Simrad RPU80 Pump

mstrpo · Posted: Fri Sep 30, 2022 1:47 pm Post subject: Simrad RPU80 Pump

Hi All,

My Tomcat has a AP16 autopilot computer that was not powering up. I found a broken connector on either power or ground and fixed it so the computer powers up now and seems ready to go (already configured and such). Unfortunately, the RPU80 pump seems frozen. I haven't found anything online to help diagnose the issue other than "bypass the computer and try to drive it directly" which I did to no affect. Anyone have any experience with these motors? Other diagnostic steps to take?

Thanks,
Pat

thataway · Posted: Fri Sep 30, 2022 2:28 pm Post subject:

can you apply 12 volt power to the pump directly. This bypasses the relays or switching diodes, and will tell you specifically if the motor is bad, Occasionally there can be hung up impellers or pistons in the pump. A quick power one way and then the other might free this up. Also you should check any fuses on line to the pump, which are often different than the fuse to the computer.

mstrpo · Posted: Sat Oct 01, 2022 11:04 am Post subject:

I did try a direct 12V feed to the motor with no visible or audible effect. I did not try reversing polarity. I did pull the brushes but they looked fine. I was thinking of pulling the motor apart to see if I could free it but am reluctant to disconnect the hydraulics.

thataway · Posted: Sat Oct 01, 2022 11:21 am Post subject:

Most auto pilot pumps run in both directions. Try reversing the leads. If it is a bad motor, you are going to have to pull the hydraulics anyway. The new pump will most likely come as a package with the same hydraulic fittings as the old.

mstrpo · Posted: Fri Oct 28, 2022 2:28 pm Post subject:

Sorry for my delayed response. Finally getting back to this.

First of all, thanks for the responses!

Hydraulic steering is new to me and so a bit tentative pulling it apart. As this system is pretty old and I'm planning to upgrade the electronics and add AIS, etc, I'm wondering how much to invest in the existing AP. I assume a new AP will be significantly better with new features and connectivity. Is that a good assumption? Is it worth the investment to repair this system? Hard questions to answer with "yes/no" so looking for some perspective.

Thanks!
Pat

thataway · Posted: Fri Oct 28, 2022 8:06 pm Post subject:

mstrpo · Posted: Sat Oct 29, 2022 10:37 am Post subject:

Thanks Bob! After posting, I read a few online articles on today's AP's and it didn't seem there are that many improvements, especially if you are not connected to a chart plotter. If you are, then the integration w/in brands is best.

thataway · Posted: Sat Oct 29, 2022 1:08 pm Post subject:

I am old fashioned and carry paper charts, although I love GPS, I want to look at the broad picture. I don't plot out routes and waypoints, unless it is a run such as to my home bayou.. I often set the auto pilot to magnetic courses. I don't use auto routing, even though the last few chart plotters had that feature.

The boat we took to Europe had a very old design (1960's) commercial grade autopilot and it was very reliable for over 40,000 miles. I could not say the same for the boat we took to Alaska and then to Pensacola, which was a "state of the art" (1990's) at that time. Accuracy and reliability are paramount. I don't use "fishing patterns".