T&T: Autopilot pumps

[Milt Baker]

Good autopilot response on a slow, tubby trawler like my Nordhavn 47 is a tough proposition because there are so any components to that which are so easy to overlook.  The best autopilot installations are those which address the boat and its steering characteristics from the get-go, and few electronics sellers have much experience there --especially with motoryachts operating at true trawler speeds.

The truth is that most autopilots are sold to go either on fast yachts where rapid hard-over-to-hard-over response isn't necessary or on sailing yachts where low power draw is important and where big rudders also mean that rapid response is not required.  If it's trimmed properly, a twin engine Sea Ray 40 going downwind and down sea at 20 knots is easy for even a mediocre autopilot to steer.  A well balanced sailing yacht with a big spade rudder is, likewise, a very resposive creature and even small tweak of the rudder produces quick response.  A Nordhavn 47 like mine going downwind and down sea with a full head of steam at 7 knots is altogether different--it needs some REAL RUDDER to turn, and often some counterudder to stop the turn.  FAST! FASTER! 

At Med Bound 2007's opening seminars for participants, Randy Morris, southeastern sales manager for Simrad (now owned by Navico), spoke to us about making our autopilots work better. Randy got a lot of flack from the assembled Nordhavn skippers because in many cases their Simrad autopilots didn't appear to be doing the job.  By the end of his session, many skippers came to realize that they (or their installers) had not done the setup routine properly, that the setup parameters were wrong, and that their hard-over-to-hard-over response times were often only has as fast as they ought to be.  One persueded Randy to go to offshore with him for a sea trial on a perfectly miserable day and came back a convert: his boat would finally steer in a straight line! 

I am with Dave on this one: a very fast hard-over-to-hard-over time is an important component of good downwind/downsea autopilot performance, and you're not likely to get that with the wimpy pumps offered by most autopilot manufacturers. But before you go there, be sure your setup parameters are correct that the setup routine has been done properly.

Aboard Bluewater each of our two Simrad AP26 autopilots (AC20 computers) is set up to drive its own AccuSteer HPU-100 constant-running, non-reversing 1 GPM pump.  These are robust pumps typically used on commercial vessels.  Except for an occasional nuisance leak where the steering fluid enters and exits the pumps, these hardworking pumps have been completely trouble-free, and Bluewater steers in a very straight line almost no matter what the weather.  Our hard-over-to-hard-over response time is five seconds and that surely plays an important role.

Before you rush our and spend a lot of boat units on new autopilot components, be sure the system you have is set up properly; if you don't have the skills to do it yourself, by all means find someone who does.  Don't be seduced into believing that any ol' guy your dealer sends is capable of doing the job--do your due diligence and find the right technician, one who truly understands how to set up the autopilot system you have.  And remember that a sea trial is an essential part of the equation.

IF you have the right tech doing the setup and IF your boat is still not steering correctly, your tech can suggest the next step.  That may well be a bigger, more powerful autopilot pump.  But there may be more to it than that.

Usual caveats: no financial interest in any company mentioned here, just a very satisfied user of Simrad autopilots and Accusteer pumps.

--Milt Baker, Nordhavn 47 Bluewater, Puerto Colom, Mallorca