When we compared three underwater ROV brands on 6 August, the finding that surprised us most had nothing to do with the vehicles: the cable was often the item that moved the budget. This is the follow-up that piece owed. It looks only at tethers and reels, and it takes all three brands from live pages on the same day — 10 August 2026 — so the comparison is same-day and like-for-like.
Sources: QYSEA's own Shopify store (currency confirmed USD via its cart endpoint), Blue Robotics' own WooCommerce store, and UrbanDrones for Chasing, which does not sell direct in the US. That asymmetry matters and I come back to it at the end.
The tether-only comparison
| Length | Chasing (dealer) | QYSEA (direct) | Blue Robotics Slim (1 pair) | Blue Robotics Standard (4 pairs) |
|---|---|---|---|---|
| 25 m | — | — | — | $260.00 · $10.40/m |
| 50 m | — | — | $250.00 · $5.00/m | $440.00 · $8.80/m |
| 100 m | **$199.00 · $1.99/m** | $429.00 · $4.29/m | $440.00 · $4.40/m | $830.00 · $8.30/m |
| 150 m | — | — | — | $1,220.00 · $8.13/m |
| 200 m | $399.00 · $2.00/m | $679.00 · $3.40/m | $820.00 · $4.10/m | $1,590.00 · $7.95/m |
| 300 m | $599.00 · $2.00/m | $1,850.00 · $6.17/m | — | $2,330.00 · $7.77/m |
| 400 m | $799.00 · $2.00/m | — | — | — |
Three brands, three pricing philosophies that do not resemble each other at all.
Chasing prices cable as a commodity. $1.99/m at 100 m, $2.00/m at 200, 300 and 400 m. Every marginal hundred metres costs exactly $200. There is no volume discount and no volume penalty; the curve is a straight line through the origin. It is the only one of the three you can do arithmetic on in your head.
Blue Robotics prices cable as manufacturing. The Standard curve declines smoothly from $10.40/m at 25 m to $7.77/m at 300 m — the termination and connector work is a fixed cost being spread over more metres. The company also sells the bare cable by the metre: $8.00/m for the 4-pair, $5.00/m for the 1-pair. Which produces the result I did not expect: at 100 m and beyond, the finished, terminated, ROV-ready tether is cheaper per metre than the raw cable it is made from. A 300 m ready-made tether works out to $7.77/m against $8.00/m for the spool of bare wire. The Slim line crosses the same way — $4.40/m and $4.10/m finished, against $5.00/m bare. If you were planning to build your own to save money, check the arithmetic first.
QYSEA prices cable as a configuration option, and the curve is U-shaped. $4.29/m at 100 m, down to $3.40/m at 200 m, then up to $6.17/m at 300 m. Look at the marginal cost rather than the average and it is starker: the second hundred metres costs $250 ($2.50/m), and the third hundred metres costs $1,171 — $11.71/m, or 4.7× the second. For completeness, QYSEA's shortest product, a 3 m tether at $50.00, works out to $16.67/m and is the most expensive cable per metre anywhere in this comparison.
Reels are a separate purchase, except when they are not
| Item | Price | Notes |
|---|---|---|
| Chasing Winder (no tether) | $59.99 | hand winder |
| Chasing Hand Reel (M2 / Gladius Mini) | $499.00 | no tether |
| Chasing E-Reel (M2 / Gladius Mini) | $699.00 | powered, no tether |
| Chasing Reel Roller Cart + 300 m tether | $999.00 | bundle |
| Chasing Reel Roller Cart + 400 m tether | $1,199.00 | bundle |
| Blue Robotics Fathom Spool, Standard (150 m) | $820.00 | no tether |
| Blue Robotics Fathom Spool, Large (300 m) | $920.00 | no tether |
| QYSEA tether spools | included | tether ships wound |
Chasing's bundle maths is internally consistent, which is rare enough in this industry to be worth saying out loud: $999.00 minus the $599.00 tether leaves $400.00 for the cart, and $1,199.00 minus the $799.00 tether leaves $400.00 as well. The same cart, the same price, at both lengths. Note though that the cart at $400 is cheaper than the same brand's standalone hand reel at $499.
