a Cork Core Canoe ??

Hello All, I just brought back a “free” canoe from my Sister-n-laws in Ohio. Strapped it to the truck and made the nine hour drive to Memphis. It survived the trip. To say the canoe is old is an understatement. It looks like a regular red canoe from a distance, but take a closer look, and it is far from. The Gunales at one time were wooden (ash maybe)… now the outside trim is gone leaving tiny sharp screws pertruding about every 8 inches. the inside trim is gone at bow and stern. In the middle the inside gunales are there (no top trim) and are holding what is left of…well, I don’t know. Which brings me to my questions. Since there are no gunales along the top edge of the canoe bulkheads I can see what appears to be…cork in between what looks like two layers of laminate…like counter top laminent. I don’t know if it is me, or if it is really fiberglass in disguise…or what. Can someone tell me if canoes have ever had…about 1/4 inch maybe more… cork cores ? I measured the canoe, she is about 12’ long, no name, or identification, no seats… there are some maybe 1"x2" boards that go across the canoe that look like they are in the vacinity of where a seat should be, but I don’t really see anyone sitting on them. They are mounted to the gunales with flat pieces of aluminum that drop down maybe 4-6 inches… If anyone thinks they can help, let me know. I can take some pictures and e-mail them if anyone wants to see what I am talking about. I just want to know what kind of canoe I have, and if it is worth anything. One thing I have tried to repair is a weak spot in the floor that looks like it has just been pushed upward. Like a dent, but very flexible. I put a layer of fiberglass on the inside floor tonight to try and reinforce it… please help.

Early Royalex
Take a trip to any dealer selling Royalex Canoes and look at a cross section of the hull. Old Town dealers usually have small sections of hull that show the various layers in the Royalex. The expanded core in the current layup looks somewhat like cork. Really early ABS canoes when they were developing the materials, may have used cork between the ABS layers as a core.

Is there a molded number in the hull up near the gunwales near one of the stems? The first 3 digits should be letters and will tell us who made the canoe.

lookin for numbers
I’ll go check for number now…

No numbers…
OK, no numbers anywhere… only thing I found was a sticker that said Penrods’ Canoes …PA. Looks like a bumpersticker almost. Also, I measured the thickness of the sides… it is exactly 1/4 inch thick… is it me, or is that awful thin for a canoe wall ??

1/4-inch is about right…
… for a Royalex hull. Good-quality composite (fiberglass or fiberglass & Kevlar) hulls are considerably thinner than that. Your description sure sounds like Royalex except for the “cork” part, but like an earlier poster said, maybe it’s possible.

cork = foam
I bet what I thought was cork is the foam layer in the Royalex… If this is true, It sounds like I have a fairly decent canoe… I just need to figure out where to get the wood (ash I guess) to replace the gunwales… any suggestions ?? Can I just go to Lowes ?

it does have seats…THWARTS.
Well I just discovered something. There are “seats” in this canoe. Since this canoe is so short, and the rocker is so great (about 3’ of the canoe is touching the floor) the previous owner had this canoe set up for a “on your knees” sitting position. The 1"x3" boards I was talking about earlier are the “butt rests”. I will get this figured out eventually. Any suggestions on what kind of knee pads to install ?? I can see where pads were placed before…the clues are starting to add up… anyone have an answer for the gunwales yet ? Where to get the wood ?

12 feet long and lots of rocker
Sounds like that’s a lot of rocker, but maybe you can be more specific. Are the ends of the canoe (just shy of where the upward curve kicks in) 3 inches off the floor, 4 inches off the floor, maybe even more? If so, it is sounding to me like this might be a specialty boat made for whitewater. It sure would be nice to know exactly what it is, but if it’s a whitewater boat, you may not even want to mess with it. Of course, if it is a whitewater boat and that’s your intended useage, great.

A twelve-foot boat with lots of rocker will be very nimble, more so than the average beginner would ever imagine. If this boat is what it appears to be, it could probably make a 180-degree pivot with a single well-placed paddle stroke, or maybe even with a single “misplaced” paddle stroke. It will not be fast, and will require a fair degree of skill to paddle straight, or in any other way “where you want it to go”. Also, in case it isn’t yet clear, this is strictly a solo boat (not for two people).

Now, I may be wrong about the boat and I may be wrong about what boat would be a good match for you, but based on your description of the boat, and based on your question about the “seats”, I’m thinking you are probably new to this, and that the boat is not a good one for a beginner to start out on, and not a good one for any kind of “typical” paddling. I’m not trying to convince you to give up hope, only to stress the importance of figuring out for sure just what style of boat you have, and whether it’s something worth putting a lot of effort into fixing.

