Gear pump standard?

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hobgobbln
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Re: Gear pump standard?

Post by hobgobbln »

Bob D. wrote: Thu Jun 09, 2022 7:39 pm I guess the only game in town would be Philadelphia/ Delaware River area.
Well done!
I don’t know the exact location and I’ve never been to that area, but from what I can find, that’s the right spot. They originally said it would be for the Schuylkill River and kept saying Philadelphia if that helps at all.

I’m from the middle of Mass, about 20 minutes north of the Connecticut line. I never knew rivers could reverse until this came up. When he originally said, “point in the direction of flow” I thought he meant sway a little with the currents not actually turn completely around. This is what I get for assuming haha

Griz
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Bill Shields
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Re: Gear pump standard?

Post by Bill Shields »

Chesapeake and Delaware canal...is tidal

Schuylkill river is NOT tidal.

The Delaware river into which it flows is barely tidal in the Phila area.

The tidewater limit is near Trenton, but tides do not flow up the Schuylkill.
Too many things going on to bother listing them.
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NP317
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Re: Gear pump standard?

Post by NP317 »

And as for the salt line, it will be heading upstream as ocean levels rise and river levels drop.
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Re: Gear pump standard?

Post by hobgobbln »

Maybe it’s just the lower portion that’s tidal? I found tide charts from NOAA but I don’t know where they measured it.
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Bill Shields
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Re: Gear pump standard?

Post by Bill Shields »

Delaware river where I live is very tidal, but it is 60 miles north to phila. The Schuylkill river has a solid flow into the delaware. ...always.

Trenton is north of phila..which is the end of the salt line.

Where the rivers meet may be a pool that is tidal, but I would not guarantee specific flow in any one direction since it is a big river 'delta' area that is the Phila Navy Yard which is considered a fresh water port
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hobgobbln
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Re: Gear pump standard?

Post by hobgobbln »

I will definitely find out what they’re talking about then. A normal, freshwater river would make this whole thing 100x easier.

Thanks Bill
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Bill Shields
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Re: Gear pump standard?

Post by Bill Shields »

😀
Both parents WW2 Navy...mom grew up in Phila and Navy Yard after college.

Feels like place was my 2nd home as youngster.

Place but the dust cause did not do nuke ship building or support.. so was expendable.

Building frigging cruise ships now...how ignominious
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liveaboard
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Re: Gear pump standard?

Post by liveaboard »

For light brackish water, 318 stainless shaft is more than sufficient.
My old boat propshaft is mild steel and lasted 40 years in the water with anodic protection.

You will need an anode close to the prop and shaft though (3-5'), and electrically bound to it and the hull.
Not zinc in your case, but aluminum.
That will need to be replaced every few years as it dissolves away to protect the expensive parts. If it doesn't dissolve, it's not working and you should change to magnesium.

If the prop is machined in the usual way, it will have to be arranged to point forward. if the mounting cone is custom machined it could be mounted backwards, so it tails in the stream.
But;
Standard props are shaped to be more efficient when pushing the vessel forward, but still able to give good thrust in reverse.
There are also bi-directional props that are 50-50. Since efficiency is not critical, and the stream will either be forward or back (not sideways), possibly such a prop would allow a fixed position without a rudder and pivot.
Because a pivoting thing is going to make trouble for sure.
There are also clever props with reversing blades. Those have moving parts and need maintenance.
Plastic can be good. My bow prop is plastic and delivers 10HP.
hobgobbln
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Re: Gear pump standard?

Post by hobgobbln »

318 or 316?
I looked up 318 and only found arguments about whether people meant 316 or some new type of “duplex” stainless.

Prop wise, a friend twice removed does a lot of small fresh water boat work. When I’m ready I’ll see what he’s got laying around for old motors with blown engines for the lower halves and props to experiment with. I’ve got 8 projects ahead of this one so I’ll have time to scrounge for parts. Plus I’ll still need to build a tank to have something to experiment with.

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liveaboard
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Re: Gear pump standard?

Post by liveaboard »

Yeah, 316.
I'm a little dyslexic...

That's what the propeller guy at the shipyard recommended I use in similar water.

I'm actually in the process of packing it up to send to the shipyard for installation (finally) next month.
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Re: Gear pump standard?

Post by hobgobbln »

I hope the install goes smoothly
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liveaboard
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Re: Gear pump standard?

Post by liveaboard »

Thanks;
I'm traveling to Amsterdam to do the job.
The old bushing is tapered; Propeller guy told me he'd never seen anything like that in 50 years.
The old shaft is tapered to match of course,
I'll try to ream the bushing out to the shaft size in situ, 45mm. If I fail it will have to come out and it's NOT pretty.
The boat is steel, 100 years old.
The old shaft isn't that old, but the shaft tunnel is rivetted to the hull, so that part is pre-war at least.
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