On my boat, pistol-style plastic washdown nozzles don't last very long. The fittings crack or the handles break or they begin to leak profusely.
Rather than buying a replacement (a "marine" nozzle can cost as much as $25) every few months, I use an Orbit sweeper nozzle with shut-off valve (about $7.00 from hardware or home stores; try homedepot.com).
The shut-off is quick and easy to use, and the pressure nozzle sweeps away grime. Rubberized collars prevent chips to the gelcoat. Best of all, this system is far more durable than the plastic pistol nozzles you get at the marine accessory store.