LYNN – Despite record-high fuel prices, July 4 ranks as the busiest boating day of the year and thousands of North Shore boat owners are expected to leave the dock for picnic anchorages, fireworks displays and other holiday adventures.Fireworks displays in Lynn, Nahant, Boston and other North Shore communities can be easily viewed from sea, which means thousands of vessels will be plying the same waters.Since boat owners are likely to take along guests, it’s imperative to bring enough lifejackets for everyone, including children, says BoatU.S. spokesman Scott Croft, noting that many marinas provide use of lifejackets free of charge.Getting home in the dark comes with its own set of complications. Boaters are advised to take their time getting home. Short-cuts are not recommended.The most-reported type of boating accident is a collision with another vessel so it’s a good idea to keep your speed down, post an extra lookout, and ensure all your navigation lights are in working order.