Fleet boat equipment id?

[sgtmac1]

Researching various pics of fleet boats for my USS TANG project, I was wondering what some of the items on or around the periscope shears were used for.
For instance the ring located between the two scope-a radio direction finder, perhaps?
The canister type object that is mounted below a bracket at the very front of the forward scope, seen just above the port lookouts guard rail?
The mast that the flag holder is mounted on-what does it do?
At the bottom of the picture, am I right in thinking that is a depth charge sensor?
Also, in the book "Clear the Bridge", Captain O'Kane wants a new piece of equipment mounted in a different location so as to not block access to his crow's nest. Can anyone describe where this crow's nest was located at on the periscope shears? I assume that all fleet boats had the port and starboard lookout platforms located about 7 feet above the deck but I can't recall a picture of a much higher location that had a rope running down to aid the lookouts fast drop to the deck, requiring gloves.
I note that I labeled the lookout platform as the crow's nest but I think I have that wrong.
Thanks!

[salmon]

Re: Fleet boat equipment id?

Yes, the loop is called a DF loop antenna. I thought this was for sub communications.

Canister object is a light. The white light was used while docked.

The flag pole is attached to the mast of a late SD antenna. It can be extended, like a periscope. Used for long wave air search radar.

I think it is the navigation light. Always thought it was, but I will defer to others on this one.

I have no suggestion on the crows nest. Sub Captains had a lot of leeway on how they set up their subs. The higher up the mast they got the further they could possibly detect a ship. It is possible a loop was added nighter up. Paul Crozier is the best source for this information. I do not think there is a more knowledgeable man.

[sgtmac1]

Re: Fleet boat equipment id?

Thanks, salmon.

[PaulC]

Re: Fleet boat equipment id?

Well, since I've been called out... My understanding of Tang is that after the first patrol they cut a hole in the upper brace between the top of the periscope shears. The loop antenna is hanging from the underside in your photo. A coaming was welded in the opening to stiffen and smooth out the hole. A lookout, standing on the next lower brace, stuck his head and shoulders up through the hole. Thus it became an upper lookout platform or crow's nest.

If I recall correctly, during a later refit period the yard wanted to install a loop antenna exactly where it is in your photo. O'Kane intervened to keep it from spoiling the crow's nest arrangement.

The object marked "depth charge indicator" is indeed the port navigation light.

Tom is correct about the aft antenna mast and the white light on the forward shears.

One thing I'm not so sure about is the "windscreen" notation. I've never seen anything like that mounted as such on a fleet boat bridge. The image almost looks like it's a frame or something in the background that happens to look like it's on the bridge cowl.

[sgtmac1]

Re: Fleet boat equipment id?

Thanks PaulC. Does anyone know who might be building a 1/48th scale sub? I figure I can learn what goes on by looking at boats that are similar in size and have similar layouts such as type IX uboats and the like.

[wlambing]

Re: Fleet boat equipment id?

Gents,

Tom is sorta correct! The white light is the "Masthead" light. A standard navigational light displayed when not in a war zone, running on the surface. If you can see it and see a port or starboard running light, you can maneuver your vessel to avoid a collision-at-sea, with a good end result when compared to not seeing them! The "crowsnest" starts at the point labeled "platform" and runs vertically up to the "guard rail", there was room for a lookout on each side. This station allowed for good visual sweeps of the area and quick clearing of the bridge when a fast dive was necessary.
The frame is indeed for a windshield. Later in the war, some Balaos and Tenches were delivered with a windshield. The venturi spray shield on the leading edge of the cockpit only worked to a point, as far as keeping spray off the bridge watch personnel. Windshields could be dismounted and stowed away below. We still have them and use them religiously, even with the height of the modern boat sails.

The "bracket" in the picture is really a welded gusset that lends strength to the bolting flange and conical tube cover of the scope shears. That metal was relatively light weight and could be torn off the shear if it didn't have some reinforcement built in. Gussets are very common in all sorts of structural steel work.

Brain hurts now!!

B^)

[salmon]

Re: Fleet boat equipment id?

Whew, I'll take sorta rather than being completely wrong. Thank you for the correction.
Bill you are one smart cookie.

[wlambing]

Re: Fleet boat equipment id?

'Most forgot!

The DF loop (Direction Finding) was a detector that would allow the boat to locate the source of radio transmissions , head down that bearing, and then kill the bad guy.
We have much fancier antennas for this now, but the same general idea applies. If you send out too many signals, someone will find you and make you feel really bad!

B^)