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Forum Category: PT Boats of WWII
http://www.ptboatforum.com/cgi-bin/MB2/netboard.cgi?cid=101&fct=showf


Forum Name: PT Boats - General
http://www.ptboatforum.com/cgi-bin/MB2/netboard.cgi?fct=gotoforum&cid=101&fid=102


Topic: Detailed photos for SO radar and mast?
http://www.ptboatforum.com/cgi-bin/MB2/netboardr.cgi?cid=101&fid=102&tid=4225



I'm building the BlueJacket Ship Crafters 1/48 PT boat (PT 187) and have in hand the SO radar with mast from Shapeways as a 3D-printed item. This replaces the early simple mast included in the kit.

The Shapeways part needs a fair amount of additional detailing, such as nuts, bolts, lightening holes, wiring, and such. I have a number of photos pulled from online, but nothing clear enough or detailed enough for my needs.

Dick's DVD has blueprints for the early mast, but nothing that I can find for the SO radar & mast. The best shot I've found is of McArthur standing by the mast looking aft, previously posted here, but this photo only shows the starboard side.

[url]http://www.ptboatforum.com/cgi-bin/MB2/netboardr.cgi?cid=101&fid=102&tid=3749[/url]

Is there any possibility that a "walk-around" series of four photos of this mast exists?

Cheers!
--Bob

Posted By: Bob Steinbrunn | Posted on: Feb 27, 2017 - 9:14am
Total Posts: 134 | Joined: Jan 23, 2016 - 9:16am



Hi Bob,
A couple of years ago I took some walk around photos of the mast we have on PT658. I will try and find them and post them here. I took several with included tape measure views next to details so you can get a perspective of the size. The most interesting thing I discovered when we installed the SOA radar mast was the big box thing at the bottom. It is the RF Generator (basically a big transformer along with some other electrical components) and the RF energy travels up to the dish via a "Wave Guide" which appears to be about the size of a 2x4 lumber, except it is actually hollow similar to a gutter downspout. So that is what those things are in the picture. I will provide the photos as soon as I can get off work and look through my computer at home.

Jerry Gilmartin
PT658 Crewman
Portland OR

Posted By: Jerry Gilmartin | Posted on: Feb 27, 2017 - 11:50am
Total Posts: 1213 | Joined: Oct 8, 2006 - 11:16pm



Hi Bob,take in account that PT 187 seems to have the mast with square top section, opposite to Jerry's pictures/measurements wich are of a round top section mast, so most of the measurements are not applicable.
See this picture

[url]http://www.pt103.com/images/ptpics/pt192/PT192_Galloping_Guillotine2.jpg[/url]

I am also having a hard time finding details about this "early" mast.[:-question-:]
Regards


Daniele Kly

Posted By: Daniele Klay | Posted on: Feb 28, 2017 - 1:10am
Total Posts: 126 | Joined: Jun 23, 2015 - 12:43pm



Bob and Danielle;
I never noticed what you are mentioning Danielle, two designs for the radar mast? As you say, there appears to be a difference. The later design looks to be better reinforced with the curved pieces, notice on Jerry's photo the "line" on the inside of the ring that looks as if this is where the pieces meet. This can be seen again, from a different aspect, in the Gen MacArthur photo of PT 490 RON 33. Maybe these photos can help you:

[url]http://www.ptboatforum.com/cgi-bin/MB2/netboardr.cgi?fid=102&cid=101&tid=3563&sc=20&pg=1&x=0[/url]

[url]http://www.navsource.org/archives/12/05187.htm[/url]

[url]http://www.navsource.org/archives/12/120518901.jpg[/url]

[url]http://www.navsource.org/archives/12/120515004.jpg[/url]

[url]http://www.navsource.org/archives/12/120514608.jpg[/url]

Take care,
TED


Posted By: TED WALTHER | Posted on: Feb 28, 2017 - 9:02am
Total Posts: 2841 | Joined: Oct 16, 2006 - 7:42am



Jerry....thanks very much! I've explored the PT 658 site and have noted many of your photos there. Great stuff.

Daniele & Ted.....I've noticed this myself, but many thanks. I see some SO radar dome bottom sections have a straight-line profile from the mast up towards the bottom of the dome itself, while others have a curved profile.

Moreover, some curved profile bottom units have a transverse channel section at the bottom of the mast both front and rear just under the RF box, some have a flat bar with lightening holes in both. Some straight profile bottom units have have a transverse channel section at the bottom of the mast both front and rear just under the RF box, some have a flat bar with lightening holes in both. So, it appears there were two different radar domes and two different masts, and you could find either on either.

