My forge is a semi-portable brake drum type that I use it under a tall (8' eave, 10' top) metal carport. Currently, the flue is a four foot piece of 8" stove pipe with a 45* top to divert the smoke to the center of the roof, as can be seen in the attached photo. Most times it draws well, but only with a fairly strong fire. I don't want to put a hole in the roof and if I divert it out to the sides, I run the risk of embers blowing out into the dry leaves, etc. on my hillside. I have two fairly easy options: (1) extend the stove pipe another 3 feet or so, or (2) make another hood but extending out over the firepot more. If I make another hood, I can increase the stove pipe to a 12" or larger size; right now I'm restricted by the hood top to an 8" pipe.
Would it be better to extend the 8" stove pipe as long as possible, keeping it inside the roof, or make a larger hood with a 4 to 6 foot 12" stovepipe?
As a Rube Goldberg arrangement, I could also make an long, angled stove pipe and attach it to the tallest part of the roof at the open end.