Cape Cutter 19 Association Forum

Hello all

"Popeye" has made a comment on one of the photos in the album "Mary Ann Modifications" about interference from the engine on his tiller pilot.

Quote: "Did you get any problems with the tiller pilot when the engine is running?
I can`t use my simrad tp10 as magnetic disturbances available if engine is running.

Any idea to solve this?":(

The short answer is yes, I do get magnetic interference from the engine when it is running.

I had a Simrad TP10 on my previous boat (Winkle Brig) which suffered interference from the outboard motor (Yamaha 4 fourstroke), but not from the old Mariner 4 (2 stroke) which I originally used.

I have a Raymarine ST1000+ and a Honda 4 (four stroke) on Mary Ann, it also suffers magnetic interference when the engine is running.

The flywheel on the engine is fitted with a magnet (to operate the ignition and charging coil). When the engine is running, particularly at slow speed, you can see the apparant heading on the tller pilot display fluctuating at engine speed by about 30 degrees. This causes the tiller pilot to "hunt" constantly when the engine is in use.

However the faster the engine is run, the "hunting" becomes less of a problem.

I have already decided to fit an external fluxgate compass to Mary Ann to eliminate this problem.
I will mount the fluxgate compass on forward side of the bulkhead under the V berth, well away from any sources of magnetic interference.

I do not know whether the Simrad TP10 can be fitted with an external compass, the Raymarine unit certainly can.

As a footnote the tiller pilot works perfectly well when sailing (engine not running).

Hi Dennis,

thanks for your answer and for publishing the case in the forum.
As the tp10 has no NMEA interface I`ll check if I can disassamble the fluxgate and to place it somewhere in the boat where now magnetic interferances are indicated.

Kind regards

Frank

Hello Frank

I hope you are successful, it would certainly be a less expensive option.

The Raymarine unit has a NMEA interface but does not use it for the external compass, I will have to use the Raymarine propriety SeaTalk interface. This means buying and fitting a Raymarine elctronic compass.

Please keep us informed of your progress.

popeye wrote:Hi Dennis,

thanks for your answer and for publishing the case in the forum.
As the tp10 has no NMEA interface I`ll check if I can disassamble the fluxgate and to place it somewhere in the boat where now magnetic interferances are indicated.

Kind regards

Frank

I found a manual here http://www.bluemoment.com/manuals/01%20TP10-20.pdf

Hello all

This is an update prompted by Ian's (x-man12345) request for info. (I assume you have read this thread Ian!)

I have bought a Raymarine ST40 electronic compass to fit to Mary Ann.

This will allow the Raymarine St1000+ tiller pilot to utilise the external fluxgate compass thus eliminating the magnetic interference from the engine.

I will be positioning the transducer on the forward side of the bulk head under the Vee berth.

As I have a Porta Potti (see Russell's recent thread) which is stored near there, and I know that the Porta Potti holding tank contents gauge is magnetically coupled the float in the tank, I have carried out some tests.

I have found that the Porta Potti will cause some magnetic deviation of the compass. With the transducer level with the top of the Porta Potti the deviation varies from 8 degrees nearest to the contents gauge to 0 degrees at the opposite corner.

I will therefore position the transducer at the opposite end to the Porta Potti contents gauge and make sure that the Porta Potti is always stored the same way around.

Dennis wrote:I will be positioning the transducer on the forward side of the bulk head under the Vee berth. ................................... I have found that the Porta Potti will cause some magnetic deviation of the compass. .

Just an update.

I have actually positioned the transducer on the forepeak bulkhead. This is not ideal in that the pitching motion of the boat will be worst at that point. But it well away from any potential magnetic interference, engine, porta-potti etc.

Hello all

I have received a PM from a member who also was having magnetic interference problems with his ST1000 tiller pilot.

I thought I would share my reponse to his message:


I fitted the ST40 readout on the cabin bulkhead immediately below the the (magentic) compass. It states in the handbook that it should not be sited near a compass, so I set everything up on my workbench and established that the ST40 had no effect on a (magnetic) compass and visa versa, no matter how close they were to each other.

I have sited the remote fluxgate compass on the forepeak bulkhead to keep it well away from the magnet in the Porta Potti, because that did have an effect if within 18".

When I completed the wiring on the boat I found that the ST1000 was not talking to the ST40. After some testing with a meter I found that Raymarine had wired the plug on the ST1000 differently to what is stated in the handbook. It was only the "Seatalk" wire which was incorrect. Once I had corrected this everything seem to work OK with the ST1000 reacting to changes in the magnetic field near the remote fluxgate.

However I also found that the ST1000 was still reacting to changes in the magnetic field near its own fluxgate. I am sure that this should not have happened. I solved this by opening up the ST1000 and unplugging the built in fluxgate ribbon cable from the circuit board. Everything seems to work fine now, But I am sure that I should not have had to carry out that small mod.

I hope to get my first sail of the season this week, I will report back when I have completed the "Sea Trials".

Dennis wrote:
I hope to get my first sail of the season this week, I will report back when I have completed the "Sea Trials".

I have now had 10 sailing days (so far) with the Raymarine ST40 electronic compass.

Performance is well up to expectations. I can now motor along without any (magnetic) interference from the engine.

Usually the boat stays within 1 or 2 degrees of the set heading.

On a couple of occasions it has gradually deviated by 20 degrees before pulls itself back into line. I suspect this is due to the tiller pilot unit (Raymarine ST1000+) temporarily losing the "Seatalk" signal from the ST40, this could be due to electrical intereference from the engine battery charging system. I may fit electrical chokes in the signal line to try to eliminate this "feature".

Interestingly, and this may just be a coincidence, each time this has happened, the boat has been on the same part of the lake and on the same heading.

The success of this unit has made reefing easier. If the wind suddenly increases (a feature of Kielder sailing) to the point that you need to put a reef in quickly. It is now easy to start the motor and use the tiller pilot to hold the boat head to the wind whilst the necessary sail handling is carried out.

I also now get about 20-30 minutes more sailing per session.
Before, I would take the tender to the boat then spend about 15-20 minutes preparing the boat to sail.

Now I cast off almost immediately and prepare the boat whilst I am motoring along using the tiller pilot. My mooring is up a creek about 0.7 Nm from the main body of the lake. By the time I reach the lake the boat is ready to sail.
The same happens when returning to my mooring. I now have all sails stowed and the boom cover on before I pick up my mooring buoy.

I am well pleased with the result.

Hi Dennis

I'm planning to install in the same way as you did. However the position of the mounting socket seems to clash with the position of the rear cleat. Putting the tiller pin 18 inches from the rudder stock results in the mounting socket being just aft of the cleat but too close. I notice on your picture the socket is actually forward of the cleat. I don't think Bob will have moved the cleats so I wonder if I'm doing anything wrong. Can you remember whether or not the positioning was an issue for you.
Regards
Paul

Hello Paul

I have been pouring over the photos I took of Sapphire at Mylor.
I think Bob has moved the cleat forward, probably to reduce the tendancy of the mainsheet getting caught around it when going about.

If I were to do it again I would reduce the distance to the centre of the rudder pintle in order to increase the maximum rudder movement. Maybe about 15".

I have attached a photo of Mary Ann which shows the cleat positions, further aft than yours I think.