I've always shot helical, but I'm messing around with the minimal fletching concepts in the extreme FOC thread.  Looks like I'll wind up at 18-20? FOC on a 610 grain arrow, which I'm shooting out of a 55-56 lb bow.  Where is a good place to start (or, for that matter, end) with offset on a straight clamp?  Do you offset both top and bottom?  Oh, I'm dinking around with 3-4" and both 3 and 4 fletch low profile bananas.

Unless it is any different from the normal way, I believe that you offset what amount it takes to lay the foot of the feather smoothly on the shaft.

I thought the purpose of a straight clamp was no offset ?? I have only used RH

I must be missing somethink here !!
From all I have learned and experimented with over the years is - the most important thing for good arrow flight and ultimatly - penertration is to have enough fletching to get that shaft straight as posible as quick as posible.
And(fact)to shoot any 2 blade Broadhead you must have helical(max I reckon) on that shaft.
But i've been wrong before !

all the wat so the feather is touching the shaft from one end to the other....Started off using that and still do for my flu-flu's.

i do mine at about 5% works awesome

You can only offset the feather so much, and yes you offset on both ends just make sure the quill lays flat on the shaft.
Tusker:
The helical fletch only came about in the early to mid 60's, if straight fletch would not stabilize a two blade broadhead, how did All those that came before that time ever get by. And you are correct good penetration comes from an arrow that straightens out quickly as possible and a straight off set will do that.
I have arrows in my collection, made in the early 1900's to the 50's they are all straight fletched.

Bob

A strong helical feather is over steering the arrow and will cover up a arrow that is not properly tuned, it also sounds like a small flu-flu.

I use-to be of this same belief, now I shoot 4x3" feather off set at 1.5 degrees, I shoot 285 grain Grizzlies and 315 grain El grady's.

First get your arrow tuned to your bow then you will need vary little guidance on the back.

Why? it's so quit, silent arrow flight    

I've played around with different fletching mounting for 50 plus years, tried them all and have always come back to straight fletching with enough off set the the feather lies flat on shaft, too me it's quietier then helical fletching.

I have only used Bitz fletchers and with these you would do both ends to keep as much of the feather in contact with the shaft.

I am not sure about degrees but I would guess it to be around 3 to 5.

Have not used offset fletching for quite sometime now. Just like my current setup of 4 x 4" naners with left helical.

Good luck and let us know how they shoot.

CS

When it comes to fletching I think many use WAY too much fletching and more helical than necessary. Our society has become if a little is good then more must be better, and unfortunately that is not so. There is a point of diminishing returns where you will loose more than you gain.
Bob

i shoot a 580gr arrow at 20% FOC out of my 55# recurve. i use 3 x 4" shield cut feathers. r/h offset. works great! i think 3 x 4" feathers is plenty at that FOC. less crosswind surface area too. here's a thought- wouldn't an arrow that is spinning really fast, (heaviy helical) magnify any imbalance, ie- misaligned b/h and/or not perfectly straight shaft?