How fix royalex canoe, previous fiberglass / abs slurry / epoxy in the way

I need advice how to repair a slightly leaking old town tripper. I took it out yesterday for the first time in 5 years. I had to plug it with JB weld marine just to make sure it wouldn’t sink on the trip. It did OK but a little water is still getting in. The canoe has previous ABS plastic / slurry (the black stuff in the photos) . I think the slurry has gotten UV damage over the past 5 years and it is cracking. It was layered over fiberglass.

What is the best way to fix this now? do I want to chip out the old ABS and do this over it again? Or just sand it down smooth? try to remove all the cracking stuff. Also now I have this white epoxy in the way. Should i try to get that out too? I don’t think I could get all the ABS off. Its in quite good shape higher up on the bow.

I’m open to whatever gorilla glue, g flex, trying to scrap it all off and do kevlar, whatever isn’t super expensive as this boat has seen better days.

If this was a virgin boat, clearly proper kevlar pads would be the way but since it already has all this ABS / fiberglass perhaps I need do stick with that method?

You have suffered a lot of abrasion and some UV damage. Dig out any loose material. Replace with thickened marine epoxy. Stop fooling around with other products. Then once you have it smooth, cover it with a layer of fiberglass cloth and epoxy. Since it is the stem which takes a lot of abuse, add a layer of 3 inch fiberglass tape and then a a roll of 2 inch fb tape with epoxy, Fill the weave with more epoxy and then paint it.

Thanks. Any recommendations on what type of Marine Epoxy? How much do I need for this entire job?

32oz of G flex for $75 from west marine. Also could get 32 oz of west system 105 for $49 and 7oz of the 205/206 hardener for $26 if that is better.

I’ve seen many say that soaking fiberglass with g flex is tough though without heating it up.

Is fiberglass cloths cut to tape size the same thing?

What type of paint is easy and will stick well?

This total boat kit appears to be a good price too: $55 for a quart of resin plus hardner:

There are many good marine epoxies now, West System, System 3, MAS etc. A quart will work fine and then you will have some on hand for other projects. I like 105 just fine.
When you cut fiberglass cloth to size you have loose edges. Tape has a bound edge.

Many kinds of paint will work. Epoxy paint, porch enamel, marine enamel, even latex house paint will work amazingly well. It needs to be applied to a clean surface and it needs to harden for a couple of days before going in the water.

G Flex epoxy will bond much more strongly to the ABS of Royalex boats than conventional epoxies like West Systems 105/205-206 or the Total Boat epoxy that was just mentioned. I have used it for repairs or installation of abrasion plates on dozens of Royalex canoes with excellent results. Before G Flex became available people did repair Royalex boats with conventional epoxies. Sometimes these repairs would be durable but I have seen many such repairs simply flake off after a year or two. Part of the problem is the compliance mismatch between conventional cured epoxy and the Royalex material. Royalex flexes much more than cured epoxy and the repeated sheer stress eventually leads to failure of the bond. I have removed many fiberglass patches applied to Royalex canoes with conventional epoxies by simply pulling the fiberglass patch off with my fingers.

Plain weave fabrics up to about 6 ounce per square yard are really not hard to wet out with G Flex unless you are working in very cold ambient temperature. I have applied many patches and abrasion plates with 5 oz/sq yd aramid cloth, 5 oz/sq yd Dynel fabric and 6 oz/sq yard fiberglass with no issues. I would not try to wet out multiple layers of such fabrics at one go, however. Always use unthickened G Flex to wet out cloth. I apply a thin layer of G Flex to the hull surface before laying on the fabric. The viscosity of G Flex does depend on ambient temperature. You can reduce the viscosity if necessary by gently warming the mixed epoxy but this will diminish pot life. You can also waft a heat gun or hair drier over the hull surface before applying your cloth and can do the same over the fabric to speed up the wet out process if you need to. I have found that it takes a little longer for the fibers of these fabrics to take up G Flex epoxy, but if you are patient I don’t think you will have any issues.

Fiberglass tape has a selvage edge on both sides of the tape which prevents fraying along those sides. That makes it easier to work with than plain weave fabrics which tend to fray. But if you are applying multiple layers you can not orient the fibers at different angles as is desirable. And once fully saturated the selvage edge tends to stand a bit proud of the hull surface and the rest of the fabric unless you sand it down.

As for how to proceed with your repair I would have to see the boat in person and work with it before deciding on the best approach. But in general I would definitely remove anything that is loose or easily removed that is not Royalex. That includes the fiberglass patch if it is relatively easily removed. You will want to cover an area of adjacent undamaged hull at least 2 inches in width in all directions with your fabric. If possible, remove the outer layer of vinyl from the Royalex in this area by sanding or using a wood chisel. Any vinyl you can’t remove needs to be sanded with 100-120 grit paper and thoroughly cleaned before your repair.

