What could be wrong with my EV-100 autopilot?

[dove]

There must be a simple answer to this. In short, the EV-100 AP (power version; no rudder reference) installed on my new boat works OK at low speed but has problems making course corrections to the right under resistance at speed. At the dock and at low speed, everything seems fine, and there is no difference in performance or feel right or left. But if there’s more resistance on the engine, as from running 25 mph, or even enough wind or current at low speed, the series of short pulses from the AP pump don’t make the intended corrections to starboard. The AP eventually believes it’s reached the set “rudder limit” of 25 degrees and stops trying, even though it has not moved the engine off dead center. This happens even though the AP is set to “performance mode,” intended to give the quickest corrections, and regardless of whether it’s in “auto” or “track” mode

Here are two interesting clues which might help. First, when the boat is veering off course to the left because the AP isn’t correcting to the right, it will quickly and fully correct if I just give the wheel a little tug to the right to help it. Second, regardless of speed or rough conditions, the AP will make any large maneuver to the right if I tell it to track to a course that is way off to the right, like 45 degrees. It has no problem maneuvering the boat around aggressively to the right when commanded. It’s the small corrections, or series of them, that seem to be ineffective against any resistance. With the AP disengaged, the boat’s helm performs normally as described in the background below.

My own observation is that the EV-100 software uses the pump in two different ways depending on the situation - either tiny, short pulses, including a series of them as for course maintenance, or long, continuous pump operation, as for acquiring a new course. It’s the first of these that doesn’t work for starboard corrections against resistance. What might be wrong? Is there anything else I should try? Could the pump have an issue, like a sticky valve?

More background: The EV-100 was professionally installed on my brand new 22' bay boat with a Yamaha F150 and Sea Star helm # HH 6541-3 and 1.7 cu. in ram # 5345. The AP seems to be set up properly with a hard over time of 14 seconds, which is the actual time measured driving the motor stop to stop in either direction with the AP pump. (I’ve also experimented with higher hard over times and other settings to no avail.) I have all the software updates except for the latest May 2016 updates which supposedly are not compatible with my Garmin chartplotter (though I would obtain the updates anyway if they fixed my problem, but that seems unlikely since no one else reports the same issue.) The boat’s helm by itself performs normally and smoothly in either direction, with 5.1 turns stop to stop (spec is 4.9 turns fully bled.) There is no feedback at the helm from either the engine or AP operation. At speed, it’s a bit easier to turn the wheel starboard, which is the normal effect of prop torque. If anything, that should help the AP correct to starboard. But as described above, it won’t stay on course at speed unless I watch and help it along.

If my pictures got attached, one shows the installation, and the other shows (a dockside simulation of) what the P70R looks like when it thinks the steering is fully to the right when it really hasn't moved.

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum dove,

Please click here to view a FAQ addressing the subject of autopilot selection. This information may also be found on the Hydraulic tab of Raymarine's Drive Unit Selection web page and Table 1-1 of the Raymarine Hydraulic Pump Installation Guide. As product specifications and product documentation are subject to change, it is recommended that customers seeking the latest product specifications consult Raymarine's product web pages and the latest Raymarine product manuals accessible via Raymarine's Manuals and Docs web page.

Unfortunately, it appears that the autopilot selected for and installed on this boat is not correct. The Seastar HC5345 steering ram has a cubic capacity of 8.34 cu. in.. The cubic capacity of this steering ram exceeds the maximum cubic capacity supported by the 0.5 Hydraulic Pump (6.7 cu. in.) included with an EV-100 Power. This upper limit is also driven by the limited power output of the ACU-100 Acutuator Control Unit. Given the cubic capacity of the boat's steering ram, the Type 1 Hydraulic Pump (supports 4.9 cu. in. to 14 cu. in.) included with the EV-200 Power should have been purchased and installed onboard this boat. Installation of an under-spec'ed autopilot will result in shorted life of the autopilot and symptoms such as you have reported. Should this EV-100 Power have been purchased from and installed by a Certified Raymarine Installer, then it would be recommended that the installer be contacted regarding this issue.

[dove]

Wow, thanks Chuck. Should have done my homework better instead of relying on anecdotal evidence that the EV-100 would work easily with a 150 hp. Looking at the table of Sea Star rams, it appears none of them is compatible with the EV-100.

When my EV-100 pump wears out, I guess I'll be looking at the EV-200. If there's a way to upgrade components to the level of the 200 without a complete system replacement, please let me know.

And in the meantime, since the EV-100 ALMOST works, if you can think of any compensating measures by way of settings, software updates, or otherwise to get it to correct more to starboard, please let me know.

Thanks again.

[Chuck - Raymarine - Moderator]

Dove,

The diagnosis of this problem was greatly aided by the detailed list of hydraulic steering components which you had provided. The problems which you are trying to overcome are the result of the hydraulic pump being unable to pump sufficient fluid volume at the required pressure to overcome the forces within the steering system. Unfortunately, the only recommendation that would have been offered to improve performance would have been to configure the Response Level to Performance. The additional demands placed on the pump and ACU may also result in shortened life of these components. With respect to replacing components to turn the existing system into an EV-200 Power, the ACU100 would need to be replace with an ACU200 and the Type 0.5 Hydraulic Pump would need to be replaced with a Type 1 Hydraulic Pump. All of the other components (EV-1 Sensor Core, p70R Autopilot Control Head, and SeaTalkng backbone) would be retained when replacing the ACU and hydraulic pump.