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Full Version: [CA11] Auto Pilot pump conundrum
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I may have an issue on hand. I have a 1994 Carver 390CPMY that had a RAYPILOT 650 installed with a type 1 pump. I bought the EV200 by the size of the pump that was on the bot lady installed.

I recently installed an Evolution EV200 system. It appears the autopilot stalls at some points. I did some looking about, and (FINALLY!) found a sticker on the SEASTAR hydraulic cylinder that gave me part # BA135-7ATM (HC5313) I did some research, and see that it displaces 8.3 cu/in or 135.3cc. I do believe this is per cylinder. I have TWO cylinders. From what I see, this places me not only in the NEXT category of pumps, to a Type II pump, but also a ACU of ACU 400 rather than the 200? Can you please confirm, if my sad news is correct? If the news is not what I wish to hear, Can I add just a TYPE II pump to this system without buying a new ACU upgrade to the 400?

Thank you as always.
Welcome back to the Raymarine Forum Tony,

As indicated within the FAQ found here, the total capacity of hydraulic fluid that will need be pumped through steering rams which have been plumbed in series will be equal to the capacity of one of the steering rams. However, the total capacity of hydraulic fluid that will need be pumped through steering rams which have been plumbed in parallel will be equal to sum of the capacities of each steering ram. Should your steering rams have been plumbed in parallel, then the total cubic capacity for two 8.3 cu. in. rams would be 16.6 cu. in., requiring a Type II Hydraulic Pump and an ACU400.

If the latter is so (recommend verifying the hydraulic plumbing), then is accordingly recommended that the ACU-200 be sent to Raymarine’s Product Repair Center to be replaced with an ACU-400 (they will charge the differenced) and that the Type 1 hydraulic pump be replaced with a Type II hydraulic pump.
AFter careful checking (Involving taking the aft bed apart...AGAIN! With the Admiral not too happy about remaking the bed, I have verified that I have only 1 steering ram, which is in the auspices off the ACU-200 and Type 1 pump. Just a query, is there any benefit to using a ACU-400 and a Type 2 pump with a 25,000LB vessel? Just wondering this.....

Thank you.

Unlike vessels which are steered with mechanical linear drives, the drive size is not dictated by the weight of the vessel within hydraulically steered boats. The latter are strictly determined by the number of steering cylinders, their cubic capacity, and whether they have been plumbed in series or in parallel. Maximum autopilot performance will be achieved when a properly sized hydraulic pump has been installed for the vessel's hydraulic steering system.
Thank you. I. Will now rest easy knowing all I have done is is done properly.
You're welcome.
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