The ugliest sail ever...

[Captain Sub]

looks a bit like Jule Vernes Nautilus

[timmyg00]

The sail-less sub is not going to happen until somebody figures out a way to get sensors and other necessary devices into the hull.

Along with providing streamlining and protection for sensor, antenna, snorkel, and other masts, the sail also provides a margin of safety and stealth when coming to periscope depth for any reason. Imaging having no sail, and then coming to PD in rough seas to copy the submarine broadcast. You'd have to come so shallow that the rough seas would toss you around enough to broach the surface - then your whole topside is exposed. Bye-bye stealth!

Even with the current moderately-sized sail, subs broach in rough seas, but mostly it's just the sail (a much smaller visual/sensor target than the whole sub!) that breaks the surface. It happens. The better the driving team, the less it will happen, but it's going to happen anyway.

The reasons for reducing or eliminating the sail were reduction of drag, and reducing the possibility of the sail acting as a big giant stern plane (control surface) at high speeds. However, the other reasons mentioned above trumped these, and small(relatively speaking) sails were retained. You should see the difference in size between the Permit-and-later-class sails, and the Skipjack and earlier SSN sails.

I can hear it now: "Why not put the sensors in a UUV or pod on a tow-cable that you let float to the surface?" For one thing, a cable can break or be fouled, rendering the UUV/Pod useless. For another, a UUV/Pod will be less stable at PD or the surface than the sub itself, more at the mercy of rough seas than the larger platform. Additionally, the UUV/pod still doesn't answer the question of what to do about the snorkel mast, which is one of the most important pieces of emergency equipment on the sub. It serves to ventilate in case of fire or toxic gas, and also provides air to the emergency diesel engine.

TG

[LoBlo]

Originally Posted by timmyg00

The sail-less sub is not going to happen until somebody figures out a way to get sensors and other necessary devices into the hull.

Along with providing streamlining and protection for sensor, antenna, snorkel, and other masts, the sail also provides a margin of safety and stealth when coming to periscope depth for any reason. Imaging having no sail, and then coming to PD in rough seas to copy the submarine broadcast. You'd have to come so shallow that the rough seas would toss you around enough to broach the surface - then your whole topside is exposed. Bye-bye stealth!

Even with the current moderately-sized sail, subs broach in rough seas, but mostly it's just the sail (a much smaller visual/sensor target than the whole sub!) that breaks the surface. It happens. The better the driving team, the less it will happen, but it's going to happen anyway.

The reasons for reducing or eliminating the sail were reduction of drag, and reducing the possibility of the sail acting as a big giant stern plane (control surface) at high speeds. However, the other reasons mentioned above trumped these, and small(relatively speaking) sails were retained. You should see the difference in size between the Permit-and-later-class sails, and the Skipjack and earlier SSN sails.

I can hear it now: "Why not put the sensors in a UUV or pod on a tow-cable that you let float to the surface?" For one thing, a cable can break or be fouled, rendering the UUV/Pod useless. For another, a UUV/Pod will be less stable at PD or the surface than the sub itself, more at the mercy of rough seas than the larger platform. Additionally, the UUV/pod still doesn't answer the question of what to do about the snorkel mast, which is one of the most important pieces of emergency equipment on the sub. It serves to ventilate in case of fire or toxic gas, and also provides air to the emergency diesel engine.

TG

Well, every sub until this point has had some of its mast penetrating the pressure hull (ie periscope) and the mast was made to extend from the pressure hull into upwards. All you would have to do is create a compartment in the pressure hull to hold the mast and extend them from there... kindof like DiMercurio's concepts...

http://www.ussdevilfish.com/diag04c.htm

So there would be one solution.

[Hartmann]

why not a sail like a shark fin ?? streamlined and able to have sensors ?

sharks are very well adapter for slide through water during millions of years...:hmm:

[Dr.Sid]

What about sensors on floating platform connected by cable ? Some of such sensors are already researched .. like that floating up-looking fish-eye scope with computer corrected image. Radio wires and buoys are used even today. Sure .. snorkel is a
problem, but you don't need it that much.

