Ideas for WiFi Topside Float design


The new WiFi Topside Module for Trident is small enough to be mounted in very tight spaces. Since the Topside is no longer designed to inherently be used as a floating buoy, I thought it would be good to start a thread on ways people who still want it to be free-floating could make that happen.

We’re waiting for the professionally built models of the WiFi Topside Modules to arrive, but in the meantime, here’s a photo of a quickly 3D printed prototype being held for sizing reference.

Additional Refinement, Updated Timeline (Trident Kickstarter Update #17)
Additional Refinement, Updated Timeline (Trident Kickstarter Update #17)
OpenROV Trident Unboxing and Test Dive video

I like the idea of kayak deployments. Here’s a photo of the topside module clipped onto the front of a kayak:


Hi Eric

Just a couple of thoughts more about the “mechanics” of the unit

Where is the WiFi Topside Float powered from? Is it up from the ROV via the tether or is it on its own internal battery?

The connection of the tether to the WiFi Topside Float. Can this be a similar connection as would be the tether to the Trident so that tether’s could be daisy chained (say 25m tether added to a 100m tether to give a 125m tether) with some sort of stain relief



Hey Scott!

The WiFi Topside Module is powered from the ROV- that way the user only has to worry about managing one battery state.

We’ve talked about making an adapter that would allow the tethers to be daisy chained but we haven’t developed that just yet. In theory, it should be fairly easy to do but if the total length of tether gets much longer than 100m, an external power supply should be attached to the tether close to the Topside in order to give it enough power. We’ve also talked about an adapter for doing that, but I figure we’ll get the base system out first and work on tether accessories later.

Thanks for the great question!



Even though the Topside Module isn’t designed to be used as a floating buoy, will it still float? Or will it sink if it would slip out of your hands or if the plastic carabiner attached to your kayak or boat breaks? Because if that happens, I guess you are pretty screwed since the connection with the Trident would break pretty instantly also then?

If it still floats with the new design, I don’t see the need of designing it in another way since most people probably will attach their own “buoys” to it if needed depending on the different situations where it is used.

But one nice feature to have on the Topside Module would be a blinking light, so it would be easier to spot during night time excursions etc. :slight_smile:


Hey Peter_S,

Indeed, the new WiFi Topside Module floats and is waterproof. I is just not designed to be used while in the water. There are also lights onboard which are used to show connection and power status which should also make it easier to spot at night.



Aha, sounds good that it both floats and is waterproof since that is pretty important :slight_smile: But since you mentioned that it isn’t designed to be used while in the water, does that mean that the connection brakes when it is in the water, or that it just doesn’t move very well in the water?

Would it be possible at all to use the Trident in the water with the topside module floating around freely?

Otherwise you could just make a very simple floating “dock” that people could buy separately if needed. I made a very simple sketch of how it could look like, but since I don’t have the correct measurements of the topside module it might look a bit strange :slight_smile: And of course you probably need to do some testing to find the right size of the dock/floating device, and maybe also consider if the module should be standing upright or if a horizontal position would be better.


This is another way you could do it, that might work even better :slight_smile: The two things on top of the module are just some simple symbols for straps or holders that I guess would be good to have also.


Can you tell me why you made this change? I was looking forward to the idea of the extra range by not being tethered to the boat.




Can you tell me why you made this change? I was looking forward to the idea of the extra range by not being tethered to the boat.



@Peter_S This is awesome! Yeah- I think something like this could work really well. We’re finishing up the topside shell design now, but maybe I can upload a draft CAD file to do sizing with soon. I really like this idea. I’ve also been thinking about some “quick and dirty” ways to get the Topside Module above the waterline for people who just want it to be separate from their boat, and the idea of stuffing the device in a child’s water wing seems like it would work pretty well too. Of course, without having a large antenna element, one probably shouldn’t get too far away from the buoy, but this sort or thing should still work well for operations within 10 or so meters of the buoy. Also, here’s a link to a high-gain radio and antenna system that can be plugged into a laptop to improve link budget:


Hey Mike,

Here’s what I wrote in part of the Kickstarter update that enplanes it.

We had built several early prototypes of the buoy design toward the beginning of the project, and were intrigued by the possibilities. But after further testing, we realized that making the WiFi Topside also a towable buoy would add a large amount of risk to the functionality and development of the system as a whole. To keep the buoy from being towed beneath the surface, it would need to be fairly large (nearly the length of Trident itself), to make it self-righting, it would need a large keel ballast which would increase its displacement and add a lot of drag, and finally, to make sure people wouldn’t lose the system, we’d need to do extensive development work with the antenna and radio to assure a solid connection and develop a return-to-home feature if the vehicle lost signal far from shore.

