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Old 29-08-2018, 17:36   #1
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Electrical drain of a HPU

Hello. I have a 50' boat. I got surgery bla bla bla make long story short bla bla bla and now I want to get rid of all my normal stuff and install electric or hydraulic winches and electric or hydraulic furling systems. I dont know a lot about hydraulic but what I know that hydraulic systems also need a sort of power supply (electricity) to operate. In shop the worker said to me that electrical winches and motors in furling deviced can drain 60amps from the betteries. But how much energy requires a hydraulic power pomp/system. Someone told me that HPU can drain much more and someone else told me that isnt true. Can somebody help me.

I think how much energy drain a electrical winch in 1h of sailing and how much energy require a HPU to push the oil threw the pump and actuators/winches etc.
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Old 29-08-2018, 17:59   #2
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Re: Electrical drain of a HPU

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Hello. I have a 50' boat. I got surgery bla bla bla make long story short bla bla bla and now I want to get rid of all my normal stuff and install electric or hydraulic winches and electric or hydraulic furling systems. I dont know a lot about hydraulic but what I know that hydraulic systems also need a sort of power supply (electricity) to operate. In shop the worker said to me that electrical winches and motors in furling deviced can drain 60amps from the betteries. But how much energy requires a hydraulic power pomp/system. Someone told me that HPU can drain much more and someone else told me that isnt true. Can somebody help me.

I think how much energy drain a electrical winch in 1h of sailing and how much energy require a HPU to push the oil threw the pump and actuators/winches etc.
An electric winch draws a lot of amps when it is running, that is true.

But realistically, how many minutes does it run in an hour of sailing? We have electric winches on our boat, and they don't even figure in our energy budget. If they run a total of 15 minutes a day, that means we did a lot of tacking. Of course, we are ocean cruisers... so a lot of tacks in a day for us is like... three.

Hydraulics are always going to be less efficient than a direct coupled electric motor. They have other advantages but until you get to REALLY big boats, electric is the way to go.
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Old 29-08-2018, 18:05   #3
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Re: Electrical drain of a HPU

I've gotten older, had surgeries, and decided a smaller boat was smarter. I don't need a big boat anymore, not if it's just more work. Poer everything sounds good... right up until it breaks and you have to go old school.


Just a thought.


Otherwise, yeah, hydraulic is going to draw a little more and have troubles of it's own.


The route cause here was a hydraulic failure, compounded by a crew that could not manage the big boat without power.
https://www.maritimenz.govt.nz/comme...eport-2016.pdf
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Old 29-08-2018, 18:13   #4
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Re: Electrical drain of a HPU

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.......They have other advantages but until you get to REALLY big boats, electric is the way to go.

So electric on 50' Catamaran are better? So if I want hydraulic then I must buy a 70' boat. Why on for example 70'boat hydraulic are better. The force increases or what?
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Old 29-08-2018, 19:57   #5
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Re: Electrical drain of a HPU

Engineering wise the problem with electric is that electric motors run fast with low torque. Yes you can gear them down but you're starting with high RPMs, especially with DC motors, and several choices of speed/torque curves that are difficult to work around. Typical winch motors are DC shunt wound and the problem is that the starting/stall torque is excessive and will break things. They also give off heat and are inherently difficult to seal completely, and are big and heavy.


Hydraulics, at the winch end of things, you have a lower speed motor that has relatively forgiving startup properties, is easy to seal, is self cooling (at the winch), and will stop without damage when overloaded. And they are small and light compared to electric. There's a catch. You have to have an HPU to run them, and another set of troubleshooting skills, parts, and tools.


If you have an HPU that just runs when a winch is turning it will maybe use 50% more power than an electric winch. I'm guessing. But not a big difference because they run so little in terms of minutes/hours a day.


There is a certain minimum size of the HPU, lines, valves, controls, etc., which means that they only make sense on larger boats. On a big motor trawler or whatever they will tend to be engine driven.


I used to farm and worked on more hydraulic gear than you can imagine. Not a big deal but another basket full of adapters, gauges, hoses, etc. The hoses and seals all fail progressively over the course of years. You can either spend the $$ to replace them early or have them blow at the worst possible time. I did some of each.
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Old 29-08-2018, 20:24   #6
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Re: Electrical drain of a HPU

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Not a big deal but another basket full of adapters, gauges, hoses, etc. The hoses and seals all fail progressively over the course of years..

So its sounds to me that electrical would be better. Maybe on economical stand point no but when something breaks up on electrical u replace the full furling device with new one and u can sail. When hydraulic system doesnt work u must found the reason and then replace the broken part. Specially if U are just like me and dont have a clue what may be wrong.
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Old 30-08-2018, 09:44   #7
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Re: Electrical drain of a HPU

Or.... or... u can buy a half inch electric cordless winch handle. Think like a right angle drill with the correct key in the chuck that mates with wench opening. Some older guys use them to get the main sails up. Especially on big arse roached mainsails.

U don’t mention what size boat u r thinking about converting.
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Old 30-08-2018, 17:06   #8
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Re: Electrical drain of a HPU

Jeez, why limit yourself to hydraulic systems or electric ones?
Why does everyone forget that STEAM can drive it all just as well. I guess you could call steam "the hydraulic fluid that never stains your floor".

Your local construction equipment (fork lift, high lift, etc.) rental store can give you a quick hands-on explanation of hydraulic systems. And all the fun stuff you get to use to maintain them.
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Old 30-08-2018, 17:13   #9
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Re: Electrical drain of a HPU

The more components you drive, the more logical hydraulic is over electric.
Just one winch, well electric of course.
But two or three furlers, the windlass, and at least two winches?
Id rather go hydraulic.
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Old 30-08-2018, 19:23   #10
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Re: Electrical drain of a HPU

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Why does everyone forget that STEAM can drive it all just as well.

Steam is like Windows 95. It's from an era when things were so hard to get right that it was really easy to make a living as an engineer.
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Old 31-08-2018, 12:59   #11
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Re: Electrical drain of a HPU

Jammer-
You do realize that capital warships, most especially the US nuclear submarines, RUN ON STEAM, don't you?
It ain't dead yet.

But powering up boat systems requires a degree of reliability and redundancy that suggest professional installation and maintenance. Or, a seagoing AAA membership.(G)
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Old 31-08-2018, 15:15   #12
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Re: Electrical drain of a HPU

Yeah, and they have engineers for that.
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