[C320-list] Linear autohelm

[Stephen Cox]

> 
>    On 8/20/2022 11:33 PM, Stephen Cox wrote:
> 
> >From the relevant Mechanical Linear Drive manual the Type 1 Linear 
> >Drive is rat
> ed at 18-36 W and the Type 2 Linear Drive is rated at 48-72w. 
>  Note the minimum of the Type 2 is greater than the maximum 
> of the Type 1.  What makes you think t he ACU-200 will 
> happily drive this without letting the magic smoke out that 
> powe rs all electronics?  Even assuming it manages for a 
> while what happens when you get into strong sea and wind 
> conditions?  The power consumption will go up and a gain, the 
> magic smoke will escape the ACU-200 and it will stop working.
> 
>    Comment:  Would be a problem if you were on a Cat 470.  
> But on a 320
>    you shouldn't be drawing much juice -- about the same as 
> if you had an
>    ACU-200 and Type 1.
> 

The load might be relatively light but the build of the Type 2 motor indicated by it's ratings is such that it appears to draw more
current with a light load than the Type 1.  A rating of 48-72w indicates to me that it will draw a minimum of 48w when operating.
That is 12w more than the Type 1 maximum or 33.3% more than the maximum rating.  Does the ACU-200 have that much safety margin?
What about when the Type 2 encounters conditions that make it draw it's full 72w or 100% more than the Type 1 can draw.  Does the
ACU-200 have the ability to handle double the expected maximum load?  Could be an expensive exercise if the ACU-200 burns out.

> 
>    Comment:  Where did you mount it on the transom?  Did you 
> have to do
>    some fiberglassing?
> 

I bolted a long thick stainless plate to the vertical part of the transom above the step, extending out into the locker by 2 1/2 to
3 inches.  This extension is angled so that the drive mounts with the appropriate angle to the tiller arm.  The plate spreads the
load into the transom over quite an area.  Sorry I don't have any pictures and the boat is a two hour each way drive to take any.

Stephen Cox
Tegwen 1141