Blue Bear:
I know exactly what your talking about with those safety lines had a few wad up on me myself. 
There is a couple of solutions out there though.
One is to draw the circle on the deck where decal will go with a pencil in a compass or a pair if calipers and slightly scribe a line. Use theses marks to guide the decal into a circle if you using as little water as possible.
Another technique I have done is to trace the decal over a piece of frisket or other stencil type making material. Cut out the pattern and place it on the deck  and paint the appropriate colors on the deck.
Now the first two techniques above you need the decal. If the decal is already gone and wadded up like alot of  mine have been. You can take the compass draw one circle on the deck. Then take the compass using the same radius and draw a cirlce on the stencil material. adjust the compass to a radius so the second cirlcle will show how wide you want the stripe and draw your second circle on the deck and stencil. Then place the stencil down and paint it directly on the deck.
This is alot of work but with a sharp knife and alot of luck can be done quickly and the results look great. 
I have done the about for the safety line you described and also the stripes on the flight decks of carriers 
I know it is wordy and as early as it is I hope it makes sense. If it doesn't drop me a line and I can answer any questions you may have and try to clear it yp for ya.
Good luck can't wait to see her. Hope this helped
Paul 
