The Ship Model Forum

Thanks Steve! :wave_1:

Brilliant.

This section of the forum has been far too quiet lately!

Parche is complete, with the exception of a five-foot acrylic cover for the base. I'll save up and have one custom-built prior to shipping it to its new home in the Fall. I have two other hulls to complete for a Seawolf reunion in Vegas and have made getting those knocked out in 1/144 scale the highest priority since they print faster and several can fit in my car.

Attached are a few P-boat renders with a shot of the final product displayed at a recent USSVI event. The hand you see covering the screw is attached to the admiral who was our guest speaker.

There are 90 keel blocks with pads on the mating surface to protect the exterior paint. Each block has it's ID number stamped on the bottom. I'll remove the hull once more for weathering prior to shipping it out.

CC

Last batch of a half-dozen resin-printed 1/72 18-bladers. Installed on one on my favorite Sturgeon class boats, destined for one of two museums. (I'll build another one when I clear out my current workload . . . measured in years . . .)

[attachment=1]Four Stages.JPG[/attachment]

[attachment=2]Sail Decals (1).JPG[/attachment]

[quote="Woodstock74"]

Just to clarify, you only saw this screw on those two boats (Aspro and Tunny)?[/quote]

That is correct good sir.

[quote="Grandahi"][quote="Tom Dougherty"]That’s an interesting factoid! I have never seen a J screw with the 11 blade attenuator on it. How widespread was it employed? What time era (1990’s?) was the attenuator added to the 637’s? Any idea on the effectiveness?

My understanding is it was a response to the Russian installation of the SOKS wake detection system. The attenuator seemed to come and go in a short period. I was never clear on whether the 688I ring screw was to control tip vortices or to protect the prop tips under ice. Or both.

[/quote]

Unfortunately I cannot comment on how widespread the employment was, only physically seeing it on two different boats, Aspro and Tunny. I was on board and decommissioned Aspro from 1992-1995, and Tunny from '95-'96. This was in Pearl Harbor btw. Other boats that were there at the time besides the usual 637s and 688s, were USS Kamehameha (SSBN/SSN-642), undergoing conversion to SSN (and the reason we never carried the DDS on Tunny during my time on her), and USS Haddock (SSN-621), which came to Pearl for inactivation and decommissioning. Fun factoid, ex-USS Aspro and ex-USS Haddock were towed together in 1995 back to Washington for recycling.
I always figured the device was installed as part of Aspro's overhaul at Mare Island ca. 1989-90, which I believe is when she got SHT, sonar and fire control upgrades, etc. With those upgrades we could do all and more than 688s, except go as fast.
For the most part we were too busy keeping her (Aspro) in a state of readiness to really delve into when which equipment got put on. Tunny was in MUCH better shape, even for being just a few years younger . . .[/quote]

Just to clarify, you only saw this screw on those two boats (Aspro and Tunny)?

[quote="Woodstock74"]Wish we had some photo evidence. There are precious few images of Sturgeon screws. And zero of this.[/quote]
Agreed! But in the meantime here are some pics that you may or may not have already, they are handy for seeing the variable pitch (twist) if nothing else .

Wish we had some photo evidence. There are precious few images of Sturgeon screws. And zero of this.

[quote="Woodstock74"]Based on Grandahi's description:

[attachment=0]Screenshot 2021-07-28 193909 Sturgeon_w_the_device.jpg[/attachment]

[attachment=1]Screenshot 2021-07-28 193834 Sturgeon_w_the_device.jpg[/attachment][/quote]

Looks as good as anything out there! Two thumbs up.

Based on Grandahi's description:

[attachment=0]Screenshot 2021-07-28 193909 Sturgeon_w_the_device.jpg[/attachment]

[attachment=1]Screenshot 2021-07-28 193834 Sturgeon_w_the_device.jpg[/attachment]

Woodstock Mike had a mockup of an example, looks like the post has since been deleted. Anyway I was unable to chime in at the time, but it looked like reality to me. Although I think it should have more pitch on the attenuator blades, as in the upper left of the attached pic. But otherwise who is going to rivet-count it?
We had the tech manual with profile and pitch drawings for the screw, and it indicated it was the same on a slew of different classes of boats, as we all know now. Of course the 688s had a bigger and newer design, to account for their larger power-plant. No books on the device.
Cheers.

[quote="Tom Dougherty"]That’s an interesting factoid! I have never seen a J screw with the 11 blade attenuator on it. How widespread was it employed? What time era (1990’s?) was the attenuator added to the 637’s? Any idea on the effectiveness?

My understanding is it was a response to the Russian installation of the SOKS wake detection system. The attenuator seemed to come and go in a short period. I was never clear on whether the 688I ring screw was to control tip vortices or to protect the prop tips under ice. Or both.

