Which is more reliable: electric or hydraulic?

[yotphix]

Learning curve I am employed as an engineer on a 110' motor luxury yacht. My experience on this yacht which has two electric capstans, a hydraulic bow thruster, windlass, steering and stabilizers, is that both are very reliable. The only weak link is the foot switch on the electric capstans which requires regular cleaning and would require more if it were on a foredeck that was occasionally awash. We have virtually unlimited power for either system.

Personally, I would rather have hydraulic lines, which rarely fail catastrophically running through my boat then heavy gauge wire running DC motors which will draw until they work thus, getting hot and possibly blowing fuses at very inopportune moments. If I was doing what you are thinking I would probably have an engine driven pump for the heavy thruster and windlass loads, parralled with a backup electric pump that could handle winch and furler loads undersail.

Main reason, neptune doesn't seem to like electric motors too much.(spent the day in the bilge today fighting the AC circulating pump for the chilled water loop on our megayacht! Saltwater corrosion from a small leak in the raw water circuit!)

[coot]

Originally Posted by learningcurve

You need to escape an exploding volcano on an island real fast and go offshore. You have two boats to choose one fitted with electric gear, one with hydraulic gear. Otherwise, the boats are identical. Which would you pick and why?

This is a very different question from your original post, but it is one I can answer:

Which: Electric - no contest, no time needed to think about it.

Why: Something might break. I would rather work on electrics than plumbing any day.

Beyond reliability, I have this non-answer to your original question: There are other questions: What sort of regular maintenance do the different options require, and how do you feel about performing that maintenance? How difficult is it to install? How hard is it to get replacement parts? Is the incremental improvement in reliability worth the extra installation cost and maintenance work?

herd cats!

Meow!

[hellosailor]

Sean-
Isn't NASA the place where precise focus on abstract questions, like "What's the best way to seal a booster rocket?" produced the answer "O-rings!".

Except, someone forgot to ask about the environment and the payload, so one cold day they blew up a rocket full of astronauts?

Focus is one thing, tunnel vision is another.

[Joli]

Learning Curve.

We use Electric for everything. Some of the gear (Windlass) is 20 years old. We have no problems with it. I recently took the unit apart and cleaned everything and installed new seals. No problems but we do carry spare brushes, seals, wildcat, and a motor. Our winches are 98 3 speed Harkens Electrics and have given us no problems. Our bow thruster is a 24 volt Vetus and again has given us no problems. The boat goes in and out of salt water. We currently have it in the Great Lakes. So electric has proven to be very durable for us. Hydraulic, we do not have so cannot comment on its durability.

Hope this helps.

[ssullivan]

Originally Posted by hellosailor

Sean-
Isn't NASA the place where precise focus on abstract questions, like "What's the best way to seal a booster rocket?" produced the answer "O-rings!".

Except, someone forgot to ask about the environment and the payload, so one cold day they blew up a rocket full of astronauts?

Focus is one thing, tunnel vision is another.

Eh... I wouldn't know. I worked on the SMEX missions, specifically FAST, CLUSTER and ACE. We didn't have fancy sub-contractors. We were charged with getting solar terrestrial physics done on a buget... so no "o ring" type decisions.

[sundown]

My background is commercial fishing. In my opinion Hydralics wins out over electrical hands down. Properly installed hydralics can withstand a heck of a lot more weather exposure than wire, is easier to trouble shoot and can provide a lot more torque. In our industry when serious power is needed it invariably comes with hoses attached. I just can't imagine sucking traps out of 500 fathoms or a full trawl with anything else. Another consideration is a chafed hydralic line either leaks or bursts - a chafed electrical line kills your battery or starts a fire.
Are hydralics practical on a sailboat - I really don't know. If I could figure out away to get a pump onto my auxillary engine I would have a hydralic anchor winch in a heart beat, but that may be my prejudice and comfort level.

