Virginia class waterline

[Timothy L]

I want to be be clear about setting the waterline on my Virginia class model. I know that the hull in the real sub sits at a depth of 30.2 feet. But I’m a little confused about the angle at which it lays. I had thought that the tube holding the towed sonar array was parallel to the water’s edge (water line). However both of these pictures clearly indicate that it is not. My questions: is the aft deck from the sail to the stern on a constant slope - and is any part of the deck parallel to the water’s surface? Thank you.

[Ed Kirk]

The first subs in the series of this class didn't have vertical launching tubes installed so they look odd in the water, high in the bow. I heard they couldn't submerge during first test dive and had to add ballast. Later versions with the forward vertical tubes set level.

They really had a strange appearance.

Edit - sorry, I was thinking about the LA class, this boat has launch doors. Probably out of trim or no weapons. When the weapons get launched the tube fills with seawater and self compensates. Torpedo tubes get drained into negative tanks so they can be reloaded. I never had to deal with vertical launch tubes but they were probably left filled with seawater unless on the surface.

[Timothy L]

That’s interesting Ed. Thank you. I don’t know the block of the two pictures I posted. After I read your comments I searched more and found this shot of a block V. Interestingly, it appears as if they towed sonar array tube is parallel to the water surface.

[Timothy L]

Finally - just found these two photos of the block III South Dakota - which I had missed on earlier searches and which happens to be the specific model that I am building. The 2nd photo very clearly shows the waterline and the angle of the deck. Problem solved - but I found your information very helpful Ed because it made me do my search by block rather than the general class. Thanks!

[Ed Kirk]

I think I retired before block V, at least I never got to see one. The only sea duty I could get was COB on a Trident and I wanted to stay with the fast boats, couldn't go back to A-Gang. Privilege of rank.

[Ed Kirk]

Sorry, I was thinking about the LA class - closer look at your first posting there are forward vertical launch tubes. Probably out of trim or tubes empty, we had to load lead ballast when not loaded with weapons.

[Ed Kirk]

Have you looked at navsource.net? Great place to get information about Navy ships.

[wlambing]

Yes, the LA Class had a normal surface angle of 1.5 degrees up. 637s were designed to sit at 0 degrees. I suspect the VAs are designed similar to the LAs. God knows what the Seawolf sits like! :)

[Albacore 569]

All subs generally roughly are 1.5 degrees roughly bow up in surface trim (Submarine attitude) if they are expected to run at any given speed on the surface.

t's not about sub class - its better surface running hydrodynamics. All boats from SS1 Holland to present. Exception might be an Alvin or DSRV but here again, these aren't built/designed for surface running per say.

FUNDAMENTALS OF SUBMARINE THEORY

In the model rc sub world I usually if trimmed in level attitude submerged that is handled by default. Any electronic 'level keeper' normally will facilitate this. I add a slight stick bow up trim on surface, so bow isn't pulled under moving ay any moderate to fast speeds.

At speed on surface its slightly & unnoticeably 'surfing'.

Basic sub rc modeling stuff but still important.

[Timothy L]

Thanks folks - this was really helpful and got me on the right track.

[Davjacva]

The first subs in the series of this class didn't have vertical launching tubes installed so they look odd in the water, high in the bow. I heard they couldn't submerge during first test dive and had to add ballast. Later versions with the forward vertical tubes set level.

They really had a strange appearance.

Edit - sorry, I was thinking about the LA class, this boat has launch doors. Probably out of trim or no weapons. When the weapons get launched the tube fills with seawater and self compensates. Torpedo tubes get drained into negative tanks so they can be reloaded. I never had to deal with vertical launch tubes but they were probably left filled with seawater unless on the surface.

Ed, with VLS tubes, when going to sea, they are either loaded with missiles, TOTEM excercise units, or ballast cans (like what they have on boomers, only smaller). If the missile had fired, yes, it would be completely flooded with seawater, but at no time, unless you were pier-side would you have a out of trim condition due to VLS tubes. All 688 flights (1-6) had the same in-port trim.

Inport, both 688's and Virginia's had an inport trim that was 1-deg up that you established when coming in to port. When you went to sea, you re-trimmed for surface transit and dive trim.

To obtain a waterline, no matter what the submarine, I'd go with the forward and after draft marks, or scale a photo and take the measurements off of that. There are plenty of photos out there.

[Davjacva]

Yes, the LA Class had a normal surface angle of 1.5 degrees up. 637s were designed to sit at 0 degrees. I suspect the VAs are designed similar to the LAs. God knows what the Seawolf sits like! :)

Bill, you sure about that 1.5-deg up? I remember it being 1-deg up for inport trim. I can't remember why though. It wasn't the pit swords, or the outboard. The old boomers used to sit deep in the mud at low tide in Kings Bay. Like 637's, they sat at 0 too.

[Davjacva]

All subs generally roughly are 1.5 degrees roughly bow up in surface trim (Submarine attitude) if they are expected to run at any given speed on the surface.

t's not about sub class - its better surface running hydrodynamics. All boats from SS1 Holland to present. Exception might be an Alvin or DSRV but here again, these aren't built/designed for surface running per say.

FUNDAMENTALS OF SUBMARINE THEORY

In the model rc sub world I usually if trimmed in level attitude submerged that is handled by default. Any electronic 'level keeper' normally will facilitate this. I add a slight stick bow up trim on surface, so bow isn't pulled under moving ay any moderate to fast speeds.

At speed on surface its slightly & unnoticeably 'surfing'.

Basic sub rc modeling stuff but still important.

I disagree. 688's were the first that I remember having that up angle, and it was purposefully established when coming into port. When you left port, you changed trim, back to at sea running, and further to get the bow down you had the stern planes positioned to kick the ass end up to keep in a horizontal aspect.

[Albacore 569]

I disagree. 688's were the first that I remember having that up angle, and it was purposefully established when coming into port. When you left port, you changed trim, back to at sea running, and further to get the bow down you had the stern planes positioned to kick the ass end up to keep in a horizontal aspect.

Of course, it's only when in port. Surfaced. When at sea 97% of the time you are submerged.

[wlambing]

All classes have their own designed surface trim angle. Even the Moored Training Ships (Old ones & converted 688) have an up angle designed in. Narwhal's was 0.5 degree up. But, that was only for sitting still, on the surface, in calm seas. Anything worse than that, you rigged for surface and went for it! That involves locking the stern planes at a rise angle so the ass-end is pushing the rest of the boat out of the water. Didn't work so well for Kamehameha at least once!

Ships plans will give you the designed waterline, but pictures are best. Inport, there are many situations that lead to different levels. Just loading water into tanks for inport use causes the ship to sit just a certain way. Then, as that water gets used up, she'll sit another way. Always in flux!! Thus, the flux capacitor!!! ;)