Blue Robotics' 300 m spool at $920.00 is 2.3× that implied Chasing cart, for a comparable job. QYSEA sidesteps the question entirely by shipping the tether on a spool, which is convenient but removes your ability to price the two separately or to upgrade one without the other.
What the cable costs relative to the robot
This is where the comparison stops being about cable.
| Brand | Vehicle (price read same day) | 300 m tether + reel | Ratio |
|---|---|---|---|
| Chasing | M2 S, 100 m, no arm — $2,699.00 | $999.00 (cart bundle) | **37.0%** |
| QYSEA | FIFISH V-EVO Standard — $1,399.00 | $1,850.00 (spool) | **132.2%** |
| QYSEA | FIFISH V6 EXPERT Standard — $2,999.00 | $1,850.00 (spool) | 61.7% |
| Blue Robotics | BlueROV2 aluminium 300 m — $5,300.00 (recorded 1 Aug, not re-read today) | $3,250.00 | 61.3% |
A 300-metre QYSEA tether spool costs 32% more than QYSEA's entry vehicle. That is not a criticism of the pricing so much as a warning about how these systems get budgeted: the vehicle is the thing in the brochure, and on two of these three brands the cable-and-reel package is somewhere between 61% and 132% of it.
One important qualification, carried forward from our August 6 comparison and re-checked today. QYSEA's consumer and professional vehicles are rated to 100 m depth, and the 200 m and 300 m spools buy horizontal working range, not depth. Blue Robotics' 300 m tether goes on a vehicle actually rated to 300 m. So the two most expensive tethers in the table are not doing the same job, and the $2,330.00 Blue Robotics spool is the only one here matched to a vehicle that can use every metre of it as depth.
The cheapest way to buy depth is at order time
A small finding with a large practical consequence. Chasing's M2 S is configurable: 100 m, no arm, is $2,699.00; 200 m, no arm, is $2,999.00. Upgrading the tether at purchase costs $300. The same extra 100 m bought later as a standalone 200 m tether costs $399.00, and you end up with two cables instead of one. Decide your working range before you order.
Catalog hygiene, briefly
Two things a buyer should know about reading these listings. QYSEA's 300 m spool comes in two case options — carton at $1,850.00 and industrial at $2,300.00 — meaning the case costs $450, more than the entire 100 m spool at $429.00. And on the dealer side, Chasing's "300 Meter Buoyancy Tether" listing is duplicated, with the 400 m variant appearing at $799.00 on one copy and $599.00 on another; only the $799.00 figure is consistent with the brand's otherwise perfect $2.00/m line, so that is the one I used, and the $599.00 copy is a stale duplicate rather than a bargain. This is the same duplicate-listing pattern we documented in pipe inspection crawler catalogs.
How I would choose
- Buying on price per metre? Chasing, without argument. $2.00/m flat is roughly half QYSEA and a quarter of Blue Robotics Standard, and it is the only curve with no surprises in it.
- Buying real depth? Blue Robotics. It is the most expensive cable here by a wide margin, but it is the only 300 m tether in this comparison sold against a 300 m-rated vehicle, and it is the only brand that publishes the bare cable price so you can check its work.
- Buying a QYSEA? Buy the 200 m spool if you need range at all. It is the cheapest point on QYSEA's own curve at $3.40/m, and the step to 300 m costs $11.71 per additional metre.
- Buying the reel separately? Only Chasing and Blue Robotics let you, and the gap between them ($400 implied vs $920) is large enough to be a real line item on a small programme.
Sources and limitations. QYSEA store (store.qysea.com) product feed and cart endpoint, Blue Robotics Fathom ROV Tether and Fathom Spool product pages, and UrbanDrones product feed for Chasing — all read 10 August 2026. All prices are USD and were add-to-cart at time of reading. Two of the three brands are represented by a single storefront on a single day, and Chasing is represented by a dealer rather than the manufacturer, so its margin structure is not comparable to the two direct sellers. The BlueROV2 vehicle price is our 1 August 2026 record and was not re-read today. Per-metre figures are our arithmetic, not the vendors'; tether construction, breaking strength and buoyancy differ between brands and are not normalised here.
