A Cold Cracking of Royalex Question

[SouthernKevlar]

How cold does it have to be to develop “cold cracks” in a Royalex canoe?

Reading this forum, I have become aware of the issue of “cold cracks” in Royalex canoes. Being in the South, where it is rare to have extreme or extended cold, it is not a condition that I have seen except in pictures and print. I have also stored my canoes inside a garage, though it is not heated.

Now that we are in a several day stretch at freezing temps in the daytime and mid-teens at night (a balmy winter’s day for you northern folk), and I currently have a We-no-nah Royalex canoe resting outside due to a too-full garage and the fact that it is on top of my car waiting for a warmer day at the end of the week to paddle, this question came to mind. It seems that most of the cold cracking issues that I have read about occur on wood-gunwale canoes, and I have aluminum gunnels on my Argosy, so that eases my mind a bit.

Any edification from you folks who are familiar with this issue of cold cracking, when it happens, methods of prevention (other than indoor storage), and even if we folk well to the south of the Mason-Dixon should even worry about this condition will be greatly appreciated.

 

[dogbrain]

As you probably know, the apparent issue is with heating/cooling causing differential expansion of the gunwales vs the royalex. I don't know if the temperature itself is the issue. In a garage, the temperature increases and decreases slowly, so you are less likely to have cracks appear. As you know, expansion of wood vs royalex appears to be greater than aluminum vs royalex. From my experience, a canoe left outside can develop cracks, even one with aluminum gunwales. The best way to get your royalex canoe to crack is to leave it outside on a cold clear night and have it stored where the morning sun will hit it.

Mark

 

[clemency]

On wood gunnels you'd loosen the screws for the winter so the gunnels and hull can move independently. Not sure your aluminum gunnels are screwed, but I doubt it. I also don't think it is an issue with aluminum gunnels.

 

[Steve in Idaho]

I've seen one canoe with aluminum rails crack when stored outside but covered by a half-shed. But the weather was far harsher than what you're going to see.

 

[SouthernKevlar]

On wood gunnels you'd loosen the screws for the winter so the gunnels and hull can move independently. Not sure your aluminum gunnels are screwed, but I doubt it. I also don't think it is an issue with aluminum gunnels.

The Wenonah has riveted gunwales, so I hope that there is no issue. I also usually paddle twelve months of the year (when possible), so loosening and tightening the screws for each trip in winter would be a bear and I'm often not sure which canoe will be used until I'm getting ready to load up.

As you probably know, the apparent issue is with heating/cooling causing differential expansion of the gunwales vs the royalex. I don't know if the temperature itself is the issue. In a garage, the temperature increases and decreases slowly, so you are less likely to have cracks appear. As you know, expansion of wood vs royalex appears to be greater than aluminum vs royalex. From my experience, a canoe left outside can develop cracks, even one with aluminum gunwales. The best way to get your royalex canoe to crack is to leave it outside on a cold clear night and have it stored where the morning sun will hit it.

Mark

Thanks Mark. I had not considered that time would be a factor in the heating/cooling cycle. I assumed the expansion and contraction movement would only be dependent temperature, but I can see how the differential in expansion rates between Royalex and Aluminum could affect how quickly the movement occurs and therefor the stresses incurred.

 

[Halpc]

The comment by Dogbrain re the morning sun is accurate from my experience. Many years ago we had my son's Royalex Mad River ME hung under our back deck. One side was exposed to the sun for a couple of hours each day and the interior side and bottom were always in the shade. We were astounded one day to discover numerous long cold cracks, primarily, I think on the sunny side. We repaired it with G-Flex and it still paddles well, but won't win any beauty contests. An early 1980's vintage MR Explorer, which we rescued a couple of years ago, has no cracks at all. The PO stored it outside and we have kept it in an unheated garage (outside temps below zero at least a few times each winter), with the screws intact. I think that the earlier Royalex layups were thicker and maybe more crack resistant. I don't know how thick your Wenonah hull material is, but would guess that it is relatively thin. I would recommend storing it in the shade, if possible, or at least parking where the sun can't hit it.

 

[memaquay]

Our club had some early Mad River royalex boats as well, and they were stored outdoors in our frigid temps, where -40 was not unusual in the winter. They had wooden gunwales as well. None of them developed cold cracks. I haven't personally seen any canoes up here with cold cracks, I've only seen pictures of them online.

 

[SouthernKevlar]

Thanks for the info. I think that I will take the safe route and squeeze the Argosy into the garage even though it is unheated and the same temp as outdoors. I was originally thinking that it was the low temps that would cause the cracking, but it sounds like the rate of change is more important.
The issue of cold cracks is not something that I have worried about in the past; South Carolina does not get overly cold in the winter, although as I am writing this there is a dusting of snow on the canoe!
Thanks again for the info and a bit of peace of mind.