Tohasu SailPro interference problem?

I have the Tohatsu 6hp Sailpro on my sailboat. I am having a odd problem with it and my Raymarine TillerPilot and wanted to see if anyone has seen anything like it before.

Basically, if I am sailing the TillerPilot works perfectly. However, with the Tohatsu running the TillerPilot is constantly resetting. As I left port yesterday under power the TillerPilot was resetting every couple of seconds. I then sailed for 3+ hours with the Tillerpilot working perfectly. Once I fired up the Tohatsu to head in the autopilot was back to resetting every couple of seconds.

This happens if I have the Tohatsu charging cable connected to my battery and also with the cables disconnected.

I am guessing the Tohatsu is putting out a lot of RFI or something that is either messing with the TillerPilot's built in compass or just scrambling it in some other way. I didn't have this problem with the old Johnson 8hp 2 stroke that the Tohatsu replaced.

Anyone seen anything like this with the Sailpro before? And if so any ideas on how to fix it?

Thanks,

Shawn

Re: Tohasu SailPro interference problem?

I've never heard of anyone having this problem. I would contact Raymarine to see if they have a fix for the deficient shielding.

Re: Tohasu SailPro interference problem?

I used to have issues like that with my old raymarine tillerpilot. of course, it had other problems in and of itself, and was repaired several times before finally being jettisoned (literally) and subsequently replaced with a (much higher quality/power) Simrad 30 unit. IMHO, the low-end ray units are "built to a dollar" and of marginal quality, especially in the shielding, which was nonexistent in mine.

I had the issue when running my Evinrude 15 (old model with points/condenser ignition). I found that I had two interference issues. One was due to poor/nonexistent RF shielding in the ray unit, and the other was its sensitivity to ripple in the 12v supply. OB's have a lot of ripple in the DC charging, and I was able to minimize the interference with a cheap radio shack noise filter (intended for automotive use) installed on the 12v line right near the autopilot, and twisting the 12v wires to reduce EMI.

Since the DC wires for both the charging and the pilot were not twisted, and ran near each other, it did not matter whether the charge wires were connected to the battery or not. Just the proximity of the charge wires to the feed wires for the ray pilot caused the pilot to go nuts occasionally. I twisted the wires for the charge circuit, and twisted the feed wires for the pilot, then added the cheap (maybe $10.00) pi filter near the pilot. That fixed 90-95% of the problem. I learned to live with the other 5-10% of the problem (hunting when powering on a straight course) until the ray was replaced with the sim.

I would suggest confirming that you have Resistor plugs (dcpR6e) in the motor, to minimize RF from the ignition.

FWIW, my Nissan 9.8A3 does not have any problem at all with the Simrad TP30.

Re: Tohasu SailPro interference problem?

Thanks, I have also contacted Raymarine about this to see what they suggest. I suspect they can't put a lot of shielding into the unit as that would also shield the fluxgate compass that is built into it.

I know it isn't a ripple problem since I tried it running strictly on battery and it was still acting up with the Tohatsu running. I disconnected the charging wiring at the battery and at the Tohatsu so it shouldn't have been causing problems.

I can try adding filtering to the wiring near the autopilot in case those wires are acting as antennas. I will also check the engine to see if it is a resistor plug or not. I did replace the plug in it but thought I used the spare that came with it.

Thanks,

Shawn

Re: Tohasu SailPro interference problem?

Since it happens with the charge wiring disconnected at the motor, it sounds like it's is either:

1- Magnetic interference to the fluxgate (you won't be able to fix that by ordinary means without relocating the pilot), which can't easily be done on a tiller-steered sailboat. I had that on a cheap compass in a car back in the '70's... Start the motor, and the compass would swing, then always read East -- turns out the compass was reading the magnetic field from the alternator.

Or... more likely:

2- RF interference, and the 12v feed wires to the pilot are picking it up, acting as an antenna.

I would put a twist in the 12v wires to the pilot (several twists per foot of wire) for noise cancellation (like you see in Ethernet cabling), and add the cheap noise filter at the pilot and see if that improves it as it did on mine. If you have additional wiring at the pilot connector for NMEA and stuff, you may want to keep those wires disconnected while testing. Double check to make sure the wiring connections to the pilot are perfect, with no oxidation on the tiny set-screw connectors. Keep in mind that any seemingly-minor corrosion in the wiring will act like a capacitor, which in turn can make the power input section to the pilot actually behave like the IF section in an old AM radio.