Category Archives: Garmin GHP-10 Auto Pilot

Garmin® GHP-10™ Auto Pilot System

Sanctuary is fit with a Garmin® GHP-10™ Auto Pilot (AP).  I like it very much, and recommend the system highly.  Garmin® bought the design, the designers, and their company in about 2006/2007.  The predecessor company marketed their autopilot system as the “TR-1 Gladiator.”  The system became available as a Garmin® branded system in about 4Q08.

The components of Sanctuary’s GHP-10™ system are the “base core pack” (course computer, human interface display module, fluxgate compass/rate-of-turn gyro) and the 2.1L hydraulic pump option.  The OEM surface area of Monk rudders is somewhat undersized for the boat, and the GHP-10™ AP handles our Sanctuary very well.  In 4′ following seas and 3′ – 4′ quartering seas, it does far better than I can do manually, and much better than I had thought it could/would.  In “heading hold” mode, the AP holds the course heading very well, but the boat is affected by set and drift from wind and current.  If a GPS is driving the AP to a waypoint contained in a route, the AP handles set and drift effortlessly.  The system does tend to “wander” around the nominal route line with a cross-track error (XTE) of +/- 40 feet, or so, before it corrects.  This behavior settles down and becomes stable within a few minutes.  The control software has several built in steering patterns, which are interesting but not oft used.

The reason for our purchase decision is the “Shadow Drive”™ technology of the GHP-10™.  That device allows my admiral to be at the helm, and if she needs to avoid a crab pot or flotsam, all she does is steer normally.  The shadow drive senses the hydraulic flow from the helm pump, and disengages the autopilot.  One-and-a-half to two seconds after the helm stops calling, the AP takes over steering again.  She does not have to worry about disengaging the AP, or about manually manipulating any “buttons” of any kind.   She simply steers.

I installed the system myself, using the Gamin® Installation Instructions.  The installation of the system involves two very different types of tasks: 1) hydraulic system changes and 2) the mechanical and electrical fitup of the components.  The  hydraulic system aboard any individual boat will always vary somewhat from boat-to-boat and brand-to-brand, but the hydraulic fitup work can be done with basic plumbing tools available from Big Box Home Centers, automotive or hardware stores.


GHC-10 System Controller installed at the flybridge helm

Following is the project plan:

Installation Preparation
9/21/2009 confirm hydraulic layout plan for Capilano/Teleflex Model 250V helm pumps and Model 50 Uniflow Valve with Garmin tech support
Aft Lazarette
9/24/2009 Locate/prepare installation space
9/24/2009 install pump mounting platform
9/29/2009 measure/fabricate new hydraulic lines
9/29/2009 install new hydraulic lines, including Shadow Drive
9/30/2009 locate/install ECU
9/30/2009 locate/install CCU
10/1/2009 install signal lines from ECU to engine room and flybridge
Engine Room
10/2/2009 complete ECU/CCU signal wiring
10/7/2009 complete ECU/CCU power wiring
10/7/2009 connect tachometer signal lines
10/5/2009 design, procure materials, fabricate mount for GHC-10
10/6/2009 mount GHC-10 on flybridge
10/6/2009 complete signal wiring for GHC-10
10/6/2009 complete power wiring for GHC-10
Restore Hydraulic System and AP System Checkout
10/7/2009 re-fill/bleed hydraulic system
10/7/2009 run “Dockside Wizard”
10/8/2009 perform sea trial
Project Finalization
10/11/2009 dress and secure wiring and hoses against vibration and shock
apply corrosion blocker to all installed components (Bo-Shield or Corrosion-X)
12/02/09 re-check hydraulics for leaks, verify proper hydraulic fluid levels
1/26/2010 create Operations Manual documentation (update electrical diagram(s), switch descriptions, plumbing diagrams, operations description(s), Leaving Boat checklist, etc., as applicable).

Click this link for a downloadable Adobe .pdf file showing the design layout of Sanctuary’s steering system after installation of the Garmin® GHP-10™ auto pilot system: hydraulic_plumbing_layout.

Hydraulic hoses must be custom fabricated for the individual installation.  This is easy to accomplish in any metropolitan area where a hydraulic shop is available.  In smaller communities, many auto parts stores – NAPA, O’Reilly’s, others – make up hydraulic hoses.  The hydraulic hoses need to be USCG-certified for marine service.  Sanctuary’s installation required the use of 90º, type “JIC,” elbows.  (“JIC” is the hydraulics industry term for “flare” fittings).  Some USCG-approved hydraulic hose is extremely stiff, and does not have any twisting capability.  I had one hose of this type that required 90º JIC elbow fittings on both ends.  If you have this situation, I strongly recommend that you plan two round-trips to the hydraulic shop.  On the first trip, have the shop crimp one 90º elbow, but DO NOT crimp the fitting on the other end of the hose at that time.  Rather, bring the un-crimped hose back to the boat and dry fit it in place.  With the crimped end finger tight (not tool tight), slide the un-crimped fitting into the free end of the hose, and fit it in place in its final position, finger tight.  Adjust the length of the hose, if necessary, at this time.  Wrap painters tape around the un-crimped hose end, and use a permanent marker to place a “witness mark” on the hose and the adjacent un-crimped fitting.  Now, take the parts back to the hydraulic shop and have them align the elbow to the witness mark you established to align the fitting in the hose.  Only then, with the elbow aligned to the witness mark, make that final crimp.  When you’re done, you’ll have a hose that will fit, on both ends, without undue tension or strain on the parts.  If you do not fit the hoses correctly, you’ll have a wrestling match to get the elbows to thread onto their mating fittings, and when fit, they will have unacceptably high side-load stresses on the fittings themselves, which could lead to steering system failure.


