Thrusters / Motors



I’m new to this forum. I’ve been reading this site as well as others for the last few weeks.
I am going to building an ROV for my Senior Design Project.

I just want to make sure I’m understanding my options when it comes to propulsion.

  1. Plug and Play with Blue Robotics T100/200
  2. Use OpenROV’s or some other brushless motor and clean / pot as required etc…
  3. Find middle ground and use a bilge pump as seen at Though I’m not sure if they are okay in seawater.

Thank you for any help and clarification


Basically you have to consider budget versus performance.

If you have the funds, then the BR T100/200 Thrusters are the way to go. They are designed to work in salt water with a minimum of maintenance and are a premium thruster for the price. I have used them in my Hybrid ROV project.

For those on a budget, the OROV DST-700 brushless motors are a good choice, but may have a limited life when used only in salt water environments, though proper maintenance will definitely enhance their life expectancy.

The bilge pump conversions have a limitation in that they use a rubber seal around the pump’s motor shaft that can possibly tighten up due to the pressure at greater depths reducing their performance and the life expectancy of the seal. They are good for MATE types of competition in swimming pools.



Thank you. If I can convince my professor to help with the costs through her grant, I think I am going to splurge on the BR T100 motors. (But only if I am keeping this ROV and not handing it over to the University after I’m done).

Are the bilge motors okay for saltwater? If not, I’ve seen people potting, or covering brushless motors with wax to help waterproof.

I am very much impressed with your ROV. Looks like you are a Navy man. If you happen to be in Norfolk, I’d love to see your rig. (I’m prior Navy myself.)

I’m still learning this all, and have a lot to read still before I start my project. I apologize if something has already been answered and I have not gotten to it just yet.


Since the bilge pump motors are designed to pump saltwater from bilges, they will work fine in saltwater. However, they are really not designed for working at depths perhaps greater than 10 - 15 ft and may either wear out quickly or fail if operated at deeper depths.

I was a Westpac sailor during the late 60s and early 70s. I live in southern FL now and have not had a chance to go up the coast yet, but I will definitely let you know if I get up your way.



Thanks. The bilge pumps are out then as I intend to do some testing in the Chesapeake Bay, i’d like to see what’s at the bottom.

It’s a pleasure to meet you. I was Westpac also. Japan and San Diego for sea duty and then Norfolk for shore.


Nice meeting you too. If you ever get a chance to visit southern FL, please let me know.

I made two Westpac cruises out of San Diego during the Viet Nam War. All of my shore duty was on the West Coast except for a month at Submarine School in New London Connecticut.


I did 3 cruises out of Yokosuka and 1 out of San Diego. I’m sure we pulled into the same places. Though the Navy now a days is not the same as it used to be. I’d love to visit and hear some stories.


I spent most of my Westpac tours operating out of Subic Bay in the Philippines though I did make it to Sasebo Japan a couple of times.Also stopped at White Beach in Okinawa a couple of times and once at Midway.


I’ve been to White Beach a dozen times I think. I’m jealous that you went to Midway. It’s one of those places that I wanted to visit before I got out.

Man, I miss the crew from my first ship. They were fantastic.

I’m pretty sure had I known about ROV’s back then I would been more likely to keep my head down.
My fellow FC’s and ET’s could of probably made something really cool over a deployment.


Actually not much to see at Midway except what appear to be fur trees bent at an angle due to the wind off of the Pacific. I was there in Nov '72 and it was cold and windy.
The White Beach water was so full of sea snakes that there were signs on the beach saying “no swimming” even though the water looked very inviting.
Had I not opted for a career in Aerospace, I think that I might have become a Marine Engineer instead. Oh well, maybe in another life.:slight_smile:


I am an engineer in Annapolis, MD and have experimented with Openrovs and Bluerovs and could answer some of your questions if you are in the Washington DC area



I was hoping to visit Midway for the Historical Significance. I also wanted my “Blue Nose” Ribbon, but somethings just never come to pass.

I am hoping to find some success with my change from the Navy with an Electrical Focus to getting a Mechanical Engineering degree. I’ve been shying away from coding but I think that is the final piece I will need to make that marriage of disciplines complete.


