The paints do require the proper primer, otherwise the paint won't stick to the fiberglass. They will cure to a mirror finish(without buffing/polishing) if properly prepared and applied. The finish depends greatly on the quality of the prep work. In fact, the paint finish can be soo shiny that it shows any flaws in your repair work and fairing.
Getting rid of any residual silicone is paramount. You need some nasty solvents, and multiple wipe downs to be sure its gone. This can also be an issue on boats that have had their gelcoat "restored" with silicone based products such as "penetrol".
For the canoe the water permeability is really a non issue. If the next project is trailerable, you could say the same. In any event, as noted above epoxy coatings are used as barriers in place of gel coat when blistered hulls are repaired.
Many of the better boat builders these days don't gelcoat their hulls, but choose to paint instead.
There is no structural strength in gelcoat or paint, but the 2 part paints will withstand more punishment than anything else.
Last edited by Faster; 06-20-2006 at 07:20 PM.