Before you buy new electronics: when a chartplotter app is enough, and when AIS or radar earns its keep

It's easy to talk yourself into a full electronics refit before you've even untied. Here's a practical way to spend on gear only where it actually helps.

Start with what a phone or tablet already does. A modern chartplotter app with downloaded offline charts handles position, routes, and depth contours fine for coastal day-sailing and lakes. Pair it with a cheap waterproof case and a backup battery, and for a tight budget that setup can carry you through a whole season.

Where a dedicated plug-in box starts to pull its weight:

• AIS — if you share water with ships, tugs, or ferries, a receive-only AIS dongle feeding your app is cheap and shows you the big traffic by name and heading. A transponder (you show up to them) costs more but is worth it offshore or in fog. • Radar — pricier and a bigger install, but the one thing that sees a rain squall, an unlit skiff, or a buoy at 2am. If you run at night or in fog, it's hard to call it a luxury. • A real depth/fishfinder transducer — apps guess depth from charts; they don't read the actual bottom under you.

Rule of thumb: buy the sensor that answers a question your phone can't. Skip the rest until the boat tells you you need it.

What's the one piece of gear you'd actually buy again, and what gathered dust?