Let us prepare. Let us weigh. Let Us Drone.

When you're a San Diego native, you eventually learn where good spots to fly are that aren't extremely crowded. If you were to Google “top beaches in San Diego”, you would indeed find some beautiful beaches, but they get very crowded with the rest of the tourists that Google “top beaches in San Diego”.

It was a breezy day, but I didn't have to work and I wasn't going to pass up the opportunity to take my Phantom out. After making the trek down a semi-hidden public access staircase in La Jolla, I launched the bird to get some good shots of the coastline. All was well until I started getting GPS errors, and my drone would switch to ATTI mode. I have practiced in ATTI mode before, but the difficulty level jumps way up when you have 10+ MPH winds and you're balancing on two rocks because you wanted to fly in a secluded spot that doesn't have nice sandy beaches. After a few unsuccessful retrieval attempts I was left with a dangerously low battery, so I ran up the staircase backward (allowing me to control the drifting aircraft), and managed to land the drone in the middle of the street as tourists looked on in bewilderment. This, my dear reader, was a precarious situation.

The million dollar question: should you turn VPS off?

Ah, one of the first questions you'll see if you look up information on flying a drone over water. One of the reasons it's commonly covered is because of what DJI has to say about flying over water in their manuals.

“The performance of your Vision System and Infrared Sensing System are affected by the surface being flown over.”

Further down it lists water and transparent surfaces as examples. In order to give an accurate answer as to whether you should turn the VPS off or not, we have to look at what height the VPS works and if you'll be flying within that height. The VPS on most DJI drones works up to 10m or 30ft.

The general consensus is that it's good practice to disable the VPS when flying under 30ft, as the drone's sensors are affected by the movement and transparency of the water. 

Living close to the beach means that I do about 50% of my flying over water. If I am flying above 30ft I don't touch the VPS and I've never had an issue with it. On the other hand, I have seen my drone do all sorts of drifting while flying low with the VPS on. I've even had my drone start to ride waves in before the GPS took over and repositioned the aircraft.

Every situation is different as there are numerous variables (ocean vs. lake, etc), so I'd recommend that you do a little experimenting in a controlled environment to see how your drone will behave. Here is a YouTube video of a guy demonstrating what his Mavic and Phantom do when hovering over a lake.

Lastly, it's important to note that some DJI drone models will respond differently than others when flying over water, so saying “yes, you absolutely must do this or that” wouldn't be fair, or wise of me.

Tips for flying over water

In some ways flying a drone over water is just like flying over land. In a way, it can be less risky as you can avoid other people or their property a bit easier, so the liability factor goes down. The obvious downside is that water landings are not good for your drone's health. There may be a lot of side-taking when it comes to the minutia of drone flying, but I really think water landings are something we can all come together on.

One big difference when flying over water is that your depth perception will be off. If you can, try to use objects in the area as reference points to give you an idea of just how close to the water you are.

We all love the altitude readings on the DJI GO apps, but they can't be trusted when you are flying over water, especially if you are flying low as the sensors cannot judge distances accurately.

There is a cliff in La Jolla that I love to launch from, but I don't dare get close to the water as I'll have negative altitude readings (your altitude is set from where you launched) and I can't trust my depth perception. I have a hard time estimating the altitude when I'm level with the drone, so it's nearly impossible to guess the distance to the water when I'm standing a couple hundred feet up on a cliff.

If you are flying at the beach, get a good idea of how high the waves are before you go out there and get up close and personal with them. Something that may be less obvious but very important to remember is that with the ocean comes sea spray. You retrieve your drone after flying for twenty minutes to find that your $1,000 aircraft is soaked with salt water. Yikes.

Guess what, it's generally windier over the ocean. When I was in the Coast Guard I didn't so much mind the warm southern California winds, but while stationed on the east coast I saw just how windy, and miserable it could be (especially during the winter). It's tempting to do a range test while at the beach as there is nothing but blue in front of you, but it's very important to find out which way the wind is going before doing so. If you fly out over the water with a 15 MPH offshore wind at your back and turnaround when your battery is at 50%, you'll never see that drone again. Check your weather app and do the ol' wet finger in the air test.

Yes, it's an FAA rule so you should be doing it anyway, but it's especially important to keep the drone within VLOS when flying over water as it can be incredibly difficult to see.

Have you ever looked out over a lake or ocean and been blinded by the reflection of the sun on the water? Well, like your eyeballs, the camera on your drone doesn't particularly like all that glare. Consider getting some neutral density (ND) filers to help with glare reduction. PolarPro is a reputable brand and I've had a great experience with their filters. You can find the ones I use for my P4A on Amazon here.

Seagulls! They've been a big enough problem for me while flying at the beach that I wrote an entire article on how to avoid and get away from them. Check that article out here.

When launching from a beach

There are certain precautions that should be taken when launching a drone from a beach. Sand comes close to rivaling salt water when it comes to destructiveness. The props would kick sand up every which way if you were to take off from the beach. Use your friend for a hand launch (safely), or pay a passerby to help you. Just kidding, I wouldn't recommend that second option, really. If you must launch the drone from the sandy beach, use a launch pad, or even a towel would be better than nothing.

Try not to launch close to the water. If your home point is recorded with you standing 5ft from crashing waves and something goes wrong where you need to RTH, I would personally want more than 5ft of cushion…unless you like to live life on the edge and/or have that much faith in GPS. I try to launch 50ft up on the sand and walk down to the water when I'm in the air.

Bodies of water tend to attract people. Whether it's a lake covered with boaters or a beach that has thousands of people lining its shores, you can expect the crowds if the temperature is right, so be cognizant of your surroundings. This is exactly why I scour the coastline for hidden spots, which, certainly have their downsides as illustrated in the opening paragraphs.

When launching from a boat

Launching from a water vessel comes with its own set of peculiarities. If you take off from a boat that is doing a lot of rocking, I'd recommend you have someone hold the drone for you. It's important that you immediately fly the drone up and away from you after it has been launched, as opposed to letting it hover a few feet away and risk the boat rolling into it. If possible, temporarily lower any rods, wires, or structures that the drone could strike once in the air. If it's windy, launch the drone off the leeward side (the side that's not facing into the wind) of the vessel.

Instead of having the home point set to your takeoff location, make sure it is set to your RC location. If there is a problem where the drone has to RTH but you have the home point set to your takeoff location and have since drifted or powered away from that takeoff spot, your drone is going to come home to an empty house. Periodically set the home point to your current location while you are flying.

If the water is rough, you're most likely going to have to have someone catch the drone when coming in for a landing as landing on a rocking boat is also not conducive to good drone health. Come in very slowly when someone is catching the drone for you. One of the riskiest parts of my job in the Coast Guard was transferring from one boat to another in rough seas because of the 6+ feet altitude changes that happened in a split second.

Trevor's Take

I'd say that some of my most cinematic shots were captured while flying over water. There is a certain amount of risk that comes with it, but if prepared, the gain can be amazing. What's your experience with flying over water? Did you take measures that I didn't mention or have some other tips for us? Comment below!