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Royalex MR Explorer Cold Cracks - Advice & Repair

I was able to get the seller to remove the wooden decks (which seem to be original, because the serial number was written underneath) and send me pictures of the cracks. He was unaware they were cold cracks and is talking price reduction now. Asked me to pick a price I thought was fair. Original asking was $800.

Is it good or bad that they are so close to the bow and stern of the canoe?
 

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Here are two videos by our member @dcloots that show him repairing three very long and deep, through-the-hull cold cracks in a Royalex canoe.

Video 1 begins where he starts talking about how he's going to approach the cold crack job:


The second video begins with the cold crack repair:

 
I have fixed a few of these and the cold crack thing isn't a big deal, at least to me as a buyer. To the seller it means get rid of it while i still can. These cold cracks seem minimal, so the repair will be easy. I would offer him a fair price with the cost of your time and materials factored in and an addition reduction based on the fact that when you go to sell it, you'll get a reduced price. Inspect everything especially the gunwales when you go look at it to make sure there are no other issues. Bring a drill and make a hole at the base of each crack as soon as you can to stop the crack from propagating. In my area this canoe is probably worth the asking price or a little less if it didn't have the cracks. With the cracks I'd offer half the asking price, but only if I was actually looking for a MR explorer. I bought one a few years ago that had a lot more cold cracks and a bit of sun fading for $50. I regularly see cold cracked MR's with punched through seats and gunwales that need to be badly oiled for $200 or so.

As far as the reason for cold cracks, it definitely has to do with differential hull/gunwale expanding/contracting with temperature. My NC Prospector with aluminum gunwales had 2 cold cracks a couple years ago when I unveiled it for the first time in the spring. The cracks were near the bow and only on one side, the exact spot that catches the rising sun. The canoe was tarped, but that didn't the keep the cracks from happening. I already had the g-flex and some green paint that was close enough, so it only cost me a couple hours time to fix it. I didn't remove the gunwale, which would have been a huge project, but I don't think that matters. I put a couple strips of glass on the inside of each crack, but most people don't seem to. It might not matter.

Mark
 
The center photo clearly shows the cracks from side to side on the exposed cross section. You can look for similar cracks along the full length of the boat. What is shown should be an easy fix with only a couple of screws to remove on each side.
 
I was able to get the seller to remove the wooden decks (which seem to be original, because the serial number was written underneath) and send me pictures of the cracks. He was unaware they were cold cracks and is talking price reduction now. Asked me to pick a price I thought was fair. Original asking was $800.

Is it good or bad that they are so close to the bow and stern of the canoe?
The most common place for cold cracks to occur is near the stems of the canoe. That is where the difference in expansion between the gunwales and the hull will have its greatest effect. That is probably for the better because the Royalex is somewhat thicker near the stems on most Royalex boats.
 
Thanks everyone. The seller and I have agreed to a purchase price of $400. I feel good about this price. The seats are basically brand new and the wood is all in good shape. I am planning to pick the canoe up this Sunday. I will continue to post updates in this thread.
That is a real good price, and I think you will be happy with that boat.

To get back to your question about the oil-canning, I'm not even sure if the hull is warped or not. It just appeared to be in one of the pictures in the way it reflected the light. It could be totally fine. If not, you probably won't notice much effect on the performance of the canoe. And I think some people more experienced than I am have used boiling water or a very carefully wielded heat gun to get the warp out. There is a canoe outfitting and repair page on Facebook that could be helpful if needed.

-rs
 
Although it is possible for any Royalex canoe to hull, V bottom Mad River hulls are relatively resistant to hogging since the V contour adds rigidity.

I really don't appreciate any hogging in the photos but you have to put a long strait edge on the hull bottom to be certain. If any hogging exists it is so little it will not affect performance in any appreciable way.
 
Here’s my story about cold cracks in my RX Mad River Explorer.

