Canoe failure analysis
probably did not cure long enough???? I had a friend whose canoes went through the same problem and the curing part was the whole reason.
#1 Wed, 10/28/2009 - 1:46pm
If it was still on the racks, maybe something or somebody hit/fell/or otherwise applied a pressure/shock load to the nose or tail of your canoe. Bummers...
#2 Wed, 10/28/2009 - 2:23pm
There is one piece of information missing from your recap... what was the temperature when you inserted the drain plug? If the drainplug was inserted when the temperature was warm and not removed, and there was not another source to equalize the pressure between the inside of the canoe and the outside of the canoe (i.e. the canoe was sealed), then you have the source of your problem. A canoe that is sealed when the air temperature is warm and then allowed to cool (even in ambient temperatures), the air inside the canoe will reduce in volume, causing the canoe to collapse in on itself (i.e. the sides will be "sucked" in toward the middle of the canoe). This happens when there is no way for the canoe to equalize the pressure as the temperature drops and air volume is reduced. Always make sure your plug has a "snorkel" that will allow the canoe to "breathe" (i.e allow air to move in/out of the canoe as the temperature changes).
#3 Wed, 10/28/2009 - 4:02pm
Second the vote that someone did a pullup on the boat then ran away.
Unless the thing was soggy wet uncured it really could not have sagged and cracked so much from its own weight and would have done do the moment you used if it was that bad. ...
Pressure differential stuff does not show up as describe either ...
Poidog, with epoxys, there is no such thing as "going light on the hardeners" You stay with the manufacture volume or weight ratios and thats it. If you do error it could be with less hardener but not for any other reason than you don't feel like putting that little bit more in and asking for trouble doing so on a regular basis. "Esters" yes but even here its to reduce cure time, not to save weight.
Sorry that thing is broken ... Call me if you want. I can help.
aloha,
pog
#5 Wed, 10/28/2009 - 5:15pm
That kind of damage can only be done by someone/something putting pressure/weight on the canoe tail end while it was tied down on the rack. I doubt a change in tempurature would be so specific as to only cause cracking right where the canoe rests on a truck rack.
The only other damage similar to yours that I remember is when someone had their OC-1 on tied down on their truck rack and a garbage/delivery truck backed into it.
#8 Wed, 10/28/2009 - 8:11pm
The manufacturer would like to know about this problem as they would like to figure out if it was a layup problem or curing problem(hardener???) or a use problem(pullups or garbage truck). Plus they would know best the solution. Poidog- why ask the FOrum when the builder would know best? Go directly to the builder.
#9 Wed, 10/28/2009 - 8:28pm
If its new it would be really shiny and if it was dropped or hit maybe there was a mark left where the point of impact. take a really long close look at it.
I dropped a surf ski of my truck and it looked fine but I loosen the Center board on the inside. always tie them down, mental note. also when I got over 200 ponds I put more pressure on the canoes but a new, modern one should be able to hold most people.
#10 Wed, 10/28/2009 - 8:40pm
Even the smallest unblocked snorkel tube will allow for proper equalization of pressure.
#12 Thu, 10/29/2009 - 2:54am
Unless that snorkel tube is bent or hull weight kinks it when it sits on the racks from roof or rack pressure (sorry JC). I saw a friends respond in the same way after transport . Not saying poidog's did but it does happen and you wouldn't know it unless you saw it before you lifted the canoe off. In my friends case the canoe had "sucked" in and when he pulled the plug it popped out. He had traveled over a good elevation change. Local repair shop fixed it nice though!
#13 Thu, 10/29/2009 - 5:04am
Yep on the tube ... as long as the air can exhange you will not have pressure damage + you gotta have some dramatic differences in temp / alititude to get major damage.
Poidog ... with that bunji on there instead of of a strap, would you say it would also allow the boat come off the racks and slam down if you hit a big bump or dip ? Is the bunji one of those multi colored ones or the contractor style black ones ?
Sorry again man, just thinking like I would if I saw it.
aloha,
pog
#14 Thu, 10/29/2009 - 8:31am
In regards to using bungy cord to tie down a hull, I've seen others use them without any problems to their hull. Granted the ones being used were pretty stretched/used already and had just enough tension to hold down and not stretch any further if you hit a bump to bounce around.
The one time I was forced to use a bungy cord to tie down the back of my hull (didn't have enough straps in the truck on the pickup point) I ended up with a 2.5 inch parallel crack in the gelcoat on the top deck just above the seam. The padded rack didn't provide enough surface support, so it actually put stress in that one point with the bungy's tension pulling it down.
#15 Thu, 10/29/2009 - 11:04am
Poidog
I feel for you man. a new canoe too. If I had to guess . and that's guess. I would say at some point , when you were not there, or sleeping someone or something hit it. other than that it was in the curing and or making of the canoe. Its tuff but you goto get on with the repair and let the Humbug go. and get back out there.
#17 Thu, 10/29/2009 - 9:39pm
What color/kind of padding is on your truck rack and was the truck parked in the sun while you were paddling?
