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Old 09-22-2020, 05:26 PM   #1
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Spare A/P Pump Config - Input Please

I've ended up with a spare A/P pump. I'd like to install as a warm-standby in case of pump failure. My theory is that if the pump/motor craps out, I'll disconnect wires to old pump and wire to standby pump.

1. What should the plumbing look like? See attached for two options. Option 1 (Tee-off existing likes to existing pump) or Option 2 (Tee off main lines). Option 1 is easier, and I'm not sure it makes any difference. Thoughts?

2. I would think the A/P pump have lock-outs so I really don't need valves to isolate the standby pump. What say the Bigger Brain of TF?

Any other considerations?

Thanks in advance

Peter

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Old 09-24-2020, 07:03 AM   #2
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For posterity, here's where I landed. No valves needed - pumps have integral lock-outs just as the helm pumps do.

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Old 09-24-2020, 11:04 AM   #3
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That looks clean and straightforward, and you can be back online without bleeding.

I didn't post this query to the thread yesterday, because I had no facts to add; but I'm curious: You had asked about valving the spare pump to isolate it until you need it (which it turns out is not necessary), but is there a good reason to put valves on the everyday pump so that it could be quickly isolated if it failed? Or do they not fail in that sort of way or it would not matter?
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Old 09-24-2020, 03:28 PM   #4
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I've never heard of an autopilot pump failing but when my a/p was getting wobblies, I steered by hand...
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Old 09-24-2020, 03:36 PM   #5
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I just had another thought (presuming you haven't done the install yet).

Might it be worthwhile to have isolation valves on the "original" pump, so that if it does go kaput (and you switch to the second one), then you could remove the original one for repair without needing to bleed or disrupt things?

XSbank: Maybe I'm just wimpy, but for long-distance work I don't like to have to hand steer (and I think Weebles is being set up for that?). I suppose then a complete second autopilot would be best; but I got the impression that Weebles already has a second pump (only) so why not "store" it in place.
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Old 09-24-2020, 04:30 PM   #6
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Quote:
Originally Posted by Frosty View Post
XSbank: Maybe I'm just wimpy, but for long-distance work I don't like to have to hand steer (and I think Weebles is being set up for that?). I suppose then a complete second autopilot would be best; but I got the impression that Weebles already has a second pump (only) so why not "store" it in place.
Frosty - good way of putting it; "store-in-place." That's exactly right.

Story-Time: On my way from San Francisco to Ensenada, the A/P goes <ERROR> code about 250-miles from Ensenada, right as I turned the corner at Pt Conception and into the shipping lane exiting the Santa Barbara Channel (in all fairness, it's not exactly a busy shipping lane). Of course it's 0200 hrs or something, so I hand-steer. I'm a bit embarrassed to admit it, but I'm an awful hand-steer helmsman, especially at night or if there is any fog out. I easily swing 25-degrees in any direction.

When my crew - one of my best friend's in the world and who has 1000's of sea miles with me - comes on-watch at first light, he's telling me "Let's see if we can fix the A/P pump."

I'm pushing-back saying "no way - these things are integral, there's no fixing it."

To which he points out "So, you have somewhere else to be? Too busy?"

Point taken. So I empty-out the aft lazaretter and unscrew the covers over the rudder and A/P. It had been so long that I forgot my A/P pump is a relic, probably from an ancient Wood Freeman (see picture). There's a reversible electrical motor (replete with case-mounted capacitor) that belt-drives a small hydraulic pump. The controls are a modern Comnav 1001 that was probably installed a few years before I purchased the boat in 1998 but the pump itself is 1960's technology. Turns out the cast aluminum sheave had split and was spinning on the shaft. We managed to drill a set screw and get it back in service.

When I got to Ensenada, I emptied all my lockers. I found a new-old-stock Comnav A/P pump that I forgot I'd purchased years ago at a West Marine Bargain Store (how I miss those!). Given labor is pretty cheap in Mexico, installing a second pump isn't much. For me, beyond a total drive-train failure, losing radar and losing A/P are about the only things that would stop me cold. I'm prone to multi-day runs, so A/P is a big deal.

Have I mentioned I'm lousy at hand-steering?

Peter
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Old 09-24-2020, 04:48 PM   #7
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Not sure how the internal valves work on your pumps. On mine they are spring loaded balls. When replumbing mine 2 weeks ago, a speck got on the surface and kept the pump from pushing to starboard. If the pump fails internally, not sure the valves prevent flow through the pump. I like that I can isolate the pump from the system by closing 3 ball valves.

The second thought is that if you have a pump failure with bits or specks going in the oil, how long before that contaminates the other pump valves? I think your design is fine to deal with a motor failure of worn out brushes, but removing one from the system would be messy. Still like mine being easily isolated with valves.

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Old 09-24-2020, 04:58 PM   #8
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I think you guys are right. If I go through the trouble of installing it, might as well put some valves in.

Thanks all so much for the feedback.

Peter
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