[C320-list] Linear autohelm

[Graeme Clark]

Stephen

As with everything in life we need to balance risk and consequence against the cost and practicality of protecting against it

Perhaps sailing is not for you unless you have unlimited funds to throw at it?

I’m happy with my linear drive as a reasonable additional cost with minimum complexity to give performance that far exceeds that of a wheel pilot. 



Plenty of sailors have boats with no autopilot at all

Regards

Graeme
#366, 1996


Sent from my phone. Excuse typos! 

> On 22 Aug 2022, at 09:21, Stephen Cox <scox at timmin.com> wrote:
> 
> 
>>   Pulse width modulation sends many short pulses of electricity each
>>   second.  A bigger motor (such as the Type 2) will draw more
>>   electricity, but will draw shorter pulses.  Thus, the ACU will be
>>   working harder when it is sending electricity, but will be 
>> resting more
>>   often.  Every second, the ACU should be sending about the 
>> same amount
>>   of electricity whether it is powering a Type 1 or a Type 2.  The
>>   question is whether the ACU-200 can handle the bigger but shorter
>>   pulses.
>> 
> 
> The Type 2 motor won't draw shorter pulses, the pulse width would be determined solely by the ACU-200 which would have no real way
> of knowing what it is what driving.  The Type 2 motor will enherently draw more power than the type 1 by virtue of it's design.
> Hence it's minimum rated draw is 48w not some lower figure.
> 
> If you look at https://raymarine.custhelp.com/app/answers/detail/a_id/3997/~/acu-specifications-%26-drive-compatibility you will see
> the ACU-400 has twice the capability of the ACU-200 for both continuous and transient current supply.  In the same table the current
> limits by drive type shows the Type 1 Linear Drive has a maximum draw of 10a and the Type 2 Linear Drive has a maximum draw of 30a.
> The type 2 Drive will on occasions demand up to 30a from a controller that maxes out at 15a from the table.  
> 
> You may get away with it in light conditions for a while but come the day when conditions have turned foul and you need the
> autopilot it will most likely fail just when you need it.  Stating that you will hand steer in heavier weather does not allow for
> when you break an arm or leg, have a heart attack, get knocked out by the boom or some other disaster and your spouse, son,
> daughter, inexperienced crew who is not coping with your need for attention or the serious weather will turn that autopilot on
> hoping it will just do the job.
> 
> Best of luck.  I have no further comment to make,
> 
> 
> Stephen Cox
> Tegwen #1141
>