Jefa Direct Drive Unit

Mk1 or Mk2?

My drive from 2008 has two wires coming out from top as you see on jefa's pages.

Seem to remember a picture of a drive unit with an access plate where wires came form. Thought this was the problem units.

Now the question: What should I do with my drive from 2008? No problem so far, but reading about it I wander if I should add sikaflex to the wire joints and try more to make it waterproof.

Or possibly open it and look for water?

I put silicon around the areas and wires where they enter the unit. No problem so far except for a fuse blowing last season. I've since bought a job lot of 12 fuses so that should guarantee that .particular fuse will not blow again.

Charles

Good idea to fill the boat up with fuses..... Then no fuse will ever break. 

I am afraid you are wrong Brufan.

Found this:

Electro magnetic clutch: On the moment the mechanical steering system on the yacht is manually operated, the autopilot drive has to be disconnected from the steering system. This is achieved with the electro-magnetic clutch and controlled automatically by the autopilot junction box. Jefa has developed a unique and patented engagement clutch. The solution is based on two electrically operated spring loaded clutch pins that engage and disengage the outer gear ring of the planetary gear step. This solution has multiple advantages over the existing friction plate clutches:
Less friction to back drive the unit.
Lower power consumption (1.4 Amp. at 12 Volt). When the clutch isn't powered, it's disengaged and engaged when powered.
The clutch doesn't wear in time.
More compact than any friction clutch.
When the autopilot is switched off, the helmsman isn't suddenly confronted with the full rudder torque, but has to put loading on the wheel to equalise the forces so the the clutch can disengage, making the manual take over much safer.

As I understand this, it says it draws 1.4 ampere only for the clutch: " When the clutch isn't powered, it's disengaged and engaged when powered."

Pitty 

Hi,

While the clutch draws something between 0.7 and 1.5 A only while engaged the total consumption of the unit depends on the conditions and the sail trim. The pilot can supply a whopping 30A to the Jefa motor and to supply this power I estimate that draws more than 40A from the battery (a 75% efficiency is normal in electronic power circuits). Of course this high consumption is only during a course correction under max load. Depending on conditions only about 5% of the time the pilot will actualy turn the rudder and I also estimate that only 30% of max power will be used so the average current will calculate something like 0.05X40/3=0.67A. To this we have to add the power drawn by the clutch and the control unit. Total amperes calculate to about 2.5A
But engage the above pilot in big wave conditions, sailing downwind carrying a spinnaker and the pilot makes corrections using maximum power at a 30% duty cycle. The the average amperage could be 0.3X40=12A plus 1.5A for the clutch and electronics which add up to 13-14A. Overheating and fuse blowing will be expected.