[/quote]

Unfortunately I cannot comment on how widespread the employment was, only physically seeing it on two different boats, Aspro and Tunny. I was on board and decommissioned Aspro from 1992-1995, and Tunny from '95-'96. This was in Pearl Harbor btw. Other boats that were there at the time besides the usual 637s and 688s, were USS Kamehameha (SSBN/SSN-642), undergoing conversion to SSN (and the reason we never carried the DDS on Tunny during my time on her), and USS Haddock (SSN-621), which came to Pearl for inactivation and decommissioning. Fun factoid, ex-USS Aspro and ex-USS Haddock were towed together in 1995 back to Washington for recycling.
I always figured the device was installed as part of Aspro's overhaul at Mare Island ca. 1989-90, which I believe is when she got SHT, sonar and fire control upgrades, etc. With those upgrades we could do all and more than 688s, except go as fast.
For the most part we were too busy keeping her (Aspro) in a state of readiness to really delve into when which equipment got put on. Tunny was in MUCH better shape, even for being just a few years younger . . .

Folks, I am on the "slightly uninformed" list as to propellers.

Are these examples of the "stuff" being talked about?
( Top Pic a Type 212 prop)
( Middle Pic: 3D printing. Thank You Mike.)
(Bottom pic a 688 class prop example)

Nino.

P.S. Top photo I will attribute to J Gibbs. (Ya know, In case)

And take a look here if building 1/350 Subs: http://www.steelnavy.net/FullerPropellers350TDougherty.html

The Los Angeles made their homeport in Pearl in '78. Soon after their arrival, I attended a class with the lead sonarman who gave us a tour of the boat. I remember him mentioning they had an 18-bladed screw - a standard 7 blade model with an 11-bladed vortex dissipater, so it was installed very early on. He said they experimented with a five-bladed screw and while the speed was significantly greater, it was a lot noisier, so the 18 bladed screw was adopted.

Compared to the 637's on the waterfront, the LA was like the starship Enterprise.

[quote="Woodstock74"]This isn't going to get me a visit from the goon squad is it?[/quote]
Jethro Gibbs is on his way!

That’s an interesting factoid! I have never seen a J screw with the 11 blade attenuator on it. How widespread was it employed? What time era (1990’s?) was the attenuator added to the 637’s? Any idea on the effectiveness?

My understanding is it was a response to the Russian installation of the SOKS wake detection system. The attenuator seemed to come and go in a short period. I was never clear on whether the 688I ring screw was to control tip vortices or to protect the prop tips under ice. Or both.

[b]Build Report on the 1/144 Sturgeon[/b]
As far as the MikroMir Sturgeon kit, I joined the two halves of the bow cap. I ran small amounts of microweld along the interior of the cap to join the pieces. Unfortunately, although the two pieces are close matches, but you end up with a slight, “overbite” lip at the very front. So, out came the 400, 600 & 1000 wet sand paper to make the two pieces meet smoothly. I was very careful to frequently change sanding directions so as not to end up with a flat spot. I also had to use Tamiya putty to hide the seam. I placed tape very close on either side of the seam to limit the putty spread. So that simple process took two hours to get to a decent result.

This isn't going to get me a visit from the goon squad is it?

[quote="Grandahi"][quote="Vepr157"]


Was that similar to the hub vortex diffuser on the 688s (a boss with a number of blades), or the propeller boss with a straight taper (see drawing)?


Jacob[/quote]

We had 11 blades on the device, (a question I asked of the nubs when they came for a propulsion train checkout), similar to what the internet shows on the 688s. As far as any other details, I didn't have a tape measure or a protractor with me, alas, so I am useless for providing any other details. The straight taper was the dunce cap we were going to be saddled with otherwise, if I am interpreting your question/drawing correctly.
Scott[/quote]

Well this is extraordinarily interesting!

Great, thanks for the info! The 688 one has 11 blades as well. Funnily enough you can look its naval stock no. up online:

https://www.parttarget.com/2010-00-106-8638_2010001068638_SSN688-203-4352721PC1.html/-B3435C4A-0154-4308-BF4F-81B35ACCC521

One thing that's always mystified me is why the 585s and 637s had that unusual straight-taper boss, but the 594s had a regular conical boss.

Jacob

[quote="Vepr157"]


Was that similar to the hub vortex diffuser on the 688s (a boss with a number of blades), or the propeller boss with a straight taper (see drawing)?


Jacob[/quote]

We had 11 blades on the device, (a question I asked of the nubs when they came for a propulsion train checkout), similar to what the internet shows on the 688s. As far as any other details, I didn't have a tape measure or a protractor with me, alas, so I am useless for providing any other details. The straight taper was the dunce cap we were going to be saddled with otherwise, if I am interpreting your question/drawing correctly.
Scott