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One piece 4 lumen 4" Dome bow section on Speargun ROV

Hi all

I have been trialling a new bow section on my 'bullet ROV and although having initial misgivings about the increase in resistance caused by its slightly larger size over the 2 lumen 3" version it replaces, I can say I am extremely pleased with it.
I have also upgraded the trigger mechanism on the speargun now using a waterproof servo from Bluetrailengineering with a spring-loaded latch for a very quick response when I press the button.
Hope you like the attached pics.



@johng - That looks great! I’ll be curious to see how the lighting looks from the camera’s perspective.

Also, how are you sealing the cables entering the enclosure? I see a plate with four screw. Is it potted behind that? Or a gland maybe?

Hi Rusty

glad you like it. It provides an altogether more business-like look to the front end and I picked up a bit of extra buoyancy from the larger camera dome as well as well as more gimbal movement.

I have tried to position the lights based on the reflective angles in the normal BR lumens so that the camera lens should be just behind where the light projects. I will find out if that works out in the near future butI haven’t potted in the PCBs and Cree bulbs yet until I am sure that everything stays dry at 200 metres. The silver parts have a double o-ringed flange which is hollowed on the inside to the dimensions of the light PCB. The cabling just comes ofd the back of the PCB and through the holes on the inside of the main section to then connect onto the electronics tray so there are no cables exposed to the outside environment thereby removing snag, penetrator or cable failure risk.

That looks really good. Is it fiberglass?

Hi Tyler

It is machined from a single block of alloy, as is the rest of the body.


No wonder it looks so good! Is it aluminum? Like 7075?

It is 6061-T6

Is it for sale? :joy:

Nice! I know 6061 is better in seawater but I’ve heard that it’s more difficult to machine relative to 7075. Did you do it yourself?

Yes, I have designed them with the intention to sell. I haven’t updated my website yet to reflect the new design cost but they will be roughly 25% more expensive than the price of the preceding version one there.

I wish I had the skills and equipment to make something like that. I have been lucky enough to find a superb machine company in China that has made the bodies of the last 4 models I have designed.

oops hit the wrong button

This is way cool! I’d love to get a fish with it. Like Rusty, I’m curious on your waterproofing - I get how your lights are built into the body, but what are the plates with 4 bolts where the thruster cables enter the housing? Is there potting or a gland behind those?

Hi Anthony

Those plates you mention are the top of the penetrator which has an o-ring between the shaft and where they bolt on to the hull. They are bolted onto the hull so it would make it more difficult to pull out a penetrator in the event of a bad snag. The penetrators are threaded on the inside to provide maximum grip for the epoxy. Hope this explains it.
You will probably note in the photos that I also have blank penetrators below the lateral motors so I can add another 4 motors if need be.