I expect you will find some exposed foam core after you get all the crap off. I fill in any exposed foam core with G Flex moderately thickened with colloidal silica powder (cab-o-sil). This usually takes a couple of applications as the epoxy settles down into the interstices of the foam core. If you overfill slightly you can sand the epoxy down fair and smooth after it cures.

After filling in any exposed foam core sand the entire area you are going to apply cloth to with 100-120 grit sandpaper. I would then wash the entire area with warm water with some Dreft dishwashing detergent, rinse very well, and clean the surface with denatured alcohol. I would apply at least two layers of 6 ounce/square yard fiberglass over any severely damaged area making the second patch one inch smaller concentrically than the first. And orient the fibers of the two patches so that the cross each other at a 45 degree angle. Completely fill the weave of the cloth with a second application of epoxy.

If you buy G Flex read the instructions carefully. You will see that West Systems recommends pretreating the Royalex hull surface by flame oxidizing it with a hand-held propane torch but indicates this is “optional”. Their test data indicates it does enhance the bond strength of G Flex to ABS but it must be done carefully to avoid overheating the Royalex and deforming the foam core. I would not try to flame oxidize any exposed foam core however, as this is very easy to melt.

I have most often used Krylon Fusion spray paint to cover any repairs although pretty much any paint will work. It will tend to get scratched off but is relatively easy to reapply.

about the same as Pete here for recommendation, with one difference in that I found after some sailboat and especially royalex canoe repairs that laying the glass down dry then dribbling and brushing g-flex into the glass worked well. Brush from the center of the patch outwards. Agree with ppine on getting what you can off beforehand. 32 oz. of G-Flex will have you leaving some to your heirs, or enough to repair multiple canoes, a rear view mirror on your truck, a rack on your truck, a drain on kitchen sinks macerator and several other odds and ends…fantastic epoxy that will seemingly attach anything to anything, so watch your fingers!!

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Thanks for the great information. G flex is it.

This ABS/fiberglass combo sucks to get off. Any tips? Here is a photo are working on removing the crap for about 20 minutes. I feel like a may have bit off a bit more than i can chew.

I guess I could get the acetone back out but now but all the exposed foam core has me worried with that.

I would try attacking that black stuff (ABS slurry if that is what it is) and 'glass with a wood chisel if you haven’t already. Use a fairly narrow one and keep the angle to the hull very shallow. If you have a relatively small area of gunk that is resistant, you can try using a rotary tool like a Dremel with a sanding drum to get it down flush with the adjacent hull. Any fiberglass that is really adherent to the hull can be left and glassed over if need be. Just sand it down smooth and fair before you lay your cloth on.

You are correct in keeping acetone well away from the exposed foam core. I have found that it is OK to use acetone on the solid ABS strata since it flashes off so quickly that there is no prolonged exposure. But it will melt the fine material of the foam core quickly. Also avoid any prolonged contact of an acetone rag with the hull.

When it comes to finally doing the 'glass work, follow Matt’s advice. As I said, I have had no problem wetting out a variety of fabrics with G Flex but the fibers take up the more viscous resin more slowly than conventional epoxies. If you become impatient you will likely wind up with a big, frayed mess. I will usually pour a bit of mixed epoxy onto the center of a patch and then carefully work it out toward the edges adding more as needed. When you get to the fibers at the very edge, dab the epoxy on repeatedly if necessary until the fibers are saturated.

I have used a variety of tools to wet out cloth including plastic stir sticks, wooden tongue blades, plastic sqeeges, and disposable foam brushes and any of them can work. I find that white vinegar does a good job of cleaning off mixing pots and application tools and it is cheap.

One of the nice things about G Flex epoxy is that the exact mix ratio of resin to hardener is not as critical as it is with conventional epoxies and the ratio is 1:1 resin to hardener by volume. This allows you to mix up batches of any size very quickly and by eye. With conventional epoxies you usually need to use mini-pumps to ensure the correct ratio and often wind up mixing up more epoxy than you need. When you are filling in exposed foam core on a curved surface like the stem, you may find it necessary to prop up the end of the boat so as to allow gravity to take the epoxy into the interstices of the foam core. You may have to do small areas at a time and reorient the boat repeatedly as the epoxy cures green enough that it does not run or sag. I have mixed up very tiny batches of G Flex by eye and I have never had a failure to cure.

use gorilla glue as a barrier between acetone and the foam core, if you want to use acetone to clean the rest off, or apply the abs slurry in the future.Apply sparingly, give it a day to cure, then grind the foamed up glue down to a thin layer. Lost power 4 times typing this…Isais is hitting…anyways, wire wheel on a drill will work pretty well, and I break out my air compresser to blow the grit out of the wound.

