1:192 USS Saint Paul CA-73 (1966-1968)

[Fliger747]

We called the iron spheres used to compensate the compass the "Navigators balls". In aircraft a similar procedure is used to swing the compass, generally on a "compass rose". A compensation card is created giving the deviation between indicated and actual magnetic direction. Even the 747 had a small whisky compass (filled with alcohol). However the main magnetic sensing is done with a "flux gate" which senses the alignment of the earths magnetic field.

Have fun!

[sgrog04]

Been away for a bit working on trying to get the hull form sorted out.

Turns out the bow is a quite complex! Main hull and stern turned out decent. Not 100% satisfied with the forecastle/bow, but it looks like it should work (nothing a little sanding cant fix). Open to thoughts, opinions, or feedback. To get this result, I used the hull lines, and placed at the correct frame, and manipulated the curves to get the right shape (more or less)...

Now with that done, working on the various components for the propulsion system, and for the superstructure I plan on making that as one detachable unit. Probably get the propulsion and internals done first so I can start printing and hopefully get testing done this winter season still!

[sgrog04]

these areas circled in red do not look right. does this look something like what you are using to get the shape of the frames?

I definitely agree with that. And that does look pretty close to what I am using. The sketches match right, but when lofting that is where I run into troubles. The first 6 stations on the bow really need a lot of work.

[DrPR]

sgrog04,

Did you use the Table of Offsets to create the stations in CAD, or are you working from the hull station lines drawing? Note that the Station 20/21 (midships) lines are not the same on the left and right sides of the drawings. There is a "step" or overhang on the right side but not on the left. Something strange there.

I found a similar peculiarity in the Cleveland class hull lines drawings. These hull lines drawings were mostly for show, and for the engineers to use for calculating the Table of Offsets. The actual hull construction used the Table of Offsets to loft the frames.

I did a CAD model of the Baltimore hull about 15 years ago. The knuckles are tricky. In my CAD program you have to mark points on the station lines where there are knuckles to cause the program to create the knuckle and not smooth it over.

It appears the knuckle is displaced high on part of the stern quarter.

Phil

[sgrog04]

sgrog04,

Did you use the Table of Offsets to create the stations in CAD, or are you working from the hull station lines drawing? Note that the Station 20/21 (midships) lines are not the same on the left and right sides of the drawings. There is a "step" or overhang on the right side but not on the left. Something strange there.

I found a similar peculiarity in the Cleveland class hull lines drawings. These hull lines drawings were mostly for show, and for the engineers to use for calculating the Table of Offsets. The actual hull construction used the Table of Offsets to loft the frames.

I did a CAD model of the Baltimore hull about 15 years ago. The knuckles are tricky. In my CAD program you have to mark points on the station lines where there are knuckles to cause the program to create the knuckle and not smooth it over.

It appears the knuckle is displaced high on part of the stern quarter.

Phil

I do not have the Table of Offsets, only the hull station line drawings. I am thinking of putting in another request for data at the National Archives, and open to any drawing documents that may be useful. Right now I only have the Booklet of General Plans, and deck logs from 1966-1968.

It does look like it displaced high on the stern quarter. I think part of it is my frame spacing of 0.38" vs what should be 0.33" spacing. Minimal, but may account for the distortion partially. The other thing I am seeing is that my inboard profile goes from 2 to 164 for frames (with F.P. and A.P.), but the station line drawing goes from 1 to 39.5 -- Roughly the same number of stations, but the frame spacing looks off. Especially when doing a curvature analysis.

I think I will start from scratch again and try a new approach.

[DrPR]

The Booklet of General Plans is just an "executive summary" for people who can't tell the pointed end from then blunt end - for marketing purpopses. The drawings aren't very accurate.

****

I don't recall much about the Baltimore Class blueprints. But the Cleveland Class blueprints were 19 reels of microfilm - mostly plumbing, wiring, furniture lists, key lists, nameplates over doors, and such.

If you are thinking of ordering blueprints from the National Archives try to get the index reel (usually reel 1). This lists all of the blueprints and you can find where the desired drawings are. Hull drawings are usually on the first reel, but things like propellers and turrets are on different reels. Unfortunately the Cleveland Class drawings didn't have a single index reel, but each individual reel had its own index. I had to buy all 19 in order to find all of the drawings I needed!

Note. The ships plans are in Record Group 19, and are listed on "reels." The Cleveland Class drawings are on reel 5537. However, this is a virtual reel, and the drawings are actually on 19 physical reels of microfilm. This can cause confusion! You can get the microfilm copied onto DVDs.

****

Another source of plans is The Floating Drydock.

https://floatingdrydock.com/

Phil

[sgrog04]

The Booklet of General Plans is just an "executive summary" for people who can't tell the pointed end from then blunt end - for marketing purpopses.

Best way I have heard it described by far. I'm more familiar with aviation blueprints as I've used them for WWII aircraft restoration, and professionally for work I use blueprints, but the naval prints are a little different then I am used to and appreciate the insight! Getting all reels will probably be the next step. The researcher I was working with mentioned there were over 30 boxes of items for the Saint Paul. I would have it all scanned, but the cost was a little prohibitive all at once. The more I dig into the ship the more questions arise.

Project is taking longer then anticipated, but the process has been fun!

[sgrog04]

sgrog04, how did you go about to get the frame measurements for your drawings?

I think if I understand correct. I took the General Dimensions "Length Between Perpendiculars" which was 4'-0", then offset planes the length of the ship at 0.33" intervals (1:144 conversion), and then fit the the sketches in that X envelope. I also took the "Breadth Extreme" of 70' 9.875" scaled and did similar for the Y dimension. to get the Z dimension I knew the "Design Water Line" was 22', and scaled the Z direction for both plan sets.

[sgrog04]

I would use the overall length of 673'5" divided by the scale to get 42.088" long overall. why are you using 1/144 scale & not the 1/192 scale as per your title?

I will give that a try! And the 1/144 was a typo. I had been going back and forth between the two scales, but the 1/192 is what I am sticking to. Using that and doing measurements for where the waterline was on the previous rendering, at 20' I should see the waterline about 1.25" from the keel. It was 1.1". The length of the model i had was 40.1" so as you propose I think that might solve some of the issues I had with proportions.

I appreciate the challenge/suggestion!

[sgrog04]

how did you go about getting the ship's frames from the drawing/plans to the cad screen?

Placing the forward perpendicular (F.P.) on the origin, I offset planes along the X axis where to the aft of the ship. I created a canvas on the XZ plane that had the frames and generic shape. I also created a canvas on the YZ plane where I scaled (from conversations here, my scaling was off) the frames sketch and at each frame used that as my guide to trace. The sketches all matched the canvas, but when I went to loft between the frames there were a lot of issues with bumps and curves in incorrect places.

[DrPR]

Even if you used the Table of Offsets to set points in your CAD drawing you could expect a few bumps and strange curves.

An engineer did all of the calculations by slide rule and recorded the results by hand. Then a draftsman rewrote the engineers numbers on the blueprint. With thousands of numbers there were many opportunities for errors.

When I made my CAD model of the Cleveland class hull from the Table of Offsets, using Excel to create decimal inch equivalents of the foot-inch-eights numbers, I made a typos. I had about half a dozen "bumps" in the CAD lines. After correcting my mistakes I found four or five values in the Table of Offsets that were off by a foot, an inch or an eighth.

Then to get really smooth hull surface curves I had to do a bit of editing of the point positions on the section lines. It was a successive approximation process.

Phil