Last, some straight profile domes have a circumferential band around the bottom of the dome where it joins the bottom piece (and some don't), whereas the curved domes seem to lack this. And the fasteners that hold the dome to the bottom section differ between the two types.

Is this esoteric, or what? [:-bigeyes2-:] [:-smilearound-:]

Cheers!
--Bob

Posted By: Bob Steinbrunn | Posted on: Feb 28, 2017 - 9:34am
Total Posts: 134 | Joined: Jan 23, 2016 - 9:16am



Bob;
Both are included in the 1/35th PT Boat Conversion kit from Italeri, but since you are working in 1/48 s-ways is the way to go.
As for the Real SO radars, as for the changes in the dome profiles, Jerry or Al might have more insight. I think I asked this same question a few years ago. From what I have seen, mostly when the Dome was changed, so did the mast. So more protection from the elements and more stable, is the curved dome.
Take care,
TED



Posted By: TED WALTHER | Posted on: Feb 28, 2017 - 11:17am
Total Posts: 2841 | Joined: Oct 16, 2006 - 7:42am



Nice catch Daniele! It looks like the square top type had a shorter X brace with the members at 90 degrees to each other. I couldn't find that type on boats later than the 369 in the images I have.

Here are links to a few photos I found, too large to post here. The 369 shots have really nice detail of the forward top:

[url]http://www.pt103.com/images/ptpics/PT_131_With_Rocket_Launcher_Sep1944.jpg[/url]

I believe the X brace members taper towards the center:
[url]http://www.pt103.com/images/ptpics/PT_150_Color_BobWieseJGSmilesMachnickLtWest.jpg[/url]

[url]http://www.pt103.com/images/ptpics/PT_150_Color_OrmacBay.jpg[/url]

[url]http://www.pt103.com/images/ptpics/PT_189_Ron_8.jpg[/url]

Another shot that seems to show the brace is tapered:
[url]http://www.pt103.com/images/ptpics/PT_195_Andys_Dad_02.jpg[/url]

[url]http://www.pt103.com/images/ptpics/PT_328_Crew.jpg[/url]

[url]http://www.pt103.com/images/ptpics/PT_328_Melville.jpg[/url]

Cropped from [url]http://www.history.navy.mil/our-collections/photography/numerical-list-of-images/nhhc-series/nh-series/80-G-257000/80-G-257978.html[/url]
[url]http://www.pt103.com/images/ptpics/PT_369_37mm_Cropped.jpg[/url]

Cropped from [url]http://www.history.navy.mil/our-collections/photography/numerical-list-of-images/nhhc-series/nh-series/80-G-283000/80-G-283915.html[/url]
[url]http://www.pt103.com/images/ptpics/PT_369_37mm_Cropped_02.jpg[/url]




Posted By: Jeff D | Posted on: Feb 28, 2017 - 12:17pm
Total Posts: 1696 | Joined: Dec 21, 2006 - 1:30am



Yes Jeff, the "early" radar mast also had solid cross braces,instead of the lightening holes on the cross braces in the later ones..
Does anybody have accurate dimensions/measurements of the radar dome at least?
I saw somewhere 27" diameter by 32" height but has to be confirmed[:-unhappy-:]
Greetings

Daniele Kly

Posted By: Daniele Klay | Posted on: Mar 1, 2017 - 3:51am
Total Posts: 126 | Joined: Jun 23, 2015 - 12:43pm



Here are photos with measurements

Height from deck to dome top 141 inches Top view
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20height%20of%20mast%20from%20deck%20up%20to%20top%20of%20dome%20141%20inches%20view%205.jpg[/image]

Height from deck to dome top 141 inches Bottom view
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20height%20of%20mast%20from%20deck%20up%20to%20top%20of%20dome%20141%20inches%20view%202.jpg[/image]

From Deck to Bottom of dome 115 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20height%20of%20mast%20from%20deck%20up%20to%20dome%20115%20in.jpg[/image]

Width of yardarms 52 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20width%20of%20yardarms%2052%20inches%20view%202.jpg[/image]

Width of mast at leaning prop hinge pins 24 inches (Outside dimensions)
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20width%20of%20mast%20at%20prop%20joint%2024%20inches.jpg[/image]

Width of Hinge Pin end of Folding Mast prop 18 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20width%20of%20prop%20at%20mast%20joint%2018%20inches.jpg[/image]

Width across bottom of main mast feet 38 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20width%20of%20main%20mast%20feet%20%2038%20inches.jpg[/image]

Width across bottom of main mast feet 38 inches (wider view)
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20width%20of%20main%20mast%20feet%20%2038%20inches%20view%202.jpg[/image]

