Hydrovane vs Monitor: Choosing a Wind Vane for Shorthanded Passages
Auxiliary rudder or servo-pendulum? The mechanical difference drives every other tradeoff.
If you're planning a shorthanded ocean passage, a wind vane self-steering unit is one of the least exciting and most important pieces of gear you can fit. It steers without electrical power, it doesn't care about heel angle, and it never fatigues. The two systems most cruising sailors actually choose between are the Hydrovane and the Monitor, and the choice is genuinely a tradeoff — not a "one is better" situation.
How they're different mechanically
The Hydrovane is an auxiliary-rudder system. It hangs off the transom on a dedicated mounting frame, and when the vane senses a wind shift, it turns its own little rudder, which steers the boat as if you'd added a second tiller. Your main rudder stays amidships and is used as trim. The Hydrovane is, in effect, a second steering system bolted to the back of your boat.
The Monitor (and its cousins, the Aries and the Sailomat) is a servo-pendulum system. The vane turns a paddle that hangs in the water; the water flow on the moving paddle generates force, and that force is transmitted via lines to your existing wheel or tiller. It steers the boat by pulling on your main rudder, not by adding a second one.
That mechanical difference is the whole story. Everything else flows from it.
What this means in practice
The Hydrovane keeps steering when your main rudder fails. That's not a theoretical advantage — it's the reason a lot of round-the-world cruisers fit them. If you snap a steering cable, jam a quadrant, or shear off the lower bearing on your main rudder, the Hydrovane keeps the boat tracking. You can finish your passage. There's a thread on the Cruisers Forum from 2023 of a Westsail 32 that lost its rudder bearing 800 miles east of Bermuda and Hydrovaned the rest of the way to the Azores.
The Monitor doesn't help you with rudder failure. If your main rudder's gone, the Monitor just dangles. But the Monitor has two advantages the Hydrovane doesn't: it's lighter (about 18 kg vs 32 kg installed) and it generally steers harder in light air, because the servo paddle multiplies force.
The Hydrovane gives up some light-air performance because its little rudder is small. Below about 8 knots of true wind, on a downwind run with a following sea, the Hydrovane will struggle to hold a heading. The Monitor, set up properly, will hold to about 6 knots before giving up. That 2-knot difference matters more on Pacific crossings than on Atlantic crossings.
Setup time and learning curve
Both systems take about a season to learn. You'll spend the first 200 miles tweaking the line tension on the Monitor and the counterweight on the Hydrovane vane. Both systems care about boat balance — if your sails aren't trimmed for slight weather helm, neither will steer well. The Monitor is more forgiving of poor trim because it has more authority on the main rudder; the Hydrovane is more forgiving of bad weather because it doesn't care about heel.
The most common Hydrovane setup mistake is mounting it too high. The mounting frame should put the auxiliary rudder fully immersed at all loaded waterline angles. If your boat trims down by the stern when fully provisioned, account for that. If the rudder ventilates in chop, you lose steering authority.
The most common Monitor mistake is line tension. Too tight, and the system fights itself in light air; too loose, and it overshoots in puffs. Run the lines through low-friction blocks (Antal, Ronstan, or Harken — the originals from Scanmar are functional but draggy), and adjust on a calm-day shakedown.
Cost and the actual decision
Hydrovane lists at about €5,800 for a complete unit; Monitor is around €4,200. Installation on either is a 2-day job for someone who's done it before, longer if you need a custom transom bracket.
The decision rule that works for most cruisers: if you're sailing a heavy displacement boat (Westsail, Cape George, Hallberg-Rassy 42+, Tayana 37) and you're going far, the Hydrovane is the right choice. If you're sailing a moderate-displacement boat that needs help in light air (Beneteau 40-46, Hanse 41-50, Catalina 42), the Monitor will steer better more of the time.
Either system is a better autopilot than your autopilot, in the conditions where they work. They don't replace electronic autopilots — they complement them. The autopilot steers when you're motoring or in fluky air; the vane steers when you're sailing offshore in steady wind.
