Downscan imaging sonar for reduced interference

1. A sonar transducer assembly for mounting to a surface watercraft, the assembly comprising:

a rectangular first transducer configured to produce a first beam defining a fan-shape and extending generally in a first plane; and

a rectangular second transducer configured to produce a second beam defining a fan- shape and extending generally in a second plane, wherein the first transducer and second transducer are approximately mounted in a single lateral plane with respect to a running direction of the surface watercraft;

wherein the first transducer and the second transducer are oriented such that the respective first and second beams extend from the single lateral plane to insonify different first and second areas each extending laterally with respect to the running direction of the surface watercraft, wherein the first transducer and the second transducer are oriented to provide a gap between the first area insonified by the first beam and the second area insonified by the second beam, with the gap extending in the running direction of the surface watercraft, and such that the first beam is outside of the second plane of the second beam, the resulting planar separation of the first and second planes of the first and second beams reducing interference between the first and second transducers.

2. The assembly according to claim 1 , wherein the first transducer and the second transducer are oriented such that the respective first and second beams insonify different first and second areas when produced simultaneously.

3. The assembly according to claim 1 , wherein the first transducer comprises a downscan transducer and the second transducer comprises a sidescan transducer.

4. The assembly according to claim 1 , wherein the first transducer comprises a sidescan transducer and the second transducer comprises a further sidescan transducer.

5. The assembly according to claim 1 further comprising a rectangular third transducer configured to produce a third beam defining a fan-shape and extending generally in a third plane, wherein the third transducer is oriented to insonify a third area that extends laterally with respect to the running direction of the surface watercraft.

6. The assembly according to claim 5 , wherein the first transducer comprises a downscan transducer, wherein the second transducer comprises a sidescan transducer, and wherein the third transducer comprises a further sidescan transducer.

7. The assembly according to claim 5 , wherein the first plane and the third plane each extend laterally from the running direction of the surface watercraft such that the first and third planes are coplanar, and such that the first and third beams are outside of the second plane of the second beam reducing interference between the second transducer and the first and third transducers.

8. A sonar transducer assembly for mounting to a surface watercraft, the sonar transducer assembly comprising a transducer housing within which are mounted at least a rectangular first transducer and a rectangular second transducer, wherein the first transducer is configured to produce a first beam defining a fan-shape and extending generally in a first plane, wherein the second transducer is configured to produce a second beam defining a fan-shape and extending generally in a second plane, wherein the first transducer and second transducer are approximately mounted in a single lateral plane with respect to a running direction of the surface watercraft, wherein the first transducer and the second transducer are oriented inside the housing such that the respective first and second beams extend from the single lateral plane to insonify different first and second areas each extending laterally with respect to the running direction of the surface watercraft, wherein the first transducer and the second transducer are oriented to provide a gap between the first area insonified by the first beam and the second area insonified by the second beam, with the gap extending in the running direction of the surface watercraft, and such that the first beam is outside of the second plane of the second beam, the resulting planar separation of the first and second planes of the first and second beams reducing interference between the first and second transducers.

9. The assembly according to claim 8 , wherein the first transducer and the second transducer are oriented such that the respective first and second beams insonify different first and second areas when produced simultaneously.

10. The transducer assembly according to claim 8 , wherein the first transducer comprises a downscan transducer and the second transducer comprises a sidescan transducer.

11. The transducer assembly according to claim 8 , wherein the first transducer comprises a sidescan transducer and the second transducer comprises a further sidescan transducer.

12. The transducer assembly according to claim 8 further comprising a rectangular third transducer mounted within the transducer housing and configured to produce a third beam defining a fan-shape and extending generally in a third plane, wherein the third transducer is oriented inside the housing to insonify a third area that extends laterally with respect to the running direction of the surface watercraft.

13. The transducer assembly according to claim 12 , wherein the first transducer comprises a downscan transducer, wherein the second transducer comprises a sidescan transducer, and wherein the third transducer comprises a further sidescan transducer.

14. The transducer assembly according claim 12 , wherein the first plane and the third plane each extend laterally from the running direction of the surface watercraft such that the first and third planes are coplanar, and such that the first and third beams are outside of the second plane of the second beam reducing interference between the second transducer and the first and third transducers.

15. A method for assembling a sonar transducer system for mounting to a surface watercraft, the method comprising:

providing a transducer housing;

mounting a rectangular first transducer configured to produce a first beam defining a fan- shape and extending generally in a first plane; and

mounting a rectangular second transducer configured to produce a second beam defining a fan-shape and extending generally in a second plane, wherein the first transducer and second transducer are approximately mounted in a single lateral plane with respect to a running direction of the surface watercraft, wherein the first transducer and the second transducer are oriented inside the transducer housing such that the respective first and second beams extend from the single lateral plane to insonify different first and second areas each extending laterally with respect to the running direction of the surface watercraft, wherein the first transducer and the second transducer are oriented to provide a gap between the first area insonified by the first beam and the second area insonified by the second beam, with the gap extending in the running direction of the surface watercraft, and such that the first beam is outside of the second plane of the second beam, the resulting planar separation of the first and second planes of the first and second beams reducing interference between the first and second transducers.

16. The method according to claim 15 , wherein mounting the first transducer and the second transducer comprises mounting the first transducer and second transducer in an orientation such that the respective first and second beams insonify different first and second areas when produced simultaneously.

17. The method according to claim 15 , wherein the first transducer comprises a downscan transducer and the second transducer comprises a sidescan transducer.

18. The method according to claim 15 , wherein the first transducer comprises a sidescan transducer and the second transducer comprises a further sidescan transducer.

19. The method according to claim 15 further comprising mounting a rectangular third transducer configured to produce a third beam defining a fan-shape and extending generally in a third plane, wherein the third transducer is oriented to insonify a third area that extends laterally with respect to the running direction of the surface watercraft.

20. The method according to claim 19 , wherein the first transducer comprises a downscan transducer, wherein the second transducer comprises a sidescan transducer, and wherein the third transducer comprises a further sidescan transducer.

21. The method according to claim 19 , wherein the first plane and the third plane each extend laterally from the running direction of the surface watercraft such that the first and third planes are coplanar, and such that the first and third beams are outside of the second plane of the second beam reducing interference between the second transducer and the first and third transducers.