Propulsion System - Motors, Gears, etc



Hello team,

I am thinking about a similar construction sealing in an aluminium box with 4 ultra thin chain gears. It is possible to accomplish the reduction 4:1. The only problem could be the weigh. It weighs more that half a kilo.


There is a topic with belt reduction which is quite similar but not as heavy, see here:Timing Belt Reduction


TY Jezza I just saw this. My jaw was dislocated for 25 years without a single doctor noticing and when it popped back it was agony after about 24 hours like my body forgot it what it was to be normal…that is about when I first asked you guys about this so thanks again.


500 grams to save $400 (I AM A HUGE FAN AND have prototped the above myself but single stage and 25 or 35 or 45 gears) and avoid wearing out and…gear chain drives are about 98-99% efficicient while planetarys are half as efficient per stage i believe (very approximate but chains rule much to my surprise, beating out even helical gears??? wtf?)



We have 2 propulsion system available?

Min 12s batery

Very eficient system


what is the thrust rating ? what is the price?


how much does it cost?


modern planetary reduction unit are quit efficient though
1 stage 97%
2 stage 95%
3 stage still 91% efficiency


What price is it, and complete, with everything? Can you contact me?


Yes but at these power requirements 10% of 8000 watts is 800 !!! watts JUST for powertrain losses verus 1%?

Now add losses in the ESC, high speed impeller versus prop losses, losses due to internal impedancwe in the motor windings… you will end up with losses of 2000-3000 watts just in UN NECESSARY design flaws.

I have the highest, absolutely HIGHEST respect for the early innovatiors on this site and we all know their names and I see those names spoken with something bordering on reverance, even th ose early innovators were the very first people to say guys we need a direct drive or belt reduction…

anyway I am behind with work so this will be last post

I wish you all the best

To PM, Amber, and some other regular contributors thank you for welcoming me to this forum and more importantly thank you for sharing (and I didnt forget “virus”) your knowledge unique skill set and more importantly your patience and passion both for this endorphin based sport and for the ancient art of ingenious innovation and application also called less favorably “engineering”.
be back soon, which could be in a hour or two years depending on work and my health
all the best
Piotr Kay
aka borntosurf and “surf naked” from my favorite bumper sticker and I wonder why cops pull my stickered van over so much !

(two years ago i replaced a leaking 15 foot aluminum boat a gift from my dementia affected father which we used to fish on lake ontario safely by never venturing further than 10 minutes from shore at 30 knots or 1 hour from shore at 5 knots…)


two years ago, the engine quit just before a storm, storm hit, 5-6 foot waves, the Police Marine unit towed my son to (my only son) and the boat caught fire exactly one hour later and was totalled

I bought another one and the bearings failed after my son neglected to winterize it properly and this time we were towed to safety by the volunteer coast guard

So my interest in reliability is very personal



As per my knowledge prop is related to speed and torque but I agree we should start a separate prop tread and many other. I’ll get a prop thread going, IU just took a pic of all my prop experiments.

complete pcb


Hello there :slight_smile: so what price on a system ? And what is included ?


new high RPM,no gearbox, direct drive jet propulsion idee
some sugestions?
fits standaard on the pacificmeister design (with special shaft)


Very interesting! I would love to ditch my Neugart gearbox and all the heat it generates. Are you using the SSS KV 500 motor? Looking forward to your first in-water test results.


This can be used as an alternative to the gearbox?


I was currently looking at that and I really don’t think it would be a bad gearbox.


I could not find a torque rating for the gearbox. The rated input speed of avg 3000 and max 5000 rpm is quite low in our application.


Hey I wanted to use this motor as well and wanted to know a good planetary gearbox that I could pair with it. In general I’m still very new at this and don’t really understand how to pick up the right motor with the right gearbox. In general how do I know which gearbox ratio I need ? I’m sorry I know this are very annoying questions but I’ve been put on this assignment at work and I’ve never worked with motors or gearboxes before :frowning:




Ah, @Downforce1 you got the MHz jet. I got it too. What amount of thrust do you get? Mine maxes out at about 15 kg. Mainly because it starts to suck in air in my super small test chamber ( Ikea box). Which motor do you use?


I have 2 of those as well. I haven’t run them yet though. I think you should have enough thrust to foil as it wont be sucking any air. I agot the 56114 500KV to use with it.