It's not a big deal, but then again you don't go out to work with a radar just in case a wild bear jumps at you at the bus stop, because this basically does not happen. This project is either a hobby endeavour, a really misguided attempt at saving lives, or a brilliant way of making money on people's inability to look up statistics and do the maths.

Several problems here. One is that the sharks can still see the fishy and yummy silhouette of the surfboard. Two, sharks could investigate electric pulses so any electronic device in a surf board could cause problems (unless maybe designed as deflector). They use electroreceptors to find hidden preys.

Other problem is that fish schools or other surfers could trigger the alarm leading to a very stressing day of beach for everybody.

But is a interesting problem and anything that can do that people do not resemble a seal is good for people and also for sharks. Even if is a real shark, and not a dolphin or an unprobable tuna, you will have just seconds to prepare for the hit.

This must be the simpler solution compared to that though. Maybe if people stop dressing up like seals (big black wet suit) they won't look so tastey to the seal eaters.