Originally written by Keith Bradley on the Keith Bradley Boat Forum (KBB) on Wednesday October 30, 2013, it was lost when the forum went down. Keith has been nice enough to give Offshore Electrics Inc OSE permission to re-post it.The below paragraph was originally in Keith's closing thoughts, I thought it was important enough to say it first, since OSE agrees so heavily."It's tough to find info about this type of stuff from people who are good at it, because most of the people who have a high level of experience prefer to keep their trade secrets to themselves. I believe that if we all make an effort to contribute the knowledge we have, it will raise the level of all of our builds."
Sand the hull thoroughly prior to doing any inlay work. This is done to give the resin more surface area to bond to. An un-sanded hull will not support a strong bond, so sanding the hull is critical and should not by any means be considered an "option". While sanding the hull, you can also use this as an opportunity to remove or reduce any blemishes that may be in the hull from the factory. High/low spots, resin and fabric chunks, loose fibers, etc. should be removed or minimized. Any "bumps" on the surface under your fabric will be apparent even after the inlay is completed, so a little extra work here will produce a better looking finished product. Sandpaper as course as 80 grit and as fine as 220 can be used here, depending on hull size and construction material.
The first step when doing an inlay (after the hull is sanded) is to make a pattern or patterns for the fabric that will be used. In this demonstration, I used paper that is available on a roll. First, a basic set of measurements can be taken to acquire a starting shape. Once a basic shape is attained, place the paper inside the hull as a template. Mark and cut this piece as needed, until you have the shape that you want. Allow for an additional 1/8" to be added to your piece when you transfer it to fabric. Hint: While only the main pattern is shown in this pic, I made another pattern for a piece that lays behind it to complete the inlay. This piece was done in the same manner, and was made to cover the area behind the hatch and the inside surface of the sponson transoms.
Once patterns are established, place said patterns on an unrolled sheet of fabric (this may be fiberglass, Kevlar, Carbon fiber, etc.). With the pattern lying flat on the fabric, outline the fabric with 1/4" masking tape. Once the outline is completed, remove the pattern and discard it, or save it for future use if needed.
Cut through the center of the masking tape that you laid on the fabric. The resulting fabric piece will have a 1/8" masking tape border, which helps to keep the fabric from fraying and eases cutting.
After test fitting your newly-cut fabric piece in the hull, apply a coat of resin/hardener mixture to the hull surfaces where the fabric will be placed. Be sure to cover all the areas that fabric will be placed in order to achieve proper bonding throughout the inlay.
Fold the fabric evenly in thirds, with the tape facing as shown. This will allow easy insertion of fabric into the now wetted hull. When in place, the tape around the perimeter should be face down. The tape will be left on but not visible when the inlay is completed. Slide the fabric into position, holding it ABOVE the hull until it is centered in place. Then, unfold each side and press the fabric into position. Once the fabric is where you want it, apply a light layer of resin to the top side of fabric, making sure that there are no dry spots in the layer. If you are doing multiple layers (It's best to do them all at once so that a chemical bond is created between layers), apply a generous amount of resin to the top of each layer before adding another.
Once the fabric has been wetted, a small foam roller can be used to help ensure more uniform resin coverage, and better press the fabric into place. This can also remove or redistribute small puddles of resin, but it won't work miracles. Pay attention to depressions in the hull, such as the sides of the tunnel and steps. Fabric can easily bridge over the gaps if not paid attention to, which will lower the overall integrity of the inlay and greatly diminish the aesthetic appearance of the hull.
Here are a couple pics of the inlay demonstrated in this thread before dry. Once dry, it will loose a bit of the "wetness" that you see in these pics. This was done with a honeycomb carbon fiber fabric, which is slightly heavier and more difficult to wet. This fabric is slightly more difficult to lay onto curved surfaces like a boat hull, but still one that is possible to lay with good results. If this is your first time laying carbon fiber, a 2x2 twill or 1x1 plain weave will be easier to use.
That's it!
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