I have a couple of A6 crucibles -- not strictly speaking "bilge" type, but shaped better than a straight pipe.
Dimensions are:
6 1/8" tall x 4 5/8" top diameter x 3 3/8" bottom diameter.
This is supposed to handle about 13.2 pounds of brass. Not sure how much iron. Well, I could figure that out. Let's see...
535 lbs/cuft brass, 442 lbs/cuft for grey iron (hey, that's different than what I found online earlier 491 lbs cuft....? Oh well..)
442/535 * 13.2 = 10.9 lbs, okay say 11 lbs, so A6 is about right for my furnace assuming a 10 lb charge.
Okay.
So say an A6 crucible is about 1/2" thick -- that's about what a steel ladle imitation of that shape should be with an allowance for the lining thickness.
So I could use the A6 crucible as a model for making a steel ladle.