Can a fiberglass seatpan support my weight?

[Andrewck]

Good evening fellow brickers!  So I am building my K75 cafe racer and just fabricated a custom fiberglass seat.  When I tried to sit on said seat the first time, it cracked on the side.   A few more layers of fiberglass resin shored everything up and another layer of fiberglass cloth and resin has made the seat platform fairly strong.  My question pertains to the strength of fiberglass...

I am using a particleboard board to give the fiberglass shell extra reinforcement (photo 1).  The board rests on top of 4 rubber stoppers to carry my weight (photo 2).  I can sit on the board/shell without cracking of the fiberglass so I don't mind riding like this.  The only issue is the height (photo 3).  You can see the particleboard adds about 3/4" height to the seat and when paired with my seat cushion...it's feeling a little snug when standing over the bike.

So I would like to eliminate the particleboard if possible, meaning the fiberglass would rest directly on the rubber stoppers.  If I lay down a few more layers of fiberglass cloth and resin, will my seat be strong enough to support me without cracking?  I weigh 190 lbs, so with all my gear on I'm probably just over 200 lbs.  Would appreciate any insight you have.  Adding photo 4 to show stopper spacing from above.  Called this the Lineage Eraser before cutting those bolts down in front.  And yes, the bolts have been shaved down.

[The Mighty Gryphon]

How much room do you have under the centerline of the seat when it's mounted on the bike? 

If you can, I would get a piece of pipe insulation about 1 1/2" in diameter, cut it in half and glue it down the center of the seat from front to back.  Then put at least three layers of glass mat, (not cloth, the mat is stronger per layer) over the insulation with at least 1" extra on each side for the first layer and each subsequent layer extends another 1/2" so the third layer is 2" from each side of the pipe insulation.

Also, if you have the room I would add a couple more layers to the inner surface of the sides under the seat.  The idea here is that any vertical glass will add the strength you need to support your weight more so than just adding more thickness to the flat of the seat. 

Before you add any more glass and resin wash the seat base well with Dawn detergent and a little ammonia to dewax the cured resin followed by a good scuffing with 36 or 80 grit paper to give the new layers a good surface to bond to.