Re: 17ft fiberglass canoe rail fix
First of all, welcome to the Iboats Dry Dock...
Yes, you need to remove all the loose stuff any way you can...
Then, depending on how thick the shell is, you'll want to grind down to good fiberglass, at least in a ration of 12:1...for example, if the shell is approximately 1/4 inch thick, then you'll want to grind back about 3" on either side of the crack, but gradually tapering from the deepest part of the crack to the surface...then cut progressively larger and larger pieces of 1.5 ounce CSM ( Chopped Strand Mat)...
Layer that in there until you are almost back to the full thickness of the shell, then lay in a final layer of 1708 Biaxial cloth...
You could also skip the last layer of 1708 and take it all the way to the finished surface height with CSM, but the 1708 is much stronger...
Another option is to make the repairs 1/2 way on the outer skin, then the other half from the inside...
You will need UN-waxed Polyester resin, NOT generally found at Home Depot or Lowes or the local auto parts store...you might find it at a wholesale auto body supply house or a local marine supplier, otherwise you might have to order it from the web from someplace like here on Iboats.com...
You will also need some PPE ( Personal Protective Equipment, to include a respiratorand some form of full body coverage like a Tyvek) suit assorted sanding grinding tools and supplies, Acetone, Disposable gloves, Baby Powder, some mixing buckets, chip brushes...
See beloow for a couple of pics of what you might be looking for...
Gloves, these stand up to Acetone and can be used multiple times...
One of many types of sanding discs, these are 36 grit for a 4.5" and 7" grinders...they require the correct backing plate...
Here is another type called a flap disk...
This is a 4.5" grinder, available cheap at Harbor Freight...
And these are what the CSM ( center large roll) and the 1708 (left, smaller roll)...you can also see some fiberglass resin in the 5 gallon buckets and Acetone in the Gallon jugs...you will obviously NOT need this large of a quantity of materials...
and this is the Full face respirator I use, but you might be able to get by with a Half Mask and some goggles...
Hopefully this will get you started...
Have fun!
GT1M
PS, if its plastic...none of the above will apply...sorry