Hull blue printing is an art form taken very seriously at Boat Customs. We are one of the leaders in bottom repair and hull blue printing for race and pleasure, performance boats. For Hull blue printing to work, it must be done correctly. If incorrect procedures are used the hull could be damaged. Most of the time we bring the hull bottom to tighter tolerances than can be done in the mold.


What is blueprinting? The term is probably familiar to most, but you've likely heard it only in reference to engines or parts. Blueprinting means to modify an object in order to bring its critical dimensions as close to original factory specifications: Production tolerances and variances often allow parts to vary. Here at Boat Customs we strive to exceed OEM specifications. Most of the time we bring the hull bottom within tolerances of 1mm to 2mm, any hook or variation in the running surface can cause substantial handling issues and top speed losses.  


The process we use is called fair fill & block,


  1. Assess where the running surface has flaws and imperfection marks and note these areas.

  2. Assess if there are delimitation issues. If not we use the original surface material we have available to straighten the surface as much as possible, in doing so we remove the gel or paint in high areas and leave it in the low area.

  3. Once we have established the high and low spots we skin coat sections roughly 2’ x 3’ leaving the low spots extra thick. We like to use an aluminum straight edge to insure consistency.

  4. Then we block numerous times repeating until we are completely happy with the surface variances.

  5. We still have one more chance to get it right, we now match the gel coat color & spray 30mils thick gel or filler coat feathering the edges. Let that dry over night.

  6. Now on to final finish we block sand by hand starting with grits 120 all the way up to 1500. We then polish the overall bottom, or apply top coat on epoxy applications. In some cases we leave 400 grit scratches in the surface to aerate the water.

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