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New Products: Fathom Spool, Fathom-X Tether Interface, Updated Fathom Tether!

Originally published at: https://www.bluerobotics.com/new-updated-products-fathom-spool-fathom-x-tether-interface-fathom-tether-r2/

Good day friends! We’re REEL excited for this release - introducing the Fathom Spool, Fathom-X Tether Interface, and an update to the Fathom Tether! Check out the new product video:

Fathom-X Tether Interface

The Fathom-X Topside Interface (FXTI) is an enclosure for the topside Fathom-X board that also contains a USB to Ethernet converter so that the user has a simple USB-to-tether interface. It also has expandability to connect other devices to tether pairs. The box has a Binder 770 Series Bulkhead to allow connection to the new tether.

Fathom Spool

The Fathom Tether Spool is a slip-ring spool for the standard tether and the slim tether. It comes in two sizes to support 150m and 300m tether lengths. The spool has Binder 770 Series connectors to connect to the tether and to connect to the FXTI. It is sold as kit with some simple assembly required.

Fathom Tether (R2)

The Updated Fathom Tether now has a polyurethane jacket that adheres better to potting compounds and increases the depth rating of the tether penetration. We expect it to work very well now to at least 300m and potentially to 1000m. This also makes for a tether that is more flexible and more abrasion resistant. The electrical construction and properties are still the same. The ROV tether now comes with a Binder 770 Series connector installed on the topside end. It comes fully-assembled. We'll also begin selling the tether by the meter, without the connector installed.

Note: All BlueROV2s purchased on August 7th or later will have the updated tether and will include the FXTI. There will be no change in the BlueROV2 price.


Great job guys! We know you have been working on this for awhile and it looks great. I have been looking forward to this and was just getting ready to do my own DIY solution for a topside reel but now I will be ordering this.


I just placed my order for the reel and the FXTI.


will get one soon i guess.

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Looks good - a couple of questions about retrofitting. First, the old standard tether is flexible enough to wind around the diameter of the spool? Second, is it feasible to cut off the end of our current tether and put the Binder 770 connectors on both cut ends, to join the tether to the spool and our keep our existing tether connection to the computer (i.e. rather than get the new tether interface to connect to the computer)?



Hi Craig,

Yes, the Fathom Spool is designed to be used with any of the three tethers we sell/have sold, including the original Fathom Tether R1.

What you suggest is possible, but may not be necessary. The Fathom Spool comes with an 8 m extension cable with Binder 770 connectors at both end to attach to the FXTI, you could cut off one of them to interface with your existing solution.


That’s great !!

Is the slipring sold separately?


Is it possible to use the binder 770 to connect the tether to the Rov ? To have a split solution ?

Do you sell the mating bulkhead connector for the 770? I also might be interested in just the slipring.

@trehoret - The slipring is not sold separately at the moment. Internally, we use a simple non-waterproof slipring and then it is built into a waterproof housing. That housing is specific to the spool and would be difficult to use without it.

@bdevis - No, the Binder 770 connector is IP67, which is splashproof, but will not stay sealed at pressure.

@Ben - We don’t sell the mating bulkhead at the moment, but it’s good to know that you are interested. For now you can also find and purchase any of the Binder connectors on their website here.

Hi Rusty,

How will the new topside interface impact the USB current load on present laptops?

Many of the newer laptops cannot source even 500 ma on their USB ports.


Hi Tom,

The FXTI just adds a USB to Ethernet converter that does not require much power. We haven’t had power issues with any laptops that we’ve tried so far. In the case that power could not be provided from the computer, it would be possible to open one of the expansion holes and feed in 5v power from another source.


Hi Rusty,

Thanks for the insights concerning powering the FXTI from a laptop, much appreciated.

I am presently running my Fathom X topside board from a 7.4 vdc Li-on battery which is able to power the board for about five hours before the battery needs to be recharged or swapped with a fresh battery.


I’m sourcing parts for a sidescan build and the Fanthom spool looks great but I haven’t found any information about the voltage and current rating for the slip ring.
Is it ok to have 48VDC across the pairs and a current draw of 250mA-300mA?

I plan to power a sidescan using 48V DC and use two pairs for power and a tether length of 150m. That will give me a round trip resistance of 19 Ohm if both pairs are used and a voltage drop of around 9V.
I will have a DC-DC converter in the sidescan that converts it to stable 12VDC.


Hi @hakan

The Fathom Spool is able to handle 48 VDC across the pairs, and the slip ring is rated for up to 2 A per pin. A few hundred milliamps should work fine.


how you giving 48v power to the ROV using battery or AC power supply.

thanks @hakan


I have just assembled the fathom spool. When connecting the long cable connector and the extension cable connector to both ends of the slip-ring’s connectors, these connectors turned, about 1/4 to 1/2 a turn, within the slip ring housing as if it had not been completely screwed in.

Is this normal? Is there any risk of damage on the wiring inside?

I guess you probably check the mating of the connectors before shipping but the stiffness of the cable connectors may vary from connector to connector and therefore it may be relevant to mention that this can occur within the instructions.

Hi @Eloi,

The bulkhead Binder connectors should be fully tightened down in the slip ring core from production. If they are not quite completely snug, tightening them down a bit more will not hurt anything. We’ll make sure we tighten them down a bit more from now on, thanks for bringing this to our attention.