Doubt it’s cork

– Last Updated: Jan-20-07 9:11 AM EST –

I could be completely wrong, but I really doubt the core is cork; you proabably have Royalex. Royalex boats are formed by heating a sheet until it's flexible enough to be pulled over a vacuum form. The heat also causes the core to expand into a foam. Cork on the other hand, would not become more flexible with heat, it'd just get hot and possibly burn.

My guess what you see is the old ABS foam core of Royalex that may have been exposed to weather and/or scum water from rotting gunwhales. The inner ABS layers Royalex is made out of are sensitive to UV light and the core is also prone to taking on water and rotting if there are any exposed/open spots.

Was the boat stored outside? The limp/flexible spot you found is probably core rot, which is serious damage. The hull may flex a little in places, but should feel pretty stiff and exhibit no sponginess anywhere. It's possible to repair core rot, but this is one of the more difficult proceedures to pull off successfully. Some folks carefully cut away an outer ABS layer, scrape out the core and replace the spot with repair putty, but this makes the boat heavier. Others completely cut out the spot and glue in a new sheet from a donor boat. Unfortunately,Royalex boats with serious core rot are thow-away items.

Like I said, I could be completely wrong,


Rolex Core Rot
You could be completely wrong, but it sure does sound like exactly what I have. When I took my sander to the floor where the weak spot was the first layer was the tan colored paint, and the second was some sort of black charcoal looking layer. I covered the whole spot (about 10"x10") with a Elmers fiberglass repair kit using a single sheet of fiber over the weak area. It should be dry this morning, (just woke up)so we will see. OH, and the last poster said that this was a 1 person canoe. I disagree, it clearly has has two sets of thwarts; the one in the back (where the stern paddler straddles the weak spot) and the one in the front where there is evidence of knee pads being removed. … OK, just measure the Rockers… 5-6" at the stern and 6-7" at the bow. About this weak spot. I was thinking about something last night. The previous owner was a anchor point finatic. there are anchor points all up and down the inside hull. Is it possible that the weak spot is from an anchor point that was over stressed ? i.e pulled too tight.

You most definately have
a WW boat. The plethora of anchor points is probably due to the ned of a WW boater to install thigh straps. It is possible to weaken an ABS/Vinyl sandwich through improper use of contact cement - that could account for the weak areas.


I agree-whitewater boat
Short, severely rockered. The anchor points also could have been meant to provide tie-downs for float bags. Short tandem whitewater canoe, probably a real pig on the flatwater.


Balsa Core
Some manufactures back in the 60’s used a balsa core in their hulls to stiffen up the fiberglass layup without adding to much weight to the boat. We still have an Old Town in our family that we bought new in the 60’s that has this layup.

Balsa core only in bottom
In the balsa core Old Town models, the core was only in the bottom of the hull and they were fiberglass models.

This canoe is an ABS layup and the core is between the structural layers throughout the hull.

The first (tan)layer you removed was the outer vinyl of the Royalex. The next layer you saw was the ABS sheet, which is the main strength of the boat. Below that would be the foam core.

Though Royalex can have many layers, in it’s basic form, it’s a heat activated ABS foam core sandwiched between sheets of solid ABS with a final vinyl outer layer to protect it from UV (ABS is very sensitive to UV light and will get brittle).

For just about all RX (Royalex) repairs, you have to sand of the vinyl down to the ABS to get good adhesion, so you did good.

There are a few things that can make RX “go limp”. First, core rot, which is usually caused by a puncture through the vinyl and ABS letting water get to the foam, literally rots the foam away debonding the other laminate layers. RX can also suffer delamition where the core is still reasonably solid, but has debonded from the other layers. This can happen from excessive hull flex (takes a long time) or improper use of glue to bond knee pads, pedestals (saddles) or other items to the hull. The solvents in the glue work their way to the core and eat away just enough foam to break the bond.

Since your boat sounds like a whitewater craft, I wonder if it didn’t have a pedestal at one time. Is a large amount of wear concentrated on a spot more or less dead center of the hull or at the stems? Boats with pedestals for seating tend to “grow” a more or less rectangular wear patch in the middle because paddler’s weight is transmitted directly to the hull floor which prevents some hull flex (while grunging over rocks) in that spot. Boats paddled with more traditional hanging seats/thwarts or kneeling tend to wear more evenly, with the stem taking the most abuse.

If your boat had a pedestal, you might have a soft spot from adhesive.

In cases of rot, the best repair is to remove an ABS layer and scrape out all of the bad material to prevent the problem from spreading; think of core rot as a cancer. Some people have had sucess injecting Gorilla glue (polyurethane glue that’s activated by water) into the spots or cutting out the ABS, applying glue and replacing. Fiberglass, as you’ve done is a popular fix, but usually in conjuction with removing the bad core. You can also repair RX wear with a special two part epoxy or JB Weld. Both are rock solid, but don’t flex as well as the original RX and add weight to the boat.