Join Date: Oct 2004
Location: Narragansett Bay
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Typically, lasers are used for scribing new lines parallel to waterlines. However, using this technique requires the boat to be perfectly level on keel blocks and boat stands to start with - not always an easy task.
If your present boot stripe (or bottom paint line) is parallel with the water level, but you simply want to raise it 4", mark the new line using inexpensive, 4" masking tape. Then make a new run of 2" blue tape above the 4" tape, remove the 4" tape and you have a new mark for the bottom paint.
Another method is to run the point of a large compass along the present waterline, marking the new line 4" above with the parallel pencil point end. Use the penciled mark as a guide for laying a line of masking tape.
Of course, the consistency of new lines marked using either of these techniques, will be off level by wide variations in hull curvature. To compensate, a small hand level held horizontally with the old line, may be utilized in conjunction with a compass. This takes steady eye-hand co-ordination, but is effective.
A third method, and probably the most accurate next to using lasers, is by using an adjustable 90 degree machinist's square with a built-in bubble level. By sliding the square's base along the length of the steel rule, to compensate for hull curvature, while keeping the base level with the old line, a new parallel line is traced at a consistently gauged vertical distance above.
True Blue . . .
sold the Nauticat
Last edited by TrueBlue; 05-15-2006 at 11:37 AM.