with her length, you will go through a lot of silkspan and spend a lot of the time between battles just patching holes. The doubles are a ton of fun though. They hit hard and can do some serious damage. The ship looks great on the water, especially when you are driving towards yourself and make a 90 degree turn to the side. You go from a nice tight narrow profile to this massive wall. One thing you really need to be effective is a very good wingman. With one, you are a mobile shoreline with lots of firepower. Without, you're just a big cruiser and have to play much more defensively.
A 2.5" prop has over 50% more area than a 2" prop, and brushless motors don't have the same RPM droop with load as brushed motors do, so with 2" prop geared around 2.5:1 the 400kV doesn't give a high enough RPM. It's also important to consider reverse speed, just because a ship can make speed in one direction, usually the reverse throttle setpoint is higher than forward, so if you need to be around 100% for forward, chances are your stopping power and reverse speed will be a good deal slower. Of course there are situations where this is not true, like if the props are put on backwards so they are more efficient in reverse (then you'll need a higher fwd throttle setpoint). I expected the 540kV motors I bought to be great for my setup, but I was very disappointed. I think the NC you referenced used direct drive, and then swapped out to 700 or 900 series motors. My 20V 775 geared setup outperformed any of the brushless setups I used by a lot, mainly because the power level of the motors was high enough to mitigate the normal drawbacks of brushed motors, and there was no time delay from fwd to reverse like there is for brushless, and no concern about maintaining bearing life. More info on pumps is covered in my pumps video I posted the other day. Around 1800kV at 12-12V gives a good balance of flow rate vs. amps. You can always run a higher kV at less than 100% throttle. For CO2 arrangement, it's really something you need to assess once the boat is put together, in terms of bottle location, where the solenoids are mounted, what angles work for the hoses. You might plan to use certain fittings but find out that the hoses would be a mess. I'd try to tackle the systems in a smaller boat first before scoping the Iowa, because you'll probably learn a lot going through the build process which would impact decisions for the larger boat
After going back through my notes I realized I had made a mistake and misremembered the 1700-1800kv pump motor suggestion as 2700kv. Eh, only a 1000kv difference . Thanks for pointing that out Kevin. For the drive motors do you have a suggestion as to what a good kv would be? Re-reading through the various threads it appears that 800kv motors at 12.8v would do it but I'd like to get a second opinion before I order anything.
800 should be fine, probably up to 1100 to keep a reasonable adjustment range, going too high will have too large of increments for speed adjustment
Slight update: the hull came in last week and it looks great! All the other parts are in and I'm hoping to start work next week. Currently building a Voron 2.4 as well which I hope to get up and running this week.
Time to bring this back from the dead (now that I finally have the free time to start working on it again). Current plan is to stick with the original build plan and make corrections from there. Picked up a Bambu X1C this weekend, which is printing flawlessly so far. I'm looking to rely heavily on it for a lot of the internal mounting points and external superstructure.
The first step for getting back into this project is to make the X1C suitable for printing ABS/ASA. It's capable of printing both out of the box, but I wanted a better filter before I started printing with it heavily. Ended up printing a Bento Box from Printables, which circulates the air inside the printer through a HEPA filter and activated carbon. It's powered through a wireless charging pad located underneath the printer controlled by a smart switch. So far I'm liking the results, with noticeably less plastic smell in my office while printing. Having confirmed the printer's able to make boat quality prints, it's time to start work on the hull design and layout.
Away for work at the moment so I decided to try switching from Sketchup to Fusion 360. I found a set of 1948 USS Missouri plans and, using BSG's how-to guide, managed to make something vaguely shaped like an Iowa turret. When I get home I'll have to compare these to my set of earlier plans to see what needs to change in the final models.
Made some progress on the hull today. Using the scale weight gives me approximately 1 1/8" freeboard. Marked the waterline and bottom of the penetrable area using state of the art technology: Finished laying out the ribs. Decided to borrow Kevin's layout with 8 3/8" ribs and 20 1/4" ribs on each side. Started drilling the corner holes out. Should finish drilling tomorrow and move on to cutting out the windows.
Made some progress. Started cutting the windows inside before quickly deciding that was an outside only job. Epoxied in the stuffing tubes, drag shafts, and motor mounts. I'll have to stand it down some once it hardens. Started work on the subdeck. Not sure who I stole the idea from but I made a template by making a layer of tape on top of the hull before tracing the inside of the rim with a razor. All taped up: And after cutting it out:
same. tape is a great method. But ............ I still manage to F things up when taping, so I always cut the wood a tad larger than the tape would suggest, then I use a hand planer to bring it slowly into tolerance. wasted a nice piece of plywood learning that trick the hard way.
