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Topic: Detailed photos for SO radar and mast? |
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Bob Steinbrunn
Advanced Member
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 Posted on: Mar 2, 2017 - 8:34am
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Wow! Thanks a million, Jerry! These photos are invaluable for modelers and will serve to illustrate some of the differences between the various masts and radar domes.
You are accordingly awarded Three Gold Stars, Two "Attaboys", and a hearty Navy "Well Done!" Really, really, great stuff! 
Cheers!
--Bob |
Total Posts: 134 | Joined:
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Bob Steinbrunn
Advanced Member
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Posted on: Mar 2, 2017 - 8:43am
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Well, from the study of a gazillion online and book photos - and those posted here graciously by forum members - it appears that this is the case:
1. The early SO radar had a straight profile on the bottom plate from the mast upwards and outwards to the bottom rim of the dome. The early mast had two short X-braces which crossed each other at about a 90-degree angle and which terminated below the pivot point for the rear brace or strut. These X-braces were tapered, the widest point being outboard where they attached to the vertical frame of the mast and narrowed inboard to create space for the vertical wave guide which was positioned forward of these braces. Some – but not all - were also hollowed out with one teardrop-shaped lightening hole in each, the point of the hole aimed at the junction (middle) of the X-braces. The early mast had a front and rear crossbar down by the base which was drilled out for lightening holes – a row of ten holes along the bottom, two on each outboard side at the top.
2. The later SO radar had a curved profile on the bottom plate, and had two long X-braces which reached up about ¾ of the way to the top of the mast. These X-braces were also tapered and some (most?) – but not all - had long teardrop-shaped lightening holes. This later mast had a front and rear crossbar in the shape of a channel-section girder (made of wood?) with no lightening holes generally, although one photo Ted Walther posted shows these holes in a later mast crossbar.
And, of course, some masts had a navigation light on a crossbar most of the way up the mast, but not all boats had this. It’s fascinating (crazy?) to try to sort all this out.
Anyway, all this is my supposition and I’m sticking with it. Even in the face of irrefutable evidence. 
Photos show PT 187 – the boat I’m modeling – had the early mast with the straight profile dome bottom plate, low X-braces and drilled-out cross-bars at the low end of the mast. The Shapeways 1/48 mast represented the later iteration. To represent PT 187’s mast I had to file the dome bottom plate to a flat straight profile, cut off the large X-braces and make up new ones from strip styrene, taper them, file off the channel-section from the crossbars, and then drill in 28 tiny lightening holes with a #77 drill (.018”).
Now I’m happy. My wife thinks all is not well with me. 
Cheers!
--Bob |
Total Posts: 134 | Joined:
Jan 23, 2016 - 9:16am | IP
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Jerry Gilmartin |
TOP BOSS
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Posted on: Mar 2, 2017 - 2:13pm
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Hey Bob,
That is fascinating information. I have never realized there were different designs for the radar mast. One thing about our mast on PT658 was although the main mast looks very solid, (as if it was made from solid wood), when you pick it up the mast is extremely lightweight. A little investigation shows that the mast is indeed hollow. They must have built it up using thin layers of vernier? Anyway it was pretty surprising that when you pick it up you say: Wow it must be hollow! I am still amazed at the workmanship and skill that went into these items. I would like to thank Don Shannon at Battleship Cove again for allowing us to have this beautiful mast on loan.
Jerry
Jerry Gilmartin
PT658 Crewman
Portland OR |
Total Posts: 1472 | Joined:
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Jerry Gilmartin |
TOP BOSS
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Posted on: Mar 5, 2017 - 10:54am
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Hi Ted,
Here are a few Photos I took yesterday focusing on finding Identification of Manufacturer and Mod number for the Radar mast on PT658. I did not find anything that specifically names either one. However, I did find some numbers.
I also took some closeups of the Furniture on the Radar mast Folding prop and the Support Yoke for the Dome when folded down. There is a y shaped cable (apparently added for strength) and the Semicircular shaped Support Yoke. Pretty interesting construction details.
Label Plate on Yoke
Stamped Number 654 and RR on round dome mounting flange
Just above Stamped Numbers possibly writing (cant read it)
Prop Yoke note pads to hold dome
Folding Prop Y shaped cable for strength
Cable Anchor Point
Anchor Point of bottom of cable underneath Folding prop
Wing nut at bottom of detachable Radar mast Prop
Jerry
Jerry Gilmartin
PT658 Crewman
Portland OR |
Total Posts: 1472 | Joined:
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Bob Steinbrunn
Advanced Member
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Posted on: Mar 7, 2017 - 7:15am
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Thanks again, Jerry. These photos are just great, and I especially value the mast crutch with all it's details: gussets, bolts, etc.
Cheers!
--Bob |
Total Posts: 134 | Joined:
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