Otterman,

So I think I follow how you're doing it. I tried a slightly different way which seems to be working. Because I have a very odd shaped hull, I made a copy of the hull and reduced it by 10% and placed it inside the other hull (aligning the best I could by eye to put it right in the middle of the other hull in all three directions). Then I did what you recommend, I created some panel lining, did a boolean dif and then cut out the lines from the outer hull, leaving the inner hull uncut and helping to form the channel.

Seems to be working OK, I'm going to try a few more lines and see how it continues to work.

Thanks for the insight, really appreciate it.

Ryan.