Every Capt. Crunch out there can take heart. Although there is no cure-all for the perils of docking, there is mechanical help. Bow thrusters, once found only on megayachts, are now common on small and midsize boats. But with this secret weapon come questions. Which bow thruster is right for your boat? Can you retrofit your boat with a thruster? And, most important, what's this going to cost? We talked with the world's largest supplier of bow thrusters, Vetus den Ouden (410/712-0740, www.vetus.com), and we met the crew from Florida Bow Thrusters (866/847-8783, www.floridabowthrusters.com), who make their living installing them. Here's what everyone had to say.