Wave guide flexible joint width 5 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20width%20of%20wave%20guide%20flex%20joint%205%20in.jpg[/image]

Folding Mast Prop length 7 feet
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20prop%20length%207%20feet%20Jason%20pointing%20at%206%20ft%20mark.jpg[/image]

Width of Signal Generator box 24 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20width%20of%20signal%20gen%2024%20in.jpg[/image]

Depth of Signal Generator 13 inches across top
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20depth%20of%20signal%20gen%20across%20top%2013%20in.jpg[/image]

Waveguide length from top of Signal Gen to bottom of dome 76 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20length%20of%20waveguide%20up%20into%20bottom%20of%20dome%2076%20inches.jpg[/image]

Waveguide length looking up into bottom of dome 76 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20length%20of%20waveguide%20up%20into%20bottom%20of%20dome%2076%20inches%20view%20looking%20up%20into%20dome.jpg[/image]

Length of X shaped gusset 45 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20length%20x%20shaped%20support%20beam%2045%20inches.jpg[/image]

Length of Base Plate 45 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20length%20of%20base%20plate%2045%20inches%20view%202.jpg[/image]

Front of Base Plate to Back or folding prop 58 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20distance%20from%20front%20of%20base%20plate%20to%20back%20of%20prop%2058%20inches%20view%202.jpg[/image]

Signal generator shelf and shock mounts height 17 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20height%20of%20signal%20gen%20and%20shelf%20and%20shock%20mounts%2017%20in.jpg[/image]

Side view of mast height deck to top of dome 141 inches
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%20PT658/Dave%20SOA%20radar%20mast%20height%20of%20mast%20from%20deck%20up%20to%20top%20of%20dome%20141%20inches%20view%205.jpg[/image]

I hope these answer some of your questions.
Jerry



Jerry Gilmartin
PT658 Crewman
Portland OR

Posted By: Jerry Gilmartin | Posted on: Mar 1, 2017 - 1:30pm
Total Posts: 1213 | Joined: Oct 8, 2006 - 11:16pm



Great work Jerry! I'm sure many modelers will appreciate this.



Posted By: Jeff D | Posted on: Mar 1, 2017 - 2:44pm
Total Posts: 1696 | Joined: Dec 21, 2006 - 1:30am



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-:]

Cheers!
--Bob

Posted By: Bob Steinbrunn | Posted on: Mar 2, 2017 - 8:34am
Total Posts: 134 | Joined: Jan 23, 2016 - 9:16am



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 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. Its fascinating (crazy?) to try to sort all this out.

Anyway, all this is my supposition and Im sticking with it. Even in the face of irrefutable evidence. [:-grin-:]

Photos show PT 187 the boat Im 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 187s 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 Im happy. My wife thinks all is not well with me. [:-smilearound-:]

Cheers!
--Bob

Posted By: Bob Steinbrunn | Posted on: Mar 2, 2017 - 8:43am
Total Posts: 134 | Joined: Jan 23, 2016 - 9:16am



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

Posted By: Jerry Gilmartin | Posted on: Mar 2, 2017 - 2:13pm
Total Posts: 1213 | Joined: Oct 8, 2006 - 11:16pm



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

[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%202017/IMG_3451.jpg[/image]

Stamped Number 654 and RR on round dome mounting flange

[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%202017/IMG_3459.jpg[/image]

Just above Stamped Numbers possibly writing (cant read it)

[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%202017/IMG_3462.jpg[/image]

Prop Yoke note pads to hold dome

[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%202017/IMG_3465.jpg[/image]

Folding Prop Y shaped cable for strength

[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%202017/IMG_3467.jpg[/image]

Cable Anchor Point

[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%202017/IMG_3468.jpg[/image]

Anchor Point of bottom of cable underneath Folding prop
[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%202017/IMG_3470.jpg[/image]

Wing nut at bottom of detachable Radar mast Prop

[image]http://i130.photobucket.com/albums/p249/ptboats/Jerry%20G%202017/IMG_3471.jpg[/image]

Jerry


Jerry Gilmartin
PT658 Crewman
Portland OR

Posted By: Jerry Gilmartin | Posted on: Mar 5, 2017 - 10:54am
Total Posts: 1213 | Joined: Oct 8, 2006 - 11:16pm



Thanks again, Jerry. These photos are just great, and I especially value the mast crutch with all it's details: gussets, bolts, etc. [:-cheers-:]

Cheers!
--Bob

Posted By: Bob Steinbrunn | Posted on: Mar 7, 2017 - 7:15am
Total Posts: 134 | Joined: Jan 23, 2016 - 9:16am