GP1870F Transducer Selection



Considering 600W with bottom definition, fish size calculation and speed VS 525TID-TMD
1KW without these three features but with more power and much better bottom definition. With the 1K is it possible to still determine whether bottom is gravel vs sand vs mud? I fish Alaskan saltwater (PWS) and I am particularly focused on structure definition but also bottom definition for halibut fishing. Will the GPS give me speed without having that feature on the transducer?
GPS will provide Speed Over Ground (SOG). Not everyone needs or wants Speed Thru Water (STW). Many people have a good idea how hard the bottom the bottom is by observing how thick/thin the bottom structure shows and the represented colors. Hard bottoms will reflect more signal resulting in stronger colors like red and have a thicker bottom. Mud and softer structure will reflect less signal resulting in a thinner bottom and softer represented colors like green.
Thanks...that makes sense! Is the fish size option another entry level feature that can also be determined by signal? It seems like the longer arches are primarily a matter of boat and fish speed and not size??
Fish size is more difficult to determine. There are many settings like picture advance that can reduce and expand your targets. Mostly you can compare the targets to other things you see on your screen like bait balls and what frequency that it shows up on. High freq will show most everything but only larger targets will show up on the Low Freq. Although digital processed sounders are much clearer and offer better displays, they still operate very much like sounders have for the last 50 years.