Or something like UUVs equipped with cameras, RWR or Radar masts. Or even better, UAV (unmaned airborne vehicle) inside UUV, with both radar and cameras.

Or just long mast supported with wires .. like snorkel on german subs - folded backward on the hull (or inside hull cavity). With non-penetrating masts this is no problem.


I think the most important reason for sail is that there must be some place for watchmen in harbors. And sub-hull is not suited for that at all.

[FERdeBOER]

The sail is needed. Not only for placing sensors, but because without it, the sub would rotate on its longitudinal axis without control.
That's why all long-traveller fishes have the upper fin (don't know the name in English ).

You could say:" Whales haven't got one". Well, whales are not fishes but mammals, some whales have it and the whales without it have to compensate this with the movements and bodyshape.

Thus, the sail is the best design at this time... removing it implicates changing the design of the whole sub... maybe even the propulsion system.

Despite this, the submarine on the photo is horrible!!

[Captain Sub]

why is it important for you to remove the sail in the future?

It is more like subs without a sail were disadvanced.

[Bubblehead Nuke]

Originally Posted by FERdeBOER

The sail is needed. Not only for placing sensors, but because without it, the sub would rotate on its longitudinal axis without control.

Um.. no. The metacentric height would prevent that. The center of gravity is below the center of bouyancy then ensuring a righting movement that would keep the top side UP.

When a sub is at PD it tends rock due to the forces acting on the vertical sail surface. Actually, I believe that a sub without a sail would be more stable at PD as the rounded surface would not be as effected by wave action.

But....

One reason for the sail is that the boat can be deeper and still pierce the surface interface. Thus the boat is less affected by wave action and surface tension/ducting.. If you place these masts and sensors in the hull, you have to have a MUCH longer mast, which will vibrate as it travels thru the water. Since you are talking a long, fairly stiff shaft, this means that you will have low frequency harmonics which travel better in the water. Also, you will be REALLY speed limited with this extra long mast supported from just one end. If you make the masts short so that these are not issues, then think of how close to the surface you will have to be. It would mean that anything over a state 2 or so sea would be impossible due to wave action.

[LoBlo]

So so far the advantages/disadvantages of the sail-less-ness are:

Sail-less
Good
-Less prone to wave action per say (mostly caused by the sail)
-Less drag = quieter and higher top speed
-Less draft = more manueverable in littoral waters
Bad
-Extremely long mast = slower and noiser 'mast up'
-If short mast used then shallower PD
-port transits complicated by no bridge (PD dependent)

Sail
Good
-Deeper PD
-shorter/stronger mastup's
-visible in surface transits
Bad
-worst in higher sea state (wave action on the sail)
-more drag = more self noise and slow speeds
-shallow water limitations

Modified sails (in picture)
Good
-more internal volume
Bad
-more drag
-Ugly as sin (induces intractable vomiting)

[FERdeBOER]

Originally Posted by Bubblehead Nuke

Um.. no. The metacentric height would prevent that. The center of gravity is below the center of bouyancy then ensuring a righting movement that would keep the top side UP.

That's ok when the sub is stabilized, but when turning at a speed the submarine would be much harder to control without a sail.

[Sub Sailor]

If you completely do a way with the sail, yes it houses mast and sensors, but what about entering and leaving port?
Where is the conning officer going to stand when maneuvering along side the pier. Also look at pictures of subs on the surface going through various canals or entering or leaving port with other ships around, they are really hard to sea, even in good light and conditions.
No doubt it is a great idea to rid subs of the drag of the sail, and nukes are not on the surface much, but I cannot figure out how to accommodate the needs when they have to be surfaced.

Ron Banks MMCM(SS), USN(Ret)

[timmyg00]

Originally Posted by timmyg00

I can hear it now: "Why not put the sensors in a UUV or pod on a tow-cable that you let float to the surface?" For one thing, a cable can break or be fouled, rendering the UUV/Pod useless. For another, a UUV/Pod will be less stable at PD or the surface than the sub itself, more at the mercy of rough seas than the larger platform.

Originally Posted by Dr.Sid

What about sensors on floating platform connected by cable ?.... Or something like UUVs equipped with cameras, RWR or Radar masts.

See, i knew somebody would say that...