In the summer of 2008, Kathleen and I moved from near Victoria, to Preeceville, SK, where winter temperatures often dip below -40 degrees.
To prepare for cold winters, I had read that one is supposed to loosen the screws that attach the wooden gunwales to the plastic hull. That way, the hull and gunwales can expand and contract at their own rates. Otherwise, severe cracks in the hull will almost certainly greet the once-proud canoe owner in the spring.

I loosened the gunwale screws at the beginning of winter in 2008. I loosened the gunwale screws at the beginning of winter in
2009. In the fall of 2010, I put the Mad River Explorer in the storage shed, and said to
myself that I would loosen the screws later. I don’t know why I said that. It only takes
about five minutes. But I would have had to walk a couple hundred metres (yards) each
way to get my portable drill. I didn’t want to take the time right then. I would do it later.

Well, later never came. I got busy doing something else. I didn’t loosen the gunwale
screws. In the spring of 2011, I slid back the door to the canoe storage shed, and literally
staggered from the horrific sight. I started counting. Thirty-seven cracks all the way
through the hull of my beloved Mad River Explorer.

This was truly horrible, and I was responsible. Perhaps the worst mistake of my entire
life. I had to rectify this situation. I sent away for a bunch of Kevlar cloth and Cold Cure, a
two-part epoxy. I spent most of a day affixing the Kevlar cloth, inside and out, to all 37
cracks in the hull. In my opinion, the Mad River Explorer, although not as good as new,
was just as seaworthy, lake-worthy or river-worthy as before.

So, after the job was completed, I returned to the house to boast of my success to
Kathleen, knowing that she would be very impressed.

“I can’t trust that boat anymore Michael. You say it had thirty-seven cracks all the way through the hull. What if it breaks
while we’re on a wilderness canoe trip?”

“But it won’t break. It’s just as strong as before. Maybe even stronger. I put Kevlar
cloth on the inside and the outside of every crack.”

“I don’t like it. I don’t want to take a chance.”

There you have it. Kathleen wasn’t happy. I had no choice. I had to buy another canoe.
I called up the primary canoe store in Saskatchewan, Fresh Air Experience, with outlets in
both Saskatoon and Regina. “I’d like to buy a sixteen foot Royalex Mad River Explorer,
with wooden gunwales.”

“We don’t carry Mad River canoes anymore.”

“Well, I need a sixteen foot canoe. What do you have?”

“We have a sixteen foot Royalex Wenonah Prospector in stock. Would you like that?”

I hemmed and hawed for a moment. I loved Mad River Explorers. I’ve owned two in
my life. I couldn’t be changing brands now. But I needed a canoe, and soon. We were
planning to paddle to Grey Owl’s cabin, in Prince Albert National Park in July, to celebrate
our 30th wedding anniversary. I needed a canoe. “OK, I’ll be out tomorrow to get it.”

Note: Back then, I wasn’t aware of sites like canoetripping.net, where I could have received much better advice on how to repair cold cracks. Too late now. I have not paddled the Mad River Explorer ever again. But I remain convinced that it is still serviceable, albeit less elegant. I have found a young family who wants to come get the canoe this spring. I am willing to give it away, But Nathan insists on paying for it. We’ll see what he says when he sees the canoe.
 
Thirty-seven cracks all the way
through the hull of my beloved Mad River Explorer.

You win the trophy for most cold cracks in one canoe in one winter on CTN and maybe all of planet Earth. I'm sure we'd like to see pictures of this X-rated horror.
 
Thirty-seven cracks
You win the trophy for most cold cracks in one canoe in one winter on CTN and maybe all of planet Earth.
I don’t feel so bad about the handful of small cracks in the boat I’m buying anymore. 🤣

PaddlingPitt, you always manage to tell a great story, and Kathleen always seems to keep you on the straight and narrow.
 
Update: I picked up the boat on my way home from Maryland on Sunday. We made it home safe in some high winds and highway speeds. Aside from the cold cracks (which I terminated with drilled holes before leaving the sellers driveway) the boat is in pretty good shape. The hull wasn’t abused and the wood just needs some sanding and oiling.