As noted by others, if your canoe was only a week old it may not have been fully cured and perhaps if a portion of the canoe was held against a hot enough surface it may have caused a small exothermic reaction in the uncured resin. Not normally a problem for a fully cured canoe ...
If you've ever mixed up a large batch of epoxy you may have witnessed an exothermic reaction as the epoxy heats and hardens quickly forming a molten, melty mess. Shouldn't happen to an oven baked canoe though...
Just a thought.
#18 Fri, 10/30/2009 - 3:04pm
Sounds like it could be how it was made. or your budgie is getting old. a new bump on your road,or a mix of these things.
I like those cradles and ratchet straps.
Its funny we want canoes that weigh a certain weight that is easy to carry to the water and when we start during races it gets up and goes with ease,,, but the lighter we get the more venerable we could be making our canoes. there is the only good reason to have a cap on our canoe weight's.
#22 Fri, 10/30/2009 - 7:46pm
Hi Poidog,
Just wanted to know ...You had a bunji on the "stern" ... Very most aft part on the boat ? Or over the boat right @ rack point ?
How much over hang from where the boat contacted the racks to most aft point on the boat ?
Just wondering.
aloha,
pog
#23 Fri, 10/30/2009 - 11:04pm
Poidog. I just have to say that I have done...and continue to do the exact same thing transporting my canoes. For close commutes, I just use bungees on my truck rack w/ padded bars like you do. One bungee just in front of the cockpit area (the pedals), and one probably about a third of the way between the cockpit and stern of the boat. For longer trips..I use straps. From what I understand, there is a bit more structural integrity built into the boat deck in and around the cockpit area. I usually try to get my bungees pretty tight so the hull doesn't bounce or slide around. I pretty much try to pull them as tight as I can KEEPING IN MIND if they're too tight, I could risk cracking a seam etc. (I have to worry about this using straps too). Like you, I've done this forever (over 10 yrs). FORTUNATELY, NO problems. You do have the canoe with the deck side down on the racks, right? Once I'm at my destination, if my canoe's going to be on my racks for some time, I usually loosen the bungees up a bit....Especially when out in the summer sun/heat. I usually try to get the canoe off of the truck as soon as I can....discourage vandalism, etc. Sorry to hear about your situation. I would first think vandalism....but you seem to think this is not the case. I think if there may be construction defects, you will find soft spots, defects, etc in other areas of the canoe as well.
#24 Sat, 10/31/2009 - 2:43am
How about snaping a few pics with the canoe on your truck and of the damaged area and post them.
#26 Sat, 10/31/2009 - 7:08am
These are some of the best straps you can buy ... And they are cheap.
http://www.nrsweb.com/shop/product.asp?pfid=1440&deptid=1188
As compared to bunjis >>>
Nice to have a little more surface to spread the load and grab the boat more ( think shifting @ speed ) at the same time.
No need to crank them down, get 'em flat, take out the slack and then just 'bump' them. They hold the boat without getting tighter and tighter.
If the boats are going to sit for more than say 15 minutes ( 5 if dark color and out in direct sun ) for sure back them off.
Poidog, I would double check with your builder about racking the boat ON the seam .... asking for trouble there too.
aloha,
pog
#27 Sat, 10/31/2009 - 9:34am
Sounds like laying the canoe on its side on the rack torqued it. Lay it on the deck- front tie down with the front of cockpit (strongest part of the canoe) on the front pipe rack secure. The back just firm should do it. Ouch!
#28 Sun, 11/01/2009 - 8:36pm
Hawaiian Canoe Canvas makes padded bags that are custom fit for your canoe and the snug fit and 1/2" closed cell foam offers superior protection for your canoe, even in neighbor island shipping. They are a bit pricey, but worth the extra money if you travel alot with your boat. http://www.hawaiiancanvas.com
#30 Tue, 03/09/2010 - 2:10pm
I was wondering if any of you epoxy gurus can give me insights into a structural failure that I just experienced. Here is the scenario: 1. the canoe is epoxy/ composite. 2. The canoe is 1 week old. 3. The canoe has been used three times in light ocean conditions. 5 knot wind, 2 foot swell. 4. The last time the canoe was used it was washed down and placed on padded truck racks. 6. When placed on the racks the afternoon temperature was 85 degrees and cooling. 7. The drain plug was not removed 8. The straps were not overly tightened and the canoe was transported at 35 mph a total of 1 1/2 miles. 9. The following morning the canoe- where it rests on the rear rack- had a large indentation with both lateral and longitudinal cracks in the gell coat leading from the indentation. The longitudinal cracks run from the bottom of the hull to the deck seam and two run from the indentation about three inches toward the hull. 10. The cracks definitey go all the way through the layup. 11. the hull seems soft in the area around the indentation. It will compress and leave indentations when pushed on with a finger. 12. Other areas in the hull seem soft and leave indentations.
This is the seventh canoe I have owned. The second from this manufacturer. The storeage and transportation methods have been virtually the same for all the canoes. Never a previous problem. I could use some advice so I can understand the prossible causes before I go discuss it with the builder. I am bummed out because the trades are back this weekend.
Mahalo for your help
Poidog
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