Place the canoe on a surface which will allow free manoeuvring around the boat. Having plenty of space to work on the canoe will not only make the refinishing task much easier but will also save time.
Use acetone (paint brush cleaning liquid) to clean the canoe. Ensure that any dirt or grime accumulated on the canoe is removed.
Thoroughly wash the canoe with clean water. Washing the canoe is meant at removing all the acetone that you used earlier. Make sure that you remove all the acetone, else it will corrode the gel coat that you are going to apply later.
Sand the canoe with sandpaper to get rid of scratches and abrasions. The sanding part will be much easier if you use an electrical palm sander. However, if you do not have an electrical palm sander at your disposal, hand-sanding the canoe would be good enough.
Clear the fibreglass dust that was created in the previous step. You can blow away the dust with a blow dryer. Alternatively, you can use a hand-held fan for this purpose.
The canoe should be perfectly smooth and clean by now and it is time to refinish it. Apply a uniform coat of gel resin with a brush just as you would paint a wall with a brush. For large sections of the canoe such as the sides and the bottom, you can use paint roller. For narrow parts where a paint roller would not go, you can use foam brushes.
Let the gel resin coat dry completely and check if another needs to be applied. You can apply as many coats as required but make sure that you let the first coat dry before applying the next one.
Allow time for the final gel resin coat to dry completely. Finally, apply a uniform layer of canoe wax to seal you work.