ARL 12 USS Poseidon

[Fliger747]

Showing skegs/props/rudder assemblies inserted under the stern and glued with epoxy. Currently removed the printing supports and puttied the transition, to be sanded and cleaned up.

Tom

[Willie]

Hi there Tom and all,

Showing skegs/props/rudder assemblies inserted under the stern and glued with epoxy. Currently removed the printing supports and puttied the transition, to be sanded and cleaned up.

I am absolutely speechless with your constructions: true ship in small scale, nothing to imagination, true inspiration, in the line of when I grow up I wanna be this guy.

Please keep them coming, and best regards from this side,

Willie.

[Fliger747]

Thank you Willie! I sanded the skegs and will put some primer n them after a bit. Overnight I printed the Kingposts complete with brackets, ladders etc. They came out well, but the booms were full of lots of kinks and bends. These were all printed vertically and were still printing this morning! Booms a total loss so may try printing them horizontally. If that doesn't work, then it will be back to traditional methods. Either wood, aluminum or brass turned on the lathe. The ones on the APA are wood, but don't have the correct taper and diameter stepping.

Cheers: Tom

[DrPR]

Tom,

I am curious about the engines/props on the ARL. Here I will show my lack of knowledge, but did the LSTs have dual propellers? Somehow I thought they were single props.

I have heard that the LSTs had diesel engines driving a transmission that had an inflatable clutch, like a big doughnut. Deflate it to disconnect the engines from the transmission and inflate it to reconnect the engines to the transmission.

The diesel powered ships needed a clutch to disconnect the engine from the transmission for stopping the propeller/shaft and shifting into forward or reverse. If you didn't stop the propeller and shaft - which usually had greater mass than the moving parts of the engines - when changing direction the inertia of the more massive propeller and shaft, plus the added force of the prop "windmilling" in the water, would stall the engines or even start them running backwards! They also needed a brake of some sort to stop the prop shaft.

My first assignment after Officer Candidate School was Engineering Officer on a small diesel powered minesweeper. It was McHale's Navy!

Phil

[Fliger747]

Phil:

Yes the LST's used twin screws, each powered by a 900 HP Electromotive 12 cyl. Diesel as used in submarines and locomotives of the era. Yes they used a pneumatic clutch as well. Not a lot of HP, but they did have exceptional range (up to 24,000 NM.) and the cruising speed was near the max. They were optimized to fit into the slow (10 knot) convoys. I have a couple of photos of Poseidon in floating dry dock showing the skegs and screws. Much like a tug boat she has large diameter fine pitched screw. This in addition to the stern anchor/winch, would help retracting from a beach. It wouldn't surprise me if the propulsive units were very much tugboat like.

Tom

[Fliger747]

Last night's task was printing booms. They are long enough that they have to be printed one at a time diagonally across the platen. A thorough drying is necessary as the thin booms tend to banana, which is unacceptable. After a thorough drying I have been correcting then to flatness under weights with their supports on. Surprisingly an attempt to print them vertically was a bust for the booms, though worked ok for the king posts. So far the best attitude was an inclination of 5 degrees or so on the platen.

The Kingposts have a 1/8" hole thru the length which will allow insertion of a brass rod to anchor the post securely in the deck.

Cheers: Tom

[Fliger747]

Not entirely happy with the booms, they have a tendency to banana, I'll defer dealing with that for a bit while I work up a real life copy of the Whelan Davits which decorate the aft superstructure. A moderately lengthy print as, though lacking in mass, they spread out. I have made a few further changes to the design while it is printing, a trial fit will allow accurate final adjustments. A problem with mixed traditional and digital construction is one must do an "as built" set of measurements rather than just rely on other parts of a digital design. An exception was checking the fit of the LCVP when i could import the boat and move it into trial position.

Cheers: Tom

[Fliger747]

As a note:

A windmilling propeller whether air or sea should continue in the normal rotation as long as the ship or plane is continuing in the original direction. Reversing of ships propulsion is an interesting subject. Many steam turbine ships had reversing turbines for use astern, usually of a smaller size. The Uniflow Triple Expansion steam piston engines, as with steam locomotives, changed the timing of the valve gears to change the direction of rotation. An example was the scene in Titanic of reversing the engines, which was actually filmed aboard the Liberty Ship J O'Brian. Turbine or Diesel electric drive reverses the polarity of the electric motors and allows for a easier change of direction. Saratoga and Lexington used such a drive setup as did other various ships such as the DE Whitehurst. After repair of the Kamikaze damage was repaired (suffered off Leyte) she was equipped with large cable reels topside to also serve as a mobile floating power station.

Tom

[Fliger747]

Slipping standards: Eye-Phone photo of the trial fit of the Whelan Davits. Now I can print the Port-Starboard davits with additional detail. Unlike the APA, the boats do not rest in cradles, but hang from the davits, which is a minor issue for modeling as to modeling the pieces from which the boats hang with sufficient strength.

A ponderable!

Tom

[Fliger747]

Apologies:

I attempted to post this upright, twice, apparently something in the forum software knows better so not sure what the issue was.

