[TG] [TG11] Axiom/RV-100 - Unclear image

[Tom - Raymarine - Moderator]

Hey Ian,

Quote:still had the monitor pause momentarily twice, display a vertical blip, and resuming scanning. This is of most concern.(Attachments: StutterBlip and StutterBlip2)

How long did it pause for? That's not something I've come across myself. Normally I'd say restricted supply or changing ping-rate because of bottom-lock-loss, but neither of those look like the case in your screenshots.

Quote: -I noticed my propwash shows really far out in space on the 3d. Like 20-50ft down when I accelerate. Is this common on the spatial relation near the boat on 3D? Are the 3 vertical lines (3 Rev/acceleration pumps) common on the downscan and 2d due to bubbles, vibrations, or is that electrical? (Attachments: Propwash, propwash2)

The three vertical streaks in the fishfinder and DV views do look like a sudden increase in background noise level, but there's no way to tell from an image alone whether it's acoustic or electical noise. I think that the increase in noise level is what's giving the appearance of a lot of clutter in the water column on the RV view, but given the range, I'm confident it's not really your own wash. The reason why it's showing to port only is, I expect, that the real signal levels are lower from that side because of the motor.
It'll be good to see what you get on the all-Manual setup when you increase speed like this.

Quote:-I noticed my motor blocks the sidescan. I don't know if I caused it with an angle to transom adjustment (likely), but I can get it out of the way by trimming up some. Kind of a pain. I will have to tweak the angle more and see (Attachment: Putmotordown)

It's unfortunately hard to avoid this kind of thing with a transom transducer. It's a bit of a compromise between the convenience and cost-saving of the single transducer against the improvement in the image that results from the through-hull split pair, with tilted elements. I always recommend through-hull faired transducers whereever they're feasible, they are just the best for optimum sounder image. Moving the transducer closer to the outboard may (slightly counter-intuitively) help in your system, at the expense of a bit more noise and increased risk of aeration. Make sure it's not putting aerated, turbulent water across the engine intakes though: starving the engine of a clean flow of coolant water isn't cool.

Quote:-The perspective of the shoreline on 3D seems far down from the boat. The xducer is parallel to the concrete when on a trailer. Is this something messed up in the angle, settings? I was about 40' off the shoreline on the first picture, and about 20' out on shoreline 2. Kind of falls in line with the propwash depiction though. (Attachment: Shoreline, Shoreline 2)

Because of the shape of the RV beams, the surface clutter and the way the signal processing is done, the bottom image won't come all the way to the 0ft depth line on the screen. Your images look normal for a shoreline (the 'deep' area further out from the shoreline on that side is the sounder's interpretation of having no signals bouncing back from greater range on that side - it thinks there's probably a big drop-off and everything behind that is in 'shadow'.)

Quote:-Is downscan supposed to be more clear than this? Seems like so from what I've seen on the internet, but this is the best it gets for me (Attachment: DownscanSharpness)

The Intensity is a little higher than I generally prefer to use, personally, which is saturating some of the bottom echoes and losing some detail there. Other than that, I suspect that you'll see an increase in clarity if you reduce the scroll-rate, and also view in a larger window (a lot of the graininess in your image is just the limited resolution of the LCD in a small window, some of the fish targets in the water column are only 2 or 3 pixels across, for example.) How does it look full-screen?

Quote:-Does the sidescan typically look like this? (Attachment: SideScanStreaks)

The appearance will change a lot depending on your boat-speed and scroll-rate, amongst other things. The streaks that you're seeing are a function of your very low speed and what I would guess is a fairly high scroll-rate: things are staying in the SV beam for quote a long time and being stretched out in the image. The bright streaks are almost certainly fish targets (nice ones, given the brightness, size and range: go after them!), whilst the 3 or 4 brighter patches with dark shadows behind that show up down in the bottom right (above-right of the Range +) are likely to be mid-water fish or schools that are casting a shadow on the bottom. You can get an idea of their size and height off the bottom from the density and size of the shadow and separation between the shadow and target. All good stuff to be looking out for. We have a championship-winning marlin skipper here in Australia who uses marks very like those when chasing small black-marlin inshore in 30-80m of water. He swears by it: spot a mark like the one half-way up your image, ~70ft out, circle round, hook up.

Does this answer some of your questions?
Regards,
Tom