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Drop Camera/ Tow Sled Frame


(Marcus) #1

Hi all,

Does anyone know of a BlueRobotics ROV frame (1or2) design being modified to be used as a tow camera/tow sled ie redesigned to accommodate the main tube, and maybe a smaller battery tube/lights, but smaller than the regular, full size frame?

Cheers,
mg


(Adam) #2

Hi Marcus,

I am not aware of anyone that has modified a BROV or BROV2 to a drop cam or tow sled. The only sled I have seen (and we have dived with) is Nathan Perry’s, it is however quite a bit bigger and heavier than one of our ROVs. It weights about 80lbs, and has a ton of lights!

-Adam


#3

I modified mine for this purpose, pictures will follow later.


(Marcus) #4

thanks Mikxie, interested to see this


#5

I made a towpoint in front and used a weight 10m from the ROV to keep the ROV near the bottom. The thrusters were used for adjustments.


(Kannappa) #6

Hi Adam,

I am also looking for HDPE material to make our custom frame. Please share some sourcing place and proper specifications. Also will HDPE material stand upto 300m depth or will it get compressed?


#7

I used PC. I think the frame of the ROV is made of HDPE/POM, no problem with pressure.


(Kannappa) #8

Thanks Mikxie…we are going ahead with HDPE Marine grade


#9

Just a little status report. We have now towed the BlueROV2 with tail wing for more than 40 km, during daytime and nighttime at 15 - 40 m depth. We were able to keep the ROV at app 0,5 meters from the bottom with no crashes. Tow speed typically 2 - 4 km/h, the ROV is stable at more than 6 km/h but made it too difficult to identify what we needed to record. By carefully controlling the depth of the drop weight, we could reduce the power usage for thrusters and this way record for app 3 hours on a 18Ah battery.


(Jacob) #10

@Mikxie Where did you get those vertical stabilizers?


#11

I bought them here:

https://www.surfline.dk/brunotti-kitesurfing-pc-twintip-finner-1-stk

They are kitesurfing twin tip fins.


(Nikos Maurommatis) #12

Hi Mikxie,

I would like to make modifications to my BR2 like yours so as to manage to tow it for long distances. May you send me some more details about your setup?

Nikos


#13

Yes, any specific details you need?


Towing the BlueROV2?
(Nikos Maurommatis) #14

@Mikxie, first of all I would like to ask you for the “towpoint in front”, wouldn’t be more convenient if you tow the BR2 attaching a rope behind it? Can you show me how you made the towpoint in front?

Second, I would like to ask you for the size and the shape of plexiglass? Is it a plexiglass, right?

Third, I can see that you have removed the front buoyancy, is that right? Do you think it is crucial?

I think I ask you a lot…

Thank you in advance
Nikos


#15

Hi Nikos,

If you want to see what is coming before you hit it, you need to tow the ROV by the front. I don’t have a picture right now of the rope, but basically I attach it to both sides of the frame, just in front of the wing, and from there, to the tether app half a metre from the ROV.

You can see the size on this photo, I don’t have an exact drawing, If you need it I can measure it though.

The material is 6mm polycarbonate also known as plexiglass. IMO Acryllic sheet is to brittle.

I am sorry about the picture without buoyancy, you should certainly not remove it, I was doing some maintenance…

I attach the wing with 6mm SS screws directly in to threads cut in the frame. to keep the wing straight, you need a spacer under the wing in the rear screws app 6 mm.

Remember to cut holes for the thrusters.

Good luck :slight_smile:


(Nikos Maurommatis) #16

@Mikxie, great details! I will let you know about my version.

Thank you,
Nikos


(Nikos Maurommatis) #17

@Mikxie, may I ask you the weights you have used and the distance between the rope and the BR? I have tried to have a tow route yesterday night with 8kgr and 2m distance between the rope and the BR2 and it was really a disaster. In depth of 48m when the boat started to move with a speed of 1knot everything was starting to travel for the surface…it was actually enough underwater current but we didn’t manage to get a decent result. Another question, when you have a current you better fly with current or against current?

I’m sorry for the many questions but finding a effective way to tow the BR2 can be a very useful tool.

Nikos


#18

We use 20 kg on a very thin dyneema line 3 mm, app 10 m from the ROV. To do this, you need some kind of winch, since handling this line with your hands will cause you pain. Unless you have perfectly flat bottom, you will need to continuosly change the depth of the weight, to avoid using too much power to keep the ROV at the desired distance from the bottom. 8 kg 2 metres from the ROV will not do the trick. Btw dont use the tether to carry the weight for extended periods of time.

If the current is slower than you want to go, it will help you reach the depth going with the current. If it is faster, you need to go against it, which meens more weight and slow speed.


(Nikos Maurommatis) #19

@Mikxie, I agree with you: 8kgr and 2 meters rope don’t do the trick! I will change my setup and I will try again. I will let you know about the results.
By the way, polycarbonate and plexiglass are two different materials. The polycarbonate is very strong and it doesn’t bend. Its price is double than plexiglass’ price. I think polycarbonate is more right for the certain job.

Nikos


#20

Polycarbonate bends but does not brake. Acrylic sheets bends less, but breaks. Plexiglass is a brand name, some use it for PC, others for Acrylic. I know PC is more expensive, but I was lucky to get some sheets for free. :slight_smile:

Did you make a wing?