Homebuilt ROVs Forum

I now consider my thruster design finished.
There could always be more things to test and improve, but I am pretty satisfied at this point.
The blades in the pictures below was the best out of all the 11+ propellers I made. And there is no hiding that they are greatly influenced by the BlueRobotics T100 Thruster.
They performed slightly better then the other designs I had, but some others came really close.

Numbers were fluctuating as the thruster still managed to suck in air.

Running at 12v, the average numbers are:
Optimal direction, Forward (When the water is sucked from the propeller side and over the motor.):

1A = 0,5kg - 1,1lb - 17,6oz
2A = 0,8kg - 1,76lb - 28,2oz
3A = 1kg - 2,2lb - 35,3oz
4A = 1,3kg - 2,8lb - 45,8oz
5A = 1,5kg - 3,3lb - 53oz
7A = 1,8kg - 3,9lb - 63,5oz
8A = 2kg - 4,4lb - 70,5oz
10A = 2,3kg - 5lb - 81oz
11A = 2,5kg - 5,5lb - 88oz
13A = 2,65kg - 5,8lb - 93,5oz
19A = 3,3kg - 7,3lb - 116oz

Reverse:

1A = 0,45kg - 1lb - 16oz
2A = 0,6kg - 1,3lb - 21oz
3A = 0,9kg - 2lb - 32oz
5A = 1,3kg - 2,8lb - 45,8oz
10A = 2kg - 4,4lb - 70,5oz
19A = 2,9kg - 6,4lb - 102oz

More details in the video:

Fantastic results! I would like to see the dimensions of your nozzle. Did you make changes to the nozzle at all during the process or just props?

I've been following your thruster threads and have been quite impressed with your work. Would you even consider selling your printed parts?

Nice work Ole! Looks awesome!

Any idea what kind of power (draw) range you are planning to use on the ROV? You can really eat up some battery power with the top of those ranges you listed.

What kind of batteries are you planning to send down in this thing and what kind of dive times are you hoping for?

Well, my setup has to be limited. I still plan on having two thrusters for vertical and four for all horizontal movement. So in theory, it is possible to draw 120amps with that setup. Thats 1.4KW
But that's overkill to say it mildly.
My weakest link is the cable and connector coming from my battery compartment to my electronics compartment. All the power will go through that connector. I mentioned it earlier in my build thread that I was lucky and got a hold of some subsea connectors. They are rated for 64amps continuous and up to 30bar pressure rating. The guy I got them from, witch is an electrician said that shorter peaks well above that should be no problem. But say if I limit my thruster in the software to max out at 10amps each (tested to 2.3kg) it should still be waaay more then I need.
Luckily I have the ability to set thrust levels in the control software so that I can adjust it on the fly.
For instance, in setting 1. the thrusters will max out at 3amps. Setting 2, they will max out at 5amps and so on. This should give great maneuverability and precision when needed.

I will be using six 4cell (14.4v) 5Ah lipo batteries. So 30Ah total. The batteries should handle the loads. Also, as it is 14.4v, the amp draw of my thrusters will be lower then in my test video. But actual watts stays the same ofc.

As for dive times I don't know. It will vary on what I do. covering ground will drain the batteries fast. But hovering around stuff, studying stuff and so on will not drain them as fast. It is something I am exited to find out myself.
If I get 1-2 hours at "normal" use I will be happy. This means I can buy one more battery pack and charge it while I'm using the ROV. Charge time should be around one hour if my brain is cooperating right now.

In my ROV I am using four 120 Watt motors. After my Thruster tests I limited them to 70% (about 7 A). For using in low current areas it is more than enough.
Last weekend I was really surprised to see that my batteries were almost full after 70 minutes of diving around. The average current was 5,4 A for the whole ROV.
But the consumtion is much higher if I use the ROV in other areas with more current. It is really hard work for the ROV to tow the Tether through the water against the current.

And this is my final test .This is the set up I will use for my thrusters
4S lipo
500 kv motor
Nozzle by OLEGODO design
propeller by OLEGODO design RESULTS (thrust forward)
BATTERY :lipo 15.68V
POWER:
20% 0.4 amb. 0.33 kg
40% 1.92amb. 1.10 kgs
60% 4.65amb. 2.00 kgs
80% 9.39amb. 3.00 kgs
100% 10.00 amb. 3.20 kgs
THRUST REVERSE
Lipo:15.6V
POWER:
20%. 0.3amb. 0.1kgs
40%. 2.93amb. 0.35kgs
60%. 3.43amb. 1.30kgs
80%. 7.88amb. 1.78kgs
100%. 11,52amb.2.30kgs

Temperature after five minutes at full thrust rise from 26 d.celcium to 31

I did a test as well with OLEGODO nozzle and Graupner 65mm prop.
Graupner does not perform well with a nozzle
At 100% power (forward) draws 7.47a - 2.2 kgs thrust
At 100% power (reverse) draws 7.17a - 0.520 kgs thrust

Impressive numbers Bubbles!
Looking good

olegodo wrote:Impressive numbers Bubbles!
Looking good

You did a nice job with nozzle and prop!

great looking thruster assembly.

I built a couple of homemade jet powered boats some time ago and found standard type props snug within a shroud were not very efficient. Better to give some clearance and simply use to protect prop. You really need that squared off edge impellor type prop and close fit for best thrust. We ended up with oversized cut down props with minimal clearance.

I had planned to make something around a cheap ducted fan for rov but just ended up with budget electric outboards. I like the idea elsewhere on the net of filling with hydraulic fluid to prevent corrosion. Will do some testing and think it will be limited via throttle endpoint setting to keep amps down. They are overkill and heavy but should last well and be re-used. Less ballast overall.

Should be good when the all in one Bluerobotics ones become available. The T100 looks good value for money for those wanting plug n play