What do you think when someone talks to you about feature finding? I bet it's a purpose-made rod, a large reel. Perhaps a braided reel line and certainly the inevitable maker float! Well, that's all well and good. If used correctly it works fine, but if used incorrectly it will cost you carp. Cast a large mark float and a 3 once lead on the top of the carp and they will bolt off never to return during your session. I only use a marker float on longish sessions, when I am confident carp are not present at the time, and I always use the smallest marker float I can get away with from Nash or ESP.
However, my fishing is probably a lot like yours. Short sessions of 12 hours or under, and I like to find the carp in the first place rather than wait for them to come to me. In such cases, I dare not scare the carp; so marker floats are not cast out. I normally use a 21/2 pound test curve rod for feature finding, and I normally tie to the line a 2-2/12 once lead. This is cast out to the spots in the water I want to find out about. Feel the lead dropping through the water and count how long it takes to drop to the lake bottom. The longer it takes the deeper it is. You should feel for features, as you ideally want to find gravel bars and clear areas, as fishing in weed really reduces your chances of catching, and the chance of your hook bait being tangled.
I find two or three careful casts is all you need. A lead around 2 ounces is ideal. To light a lead and you will feel nothing, too heavily and it will keep sticking. Marker floats will never be redundant, but think about what you are doing and you will be able to find the perfect spot.