Tom

[Fliger747]

Lots of items (everything just sitting in place) on board. The Whelan davit is a test horse, the more detailed final items printing. The increased diameter of the forward boom resulted in a more useable item. Before a lot of these items are finally attached other detail must be accomplished such as rails, maybe some painting etc in proper order since some of these areas will be difficult to access once some items are in place.

A somewhat rough and ready on the ways photo, but I am using a long focus (100 mm) macro lens and two studio flashes with soft boxes. To get sufficient depth of field with a long focus lens, photo stacking is due where a series of photos are taken with each having a different focal point. The software combines the series of images into an image with greater depth of field.

Tom

[BB62vet]

Tom,

Quite impressive - that's all I can say at this point. I think the davits and kingposts are really nicely done - detailed and when painted, should prove to be very attention-getting. Your overall effort is really taking shape - the hull work is also outstanding - the skegs have blended nicely into the rest of hull and don't seem to present something that would not pass muster.

Kudos!

Hank

[Fliger747]

Hank:

A good reason do an off the wall project, If I was doing an Iowa, someone would know the exact position of every hull plate and rivet. When I did my Master's thesis I did a project that absolutely no one else knew anything about so got no substantive questions during my thesis defense. I have to wait to do the portside boom till after the Davits are printed.

Currently working on the boat winches, a similar type as used on the APA. Those were however made by traditional methods, so no file on hand.

Tom

[Fliger747]

Found it and after updating my scanner software produced an image of Poseidon in a floating dry dock for some hull work. Maybe Ulithi, maybe San Diego, not sure of the location. Note the twin large fine pitch props and solid skegs.

Tom

[DrPR]

Tom,

It is looking really nice!

About the davits. They are single bank, double arm trackway gravity davits (there are single arm davit systems for small boats), but are they Whelan davits?

I ask this because we had similar davits on the OK City but I have never been able to find good documentation about them or learn what the "official"l name is.

https://www.okieboat.com/CAD%20miscellaneous.html

Also, did the ARL boat winch look like the whaleboat winch shown on the link above? If so, I have the patent drawings for it.

Phil

[Iceman 29]

It goes fast!

Bravo Tom, a pleasure to follow.

[Fliger747]

Phil:

It would appear that Okie Cities winches were from the same manufacturer or of similar origin. From the BOGP I have it appears that the ARL's used the same boat winch and davits that were on the original LST's before they were converted. From the info I have divined these look to be the same units as used on the APA as well. There are some good photos available that show the winches in use on the LST's. The motor/gearhead units look similar to the OKC ones, but with a rectangular cover housing the double drum cable reels.

With the ASSumption that the ARL used the original winches from the LST's, I proceeded accordingly. On the APA I hand constructed these winches and davits. It might or might not be worthwhile to replace the ones on the APA, but that would be major surgery.

As to the official name? The Navy nomenclature would likely be descriptive. My understanding (subject to error) is that the Whelan firm invented this style davit. Sort of the Kleenex of gravity davits.

The cargo winches are somewhat more opaque, I have photos, usually just one partial view and all five appear to be different from each other.

Tom

[raggs]

Tom,

You are correct on the rectangular housings of the winches on the LST. I have pic somewhere in the stash where I can
see a single drum inboard, facing stern to the davit, but not a dbl. The housing is placed at a certain angle to the deckhouse
which leads me to believe there was a block placed somewhere centered in between the davits to lower the boats. Just my guess.

Perhaps you can contact the LST 325 folks to send you a pic.

Paul

[Fliger747]

Paul:

Yes there are some good winch photos taken on LST 325, including a sequence of lowering a boat. HNSA has a BOGP of a LST 525 Class which shows the location of the winches and how the cables were run. Somewhere (Cann'a find em) I have some technical drawings of these winches. They used two drum spools side by side and the cables paid out simultaneously across the deck to a double sheave and ran each fore and aft to another sheave by the inboard bulkhead and up into the head of the rails to attach to the actual arms. I have seen photos of these cables running several inches above the deck, in the same manner as on the APA's. The Sphinx BOGP plans show the winches in about the same location as on the LST, under the bridge wings.

LST O1 deck.jpg (62.41 KiB) Viewed 1961 times

A greasy stripe on the trousers six inches up was an insignia of the amphibious forces.

Cheers: Tom

[DrPR]

Tom,

The patent for the W. F. Hickson boat winch is #3,081,067. It was owned by the Welin Davit and Boat Division of Continental Copper and Steel Industries, Inc. It has 11 drawings, including recommended rigging for the double arm trackway gravity davits. At the end of the document are references to earlier relevant patents.

The file isn't too large, but the forum won't allow me to attach a PDF or ZIP file.

It is easy to get a copy on the US Patent Office web site if you know the patent number. I got the patent number by searching the patents for "winch." It wasn't the only instance in all US patents where "winch" was used!!!

I got the name "double arm trackway gravity davit" from a US Navy bosun mate training manual. I have never been successful getting blueprints for them. I made the davits on my OK City model by guestimation from photographs.

Phil