Hydraulic Steering Ram Bypass Valve

[PeteW]

Risto,
The 7" linear drive from Octopus would be classified as Type .5 (500-1000 cc/min). The 1212LAM12 has the 1212 Type 1 pump (600-1200 cc/min) and is compatible with The Pearson and the ACU-200 controller. But here's what I don't like about it: 12" stroke means your tiller arm radius will be 9.82" to achieve the desired +/- 35 degrees of rudder movement. With the forward facing tiller arm (Buck Algonquin part# 10TA15X130) its going to be further forward and when your hard over the cylinder rod will protrude well into your sail locker.

What I was hoping to see was a 1212LAM9.  That's the 1212 pump on a cylinder with a 9" stroke and a 45mm bore versus a 12" stroke and a 38mm bore. This is what I put in my Pearson. The 9" stroke is a little more compact. The tiller arm is reduced to 7.3" radius and the rod does not protrude as far into the sail locker. You are correct about the 12" stroke and longer tiller arm having more leverage. But in hydraulics we don't care so much about that because a shorter stroke hydraulic ram with a larger bore does the same work as a longer stroke cylinder with a smaller bore provided their volumes are the same. And in this case they are both around 290cc. The larger bore  produces more force but over a shorter distance meaning between the 2,  the work done is identical.

So with my setup I currently have a 1210 pump ($99)  but will upgrade that to a 1212 when I get the desired smartpilot. My cylinder is a Hynautics HC5373, 9" 290 cc. The only other minor difference is I think the cylinders that Octopus supply are aluminum. The one I have is bronze.

I suppose the 12" stoke ram could be mounted forward/aft orientation but would require a different custom tiller arm, with the key machined 90 degrees off from the Buck Algonquin split cap. This is what Garner did, he used the Edson part and its probably a cleaner way to go. To get that on you will need to remove the quadrant if you can't mount it on the top. This is why I opted for shorted stroke transverse mount in my boat.

I'd be curious to hear why Octopus does not offer a 1212LAM9?

Pete