16ft Cedar Strip

Minnesota Ted

Curious about Wooden Canoes
I'm new to the forum and hoping to get some advise...
I just picked up a 16ft cedar strip that is approx. 20 years old. The general condition in good. The canoe is complete but the hull has only been fiberglassed on the outside and was never sanded. The inside is not fiberglassed. The bottom of the canoe seems to have a permanent "oil can"
bulge where the inside of the canoe appears to have a hump in the center about 3-4 inches high. This hump can be pushed from the inside and it reduces to almost flat. What can I do to correct the hull?
Thanks from Minnesota....
I beam...

Hey Ted, I probably should not post reply as I don't have any answers except to say that it will be interesting to see the responses. I do know that the whole idea of fibreglass is like having an "I Beam" through the cross section. The filler material, cedar, has nothing to do with the strength of the canoe, only the inside and outside glas forming the sides of an I beam. With no inside glas, there was no strength and that's why it oil canned... GOOD LUCK...

I'm a bit confused as to what you got, if it's a stripper, and finished, it should have been glassed on the inside also, or it would be very weak.

Or is it a all wood canoe that somebody added glass to the outside?

Or something else.

As for the hogging, push it out and glass the inside??

I'd want to know more abot it before doing anything to it.

If your in the MPLS area I'd love to take a look at it.

Hi Dan,
Thanks for the note. I'll try to clarify.
The canoe is a stripper (no ribs) and I should have to said that it was not completely finished due to the fact that the inside was never glassed however, seats, yoke, and gunwalls are all attached to the boat.
I live about an 1 1/2 hours from Mounds View (25 minutes east of Medford off of I35)
I have some pics I can email but they don't show the bulge in the bottom of the canoe too well, they do give you an idea of the general condition.
I hope fixing the hull can accomplished by glassing the inside, I wonder about the usefulness of a rib(s) or a verticle brace up to the thwart from a rid or is that over kill?
I'm also looking for advise on what I should do with the rough exterior.. You can see the pattern of the cloth so, should I plan on doing a coat of resin 1st or go right to sanding it.

I'm guessing that glassing the inside will take care of it, though you might want to add a "rib" or 2 to stiffen it even more, ie, a doubled layer or two of glass across the canoe. I'm a bit surprised that it didn't fall apart w/o the inner layer of glass.

The outside, I'd do a light clean and sand and then apply more epoxy resin. When it's done right, the outside should be a smooth as glass.

Hi Dan,
Thanks for your advice I hope that glassing the inside will do it and I'm going to plan on a rib or two as well for good measure.
Regarding the outside, What would you recommend for cleaning it? Also I mentioned it was rough on the outside, that is due to the weave in the fiberglass not being completely filled with resin should I add a coat of resin before sanding? and I was reading that I need to determine what type of resin was used on the outside, epoxy or polyester. Apparently you can't mix these two. Do you know anything about that or how I can determine what is currently on the canoe now?
Hi Ted,

I'd probably clean it with a strong soap/water, and then wipe with alcohol.

I don't know how to tell the difference between poly and epoxy resin. If you find out please post it here. Some poly resin I'm seen was colored, green, but I know some is clear. I don't know much more then that.

Also, I think I've read/heard that you shouldn't mix poly/epoxy but that one can go over the top of the other, I don't know/remember which it is though.

Also, was this canoe varnished? if so you should remove it before applying anymore resin to the outside. Sence it probably will take a chem stripper, be carefull and watch to see if anything is happening to the resin. Might want to start with a small patch to see what happens.

Dan Lindberg said:
Hi Ted,

I'd probably clean it with a strong soap/water, and then wipe with alcohol.

I learned that if the resin is epoxy, it should be wiped clean with acetone between coats to remove amine blush (a residue of the chemical reaction of resin and hardner + air?) Of course, you'd need to take the usual precautions when working with volatile solvents ie. ventilate, work out doors, etc.
Acetone is not needed to remove amine blush! Scrubbing with water and a Scotchbrite pad is all you need. Don't skimp on the water and you should have a good supply of clean rags. You don't want to simply smear it around with a dirty rag - you want to clean it off. If you want, you can add a capful of household ammonia to the water, but it usually isn't required. You need to be pretty careful about using solvents and other chemicals on a resin surface which you intend to re-coat with more resin or varnish. Many times subsequent adhesion and/or curing problems seem to be directly traceable to foreign solvents used with the good intentions of getting a clean bonding surface. It's just not worth the risk and they don'y yield a surface that's any cleaner than the water. If the hull is really dirty, wash it first with water and dishwashing liquid, just like washing a car, then do a final cleaning with more water, the Scotchbrite pad and rag wipe-down.

You can tell the difference between polyester and epoxy by the way it smells when you sand it. Polyester has a distinct styrene smell (like plastic model airplane cement). Epoxy has less odor and smells like ......well like epoxy - but it doesn't smell like styrene monomer or model cement. Epoxy resin will bond better to cured polyester resin than just about anything else (including more polyester resin). Polyester will stick somewhat to cured epoxy, but not particularly well and may indeed flake-off down the line.

Ribs made from doubled glass probably won't add much bottom stiffness at all. The light weights of glass used on strippers just don't have enough beef to make much of a rib - it's amazing how many layers of six-ounce cloth you need to laminate to get much stiffness, try it on a sheet of waxed paper and you'll see...

If you want or find you need to add ribs, you're probably better off glassing the inside first and then adding balsa or cedar ribs across the bottom made from half-round stock (maybe 3/4" wide and 1/2"-3/4" high) and then glassed-over with a couple strips of cloth. You glass the inside, bracing or weighting it into shape, if needed, with whatever it takes until the resin cures -including dropping the wooden ribs into the wet resin on top of the cloth, bracing them from above and letting the resin stick them down. Then they get covered with the extra strips of cloth. The ribs should taper out at the edges of the floor, run cross-wise and be spaced 12"-24" apart on the wide portions of the bottom.

When glassing the inside, if you use six-ounce cloth with a double layer over the bottom, football area and can get the hull into the proper shape while it cures, there's a pretty decent chance that no other ribs or reinforcements will be needed.
Thank you all very much for the replies and generous advise!!
All of the information has been educational and helpful. I'm feelling a lot better about working on this canoe and decided that I really should shoot for a functional canoe versus a "restored like new" canoe. From the information you all have provided I think I can put together a plan to restore it into a fully functional (maybe not pretty) canoe to be out on the water by next summer.
I have another question to ask; I have visualized needing to remove the gunwalls, thwart, and seats to fiberglass the inside, what can I do to ensure that the canoe wont warp out of shape? Is this a concern at all? Can I leave the gunwalls and thwart in and still fiberglass the inside properly?

Ted Pletta
Seats out for sure. Removing gunwales and thwarts is a pain, but probably easier and better in the long run. Beware that the hull may be much more flexible without them and if lifted by it's ends, it may fold in half, cracking strips or joints between them. A couple 1/2's screwed to the sides for temporary thwarts and/or strips of strapping tape across the hull to keep it from spreading may also help keep it's shape. It doesn't need to be exactly the normal width for glassing, but you want it pretty close. The reinstallation of the gunwales and thwarts should bring it back to normal width.

If time isn't really critical at this point. I'd be tempted to weight the inside and let it sit that way (hog-free) for a month or so to see if maybe the hog will go away. If the inside was raw wood, I'd mist it first with water. This time of year it's hard to say if it will help, but a few days in the hot summer sun would probably bake it into it's proper bottom shape long enough to get the glass inside and stabilize it.