Re: [MV] 165' ex-USN

From: MV (MV@dc9.tzo.com)
Date: Mon Apr 25 2005 - 22:43:21 PDT


No doubt.

We just need some more cash!

Dave

Mil-Veh Co. wrote:
> Amazing the talent you find on this chat net.
>
> I'm pretty sure we could crew that gun boat or almost
> anything, from tanks to bombers with the talent we
> find right here.
>
>
> --- Fred Martin <mung@in-touch.net> wrote:
>
>>As a former tender sailor....machinery repairman
>>(machinist) I've had
>>some experience machining the thrust bearing
>>surfaces...on a tincan
>>about 3' diameter....pretty good sized lathe
>>required and a horizontal
>>boring mill to bore and cheek and oil groove the
>>spring bearings that
>>support the shaft as it goes back thru the shaft
>>alley. The thrust
>>bearings were segmented and there were several of
>>them fitted around the
>>thrust surface of the shaft. Also the bearings had
>>to be hand scraped to
>>fit the shaft with Prussian bluing and hand
>>scrapers. Would also need
>>molders and pattern makers to make up the molds for
>>the bearings and
>>pouring them and plenty of high speed babbit. If
>>you can picture a
>>destroyer with it's wake behind it pushing the ship
>>forward...it puts a
>>lot of push against the propellor shaft and it
>>requires a lot of bearing
>>surface to handle it....and you can't forget to cut
>>in the lube oil to
>>it as in one case I'm referring to. They court
>>martialed the black gang
>>that forgot. Had to cut hatches and doorways just to
>>get it out and over
>>on the tender. Took pictures of it after every
>>move....even me as I
>>machined it and afterward when it was done. Fred
>>Martin USS Arcadia
>>and USS Shenandoah....tenders.
>>
>>Mil-Veh Co. wrote:
>>
>>
>>>I believe the shafts are considered rebuilt when
>>
>>they
>>
>>>are cleaned, checked for true and for metal
>>
>>fatigue,
>>
>>>then balanced and the bearing surfaces are turned.
>>>Sometimes they are sprayed with molten metal on the
>>>bearing surface and then turned. No small feat on
>>
>>a
>>
>>>1000-2000+ lb. shaft, but its been 30 years since I
>>>had a class in that, so they might do a lot more
>>>now...I dunno.
>>>
>>>Ship shafts (say that 10 times real fast) have one
>>>problem area where the shaft passes thru the hull.
>>>This is typically where you might find a thrust
>>
>>block.
>>
>>>The thrust area is usually controlled by some
>>
>>modern
>>
>>>version of an old "Kingsbury" type bearing with
>>>collars holders that are rigid mounted to the hull
>>
>>and
>>
>>>this is what gets rebuilt in port..expensive.
>>>
>>>On older vessels this can also be a thrust bearing
>>
>>in
>>
>>>conjunction with an "iron wood" bushing type
>>
>>bearing
>>
>>>which doubles as a seal, cheaper.
>>>
>>>In the more modern version there is several
>>
>>composite
>>
>>>seals and a soft metal bushing which is designed to
>>>wear out at the same rate as the thrust bearings,
>>>which is ok because its saving the shaft bearing
>>>surface which is harder and expensive to fix.
>>>
>>>If the drive shaft is pretty long, say 1' wide
>>
>>shaft
>>
>>>that is more than 10' long, then that would require
>>
>>an
>>
>>>additional support bearing to handle the vibration,
>>>torque and keep the shaft from warping at rest,
>>>another additional cost too.
>>>
>>>Those support bearing points almost never wear out
>>
>>and
>>
>>>long as they are greased...thrust bearings wear out
>>
>>oh
>>
>>>around 6000-10,000 hours on avearge depending on
>>
>>the
>>
>>>type of vessel and power. On the real large ships
>>
>>the
>>
>>>shafts must be rotated even while in port to keep
>>
>>them
>>>from warping.
>>
>>>I'll bet you can get the props and shafts cleaned,
>>>balanced, trued and surfaced for well under
>>
>>25k...IF
>>
>>>you are at the right ship yard.
>>>
>>>So who wants to sign up for the black gang (engine
>>>room for you landlubbers)?
>>>
>>>....Bridge to Mr. Scott, we need MORE power, now
>>>Scotty! Aye Capt., I'm given er all she's got and
>>
>>if
>>
>>>I give er any more she'll blow!
>>>
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>>
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>>
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>>
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>>
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>>>
>>>
>>>
>>
>>
>>===Mil-Veh is a member-supported mailing list===
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>><mil-veh-off@mil-veh.org>
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>>
>
> ===Mil-Veh is a member-supported mailing list===
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