Submarine bow types

[Brother D]

I have a pretty healthy interest in submarines, and this is the first video (and images) I can ever recall where they discuss the passive sonar sphere in the bow of modern subs.



I would be interested if anyone else with a passing interest in sub were aware that some subs don't even have bow mounted torpedo tubes (or that they had giant spheres on the front of them as a result).

Gratuitous picture of the WW2 sub a few stories below ground in Chicago at the museum (pointy/ship bow) from a evening event we went to a couple of months back:

[hidetheelephants]

WW2(or older) subs were really submersible torpedo boats, a lot of their fighting was done while surfaced, also most long distance travel was on the surface, so the hull shape and bow was optimised for this and quite inefficient(and noisy) while submerged. True submarines start with the USS Albacore, as the name suggests shaped like a fish for greater efficiency and less flow noise underwater. Modern subs are generally tubular as this is easier/cheaper to build but still pretty efficient.

[take-good-care-of-the-forest-dewey]

OP... If you like sub stuff, have a look at H I Sutton's site and videos.

He goes into a lot of detail.

One thing about the bow array.... They make an effectivev crumple zone in the event of a nav errors.

As USS San Fran and HMS Traf found out.

https://nationalinterest.org/blog/reboot/what-happ...

[Simpo Two]

Brother D said:

I have a pretty healthy interest in submarines

Plan your holidays https://militaryhistorynow.com/2014/05/31/permissi...

[Krikkit]

Simpo Two said:

Brother D said:

I have a pretty healthy interest in submarines

Plan your holidays https://militaryhistorynow.com/2014/05/31/permissi...

U-995 is a fabulous visit if you have time - they've cut access doors in the bow and stern torpedo and you work your way through the whole boat at your leisure. It feels tight with 20 tourists in there, what it was like with 40-odd sailors and provisions boggles the mind. If you're towing family along then you could take them to Lubeck and/or Travemunde while you zip off to Kiel for the maritime museum.

Annoyingly I didn't have time to get to the Type XXI at Bremerhaven, I've put a pin in it for now and might do both again at some point.

[dvs_dave]

[MBBlat]

The giant spherical sonars are a US and Russian thing. Germany prefers cylindrical sonar arrays while the UK uses horseshoe shaped arrays.

The teardrop with a cylindrical mid body is basically the starting point for modern designs.

[CanAm]

Krikkit said:

U-995 is a fabulous visit if you have time - they've cut access doors in the bow and stern torpedo and you work your way through the whole boat at your leisure. It feels tight with 20 tourists in there, what it was like with 40-odd sailors and provisions boggles the mind. If you're towing family along then you could take them to Lubeck and/or Travemunde while you zip off to Kiel for the maritime museum.

There is a similar set-up of a Swedish submarine, U3 at the Technical Museum in Malmö. Unfortunately the doors are on the other side!

Edited by CanAm on Wednesday 2nd March 23:48

[thewarlock]

MBBlat said:

The giant spherical sonars are a US and Russian thing. Germany prefers cylindrical sonar arrays while the UK uses horseshoe shaped arrays.

The teardrop with a cylindrical mid body is basically the starting point for modern designs.

Pressure hulls are almost exclusively cylindrical.

The outer hull is the one that's designed with hydrodynamics in mind, but most modern subs have a 'straight' pressure hull.

50mm+ thick 500MPa+ yield steel is hard enough to roll as it is, without having to do compound curves.

[lufbramatt]

There's also HMS Ocelot (Oberon class sub) at Chatham Dockyard in Kent.

[Jader1973]

lufbramatt said:

There's also HMS Ocelot (Oberon class sub) at Chatham Dockyard in Kent.

Another Oberon Class, HMAS Otway (well the bit above the waterline) is in Holbrook in NSW - about 200km from the nearest coastline. It is a slightly surreal sight as you drive past!



Built in Greenock and now in rural NSW in a town which was renamed to Holbrook after Lt Norman Douglas Holbrook VC during WW1, after it was decided the original name of Germanton was unpatriotic.

https://en.wikipedia.org/wiki/HMAS_Otway_(S_59)

[Chainedtomato]

lufbramatt said:

There's also HMS Ocelot (Oberon class sub) at Chatham Dockyard in Kent.

HMS Ocelot is the next sub visit I’m planning. Been to HMS Alliance in Gosport and USS Gowler in New York

[hidetheelephants]

There's an X-craft on display in the submarine museum in Helensburgh.

[2xChevrons]

Chainedtomato said:

lufbramatt said:

There's also HMS Ocelot (Oberon class sub) at Chatham Dockyard in Kent.

