Wide seismic source systems

1. A marine seismic system comprising:

two vessels; and

three sources deployed, wherein the three sources are deployed offset from one another in a cross-line direction;

wherein a first source of the three sources is towed solely by a first vessel of the two vessels, the first source including all sources towed solely from the first vessel;

wherein a second source of the three sources is towed solely by a second vessel of the two vessels, the second source including all sources towed solely by the second vessel;

wherein a third source of the three offset sources is connected to one of the two vessels by a first tow member and connected to the other of the two vessels by a second tow member; and

wherein the marine seismic system comprises a ratio of less than one vessel per offset source.

2. The system of claim 1 , further comprising a streamer carrying a receiver.

3. The system of claim 1 , further comprising a streamer carrying a receiver, the streamer deployed by one of the two vessels.

4. The system of claim 1 , further comprising:

a third vessel;

a fourth source towed solely from the third vessel, wherein the fourth source includes all the sources towed solely from the third vessel and wherein the fourth source is offset in the cross-line direction from the three sources; and

a fifth source towed jointly from the third vessel and one of the two vessels, wherein the fifth source is offset in the cross-line direction the three sources and the fourth source.

5. The system of claim 4 , further comprising a streamer carrying a receiver, the streamer deployed by one of the two vessels.

6. A wide-azimuth marine seismic survey system, the system comprising:

a streamer array;

a first source towed solely from a first vessel, wherein the first source includes all sources towed solely by the first vessel;

a second source towed solely from a second vessel, wherein the second source includes all sources towed solely by the second vessel; and

a supplemental offset source towed jointly from the first vessel and the second vessel, wherein the first source, the second source and the supplemental offset source are offset from one another in a cross-line direction and wherein the wide-azimuth marine seismic survey system comprises a ratio of less than one vessel per offset source.

7. The system of claim 6 , wherein the streamer array is towed from the first vessel.

8. The system of claim 6 , wherein the sources are offset from each other in the cross-line direction of at least 100 meters.

9. The system of claim 6 , wherein the sources are offset from each other in the cross-line direction in excess of at least 200 meters.

10. The system of claim 9 , wherein the streamer array is towed.

11. The system of claim 6 , further comprising a third vessel towing a fourth source.

12. The system of claim 6 , further comprising:

a third source towed solely by a third vessel, wherein the third source includes all of the sources towed solely by the third vessel; and

a second supplemental offset source towed jointly by the third vessel and one of the first vessel or the second vessel.

13. The system of claim 12 , wherein the streamer array is towed.

14. The system of claim 12 , wherein the streamer array is towed by the first vessel.

15. A marine seismic survey method comprising:

deploying a marine seismic survey system comprising:

deploying a streamer array having receivers;

towing a first source solely from a first vessel, wherein the first source includes all sources towed solely by the first vessel;

towing a second source solely from a second vessel, the second source offset from the first source in a cross-line direction, wherein the second source includes all sources towed solely from the second vessel; and

towing a supplemental source offset in the cross-line direction from the first source and from the second source, wherein the supplemental source is connected to the first vessel by a first tow member and the supplemental source is connected to the second vessel by a second tow member, wherein the marine seismic survey system comprises a ratio of less than one vessel per offset source.

16. The method of claim 15 , wherein deploying a streamer array comprises towing the streamer array.

17. The method of claim 16 , wherein the streamer array is towed by one of the first vessel or the second vessel.