dsergison
Diamond
- Joined
- Oct 23, 2003
- Location
- East Peoria, IL, USA
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Leaning machine shop
- Thread starter dsergison
- Start date
- Replies 11
- Views 2,662
I was on a little 450 ft FFG and it would get tossed around like a toy in 25'+ seas. We traveled between two converging Typhoons in the South China Sea in 30' seas and 140KT winds. The pilot house had to figure out how to keep full power to the prop while going vertical and let off at just the right time so the momentum of the 20' prop didn't tear the back of the ship apart when it came out of the water. I was one of 4 people in engineering that didn't get seasick. My job was to man the console next to the main engines and hold down the power turbine overspeed override button when the pilothouise didn't let off quick enough otherwise the turbines would shut down (very bad things happen with no main engines).
The ship wasn't that big, but you could look down the passageways and see the ship twisting, especially at the rear when the prop started coming out. The top of the ship was all aluminum, joined by an explosion welded strip. During the trip through that storm that strip split apart in one section about 30' long. The wind (140KTs is like 180 MPH BTW) ripped off anything outside that wasn't part of the main structure. All the helo safety nets and posts were gone. All the firehoses and several of the antennas tore clean off.
We weren't allowed to open any hatches, but a couple friends and I were too curious and when the wind wasn't howling so bad We tied ourselves off and I pushed a hatch open to take a look. Looked just exactly like that Perfect Storm movie. Not a sight I will ever forget.
The ship wasn't that big, but you could look down the passageways and see the ship twisting, especially at the rear when the prop started coming out. The top of the ship was all aluminum, joined by an explosion welded strip. During the trip through that storm that strip split apart in one section about 30' long. The wind (140KTs is like 180 MPH BTW) ripped off anything outside that wasn't part of the main structure. All the helo safety nets and posts were gone. All the firehoses and several of the antennas tore clean off.
We weren't allowed to open any hatches, but a couple friends and I were too curious and when the wind wasn't howling so bad We tied ourselves off and I pushed a hatch open to take a look. Looked just exactly like that Perfect Storm movie. Not a sight I will ever forget.
winger
Stainless
- Joined
- Dec 28, 2005
- Location
- portage county, wisconsin
joined by an explosion welded strip
Not familiar with this, care to explain?
A navy machinist I knew said their machines were mounted on thick steel plates which were in turn mounted on three points so the ship didn't twist the machines. they normally didn't do any machining while under way.
Dave
Not familiar with this, care to explain?
A navy machinist I knew said their machines were mounted on thick steel plates which were in turn mounted on three points so the ship didn't twist the machines. they normally didn't do any machining while under way.
Dave
DocsMachine
Titanium
- Joined
- Jan 8, 2005
- Location
- Southcentral, AK
-Explosion welding is a method used to join dissimilar metals, like steel and aluminum. Garwood mentioned the top half of the ship was aluminum, joined to what was presumably a steel hull. Rather than being bolted (or perhaps more likely, in addition to being bolted) some of the seams were explosively welded.
Simply put, you take a sheet of steel and lay it flat, and a sheet of aluminum and lay it just over the steel, but not touching, and at an angle.
On top of the aluminum you lay a sheet of plastic explosives, which are detonated starting at the low end. As the shockwave travels up the explosives, the aluminum sheet is forced into contact with the steel, with the "wave front" basically blasting all the oxides off of either piece.
When the smoke clears, the two pieces are joined as tightly as if they'd been brazed or welded together.
Doc.
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
A memoir speaks of the risks of steel hull/aluminum superstructure construction: The End of an Era: The Memoirs of a Naval Constructor - R. J. Daniel - Google Books
The strip was about 2" wide and 3/8" thick. One inch of it was aluminum, the other inch was steel. I don't know how they made these strips, but that is how they attached the aluminum top to the steel bottom on an FFG. I have a piece of that strip somewhere that I saved from a period when we were in drydock. It's kind of a head scratcher to look at.
I never looked at how the lathe we had was bolted down. I doubt it was too fancy. They were probably most concerned that the 3 ton lathe didn't become a missile than how straight the bed was.
Hard to find a decent picture that shows the entire ship well. In this one you can see helo hangers and all the stuff behind the pilot house. A lot of the stuff above the helo hangers was torn clean off and everything on the back of the ship (helo pad and poop deck) was wiped clean.
The hull is steel, but everything above the main deck (above the hull) including the pilot house is aluminum.
The hull is steel, but everything above the main deck (above the hull) including the pilot house is aluminum.
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Bill D
Diamond
- Joined
- Apr 1, 2004
- Location
- Modesto, CA USA
I believe some USA coins are explosion welded? maybe everything except the penny.
Bill D
Bill D
winger
Stainless
- Joined
- Dec 28, 2005
- Location
- portage county, wisconsin
thanks for the info
Dave
Dave
duckfarmer27
Stainless
- Joined
- Nov 4, 2005
- Location
- Upstate NY
And this is why some of us - even if fascinated by the mechanical marvel of a ship - were content to be down in the mud combat engineers or even grunts. Never got seasick in the mud.
Dale