Walter, I’m only a few hours away as I’m in Hampton Roads. I appreciate your willingness to help.

I’m starting to sketch out what I need.

-Some sort of Control Board (Arduino, etc…?)
-Top side control box / display
-Teather / Data Cable

What else, if anything am I missing for a basic set up?


I wanted to be a Sonarman when I signed up for 4 years. but got talked into going Nuc for 6 years. I went to Electronic Tech school at TI and then spent a year on the heavy cruiser St. Paul (CA73) up on the Viet Nam DMZ. After a year at Nuc School I went to submarine school and then to the Daniel Webster SSBN626. I spent about a year and a half on the Webster then got transferred to the surface fleet when I did not have enough time on my enlistment when the boat went into the yards for core replacement. I spent my last year and a half on the USS Dubuque LPD8 conducting electronic intelligence sweeps along the North Viet Nam coast until the war ended.
The Dubuque spent 40 years in the Navy and was just recently decommissioned. The Webster is now a MTS used to provide submarine reactor training for Nucs. I qualified on Rickover’s Nautilus prototype (SW4) at Idaho Falls, ID.
I used my GI Bill and a work-study program to finish my BSEE and went to work in the Aerospace Industry.:slight_smile:


They almost got me to sign up for Nuke school as well. I had a nuke, sub, et recruiter in my office. He was VERY weird, super smart but weird. After I took the ASVAB they told me that the test sort of groups people that are similar in skills and personality into the same types of jobs. Once I realized that I could be working with more of the Nuke recruiter I went FC. I didn’t escape the weird though. :slight_smile:


I hope you don’t mind if I jump in here with a comment / question. I understand that this is a project, but what do you intend the end use to be? Photography, exploration, recovery, multi function, etc. Where do you plan to use it, fresh/salt water, Standing water or tidal / strong current? Do you want a large stable platform or a small nimble unit. All of these factors should impact your design, along with budget.

I am in the process of building a small photo recon unit for a project where we will be looking at tree trunks and main branching limbs in a flooded forest, 120’ deep. We are dealing with a large amount of suspended particulate in the water so I am trying to use a very low light camera to avoid the back splatter caused by bright lights. I also plan to use a 3 laser measuring system for size and depth of field. ( I notice you did not have lights or lasers in your list) The other piece of important equipment is a compass/ depth module for heading and depth.


I don’t mind at all. I derailed the thread. Thank you for getting me back on topic. I’m actually thankful you are willing to help.

To answer your questions:

  1. End use will be exploration.

  2. Operating environment will be saltwater 100% of the time after the project is completed. I do have access to the University pool before then. I am not adverse however to modifying the ROV’s motors after the assignment as been completed. The T-100 Thrusters while nice, might eat up half the funds my professor is willing to give me to help fund the project.

  3. Looked up on the NOAA site, they state the average tidal current is 0.7 as per 2011.

  4. The platform size I’m still debating on. 20"x 20"x15" seems like a manageable size constraint to me.

I completely forgot to list about cameras and lights, though they appear on my list I’ve written in my notebook. The water in this area is really dark, so I imagine I will need some powerful lights and have just started to look at options. Buying Off the shelf, or building my own assembly.

Thank you for listing the compass and depth module.

I have to remind myself that this is a school project and it is my first time. I’ve experienced scope creep already and have to keep removing bells and whistles I want to add. If anything to keep it easy for the control box. Less things to display / program.


You might want to follow my OROV 2.8 motor conversion project to get an idea of what an OROV 2.8 looks like with Blue Robotics M100 motors and propellers in place of the DST-700 motors and Graupner propellers.


I’ve been researching other items for my ROV and have come back to the motors.

A few questions.

If I were to do the OROV DST-700 or the M100 from Bluerobotics, can I make a housing for the motors to sit inside and then fill that housing with a potting material?

Would the motors overheat? Would such measures keep water from entering the motor through the shaft side?


The Bluer Robotics M100 motors are designed to run directly in the water and require water for cooling and bearing lubrication.