Differences between a 12v and a 24v windlass

[Brann-]

Hello,
I'm wondering about the differences between a 12v and a 24v windlass.

Apart from the lower amp and the associated smaller wires, I don't really understand the figures I'm seeing on the manufacturer fact sheet.

If you look at the two last rows (same windlass in 12v and 24v), they are mostly equal, but:
- the working load is 90Amp vs 160Amp. The windlass is rated for 1500w, which doesn't match those figures (90x24=2160W and 160*12=1920W). Why those discrepancies ?
- The maximum pull is slightly higher for the 24v model (1350kg vs 1400kg), and the line speed is slightly higher as well (16m per minute instead of 14). Which is coherent with the higher Amp (see previous point), but not with the rated power.

Does anyone know the cause of the better performance of the 24v model ?

Regards,
Brann

[estarzinger]

electrical motor ratings are 'shaft power' - eg mechanical watts.

The difference between the motor ratings (mechanical watts) and your amps x volts (electrical watts) is the motor efficiency.

Your numbers are suggesting these particular 12vt motors are more efficient than their 24vt ones (or the 24vt ones are just rated more conservatively)

[a64pilot]

Likely maybe different motors?
I'd guess they buy what is widely available at a good price, not have motors custom wound

[noelex 77]

It is not unusual for high consumption 24v motors on devices like windlasses, bow thrusters and even autopilot drives to have better performance (higher thrust and/or lower power consumption) than their 12v counterparts, as is the case here.

This is one of the attractions of the higher voltage.

[estarzinger]

The motors rated numbers in this case suggest the 12vt motor is more efficient than the 24vt. However, I would guess that the 24vt motor rating is rather conservative, because really it should be over 75% efficiency (you can read all about motor efficiency here - https://www.energy.gov/sites/prod/fi...ndbook_web.pdf)

And yes, these are surely standard industrial motors, not special made for the windless.



When you look at the windless performance . . . . it does suggest the 24vt motor shaft rating is conservative because it is both putting out more (14% more) WL line speed and (a very little) more max pull than the 12vt. The windless efficiency (a bit higher efficiency line speed at wl, and a bit lower efficiency at max pull) suggests the 24 vt gearing is a bit more tuned to faster line speed.



Generally a 24vt dc motor will be smaller and lighter than a similar output 12vt motor - I dont see anywhere specs for size and weight for these motors.

[estarzinger]

Originally Posted by Brann-

My boat . . . . aluminium sailboat

is your hull floating or grounded?
just be sure you know and do whichever properly when you install new windless.
I personally prefer floating, but it is a bit tricky to install windless so it does not ground to deck - can be done but you need to be careful - especially with bolts that go thru deck.

[Brann-]

Originally Posted by estarzinger

is your hull floating or grounded?
just be sure you know and do whichever properly when you install new windless.
I personally prefer floating, but it is a bit tricky to install windless so it does not ground to deck - can be done but you need to be careful - especially with bolts that go thru deck.

I had no idea some people had grounded Aluminium hulls. My hull is fully insulated from the ground, as a matter of fact I have a leak detector to ensure that this is the case.
I plan on using tefgel on the bolts,nylon washers on both sides, and a nylon plate between the deck and the windlass, and on the whole path of the chain as well as I don't want it to touch the deck either (since it's metallic and in contact with the windlass).

Thank you for the word of advice though, it might certainly be useful to someone else at some point !
Cheers
Brann

[estarzinger]

Originally Posted by Brann-

I plan on using tefgel on the bolts,nylon washers on both sides, and a nylon plate between the deck and the windlass, and on the whole path of the chain as well as I don't want it to touch the deck either (since it's metallic and in contact with the windlass).

You might consider putting sleeves on the thru deck bolts. I used Phenolic tubes/sleeves. G10 is also good choice.

I had no idea some people had grounded Aluminium hulls.

Yea, I prefer your floating system, but there is a perfectly good fully grounded hull approach also.

..............

[camel2012]

One other thing to think about is boat DC voltage . I assume you have 12 V since you are even considering 12 V option. The final electrical system is simpler and more redundant if done w/ a 12 V windlass and thoughtful electrical/charging connection scheme you can get a backup bank for house bank. I did this with my bow thruster install. But as you have highlighted there are alway trade offs.

[JOHNMARDALL]

Most windlass manufacturers will offer a particular model in 12 volt, 24 volt and hydraulic, each having the same theoretical lifting/pulling power. The main difference between 12 volt and 24volt for the same nominal power output is that the higher the voltage, the lower the amperage. The higher the amperate,the more heat is generated in the wiring and windlass motor, resulting in lower efficiency and shorter run-time before the windlass motor overheats.
For that reason, if the boat has a genset that can be connected to a 24 volt charger, or has some other source of 24 volt charging, 24 volts is preferable to 12 volts for any DC motor device- less heat, longer run-time.

All the best

John Mardall
Vetus Maxwell Group