Hydraulics

[Caleb_Grey]

Useful on a sailboat or just another complicated system?
Bowthruster, windlass, steering, all of the above? seems out of fasion, but energy efficient.

[tkeithlu]

Steering: Hydraulic is common,and a good way to transfer wheel motion to the rudder without having to worry about routing of cables. Also works well with an autopilot. On sailboats cables are often preferred, I suspect because the wheel usually is close to the rudder. Steering hydraulics are usually manual, the pump being driven by the wheel.

Bow thruster: First, do you want one at all? If you do, then electricity is the more common solution, because this use requires an active pump, which in turn means either running the engine or an electric pump, in which case why do it?

Windlass: You want one, but the same comments apply.

In all, I'd say that active hydraulic systems belong on power boats above some certain size. I've toyed with the idea, including for steering (no wheel), but doubt that I will pursue it.

[rslifkin]

For steering, many sailors dislike hydraulic steering because it's typically check valved. The setup on my powerboat (manual hydraulic) is, so when you let go of the wheel, the rudders stay where you left them. You can feel rudder load as increased steering effort, but it's much less feel than a typical cable steered sailboat as the rudder can't back-drive the wheel. Hydraulic steering does give you lots of good autopilot options, however, as the drive is just a hydraulic pump (and you can use a bigger one to get faster rudder movement). On bigger boats it's common to steer with a jog lever and the autopilot pump and have the manual hydraulic wheel only as a backup.

For powering stuff like a bowthruster or windlass, the boat in question and what other systems already exist (and where everything is placed on the boat) will help determine what's most practical. Hydraulic stuff is definitely out there, but it's become more practical to power big stuff electrically over time (as higher voltage battery banks have become more common, etc.) so there's typically less reason to go hydraulic unless on a rather large boat.

[Lepke]

As a former commercial fisherman and farmer, hydraulics go decades without problems and very little maintenance. When used on a thruster, the hydraulic pressure is much higher on the oil side than the sea water side. So seal failure doesn't allow sea water into the motor and ruin it. And the leak may be noticeable before complete failure by a sheen.

[Pitchondesign]

Hydraulics require a hydraulic pump to be operating as you need hydraulic pressure. When the pump is off, none of the Hydraulic systems operate. No problem on a power boat. On a sailboat, not so. So, for a windlass, probably not a problem as the engine is most likely running. Same with a bow thruster. For winches on a sailboat, its too cumbersome. Hydraulic steering typically is its own system and doesn't require a separate pump. The wheel is effectively the "pump".

Hydraulics win when there is a requirement for a lot of power in a small space as hydraulic motors are very small compared to eleectric motors. A big electric motor powering a pump can be in one part of the boat, and a physically small hydraulic motor can be in another part of the boat, with all the power of that electric motor.

Virtually all very large boats use some form of hydraulics. Could you make it work on a smaller cruising boat? Yes, but why bother.