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From a Bare Hull:  The Deck (Page 6)

Fiberglassing the Decks

In order to weather proof the decks, as well as make them more impact resistant and to tie the entire deck and hull structures firmly together, I had decided during the initial stages to sheath the plywood decks with fiberglass.  The traditional means of weatherproofing wooden decks used treated and painted canvas, a tried-and-true method but one best reserved for truly traditional craft and associated restorations.

The deck as constructed did not need the particular added strength of heavy fiberglass--the wooden deck beams and epoxy-laminated dual  layer plywood deck was strong enough as is.  Therefore, I decided to use two relatively light layers of material:  a first layer of 15 oz. biaxial cloth, and a second, overlapping layer of 7.5 oz. cloth.  The overlapping second layer's main purpose would be to cover the seams left behind by the first layer without leaving hard-to-fair ridges behind.  I also thought the second layer of light cloth would be effective at absorbing excess resin from the first layer, and prevent the laminate from being overly resin rich.

Over a period of two separate days, I measured and cut the numerous pieces of cloth needed for each layer.  I rough-measured each piece's maximum width requirement, then cut a section of cloth.  To make cutting and measuring easier, I hung the roll of fiberglass from a pole adjacent to my largest shop bench, enabling me to pull the material easily out onto a flat surface. 

Next, I draped each piece, one at a time, over its place on the deck, and then measured for the hull overlap.  I intended the first (bottom) layer of 15 oz. biax to extend off the deck and downwards onto the hull for about 6", and for the top layer of 7.5 oz. cloth to extend a further 1" beyond that.  (Later, during the hull fairing process, it would be easy to fair this new material in with the existing hull.  More on that later.)  With each piece measured, I cut off the excess and carefully folded the cloth into a neat package for later use, marking each piece as necessary.

The next day, I repeated the process with the lighter cloth for the second layer.  The heavier biax cloth was 50" in width, while the lighter cloth was 38".  This allowed for a convenient overlap distance, so I needed no special measures to provide for the overlap.

I had enlisted help for the fiberglassing day, mostly to assist with mixing resin, fetching material or tools, and for additional help on some of the larger pieces of cloth.  To prepare for the big day, I spent the rest of the afternoon cleaning the deck to remove any dust, organizing tools and fiberglass up on the deck for convenience, and ensuring that all the resin, solvent, and other materials I needed were in stock.

Fiberglassing was a big job and took two of us about 3-1/2 hours to complete the entire boat with both layers.  We began at the stem with the first layer of the heavier material, first by wetting out the plywood and sides of the hull (where the material would overlap), and  then laying the dry cloth carefully over the top.  For this project, I chose MAS low viscosity resin and medium hardener. 

After rolling the cloth into the resin beneath, we added more resin as needed to completely wet out the piece.  When it was completely saturated, we rolled it out with air rollers, paying close attention to the deck surface and the roundover where the material extended down onto the hull on each side.

When the first piece was complete, we could immediately add the second layer of lighter cloth, since the light cloth was only 38" wide, while the heavier cloth was 50".  In this manner, we continued, applying both layers in sequence.  The first three pieces were the most difficult, as they extended across the entire foredeck.  If the boat had been any bigger or wider, these pieces would have to have been ended at the centerline, as they simply would have been too large to handle.  As it was, we had no time to relax, and kept working.  I concentrated on positioning, rolling, and air-rolling, while Nathan, my helper, mixed additional resin as needed and assisted with rolling.

Once we completed the foredeck, the pieces shrank dramatically in size, making the job easier.  Alternating side to side, we continued down each sidedeck to the transom.  I let the fiberglass extend past the inside edge of the carlins for later trimming.  It was a messy and  tiresome job, but one completed with great success.  I left the material to cure overnight before continuing.

The next day, the fiberglass was cured enough to begin sanding the surface.  First, however, I scrubbed the entire area with a Scotch-Brite pad and plain water, in case any amine blush had formed on the surface.  The product description indicated that it was a low or no-blush resin, but it was better to take no chances.

When the washing was complete, and the surface dried, I commenced sanding to roughen the surface for later steps and remove any high spots.  I used 80 grit sandpaper on a random orbit sander for this chore.  Later, I also sanded the overlapping fiberglass on the hull, and sanded away any resin that had dripped down the hull; there was quite a bit in a few places, particularly forward, where more substantial amounts of resin had been needed in the cloth to get it to lay down properly on the hull.     

The new fiberglass stiffened the deck noticeably, though the decks had been strong and nearly flex-free before, and would provide the decks with the requisite watertight integrity.

Next:  Fairing and final preparations. 




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