maxload wrote:

I really struggled with the straight brass tubes I got from mcmaster carr because they were so "hard" - I split a couple even after annealing them and struggled even with the air hammer to flare them. The preflared tubes I could literally hold in one hand, angle the preflared side to match the interior angle perfectly with the air hammer in the other. I didn't even need to anneal them. Then I could slip the preflared end in the boat (I bedded it w 4200, clean up with acetone not denatured alcohol) With a friend backing up the inside holding the preflared end and o-ring tight to the hull I could easily flare the outside to match any angle on the hull.

good luck