I am looking to build a series of rods specifically for trolling for White Marlin. I an thinking 6' with a little bit of a softer tip but enough back bone to handle any White. Also weight is a factor, I am looking for the lightest(weight) blank possible. The blank needs to be rated at 30lb-50lb. Thanks for the info.
Tightlines

I know nothing about this type of fishing, but for a 30-50# blank, I don't think thre is all that much of a difference in weight between most blanks. My guess is that you could find a graphite blank like a GUSA or even a Cape Fear, or a Composite Calstar, Seeker or LAmiglas - and they'd all be within the same ballpark weightwise. You'd add a lot of weight depending on which guides you use, and what material you use for the handle assembly.

imo - I've never White Marlin fished, I always though of Marlin needing 130# blanks, not 30-50#

I personally have several Cape Fear rods and have caught hundreds of billfish on them. I my opinion you won't find a better blank. I use the Bluewater series. But when I go fishing for White Marlin I never use more then 20lb test. I know that Raeford does make a blank that would work for you. Mud Hole sells several different styles of Cape Fear Blanks. You won't be dissapointed. Scott

White Marlin are much smaller than blues. People frequently catch them on 30# tackle. I would reccomend a calstar blank. I have a bunch of E-Glass 20-50 line rated stand up blanks. Using them for school tuna, wahoo, dolphin, king fish, sails and smaller marlin.

Cape Fear - the 7' model, either the 16-25 or the 20-30.

Seeker BT-20 would be a great choice. It has a soft 20lb tip matched up to a 30lb butt. Trim to desired length. Ed

i use calstar grafighter blanks in 6 1/2 30-80lbs for white marlin rods which are also a nice fit for sailfish and sm.tuna....the blanks are sensitive and light and i use tuff butts to keep the weight down as well...it couples really nice w/tld 25's.

Josh, which Calstar graphiter blank are you using, the GF7465L or the GF765L? Thanks for the info

Though I've only fished the salt twice, both on charter boats for big game, a rod rated for anywhere 20-30 would work for white marlin. Out west, we don't have any whites; however, we have the Striped Marlin, which is usually much smaller than the Pacific Blues & I would think is about the same general size as the whites. On the charter boats, obviously they use the 60-80 lb. classes for the stripes so the clients can't break fish off if they're inexperienced; but regular marlin guys out here just use 20 or 30 with an 80 pound leader. This setup can handle most small marlin & does just fine as a rod for yellowfin tuna, wahoo, dorado & the like. As for the blank, I know nothing about building a saltwater rod, but the other guys who posted sound like experts, they'll definitely will help you out on that.