What's This Part? (RC Boat Edition)

[Billy Hill]

Anybody do RC Boats and know what this part is?

Guy said he couldn't find this replacement part for his RC boat. The top one is the original and worn thin. I made the bottom one to replace it but don't know what it does.



Thanks!

[kf2qd]

Need a picture.

[vincemulhollon]

Boats are a wider range than cars or RC airplanes. It doesn't look anything like any part from my 90s era RC sailboat which is about 20 miles from here anyway. Also does not resemble any '80s era scale fireboat parts or '80-ish era outboard tunnel hull parts. Most of that stuff I don't even have anymore. I remember distinctly the outboard tunnel hull had a flexible drive cable that was expensive and wore out fast, and the fireboat had a unique way of sealing the propeller shaft, it didn't bother, unlike the real thing the motors are pretty light so mounted way above the waterline and the driveshafts were very long brass rods nested in unsealed brass tubes. I always thought that was a rather elegant solution to the water tight shaft seal problem. The other thing I remember about the tunnel hull is it was incredibly fast yet tremendously unstable so it flipped over at the slightest provocation, yet despite sucking up lake water at the end of nearly every run, it never was damaged, which mystified me. Every time I flipped it I assumed it was hydrolock time but it never happened. Doesn't mean it couldn't, just means I was amazed. Maybe there's something special about that engine design or I'm really lucky. Probably having approximately zero flywheel helps a bit (yes it only had two speeds, way too fast, and insanely fast)

[wierdscience]

I made something similar once,it was a metal bearing seat that epoxied into a fiberglass structure to hold a ball bearing and allow it to be replaced.

[Billy Hill]

Boats are a wider range than cars or RC airplanes. It doesn't look anything like any part from my 90s era RC sailboat which is about 20 miles from here anyway. Also does not resemble any '80s era scale fireboat parts or '80-ish era outboard tunnel hull parts. Most of that stuff I don't even have anymore. I remember distinctly the outboard tunnel hull had a flexible drive cable that was expensive and wore out fast, and the fireboat had a unique way of sealing the propeller shaft, it didn't bother, unlike the real thing the motors are pretty light so mounted way above the waterline and the driveshafts were very long brass rods nested in unsealed brass tubes. I always thought that was a rather elegant solution to the water tight shaft seal problem. The other thing I remember about the tunnel hull is it was incredibly fast yet tremendously unstable so it flipped over at the slightest provocation, yet despite sucking up lake water at the end of nearly every run, it never was damaged, which mystified me. Every time I flipped it I assumed it was hydrolock time but it never happened. Doesn't mean it couldn't, just means I was amazed. Maybe there's something special about that engine design or I'm really lucky. Probably having approximately zero flywheel helps a bit (yes it only had two speeds, way too fast, and insanely fast)

Interesting take on boats, Vince. I've never gotten into them, just cars and an almost-start into heli's. Some research on RC boat drive trains shows the types of systems are wide ranging.

I made something similar once,it was a metal bearing seat that epoxied into a fiberglass structure to hold a ball bearing and allow it to be replaced.

I'm thinking it's something along these lines. I won't be able to talk to the guy until next week so it may have to wait 'til I get back.

[Davo J]

I think it goes on the end of the prop tube and a nylon type washer rubs against it to stop the prop pushing forward.

Dave

[jnissen]

Doesn't look like anything I recognize and I have been running RC boats for 20 plus years. I run a web site for the hobby at www.jrcbd.com. It could be a thrust washer retainer on the prop shaft. Older sub surface drives would use U-joints and solid shafts to transmit power to the prop. A thrust washer was used down on the strut to take up the thrusting forces. Yes a Teflon washer is used in there if that is what it is. It could also be a stiffener for a rubber isolation motor mount. Only problem is those typically don't wear out over time.

Modern drive systems mainly use flex cables to transmit the power now. A collet on the motor end grips the cable and the end of the cable normally has a solid prop shaft brazed on to form a smooth single piece cable. The cable rides in a brass stuffing tube and goes into a surface drive strut. The solid prop shaft rides in lead Teflon or brass bushings in the strut. A drive dog is firmly attached to the prop shaft and then the prop goes on and a prop retaining nut over that. The flex drives setup like this leave a space between the drive dog and the strut to allow the cable to shrink with the twisting torque. Some drive system use a square drive collet at the motor and the cable is free to move fore and aft. The thrust is then taken up at the strut to drive dog contact area. This is where a thrust washer would most likely be placed but again I have not seen one like the above with a cup shape.