I took off on a calm beautiful day with my Phantom 2 V3+ close to the launch site of our RC scale model boat club. Probably flying at ~20' as I approached their launch area. There was a group of 3 or 4 boaters there and as I passed over them, my bird seemed to go into "Fail Safe" mode, totally out of my control, and landed in the middle of the model boat captains with my transmitter still on. No damage to any folks, boats or my Phantom but was a couple tense moments when this happened. Fortunately I am also a member of this model boat club. Unfortunately, they now have an issue to harass me about. Aargh! I know the RC systems used in the scale boats are also on the 2.4 gHz frequency. It appears their signals overrode my transmitter causing the Phantom to go into a "Fail Safe" mode landing. I have never had this happen before in hundreds of flights but this was at a lower altitude than any times before. If anybody has had this experience I would like to hear from you. I know the "Fail Safe" is triggered by no signal from a transmitter but didn't even think about the signal override issue.