Current is the most common reason a drone does not get where its pilot wants it. In the worst case it drifts off, the tether snags, and the way back uses more battery than expected. With a little preparation and the right technique, that rarely happens.
What the manufacturers say
Current is given in knots. One knot is roughly 0.5 metres per second, about a leisurely walking pace.
| Model | Manufacturer's figure |
|---|---|
| FIFISH V-EVO | Current up to 2 knots, top speed 3 knots |
| FIFISH V6 Expert | Top speed 3 knots |
| Chasing M2 | Top speed 1.5 m/s (3 knots) |
| Chasing Dory | Top speed 1.5 knots |
| Chasing Gladius Mini S | no official figure |
Important: top speed is not the same as the current a drone can safely make headway against. Always plan with a clear margin. Incidentally, QYSEA expressly excludes damage caused by “strong currents or large waves” from its warranty.
The underrated opponent: the tether
In a current the water does not just pull on the drone, it pulls above all on the tether. The more cable is hanging in the water, the larger the surface the current can act on, and the harder the drone is pulled back. So the rules are:
- Pay out as little cable as possible. Let only as much into the water as you need right now.
- Guide the cable instead of letting it drift. Hold the tether in your hand and release length in a controlled way.
- Avoid obstacles. Buoys, anchor chains and water plants are real tether traps in a current.
Flying technique
- Start against the current. That way you have the current behind you on the way back and save battery.
- Fly deep. Near the bottom the current is often weaker than at the surface.
- Use hold functions. Depth and heading lock (on the Gladius Mini S according to retailer information) or AI Vision Lock (FIFISH V-EVO) take some load off you while filming.
- At sea, wait for slack water. Around the turn of the tide the current is at its weakest.
- Test first, then dive. Near the shore, fly a few metres against the current and watch how much power the drone needs.
Safety and battery
In a current the motors use much more power. The manufacturers' run-time figures refer to calm water. Chasing recommends not diving below 25 percent; in a current you should turn back even earlier. And never dive where ships are travelling: besides the danger to your drone, a cable in a shipping lane can put others at risk too.
In video
QYSEA shows how hold functions help in a current in these official videos:
Attach a small marker, such as a piece of coloured tape, to the cable every ten metres. That way you can see at any moment how much cable is in the water, and judge how hard the current is pulling right now.
You can find reactions and comments on this article in the Unterwasserpilot forum (in German, English posts welcome).
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