AP Linear drives

[BigAl.NZ]

We have upgraded our Hood 38 (12 ton) from a autopilot (AP) that looked like it was from the Ark to a Raymarine Evolution.

We didn't change the hynautic hydraulic cylinder that attaches to the rudder quadrant, nor did we change the 1/4Hp pacific scielinear ntific electric pump - they are original and look to be maybe early 90s technology.

All seems to be working well, BUT (isnt there always a but) in a quartering following sea running downwind the AP really struggles and uses a lot of power. The other day in inner harbour seas (moderate) we were yawing 15 degrees either side of course - no weather helm well trimmed. Manually I could predict the waves lifting the stern and hold far better.

I suspect that the old tech might not be as responsive (read hard over time) as newer tech and this is affecting the ability of it to respond to command inputs.

So the question becomes - whats a good brand of linear drive (is that the right term?) to get that is responsive and reliable?