“When conflicted between the two, always remember that water and electricity don’t mix. So if your trailer is carrying a boat, you probably don’t want an electric trailer system. As a matter of fact, there are only a handful of boat trailers carrying electric brakes (most of these are designed for marine applications).
On a related note, surge brakes are effective at 8,000 lbs maximum; 3,000 lbs is basically a recommendation from Sundling. Electric brakes also work, but you can save money with surge brakes, especially if the weight of the trailer doesn’t need a lot of braking force. Ask your local dealer like Champion Trailers for quality utility trailer kits, which may include brake units.”
http://blog.championtrailers.com/utility-trailer-parts-braking-surge-electrical-trailer-brakes/
Champion Trailers 