While all of these features could have been designed, they would add months to the development process and could reduce the reliability of the system. We decided to stick with a simpler design that we knew we could trust. The new topside module is something we are very proud of. It is simple and robust, and makes the system a lot more transportable due to its shape and size. Although it is not a floating buoy, it’s still designed to be waterproof and positively buoyant so if it falls overboard accidentally, the system won’t be lost. Though not hydrodynamic, users on the water who (at their own risk) want to decouple the buoy from their boat may still be able to experiment with putting the buoy on other floating devices. A wifi buoy is just one of the possibilities for the modular, smaller design. We’ve talked with a few people about the new design, and have already heard several ideas of how folks will be adapting it to their specific purpose.

A big perk of the new Topside design is that it is now small enough to be attached to the hub of a tether reel, which will make tether management much more elegant for people who ordered a 100m length of tether. The image below shows a 3D printed prototype of the WiFi Topside Module (we’re still waiting for the nicer prototypes to come in) attached to a tether reel. This configuration allows the reel to be used without a slip-ring because the WiFi Topside can just rotate with the tether.

Hopefully this helps explain the change. Please feel free to post if you have any other questions or ideas!



Thank you and I like your reasoning. As most boats have a fishing pole, I see myself attaching a light line to the topside module and experimenting with range and floats without the risk of losing the system.



Could you elaborate on this daisy chaining? What is it about this design that prevents you from connecting two lengths of tether to a maillon rapide (“chain link”) or 4-part shackle that passes through the existing hole?

Does the antenna coil pass through the loop of the body? If so, would the RF performance be affected by putting a conductive loop (maillon or shackle) through this antenna loop?

“Strain relief”? For reducing kink at the entry of the cable into the body, or for reducing the jerk if the tether comes tight? There’s no shortage of the latter in cabling accessory suppliers - check your RS or Farnell or whoever catalogue. For the former, gather a fist-size hank of loops of the cable and pass a “snoopy” loop (bungee cord or more traditionally from diving, a loop cut from a car or motorcycle inner tube) over the hank. If the cable comes under tension, the loops will pull out of the hank with moderate tension until the hank is pulled straight. Shock loading considerably reduced.


Hi @Aidan_Karley

What I was alluding to is that it would be great if the same full depth rated connection plug is used at both ends of the cable (ie so that OpenROV do not use a less expensive splash proof plug (say a std IP68 plug) to connect to the WiFi Topside but rather the full depth rated plug that is mounted on the Trident [say their version of an EO or Subconn plug]) and additionally that they have opposite sexes so that one cable can be plugged into the other to extend it.

I wouldn’t be “dunking” or linking via the WiFi unit just changing out to extend (or shorten) the cable

The Strain relief I was referring to was not so much on the cable out of the plug but the jointing of the 2 plugs you want to remove the tendency for the unit to want to unplug itself. Ideally the strain relief should be back to the Kevlar core of the neutrally buoyant tether and this should be a shorter length than cable so that it transfers the strain.

I wouldn’t recommend just simple loops that could be pulled out of a captured loop system (bungee or otherwise). If you can’t get back into the central Kevlar core of the cable then look at a Kellums to transfer the load (remember the Neutrally Buoyant Tether is rated to 500 Newtons [

Have a bit of a read through

As an aside @Eric_Stackpole can you share any info on the bottom plug yet?


@Scott_W the same connector is used on both sides of the tether so that it is symmetric and does not matter which end is connected to the ROV or the topside.

We are not able to release any additional detail about the custom connector we are designing at this time.


OK, I see what you mean now. Having had to do enough rigging up and rigging down of sensor systems in explosive atmospheres I can see where you’re coming from for cables with symmetrical connectors so that you can link them end-to-end. Our first system used asymmetric connectors, so it mattered which way you uncoiled the cables - a right PITA.
My trainees over the years didn’t understand why I’d go through the procedures for making up connectors or glanding up junction boxes in nit-picking detail. But they didn’t have the joy of coming back to a JB which someone had mucked up a gland on, and was now flooded with water and oil, and all the terminals are corroded, the cables are corroded a metre up from the gland, so needing a splice to get to the JB. Making connections in cables in hostile environments is just a bit more demanding than putting a new plug on the toaster.


Your looking at it the wrong way they were just making it suitable for a Zone 0 Area EX ma Safety by Encapsulation :wink:


How do we “DIY” to get the WiFi topside to transmit longer distances?
The original id´e with a tow-able topside boy was one of the main reasons this looked different then other underwater ROVs on the market. I was hoping to anchor my dingy and search big areas around the dingy before moving the anchor. To take my laptop in a kayak is not an option and to not anchor the dingy will make it hard to make accurate search patterns.


Hey @pelle_diver,

Instead of increasing gain on the Topside, you can improve range by increasing gain on the computer/controller side. I’ve used an external WiFi Radio with high gain (9dB) antenna and it has allowed me to increase range significantly.

It’s hard to say exactly how much this sort of thing will extend the range (a lot of that depends on other conditions you’re operating in) but I’d imagine you’ll see a pretty significant improvement.

Just about any type of float should work for keeping the topside out of the water. Out of curiosity, what are you planning to use Trident for?