Top of photo, Left: GHP-10 2.1L Hydraulic Pump showing hydraulic connections with custom 45º hydraulic hose fittings.  Top of photo, Right: Power Control Module that powers the GHP-10  hydraulic pump.


Top, foreground: GHP-10 Shadow Drive hydraulic sensor


Top, left: Shadow drive sensor.  Top, right: Capilano Model 50 Uniflow Valve with GHP-10 hydraulic connections

Opening, draining, refilling and bleeding the hydraulic system after the Autopilot components are installed is not difficult.  Follow the directions provided by the steering system manufacturer.  Sanctuary is fit with Capilano (Teleflex) 250V helm stations with a Model 50 Uniflow valve.  I used the OEM Capilano instructions to re-fill and bleed the hydraulic system after installing the autopilot plumbing.  These tasks are easiest with the help of an assistant.  The mechanical and electrical fitup consists of all of the normal tasks associated with installing technology systems: locating and mounting components, installing DC power wiring to ABYC standards, installing electronic control circuits, etc.

The GHP-10™ system design requires an NMEA2000® network backbone.  My installation was a net new, stand-alone autopilot installation.  I installed an NMEA2000® (N2K) network to interconnect the core pack components.  Garmin® provided all of the necessary parts with the base core pack kit.  That was easy; just a couple of cables, and very straight forward connections.


NMEA2000 Backbone showing terminating resistor (far left), power connection (yellow) and drops to individual N2K devices

One small surprise was that both the Garmin® display unit (GHC-10™) and the course computer (ECU) contain imbedded firmware.  The initial draft of the GHP-10™ AP system marketing materials did not make clear that to update the firmware, the preferred way is via a “compatible” Garmin® chart plotter on the NMEA2000® network.  At that time, we did not have a “compatible” Garmin® chart plotter.  For those without a Garmin® compatible chart plotter, Garmin® now makes an NMEA2000® “Updater” that can be attached to the network to enable updating the AP firmware.  This is a  “kludgy” solution; clearly, an after-thought.  We do now have a compatible Garmin® chart plotter, which we quite like.

The GHP-10™ is designed for use in both slow (displacement) and fast (planing) power boats with hydraulic steering systems.  The 2009 version of the Garmin® documentation appeared to be heavily oriented toward outboard-driven, go-fast planing hulls, and did not have installation diagrams for the many configurations found in older and newer cruising boats.  The early Garmin® installation instructions were, frankly, incomplete and weak.  Later versions have been improved, but remain below my expectations for an otherwise high quality technology company for a product intended to be DIY-installed by its purchaser/owner/operator.  In 2009, I needed several interactions with Garmin® Technical Support to get it all sorted out.

The initial setup of the system requires configuration of the engine speed at which the hull “transitions” from displacement to planing mode.  The Autopilot computer gets engine speed from the boat’s tachometer drive circuit.  What the documentation does not explain is that, for hulls that do not plane (trawlers and displacement cruisers), tachometer input is not needed for the autopilot system to work.  I didn’t learn that until after I had the tachometer input completely installed. but it was not required to have a functional autopilot system on our trawler.

No actual user manual or operator’s guide is available for the GHP-10; there is only a quick start brochure and a sheet of installation instructions.  Operation of the firmware settings of the system are not documented anywhere.  Some of the firmware options that are available for user configuration are obscure and difficult to interpret.  Setting up the parameters affecting route following and XTE sensitivity would be much easier with an proper user guide and an explanation of what the controls actually do.  When you understand the right question to ask, Garmin® tech support can usually help, but that’s a poor means to learn to set up user selectable performance parameters.

In general, my experience has been that Garmin® tech support is hard to use.  They do well if the nature of the call lends itself to being resolved in one single interaction with the tech support team.  For more complicated situations where callbacks are required, it’s really quite difficult; the more callbacks, the worse it becomes.  Garmin® does not provide a way for callers to get back to the same technician with whom they talked on a prior call.  Thus, every time you call back, you have to talk a new technician through the call details and prior action history.  It’s very tedious and frustrating.  They will also put you on hold to consult among themselves (several times, in my experience) each time you call them.

Once installed and operational, the GHP-10™ AP system is an excellent AP, and I do recommend it.  Just be aware that experience building Heathkits in a previous life will be most helpful here.