I’d get a grinder with flap discs or an orbital with an array of discs and a good mask/hearing protection to remove that. If it’s that stuck on, leave it and just re contour it.

Thanks for the idea about GFlex. You made me realize I have never repaired a Royalex boat. I have owned only a couple of them and never dinged them up enough to require repairs. There is plenty of science involved in boat repair, There is plenty of knowledge around here.

I probably will but I’m a bit hesitant to pull the trigger bc of the price ($90 total). This canoe is in rough shape and just want to get it usable again. Was starting to look on craiglist for other boats. There’s an explorer nearby for $650 and a tripper a little further away for $500.

Do I really need 32oz of this stuff ($68)? Seems like I probably need that much to be safe. How much cloth can I wet with the 9 oz (two 4.5 bottles- $24) of the gflex?

Is Gflex that amazing that it will keep forever and be handy to have for many years?

The dynel skid plates I commonly put on canoes are about 90 square inches and I need 3oz of gflex to paint the hull and wet the cloth. Given the size of your project I don’t think the two 4 oz bottles will be enough.

I’m not sure of the shelf life but I know I’ve used 5 year old gflex and haven’t had an issue.


No epoxy doesn’t last forever.

Your thinking is correct… that boat is what it is, don’t throw much money at it.

The G-Flex 650-8 will cover about 6 sq. ft. of 10 oz. fiberglass according to West Systems. That would be about 2½ x 2½ feet or 864 sq. in.

It’s available for about $20 online.

If you cannot get all the old stuff off gently so you do not damage whats left of the core and outer hull, I would just sand it smooth, fill any depressions in the core with 5 minute epoxy from Wal Mart so you have an even surface, then cover the whole shooting match with your glass and GFlex. I did an old OT Kennebec that was way worse than the photo above on both ends and I ended up using less than two of the 9 oz kits to do the whole thing and I used cotton felt which soaks up more epoxy, so if you do it with glass that should be more than enough. I spent more replacing the seats, thwart, yoke and grab handles than I did on hull repair.

I believe that 4 ounces of resin and 4 ounces of hardener will be enough to do the job but I can’t give you and iron clad guarantee. Dynel fibers soak up considerably more resin the fiberglass fibers do.

I’ll get 2 for a total of 16oz from walmart its 19.99 each. That plus the fiberglass and silicia will be an even $50, which is fine.

Here’s a photo after getting as much crap off as possible. There is a huge crack. Should I drop some gflex on the crack on the inside of the boat too. I don’t want to even look under the front of the boat. I may just put a strip on the front right on top of the ABS.

Well, you have found where the leak is. Yes, for a through and through crack I prefer to apply patches to both the interior and exterior of the hull. You will need to remove the grey vinyl layer from the interior of the Royalex to determine the full extent of the interior crack. The vinyl is more elastic than the solid ABS so often there is no damage or just a small, limited split in the vinyl covering a more extensive crack in the interior solid ABS lamina. The vinyl stretches and the less compliant ABS cracks. I would “gutter out” this interior crack at a 45 degree angle. A Dremel tool with an appropriate grinding bit works well if you have one. If not, an old “church key” can opener or a cabinet scraper with a triangular head and some sandpaper wrapped around a safety razor blade will work. Fill in the interior crack with G Flex and sand smooth, then cover with at least one layer of glass cloth.

It looks to me as if the entire area of damage can be covered with one generous sized abrasion plate if you wish to continue. I have repaired canoes that looked worse, although I can’t say with certainty it was the sensible thing to do.

It looks as if you have likely exposed the portion of the Royalex hull that needs to be repaired. You are going to need to patch over that entire tan-brown area of exposed ABS after filling in and fairing the exposed foam core, and your patch should extend at least two inches onto adjacent hull in all directions. To get your cloth to lay flat for a good bond, you need to either remove or sand flat and smooth that black crap. If it is adherent you can leave it and just smooth it out. If you have a finishing sander I would try that. Otherwise just use sandpaper and a small sanding block starting with something fairly coarse like 80 grit. I would apply one 6 ounce/square yard fiberglass patch over the damaged area and then cover the entire black area with a generous sized abrasion plate. But when you cut the cloth for the abrasion plate make sure it is cut on the bias so that the fibers of the weft and weave run at 45 degree angles to the long axis of the patch. That will allow it to lie down over the curvature of the stem with less tendency to pleat and will also maximize strength since the fibers of the two patches will be crossing at different angles.