I've seen that quite a few Sidescan users arent sure what to expect of their units, or how to properly use them to get the best results and to understand what they are seeing. A few guidelines.......please feel free to add more - and maybe some screenshots of problems and solutions.
1. The image on the screen will become more and more truncated the faster you go. To get an approximate 1/1 image while looking say, 80ft to each side you need to be doing 1 knot. After that the objects you see are becoming increasingly squeezed longitudinally i.e , say at 4 knots a 10ft tree lying on the bottom parallel to your course will appear on your HDS screen the same as a 2.5ft long tree would do if you were doing 1kt. Once you go over 6 kts you will lose the possibility of detecting smaller objects altogether. So if you want to detect small objects, or achieve good image definition SLOW DOWN. 2-4 knots is good.
2. Record small chunks of data – 30 mins is probably an ideal maximum. You never know what you may want to do with it.
3. Record all channels
4. If you are planning on stopping and drifting , start a new recording.
5. Don’t use cheap SD cards. You may be lucky – there will always be someone who buys the cheapest and never has a problem. It’s not me, and it probably wont be you.
6. Use a good power supply – and avoid direct connections to the motor circuit. HDS are voltage sensitive and cranking the motor, or running on reduced power will produce all sorts of strange effects (lines, interference, reboots, fadeouts)
7. Position your transducer carefully. It does not work in air, nor was it intended to. When your bow lifts out of the water it is forcing air out under the back of boat. Some hull forms trap air even at low speeds. Assess it carefully. You need a perfectly clean water flow past the transducer to achieve top class results.
8. Your outboard is an obstruction. You either need to jack it out, or trim it up to ensure that the sound beam can shoot past it unobstructed.
9. If you want to snip your sl2 files in half, or extract only small sections of it, then set it as the data file in the simulator in your unit and replay it, and record at the same time. Stop and restart the recording to extract the bits you want as separate files. It takes a little time of course, but it’s the only easy way.
10. Do not lead the transducer cables or Ethernet cables close and parallel to or secured to any power cables in your boat. It’s a likely way to get interference and poor definition.
11. Do not obscure the GPS receiver / antenna. A high quality position contributes massively to high quality imagery.
12. When using ss and a transom mount to carry out high definition surveys you need to plan in advance. The micro bubbles introduced into the water column by your propeller attenuate the signal. After a couple of passes the return quality is seriously degraded. I’ve found that in a lake around 15 minutes normally gives it time to settle down again when I'm doing archaeological stuff that concentrates on small areas.
13. 3ft Waves aren't good. Smooth water is.
14. Try and keep to straight lines, but Reefmaster's SS editor is now so good that you can easily chop out and nasty corners when you make the mosaic.
T
