How can I find out what material my Sawyer cruiser is built of? I need to make a small repair so i need to determine what layup was used on this boat. Problem is I don’t know how to go about finding out that kind of information now that Sawyer is gone.
Thanks John R
You can use glass and epoxy regardless
of whether the canoe was glass or Kevlar.
Kevlar is good for inside repairs, but not for outside repairs.
Epoxy resin will stick well to whatever resin Sawyer was using; probably they used a quality polyester.
Sawyer cruiser repair
Thanks for the quick information. If I use epoxy will gelcoat repair adhere to that or will I have to paint to match the hull color?
Thanks John R
Don’t know about gelcoat adhesion.
Sawyer Cruiser
Sawyer made their boats with epoxy resin at one time. They may well have switched resins over the years.
Gel coat is typically a polyester. Polyester will not cure reliably over epoxy. I have heard of some people getting away with it, but you could wind up with a real mess.
Epoxy repair
If I cut out the damage and repair with epoxy and glass, then fill with??? (Marine filler) should I fill the repair level with the old gelcoat and paint over the repaired area? Is this the proper method for leveling the patch?
What is a good filler to use over an epoxy repair? I assume epoxy filler would not adhere over the edges of the old gelcoat but I’m not sure about that. Sorry about the basic questions, never worked on boats with gelcoat before
Thanks John
Post some pictures of the damage
It would then be a lot easier to offer advice.
A few general principles:
I would debride any loose and delaminated material from the damaged area, but I would not necessarily “cut out” the area of damage. Save what is still intact and patch over it. If you have a through and through hole or crack you may need to find a way to align the edges while the epoxy of your first patch cures. This can sometimes be done using flexible plastic or tape.
Try to do as much of the repair on the inside as possible. This will usually give a better cosmetic result. If the interior of your canoe is painted, you need to sand off all paint from the area you need to patch. If not, still sand well the area to get as good an epoxy bond as feasible. Clean well with acetone before patching.
Your patch should overlap any areas of severe damage by a couple of inches. If a multi-ply patch is called for, the individual layers should be made concentrically smaller so that the edges do not line up.
If you need to apply an external patch, you need to sand off the gel coat until you see fibers of the outermost layer of fabric.
You can usually find some type of paint that is a reasonably close color match to your gel coat. To get a really nice cosmetic result, after completing your external patch feather the edges smoothly. You may well then need to fill and fair the area of the patch up flush with the surrounding hull before painting. Adding a fairing compound to your epoxy makes this easier. The fairing compound adds bulk to the epoxy allowing it to fill depressions better but can be easily sanded. You generally need to overfill the repair with the fairing compound then sand it down flush.
The epoxy will bond to the underlying patch. You do not need it to bond to gel coat but it generally will do so without any problem. Epoxy will bond to cured polyester. But the reverse is not necessarily true.
I don’t fully understand the chemistry but I have read that epoxies have an excess of unreacted amines that remain in the cured resin. When polyester resin is applied over epoxy, these amines can be leached out of the cured epoxy and interfere with the polyester curing.
Not a puncture through the hull
Just a split in the gelcoat, top to bottom about 3 or 4 inches and a peice of gelcoat about the size of a quarter that is popped lose but still attached. Hull under the crack feels like it may flex a little more than the rest of the hull in that area so the glass underneith may be cracked also. Looks like this damage was probably from a side impact but I’m not sure, it was there when I got the boat.
I thought I would get the gelcoat out of the way then see what kind of damage is underneath. Grind / cut out any bad glass and patch. No damage is visible on the inside of the hull but the inside is painted. Better ideas for this repair???
Thanks John R
sounds reasonable
– Last Updated: Sep-13-15 10:51 AM EST –
If the area of gel coat damage feels soft I suspect you will find broken fiberglass beneath it. If so, I would sand off the gel coat over an area that extends 2" beyond any visible fiberglass damage. If the outer layer of fabric of your boat is fiberglass, you should have no difficulty sanding until you clearly see the glass fibers. If your boat has an outer layer of Kevlar the aramid fibers may start to "fuzz up" as you start to abrade them, at which point I would stop sanding. Try to feather the edges of the intact fabric at the edges of the portions you had to cut away.
Debride any broken fiberglass or Kevlar that has delaminated from the resin matrix. This might leave a void that will need to be filled. I will sometimes fill in a depression with epoxy thickened with colloidal silica powder (cab-o-sil) to build the area up flush with the surrounding intact fabric. This will allow your cloth to lay flat on the area of repair and you will be less likely to get epoxy voids where the cloth dips down over the edge of the intact fabric.
If there is a big depression to fill it is sometimes best to fill it in using multiple layers of fiberglass cut concentrically smaller until you have built the area up to flush with the surrounding hull. This will avoid a large area of epoxy unsupported by fabric and will be much stronger.
Fiberglass sands quite well so you should be able to feather the edges of your patches and fair down any areas that get built up too high and wind up sitting proud of the surrounding hull. In order to get a good cosmetic result you will need to fully fill the weave of your fiberglass cloth with epoxy. If there is irregularity of the patch surface (and there usually is) adding some fairing compound such as West Systems 410 Microlight or 407 Low-density microballoons will allow you to fill the low areas more efficiently and any areas that wind up overfilled will be easier to sand down than pure cured epoxy would be:
http://www.westsystem.com/ss/filler-selection-guide/
This pdf file from West Systems has a lot of info on fairing and finishing prior to painting:
http://www.westsystem.com/ss/assets/HowTo-Publications/Final-Fairing-and-Finishing.pdf
If you should be so lucky as to remove the damaged gel coat and find no hull fabric damaged badly enough to require repair you could simply repair the gel coat with a gel coat repair kit. There are quite a few youtube videos demonstrating gel coat repair.