[TG] [TG11] adjust scroll speed

[Tom - Raymarine - Moderator]

Hello Geoffro,

The display defaults to the maximum sounder scroll-rate for the depth of water and the sounder channel(s) in use. There are several controls/factors however which will slow down the scrolling:

1. Menu > Settings (gearbox) > Sonar Display > Scroll Speed (defaults to 100%, values higher than this will essentially 'stretch out' the image)
2. Menu > Settings > Sounder > Ping Rate Limit (defaults to 80, lower values can reduce scrolling rate depending on the depth of water)
3. Range / water depth: because sounders have to wait for the echoes from the last ping to come back before they can send the next one, larger ranges/water depths mean that the ping rate and hence scroll rate of the sounder reduces. The speed of sound in salt water is approx. 1,500m/s, so in 750m of water it takes a full second for the ping to travel to the bottom and reflect back (1 ping per second); in 75m this means approx. 10 pings/second, and so on.
4. Frequencies/channels being used. In most cases, with a single transducer if you're pinging multiple channels at once then the system has to alternate pings between the displayed channels, so if you display both 50kHz and 200kHz (for example) at once then each channel gets half the scroll rate that it could if it were being used on its own. Generally speaking separate transducers don't fall under this limitation, nor does a Chirp transducer connected to a CP570 (the key advantage of the CP570 is that it can look at shallow and deep ranges - bottom tracking and pelagic fish - at the same time with fast scroll-rate on the shallow range.)
   

So, you should make sure that Scroll Rate is on 100%, that Ping Rate Limit is not set too low, that you're not using a deeper range-scale than you need to and that you're only displaying a single sounder channel. That will give the best scroll-rate for the current water depth.

Regards,
Tom