rod differences

Just taken the game back up at 45 having not fished since i was 15, getting my tackle together has een a minefield. could someone please tell me why float rods are measured by line rating and carp rodsare measured by test curve. Also why so many different rods? EG spod rod, marker rods, surely a carp rod could perform all these tasks.
Tight lines everyone

Hi Stephen not a carp man myself but I think the spod and marker rods have a greater test curve because of the greater weights they cast out.

You could try posting on the carp forum you may get a better and more enlightening response

Welcome back to the fishing fraternity!
The line rating on float rods basically shows the minimum and maximum line strengths that the rod is designed to handle. Perhaps more importantly it gives a guide to the strength of line that can be used for the hooklength, around 80% of mainline strength.
I have a ready reckoner card that I took off the front of IYCF several years ago that gives appropriate mainline, hooklength and hooks sizes for different balanced tackles. I will post it when I get home.
CArp rod test curves give the line strength that can be used, between 4x and 6x the test curve of the rod (i.e. 2.5lb test curve = 10lb-15lb line)

Thanks for that, it now makes sense. It would be nice to know what line to use safely on certain test curves.