jackieschmidt
Gold $$ Contributor
That vessel uses a 74 inch diameter X 54 pitch wheel. The engine is a KT -38 Cummins at 1000 HP at 1800 rpm. It goes through a 5.9 to 1 reduction gear, making the shaft speed at around 300 RPM.
The Captain Reported A Severe Vibration!
- Thread starter jackieschmidt
- Start date
jackieschmidt
Gold $$ Contributor
99% of inland and river push boats use a 6 rudder system the rudders aft of the propellers are the main steering rudders. The 4 rudders forward of the propellers are flanking rudders, used in backing up and allowing the captain to actually shift the vessel sideways by skill use of the main rudders and flanking rudders.
Here is a picture of one of the main rudder,, prop, and flanking rudders on a new 3200HP tug that is going into service soon.
The other picture is the vessel when we align bored the shaft line back in July.
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Jackie I will bet you have a million stories of how people butcher these vessels. You should write a book! I am assuming these are river and saltwater vessels you work on.
ELR LVR
Silver $$ Contributor
I tell my customers
"This is an at your own risk facility, I accept no responsibility for how you treat your machine"
And there are no warranty on China Parts (when they dont wish to pay for OEM)
jackieschmidt
Gold $$ Contributor
Yes, I do.
You would be hard pressed to find a more abused piece of equipment than an Inland Pushboat.
It’s more due to the extreme environment that they work than human fault.
The darned things just seem to be self destructing on a daily basis.
I rather jokingly say that in my Shop, we have a rather simple business plan, “They break it, we fix it, we bill them, they pay us”.
PhilC
Silver $$ Contributor
Do my own as well, that way there's only one person to blame if wrong.
ELR LVR
Silver $$ Contributor
When I ran my welding business for some 15 years or so
My main income was repairing Heavy Equipment
Such as Bulldozers D8's, excavators, backhoes etc
They are very tough but not indestructable
Every person that operates one, except for the Owner of one
treats them as if they are indestructable, No finess
When I run equipment I try to finess things like the hydraulics, ease into it, absorb the load like working a human muscle, rather than working it like a ...muscle car ...haha
----
I bet people treat their big boats the same way as a big heavy piece of equipment
thinking that since its so big, and heavy it must be indestructable
---
worse yet, is instead of maintaining them to prevent downtime
(Keep nice machines, running nice)
they wait until it's broken before deciding, maybe its time to give it some maintenance
and then try to suggest it's an emergency and can't afford the downtime
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So if I did the math right, 1000 HP at 1800 rpm = 2918 ft-lbs of torque at the crank shaft. *5.9 = 17,216 ft-lbs of torque at the prop. So that's the equivalent of 5739 pounds hanging from the OD of the prop. I'll let someone else ponder what the pressure is on the face of those blades. Seems like the wrong place to go cheap.
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jackieschmidt
Gold $$ Contributor
They are. Plus, props are always encountering something. The Intracoastal Waterway System, despite the best effort of the Corps of Engineers, is full of all sorts of junk. That, and you are only guaranteed about 8 feet of depth at any given time. Fronts come through, north winds, low tides, the depth goes down, but they keep running.
The ability in Straightening shafts is a necessary requirement in our line of work. We have four special “straightening rigs” that we designed and built that we straighten both Prop Shafts and Rudder Stocks in. The smallest has a 150 ton capacity, the largest 750 tons capacity.
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I've seen the pictures of the shaft straightening equipment that you posted a long time ago. It is totally impressive. Every time the guys in the neighborhood try to straighten something I suggest sending it to Schmidt Marine Machine. They have no idea what I am talking about. But I like the big lathe the best.
Retired shooter
Gold $$ Contributor
Short story,
Years ago in dad's welding shop. Farmer brought in a bent shaft from hydraulic cylinder. Asked if it could be straighted. Dad working on a different repair for someone else said maybe, when I get done with this one I will try.. Guy threw a fit, I need it now. We had a 120 ton press in the shop. Dad put shaft in press started working it. He got shaft straight in 20 min or so. Took it back to front door, fellow was happy, asked what he owed. $ 20.00 dollars Dad replied. Fellow through a fit. That took you 20 min. Dad looked at him says wait a min. Took the shaft back to the press, Bent it again I thought he was going to make a horse shoe out of the shaft .Took it back up front, put it in guys truck, told him. " Now you owe me nothing. Dad came back in passed me, & said Don't you say a G D word.
Amazing how some people can screw up an anvil in a pile of saw dust.
To all a good day.
Tod Hendricks
Gold $$ Contributor
It also surprised me the blades were hollow, I have similar sized props, although they are CP and each blade is cast, the fixed props I’ve been around I assumed were cast and solid.
Is that a Chinese thing?
jackieschmidt
Gold $$ Contributor
The blades are solid cast, it just looks hollow.
Very few uses Controlled Pitch, (variable pitch), props in “The Ditch”. It goes against the “kiss” system. Keep it simple and when it does self destruct, the cost of getting it pushing barges again is not too prohibitive.
You also see very few Z Drive units, for the same reason.
They do appear on the Mississippi River system. But the mainstay is still the typical propeller and rudder system.
Very few uses Controlled Pitch, (variable pitch), props in “The Ditch”. It goes against the “kiss” system. Keep it simple and when it does self destruct, the cost of getting it pushing barges again is not too prohibitive.
You also see very few Z Drive units, for the same reason.
They do appear on the Mississippi River system. But the mainstay is still the typical propeller and rudder system.
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NorCalMikie
Gold $$ Contributor
Jackie,
I've got to give you PROPS for the entertainment value you provide!
I've got to give you PROPS for the entertainment value you provide!
jackieschmidt
Gold $$ Contributor
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