Originally Posted by Dr.Sid

Sure .. snorkel is a problem, but you don't need it that much.

Right, and when you need it and don't have it, how would you feel about it then? Pretty chagrinned that you let the bonehead engineers back on land sell you a sub with no snorkel, after you suffer a major power plant casualty, battery runs low, and you with no diesel generator...

Originally Posted by Dr.Sid

Or even better, UAV (unmaned airborne vehicle) inside UUV, with both radar and cameras.

and how do you propose to control it without radio masts?

Originally Posted by Dr.Sid

Or just long mast supported with wires .. like snorkel on german subs - folded backward on the hull (or inside hull cavity).

More drag and self-noise. Not an option. This is why submarine designers (including the Germans, with the Type XXI sub) removed external projections, such as guns and railings, and moved antennas and sensors into a protected, streamlined sail.

Originally Posted by Bubblehead Nuke

One reason for the sail is that the boat can be deeper and still pierce the surface interface. Thus the boat is less affected by wave action and surface tension/ducting.. If you place these masts and sensors in the hull, you have to have a MUCH longer mast, which will vibrate as it travels thru the water. Since you are talking a long, fairly stiff shaft, this means that you will have low frequency harmonics which travel better in the water. Also, you will be REALLY speed limited with this extra long mast supported from just one end. If you make the masts short so that these are not issues, then think of how close to the surface you will have to be. It would mean that anything over a state 2 or so sea would be impossible due to wave action.

Much better technical explanation than mine.... typical nuke...

TG

[LoBlo]

Originally Posted by timmyg00

Much better technical explanation than mine.... typical nuke...

TG

Well, the mast can easily be telescoped into the depth of the pressure hull. 30ft base telescope half extended with a 30ft interior telescope half extended would give a 30 ft reach. If strength and resonance is an issue one could choose high strength composite materials (modern day composites have 2-3 times the strength of titanium) which would provide more strength and decrease resonance. With 30 ft mast, periscope depths would be 30 ft mast + 33 ft to keel = 63 feet PD, roughly the same as some PD depths now if I understand correctly... and if BH is right the sail-less hull would be less prone to wave action. The captain would just have to except the fact that the design doesn't allow him to drive as fast with 'mastup'. Its the trade-off for better littoral maneuverability, shallower draft, less drag...

... And it sounds like the US Defense Science board recommendations believes its worth the tradeoff

Originally Posted by US Defense Science Task Force on Submarine of the Future

We believe that this "bomb bay" innovation should be part of a redesign of the entire front end that should include considering:

• eliminating the sail (and thus gaining speed and agility at shallow depth at high sea state and reducing radiated- and self-noise)

• replacing the sonar sensors with an integrated system having much improved performance.

[LoBlo]

Originally Posted by FERdeBOER

I'm not saying the sail must be big, I'm saying that is good for stability when navigating. Of course can have cons, everything is good for something and bad for another things.

And, please, what does "Skipjacks were the worst" means? My English is not as good

He's saying that its the sails that's causing the snap roll effect when turning (the sub turns, and the water pushing on the sail makes the sub roll). From what I read, at higher speeds, the sail also tries to pitch the nose of the sub up and also causes flow irregularities at the aft control surfaces.

[timmyg00]

Originally Posted by LoBlo

Well, the mast can easily be telescoped into the depth of the pressure hull. 30ft base telescope half extended with a 30ft interior telescope half extended would give a 30 ft reach. If strength and resonance is an issue one could choose high strength composite materials (modern day composites have 2-3 times the strength of titanium) which would provide more strength and decrease resonance. With 30 ft mast, periscope depths would be 30 ft mast + 33 ft to keel = 63 feet PD, roughly the same as some PD depths now if I understand correctly... and if BH is right the sail-less hull would be less prone to wave action. The captain would just have to except the fact that the design doesn't allow him to drive as fast with 'mastup'. Its the trade-off for better littoral maneuverability, shallower draft, less drag...

This might be OK if the masts in question were not hull-penetrating, i.e. if the "bomb-bay" is not part of the pressure hull. I wonder how they justify the part about the gain in speed and agility at shallow depth and high sea state.

TG