T&T: Autopilot

[Bucks2 at aol.com]

I was happily surprised with the autopilot on our new to us boat this year.  
It is a WH Autopilot, made on Bainbridge Island here in WA state. I couldn't  
believe it's ability to steer a course in following seas and quartering seas. 
It  was head and shoulders above any unit I've used in the last 28 years. 
 
Long story short.... I wanted a remote for the flybridge so I wrote an  email 
to the company. Their engineer calls me, twice, since I wasn't home the  
first time. He knows my model which is 20+ years old, and they made about 12 of  
my model, the AP3. He advises there will be no problem getting a remote.  "Just 
confirm there is a port with a green dot on the brain box and I'll send it  
out. If there isn't a green dot port, let me know and you can bring the box in  
(since I live within 30 miles) and I'll put the port in for you while you 
wait."  Hmmm.... that sounds like good customer service, a rare commodity 
nowdays. 
 
Then we start talking about how well the unit works for being as old as it  
is. I know some of you have some great old Wood Freeman's and some good 
Benmars,  but you Cetek owners might be interested. (yes, my last Cetek unit was, is  
and always will be a piece of junk) The engineer was explaining how  their 
units are set to start correcting well before the industry standard of 10  
degrees. And that their pumps and rams are set to be faster than others. I've  
never timed hard to hard on mine but it is noticeably faster than others. 
 
If you are in the market for a well built, well supported auto pilot,  give 
WH Autopilots a call.  Apparently they are well known to the  blue water 
cruising crowd.   
 
Ken Buck
40' Puget Trawler
No financial interest, just a happy customer
 
Subject: Re: T&T: Autopilot Pumps
To:  <trawlers-and-trawlering at lists.samurai.com>
Message-ID:  <003c01c7e59f$c3148090$1801a8c0 at Dell>
Content-Type: text/plain;  charset="us-ascii"

<Mike wrote: There is a practical limit to the size  of motor that can be
reversed. It is around 1/4 hp, I  suspect.>

Power consumption and the sailboat crowd with their minimal  power
requirements seem to drive the major recreational autopilot  market
manufactures. Seldom do we see robust commercial rudder drives on  our
trawlers.

Swan Song is not a minimalist trawler and as such we  have the power to use
to run a commercial sized rudder control system. We  nearly went with a
constant running dual DC pumps with dual direction  manifold system which
unfortunately don't have the MTBF of the reversing  motors especially in
brush life. They also add complexity and component count  to the system which
decreases its reliability, IMHO. Our reversing DC motors  draw 25 amps at a
nominal 24 volts each. This is about 600 watts or about 3/4  horsepower if
they were 100% efficient. We have two of them. They are rated  180 cu/in per
min. They aren't cheap...~ Over $1500 each but have performed  without issue.

Our rams are 15.5 cu in each, full stroke (2 1/2" X 11")  and we use about
75% of that stroke for +/- 40 degrees of rudder. and the  hard over hard over
time is 4 secs with both pumps working so we should have  23.25 cu in divided
by the two pumps divided by the time (4 sec) or 2.90 cu  in per sec. Rounding
that back up = ~174 cu in per minute. So it checks both  ways.......I think
;-)

I did know the ft-pounds of force but can't  seem to find that data right
now. My feeling at the time I designed it was  that the rudder itself is the
weak link not the quadrant nor the rams nor the  ram support structure nor
the pumps. Our pressure bypass is set at ~1200  lbs....perhaps a bit high
but.....

Simrad, Raymarine and a few other  manufactures I had contacted recommended
pumps in the order of 90 to 120 cu  in/min. They seem to consider hard over
hard over times of 8-12 seconds good.  This is 1/2 to 1/3 less than we have
now and which we are very, very  satisfied with.

I haven't found another boat with this response time nor  one that tracks
dead on under virtually any sea state. I have to chock it up  to rudder size,
the autopilot and the rudder response time.

As always  YMMV....

Dave & Nancy
Swan Song
Roughwater  58





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