Threaded Mode | Linear Mode

***Derek - Raymarine - Moderator***

Hi andgers

Thank you for your enquiry.

The Control unit p70s and EV1 sensor can be used with all variants of Evolution autopilot, you just need to match the drive unit to the steering system and then match the ACU to the drive unit selected.

You advise the vessel displacement is 8 tons, so a wheel mounted autopilot is underspec'd for this application.

The choice of drive unit depends on the type of steering system installed.

If the primary steering system from the wheel to the rudder is mechanical, that is to say there are cables from the wheel to a quadrant secured to the rudder stock, or there are draglinks or rods connecting the wheel to the rudder stock, then a mechanical drive is the most suitable on most cases. The key check here is to move the rudder by hand/ foot and check the steering wheel rotates freely. if it does, this indicates the steering system can be 'backdriven' and so a mechanical linear drive can be fitted, if it does not, then it is likely there is a gearbox which is preventing this and an alternative solution using a rotary drive and chain might be needed.

If the steering system can be backdriven, then based on your boat displacement, a Type 1 linear drive would be used, this is an electromechanical drive, ( very efficient) which is mounted in the lazarette and securely mounted onto a solid platform and alumininium support base bonded into the hull of the boat and the other end attached to the rudder quadrant or tiller bar pinned or keyed onto the rudderstock. (we do not advise drilling into the quadrant - advice from the steering gear manufacturers should be sought as to the best method of attachment - ideally we recommend the services of a professional shipwright)

If Hydraulic steering is already installed onboard, then click here for more information about choosing the correct size autopilot pump.

If a T1 mechanical drive or hydraulicpump is used, then an ACU200 will also be needed.

Regards