HMS Ocelot is the next sub visit I’m planning. Been to HMS Alliance in Gosport and USS Gowler in New York

I went round Alliance many times as a kid but haven't been back since she was refurbished and they opened up the fin and the underside to the public. I need to go back some time.

I keep meaning to find time to go to Chatham, partly because I've never been and there's lots of stuff there that I know I'd enjoy seeing, but particularly for Ocelot. I'm old enough to just about remember the last couple of O-boats being based at Dolphin and I very clearly remember seeing Otus, Opossum and Opportune being rafted up in Porchester Lake (I spent a lot of time sailing triangles around them when I was learning to sail) before being shifted to the Harry Pound yard for breaking up.

[hidetheelephants]

The amusingly named USS Growler in New York is a good one to visit; they've done a good job of making a manageable path through a cramped sub and the adjacent USS Intrepid museum has plenty to look at too.

[Talksteer]

thewarlock said:

MBBlat said:

The giant spherical sonars are a US and Russian thing. Germany prefers cylindrical sonar arrays while the UK uses horseshoe shaped arrays.

The teardrop with a cylindrical mid body is basically the starting point for modern designs.

Pressure hulls are almost exclusively cylindrical.

The outer hull is the one that's designed with hydrodynamics in mind, but most modern subs have a 'straight' pressure hull.

50mm+ thick 500MPa+ yield steel is hard enough to roll as it is, without having to do compound curves.

My non subs understanding of hydrodynamics (big object, low velocity, dense medium) would suggest that drag due to the shape of the sub would be a much smaller component of the drag than the surface friction (assuming that everything has a decent radius on it). Ergo its not worth producing a shape inspired by a blue whale especially when you have a nuclear reactor pushing you around that doesn't run out of fuel.

I presume that the primary geometric factors on the sub are 1: Fitting everything in 2: Reducing turbulence in specific areas as these generate noise.

[thewarlock]

Talksteer said:

My non subs understanding of hydrodynamics (big object, low velocity, dense medium) would suggest that drag due to the shape of the sub would be a much smaller component of the drag than the surface friction (assuming that everything has a decent radius on it). Ergo its not worth producing a shape inspired by a blue whale especially when you have a nuclear reactor pushing you around that doesn't run out of fuel.

I presume that the primary geometric factors on the sub are 1: Fitting everything in 2: Reducing turbulence in specific areas as these generate noise.

It doesn't run out of fuel, but it does produce a finite amount of power. The better the shape, the faster you can go, and more quietly.

But consider the pressure the hull sees at 500m depth, that's 5000kN/m^2

500 tonnes per square metre.

Something like a 25mm deviation out of roundness on something with a 10m beam can result in 25%+ reduction in max permissible hydrostatic pressure. A circular profile the strongest shape, and ther're usually stiffener circumferentially, as the hoop stress is twice that of longitudinal stress for a cylindrical pressure vessel.

On surface ships, there are still water bending moment and shear force, and wave BM & SF cases to think about when considering global strength of a hullform, which is why they tend to be longitudinally stiffener as opposed to trasnsversely. With subs, it's all about that hydrostatic pressure case. Everything else pales into insignificance.

[.Adam.]

Chainedtomato said:

HMS Ocelot is the next sub visit I’m planning. Been to HMS Alliance in Gosport and USS Gowler in New York

There's a privately owned Russian sub moored in the Medway just up the river from Chatham Dockyard as well.

https://en.wikipedia.org/wiki/Submarine_U-475_Blac...

[MBBlat]

.Adam. said:

There's a privately owned Russian sub moored in the Medway just up the river from Chatham Dockyard as well.

https://en.wikipedia.org/wiki/Submarine_U-475_Blac...

The French have Redoutable in Cherbourg, mid 60's SSBN and I believe the only (ex) nuclear sub open to the publicc.

Here's her bow to get back on topic:
french connection_166 by MBBlat, on Flickr

[lufbramatt]

.Adam. said:

Chainedtomato said:

HMS Ocelot is the next sub visit I’m planning. Been to HMS Alliance in Gosport and USS Gowler in New York

There's a privately owned Russian sub moored in the Medway just up the river from Chatham Dockyard as well.

https://en.wikipedia.org/wiki/Submarine_U-475_Blac...

I'm amazed that Russian sub hasn't broken up yet. The Medway is quite brackish as it's tidal through the Medway towns which hasn't done that Russian sub any good at all. It did have a bad list for a while but the owner managed to straighten it up a bit.

It's a shame to see it slowly deteriorate. I went inside it when it was moored at Folkestone, really interesting to see. I think it was used as a set for a Jude Law film a few years ago.