[never monday]

Learningcurve,
Either system will do the job you've requested. The decision is going to be price in the initial upfit and the subsequent refit in 10-15 years.
I would take either, with a slight advantage to elecrtic. Why? it's easier to recrip a cable end at sea, then recrimp a hose end, refill and bleed the hydraulic system, clean up the mess from the failure...etc

[rleslie]

Learningcurve
I can't find where you indicate what will be driving the hydraulics. In most boat applications won't you be relying on 12V motors to drive the hydraulic systems? We have hydraulic steering and the auto pilot uses a 12v motor.

[delmarrey]

Originally Posted by never monday

I would take either, with a slight advantage to elecrtic. Why? it's easier to recrip a cable end at sea, then recrimp a hose end, refill and bleed the hydraulic system, clean up the mess from the failure...etc

And that's the difference between the two. Hyd. lines just don't brake, corrode quickly, or leak if installed properly. What ever would cause hyd. hose damage, would distroy any electrial wiring.

Even if a hyd. system look real bad on the out side, it's still funtional on the inside. It's just the teardown that gets nasty.

One can buy hose end fittings that can be installed in the feild with two open end wrenches. If a hose get damaged enough to leak, cut and splice it. Carring a set of hose to hose couplers is the same as a wire connector. And carry some of the largest size hose that is used. There's very little chance of an END fitting going bad.

I would think fishing boats would be the only concern for me since the system is exposed to the elements.

BTW steering systems are normally hard plumbed up until the last 1-2 feet. Positive displacement is important for steering. Hoses expand and contract with pressures.

And hyd. systems bleed themselves, once established, by being used. With exception to steering and stay cylinders......................................._/)

[Starbuck]

LC,

Part of the learning curve around here is accepting the fact that very few will have the mental discipline to constrain themselves to respond strictly to the hypothetical: they will assume you're in the middle of a project and will begin to immediately offer advice based on whatever experience they have and/or opinions they have to pass around, sources sometimes unknown.

That being said, there are always practical considerations pertaining to the actual individual application that will influence the validity of any opinion, e.g., boat size & intended use. Most of the responses here are either offering opinion based on specific experiences they've had, or trying to find some specific situation to apply their knowledge/opinion to, even if some are creating scenarios that you didn't specify in your original question.

Don't despair. I've noticed that after the initial knowledge dump, continued redirections by the original poster often start getting him what he's after.

[coot]

Originally Posted by sundown

Are hydralics practical on a sailboat - I really don't know. If I could figure out away to get a pump onto my auxillary engine I would have a hydralic anchor winch in a heart beat, but that may be my prejudice and comfort level.

Yes, but don't underestimate the importance of that comfort level!

In my comments on the volcano example, I say I would rather have electric any day. That directly reflects my knowledge and capabilities. I take it from your comments that you really know hydraulics well, and have no questions about your ability to maintain and use them. With your knowledge and capabilities, the boat with hydraulics is the better choice for you. We each prefer a different system, but we are both right.

( This works out for the best -- there is a boat for each of us, and together we can get a lot more people off the island than if we both wanted the same boat. )

The second issue of Pacific Yachting - Boating in the Pacific Northwest : : Launching Spring 2007! has a technical article by a fellow who installed hydraulics on his 44 foot sailboat.

FYI

[Lancerbye]

Love hydraulics and have used many applications of both. Even retrofitted a 24Ft. Reinell with a flying bridge with two station hydralics once. Had the pumps left over from a commercial fishing boat. The rack type with the single push-pull cable failed so I converted it. Worked great and still felt the feed back. My present boat has electric windlass, electric bow thruster, electric winch for the sails, hydralic steering with electric 12v auto pilot pump. Good maintenence keeps everything running like it should. I don't like surprises. They all have a place and will give many years of service with proper maintenance.

[cat man do]

I was originaly going to use an oversize electric anchor winch, but am leaning toward's hydraulic for reliability and strength.

A mate in Vanuatu on a 47 tonne boat has 4 Ni-Van crew on board.

At $50/week much cheaper than any anchor winch.

Dave.