My boat has a modified stock merc power steering that uses 2 external steering rams. When you put extension boxes on a boat you have to go with a full hydraulic system, right or wrong? I would assume that you do since there is no way to hook up the steering cable and power steering valve. How does the stock system work? Does the steering cable push or pull on a priority valve and direct fluid to the proper side of the steering ram? Has anyone reworked the stock steering system to still use the cable and power steering valve with external rams?

You will need a fully hydraulic system. The stock system will be totally removed including the inner plate.

They sell hydrualic add on kits that utilize the stock steering valve which is called a brazil valve. With extension boxes you can't use any of it though. With extension boxes you have to go full hydrualic and it's the best way to go anyway.

I agree that the full system is the best but why can't the half system work? On his pictured setup, the steering wouldn't know if there is a box or not. I don't see why it wouldn't work.

I don't know who the manufacture is of the current system, but can you get the plates from Latham to add a 12" box or the "wing plates" from Imco for their set up. These are needed to extend your current steering. Just not sure how it will work with what you have got now. I just spoke with both Imco and Latham about adding a boxes to my boat and the "other pieces" get rather pricey ,so be prepared for a little sticker shock.

Dave