Been Doing A Big Job For Past Three Days

[jackie schmidt]

One of our customers, G&H Towing, who operate all of the Harbor Tugs in the Houston/Galveston area, did a emergency dry docking on one of their 5000 horsepower tugs. The vessel is full ABS class.
Inspection showed that both Stern Tubes were severely wasted. This meant replacing the tubes, then align boring the tube’s bearing mount straight with the reduction gear and aft strut bearing.
We rough machined two new tubes, and the Shipyard fit them and welded them in place close enough to align bore.
Here are some pictures. The holes for the bearings are bored to a nominal 14 inch diameter, 30 inches long. I finished up the boring this morning. I will machine the new bearings in the morning to press in.

The prop shafts are 11 1/2 inch and 30 ft long.

http://benchrest.com/attachment.php?attachmentid=24198&stc=1&d=1608004037
http://benchrest.com/attachment.php?attachmentid=24199&stc=1&d=1608004111
http://benchrest.com/attachment.php?attachmentid=24200&stc=1&d=1608004192
http://benchrest.com/attachment.php?attachmentid=24201&stc=1&d=1608004303
http://benchrest.com/attachment.php?attachmentid=24202&stc=1&d=1608004371
http://benchrest.com/attachment.php?attachmentid=24203&stc=1&d=1608004438

As you can see, I’m working off of a 10 ft scaffold, lots of climbing. Everything came out great.

 

[BillBrawand]

[QUOTE GREAT JOB TOUGH TO KEEP AHEAD OF YPOU SHARPIES.=jackie schmidt;840462]One of our customers, G&H Towing, who operate all of the Harbor Tugs in the Houston/Galveston area, did a emergency dry docking on one of their 5000 horsepower tugs. The vessel is full ABS class.
Inspection showed that both Stern Tubes were severely wasted. This meant replacing the tubes, then align boring the tube’s bearing mount straight with the reduction gear and aft strut bearing.
We rough machined two new tubes, and the Shipyard fit them and welded them in place close enough to align bore.
Here are some pictures. The holes for the bearings are bored to a nominal 14 inch diameter, 30 inches long. I finished up the boring this morning. I will machine the new bearings in the morning to press in.

The prop shafts are 11 1/2 inch and 30 ft long.

http://benchrest.com/attachment.php?attachmentid=24198&stc=1&d=1608004037
http://benchrest.com/attachment.php?attachmentid=24199&stc=1&d=1608004111
http://benchrest.com/attachment.php?attachmentid=24200&stc=1&d=1608004192
http://benchrest.com/attachment.php?attachmentid=24201&stc=1&d=1608004303
http://benchrest.com/attachment.php?attachmentid=24202&stc=1&d=1608004371
http://benchrest.com/attachment.php?attachmentid=24203&stc=1&d=1608004438

As you can see, I’m working off of a 10 ft scaffold, lots of climbing. Everything came out great.[/QUOTE]

 

[antelopedundee]

Do you normally keep stock on hand to make prop shafts or is it usually readily available?

 

[Jim Kobe]

How do you feed that boring bar? Handwheel?

 

[jackie schmidt]

How do you feed that boring bar? Handwheel?

It’s a traveling head bar. That feed head you see at the end has a 12 to one reduction. When you hold the hand wheel with a rope tied off, it causes the feed screw to turn 1/12 the revolution of the bar. The cutter head has a threaded key that advances the head.
Here is a short video of me align boring the struts and stern tube in a new boat. I have two bars running at the same time.


https://www.youtube.com/watch?v=NgFpC6jBdJU&list=PLt3TQdSqIPVz30FEyVjvqTAnwNa3D33J7&index=7

 

[jackie schmidt]

Do you normally keep stock on hand to make prop shafts or is it usually readily available?

We keep a certain amount on hand, usually in the 7 to 8 inch diameter range. If we get a contract for a series of vessels, we will Oder a quantity to insure delivery and to get a better price.
Here are six 38 ft 9” diameter bars we got in to satisfy a three boat contract we wil be doing over the next two years.

http://benchrest.com/attachment.php?attachmentid=24204&stc=1&d=1608045174

 

[Al Nyhus]

Wow!

 

[Gene Beggs]

Jackie, that is some awesome equipment and amazing technology!
Thanks for sharing with us.
Fascinating stuff indeed.

Gene Beggs

 

[rsmithsr]

jackie,
what does this cost the customer...pure custom large work ??
you can say pass or ignore,not an issue
just wondering

 

[Engrbill]

Wow!!

Awesome work. Just don't drop one of those babies on your foot Jackie.

 

[dmort]

Nice photos. Your pneumatic boring system has seen some use and is still kicking.

Mort

 

[Jim Kobe]

Now, how do you get the prop shaft in with the bearings pressed in there? How much clearance between shaft and bearing and what keeps out the water?

 

[jackie schmidt]

Now, how do you get the prop shaft in with the bearings pressed in there? How much clearance between shaft and bearing and what keeps out the water?

The shaft simply slips through the bearings. The bearings are water lubricated. They are a brass shell with a hard rubber inside that has grooves molded in to enhance water flow.

This size bearing starts out with .035 inch clearance over the shaft journal. Here is the brand.


https://www.duramaxmarine.com/bearingLine2.ht

And a picture of me machining the brass shell to fit. We give them an average .002 interference fit in the housing.


http://benchrest.com/attachment.php?attachmentid=24207&stc=1&d=1608236201

The shipyard installs the shafts with a crane, chainfalls and comealongs.

 

[Louis.J]

Jackie thanks for sharing your work and I highly do appreciate your doing so. It is beyond interesting to me and I hope you will continue to share more.