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I have a small basement space to work in, so after moving my other canoe to my dad’s garage and building some cradles I got this one inside and got to work removing seats, grab handles, gunnels, and yoke.

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I found 9 separate cold cracks, the longest being around 3 inches. All located near bow and stern. I think the previous owner may have been lifting and carrying the canoe from loops of rope he had tied through the holes at bow and stern, I wonder if this could have contributed to the cold cracking? He also stored the boat under a carport outside year round which is the obvious culprit.

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I followed advice from all of you as well as dcloots/maintripper’s YouTube videos for the repairs. I ordered some g-flex and went to the store and got some new toys.
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I started by using a jig saw to open the cracks.

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Then a dremel tool with a #94 cutting head to bevel them on the inside and outside.

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Then I lightly sanded my bevels with 80 grit sandpaper and wiped down the area with acetone. I applied heat for a minute or so with a heat gun to attempt to “oxidize the plastic surface and improve adhesion” per g-flex instructions. They note that no obvious change occurs when you do this, but that it helps. I then taped the exterior of the beveled cracks with packing tape so I could fill with epoxy from the inside. I did this to minimize/eliminate any cleanup on the exterior of the hull.

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After the beveled space was filled with epoxy, I added a piece of packing tape to the interior and then clamped with a spring clamp.

I did notice a few bubbles behind the tape and did my best to poke holes and squeeze them out, but I wasn’t able to get all of them. I wonder if there is something I should have done differently to prevent this?

The epoxy is currently curing. I plan to continue posting updates. So far I am happy with the process. Thanks for all the advice everyone.
 
Aside from the cracks, that canoe looks in good shape and should last you for a long time. Thanks so much for photo-documenting your repair procedure. It will be a great help to anyone in the future who has similar problems and is looking for help.
 
What strikes me is that the cracks are the same on both sides. Where the canoe deck was screwed on ... ?!
Could it be that the deck was attached under too much tension? - or why is it so even?

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After you fix the cold cracks and refinish the wood trim it will be a great boat. The location of the cracks are typical, one might say classical, for cold cracks. It is the gunwale screws that is the culprit, not the deck plates.

By the way, flame oxidation is completely different from heating. A heat gun will not flame oxidize. It shouldn't matter because you can get a good bond with G Flex to ABS without flame oxidation, unlike with polyethylene where flame oxidation is critical.

Oxidation (ionization) is a chemical process in which electrons are stripped away, in this case electrons from the hydrogen atoms on the surface of the polymer by oxygen, in this case by a combustive process. Heating is a thermal transfer process which does not alter the chemistry of the polymer. During flame oxidation you would prefer not to warm the surface at all, although that is not possible for obvious reasons.

Although West Systems describes flame oxidation as optional for ABS, I recommend against it when foam core is exposed as the thin trabeculae of the exposed core are easily melted. All those open cells provide an excellent mechanical foot for the epoxy bond anyway.
 
After you fix the cold cracks and refinish the wood trim it will be a great boat. The location of the cracks are typical, one might say classical, for cold cracks. It is the gunwale screws that is the culprit, not the deck plates.

By the way, flame oxidation is completely different from heating. A heat gun will not flame oxidize. It shouldn't matter because you can get a good bond with G Flex to ABS without flame oxidation, unlike with polyethylene where flame oxidation is critical.

Oxidation (ionization) is a chemical process in which electrons are stripped away, in this case electrons from the hydrogen atoms on the surface of the polymer by oxygen, in this case by a combustive process. Heating is a thermal transfer process which does not alter the chemistry of the polymer. During flame oxidation you would prefer not to warm the surface at all, although that is not possible for obvious reasons.

Although West Systems describes flame oxidation as optional for ABS, I recommend against it when foam core is exposed as the thin trabeculae of the exposed core are easily melted. All those open cells provide an excellent mechanical foot for the epoxy bond anyway.
Thanks for clearing up the oxidation topic. That’s not something I was versed in prior to this.
 
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