Food Fight? - Three bladed US Submarine screws

[mkeatingss]

I don't want to start a food fight, but I just got a picture that blows away something, I thought, I knew about US subs.
The Germans use three bladed, a given, OK?
But all the pictures I ever seen (before this) show the US Fleet Boats with four bladed screws.
I'm qualified in submarines. From first hand experience, I know, USS Atule (SS-403) 1963, USS Quillback (SS-424) 1963 and USS Amberjack (SS-522) 1972 had 4 bladed screws.
The guy who sent me the picture reported aboard Amberjack for the keel laying in 1944. And was aboard her until 1948. He was aboard her when she went through her Guppy modernization around <>46-47.
The picture was taken from the dry dock floor. Lo and behold there are two 3-bladed screws. They appear to still have the protective coverings on the blade edges.
I've written him, asking, when she got them and how long she had them, if he knows.
I'm hoping some one, here, can provide more information on this.
D*** Guppys!! Here I thought the only underwater differences were the sonar domes. Now I find that not all had 4-bladed screws. Wonderful! Just wonderful! One more thing for the nit-pickers and rivet counters to nails us on.
Mike

[mkeatingss]

PS. If any one wants

PS. If any one wants a copy of the picture, email me at mkeatingss@cox.net . I'll email you a copy.
Mike

[JWLaRue]

Mike,

That's an excellent example of

Mike,

That's an excellent example of what makes this subject/hobby so interesting! There always seems to be something new to learn and discover.

-Jeff

[mkeatingss]

OK. I got a reply.

OK. I got a reply. Here's the jist of it. It applies for all earlt Guppys, Not, just Amberjack.

"There is no specific dating for 4 versus 3 bladed props as both were used at different times for different things. Especially during the early guppy period. Lots of trial and error. Anglejack had many test rigs tried. ......"

Now you can use 3 or 4 bladed props, and the revir-counters can only grind their teeth.
Mike K.

[tom dougherty]

Hey, Mike, I thought Guppies

Hey, Mike, I thought Guppies eventually got upgraded to a five bladed propeller?? I have some photos of the 5 bladed variety both sitting by themselves & on a Guppy hull in drydock. Just to add to the confusion....

Tom

[mkeatingss]

Hi Tom,
I heard the

Hi Tom,
I heard the Guppy IIIs got the 5-bladed, but I don't know about the rest. (Amberjack still had 4 bladed when she went south.)
But If you do Guppy III, you'll have to add that 15 foot section. Except for Tiru, which got a 12.5' section.

Mike K.

[crazy ivan]

What is the diameter of

What is the diameter of the original 4 bladed screw?

[mkeatingss]

Sorry about the delay in

Sorry about the delay in getting back to you. The four bladed props were 8 feet in diameter.
Mike K.

[crazy ivan]

Thanks Mike, no problem. I'm

Thanks Mike, no problem. I'm just making some long term plans for when that Revell Gato comes out. Thought I might get a jump on the propulsion system.

Big Dave, you hear that? Shall we get an order in for some 1/72 scale props? That would be 1.33 in. or just under 34mm.



Edited By Crazy Ivan on 1142206647

[JWLaRue]

Sorry about the delay in

Sorry about the delay in getting back to you. The four bladed props were 8 feet in diameter.
Mike K.

Mike,

Can you verify? The Floating Drydock Book of Plans shows the diameter 7 feet 9-1/2 inches. If the BoP is wrong, it would be worth noting. (wouldn't be the first time, eh?)

It's not much of a difference for a 1/72nd scale boat (only 1mm), but us anal modeling types like to know!

-many thanks,

Jeff

[crazy ivan]

Well, the closest thing I

Well, the closest thing I see in the Raboesch catalog is 35mm, so it will be a file and trim job either way.

[mkeatingss]

Jeff, all I can tell

[color=#000000]Jeff, all I can tell you is, we called them eight feet. On the only plans available, they measure out at eight feet.
But, since all my plans are 1/96 (1/8"=1"), you're talking less than the thickness of the lines on the drawings.
But if Tom calls them at 7'-9.5", I'd go with him. Dead accuracy on size wasn't important to most of us. For the screws, anyhow. So most guys would round the dimension. And that's what I got.
But you're talking .88 mm (.034"), on the model. At my age, I couldn't see the difference, if my life depended on it. If you want me to see a .2% difference, (even with a scale in hand) you'll have to go to 1]

[JWLaRue]

Hi Mike,

...yea, at something like

Hi Mike,

...yea, at something like 1/96th scale we'd be pushing it to find or measure any real difference. Since I am looking mre towards a 1/48th scale boat, it does have at least some nominal difference.

And as I said earlier, the anal modeler in me just likes to know!

-many thanks,

Jeff

[boss subfixer]

FYI Gents,
The drydocking plan I

FYI Gents,
The drydocking plan I have for the USS Cobia has the four bladed prop diameter as 8' 2 1/2". This is the Electric boat drawing dated 1944 and is very accurate, it has to be or the boat could be damaged during the docking procedure.

[mkeatingss]

This sounds as accurate as

This sounds as accurate as you can get, without laying the screw on the ground and slapping a tape measure to it.
Something I find fascinating is that, the variations from eight feet is + or - 2.5". Anybody know where we can find a four bladed "Smoke Boat" screw?
And, while we're on the subject, what was the hub diameter?

Mike K.