Furuno Navpilot 520/711

[Jonty]

Hi

Has anyone had problems with the Furuno Navpilot 520/711 controlling their yacht properly?
Our Navpilot 520, which had roughly the same problems as below, failed after 4 years of summertime use and, as we were en-route to join the Vasco de Gama rally we had to get a new autopilot (or hand steer!!) A UK dealer told us the course computer wasn't repairable. Not the usual Furuno reliability one would expect. So, thought I, the new 711 should be an improvement and as the heading sensor, PG 500, rudder ref and wires are all there we bought the 711.....

On flat, calm water with "Full Auto" selected it will not steer straight. the course keeping is fine but the pilot produces large wheel turns as much as half a wheel spoke to either side so the steering is constantly working and the vessel steers an erratic course (as though the rudder gain is far to much). When "Manual Parameters - calm" is selected (set to Weather 0*, gain 1 & Counter rudder 1* the lowest setting) all that happens is wandering is increased as the autopilot is slower to respond. With rougher conditions (especially down wind) the unit hunts from side to side trying to counteract the roll even if there is no course change. Often it will make a correction and immediately turn back before the boat can respond. When we try different settings in the "Manual - Moderate or Rough" it doesn't seem to make any difference. Having experienced an Autohelm 7000 on a very rolly Island Packet in calm an rolly conditions where the autopilot adjusts the helm by small increments makes me believe there is a problem with Furuno Navpilots or there is a way of adjusting the course computer that Furuno don't want disclose.

The "SET CENTER RUDDER POS" has been set and re-set I don't know how many times. as has the heading sensor. Our yacht is a Roberts 45, about 17t and does have a rather large rudder. Maybe I'm missing a trick but both installation guides seems pretty straight forward.

I have tried repeatedly to contact Furuno UK directly and through dealers but to date have only had one reply asking me if the unit was installed by a dealer "because the calabration of these units is critical to the performance" and offering to find more details on setting it up. I replied to them but heard nothing more. Sorry this has been so long-winded.

John sySondela

[marine1]

Have you check the rudder positioning unit for correct installation. If there is any play in the steering system it will transfer to the positioning sensor and then the unit will steer but will also "hunt" if the linkages are loose.

[Paul L]

I've had both the 511 and the 700 series Furuno AP computers. They both worked flawlessly and they had far better reliability than the previous Ray units we had. Since your boat is steel, I suspect that there is an issue with the compass installation. Did you follow the PG500 specific install instructions on how to test the proposed location for the compass install? The rudder sensor should hold its setting within 1 or 2 degs with no problem, so I suspect something is not right with its install. For the AP to work right it has to have a compensated compass.
If you aren't getting support from Furuno UK, then you could try the US forum at Furuno USA Forum They won't take private support from outside the US, but will often answer questions on the public forum.

[Jonty]

Hi Paul L and Marine 1,

Thanks for the replies. The yacht is Fiberglass and the PG 500 sits about 1.2 m in front of the engine on the center and water line. The rudder drive is a Lewmar sprocket drive and produced dead band reading of 0.4* so I set the "rate of turn" to 3* in "Ship's Characteristics" . The RFU is straight onto the quadrant and has no play. Auto Compass calibration seemed to have been done successfully (many times) and the Navpilot is connected to a GP 32. I have tried damping the heading sensor more but no improvement. We managed to get a s/hand PG1000 which has yet to be tried. Would a larger or smaller boat length in "Ship's Characteristics" produce smaller course corrections?

Thanks again.

John

[Paul L]

As already mentioned, did the compass pass the install location test that is built into the compass electronics? Second, isn't the rate of turn computed by the At Dock installation calibration, or dd you try and set this manually? There is something wrong in this setup for you to have this many issues.

[Jonty]

Hi Paul,
There's no location pre-test for the PG 500 (according to the manuals), they just say to mount as far as possible away from cables, ferrous materials, vibration etc. With the PG1000 we have just acquired this can be done and I will try it in that location.
Rate of turn (3*/sec I've put) is entered in "Ships Characteristics" along with boat type, length and cruising spd, but mustn't exceed the rate of turn determined in rudder test, which is 4.8*/sec.
Yes I'm aware there is a problem but where.....
Thanks again

John

[Paul L]

John
The PG1000 is a nice compass. I have always left the rate-of-turn set to the max that the rudder test found. The compass should be much better than the 500, but I still don't get why you are also seeing issues with the rudder position. I think you'll need to address that also.
Good luck with the experimenting and let us know how it works out.