"splotchy" kevlar?

Hey folks,

I have a Wenonah Voyager which I purchased new in January of this year. It’s Kevlar with a skin coat. I’ve owned other Kevlar boats in addition to carbon & glass boats with gel coats. I’m seeing something on the Voyager I haven’t seen before.

The Kevlar is “splotchy”. There are irregular areas that are significantly darker than the rest of the boat. I have another much older Wenonah Kevlar boat in the garage & don’t see anything similar on that hull. This isn’t the normal darkening or “golden” color Kevlar takes on as it ages. The spots occur in random positions on the hull too - some are in areas where the hull is reinforced with the foam core, some are in “thin” areas of the hull, and they are relatively prevalent in the areas near the flotation chambers at the bow and stern. There is no rhyme or reason as to where the spots are happening so far as I can figure out.

I should also mention that I cleaned and waxed the boat this evening (per Wenonah’s instructions) just to be 100% certain I wasn’t looking at dirt or “river scum”.

The boat has spent a good bit of time outside - I paddle pretty much every weekday so the boat typically lives on my truck. I do park in shady spots at work and keep it in the garage at home.

Any thoughts as to what might be going on? Did something go wrong with the vacuum process when the boat was built? I sure would appreciate some insight as to what might be going on.


I have seen similar darking on areas with a floataation tank behind it on a stitch and glue boat. It reminded me of “gas ghosting” we get in printed sheets when the vehicle in ink discolors the color of the ink on the other side. Is this discoloration always adjacent to a rib, float tank etc?

Ask Wenonah. Discoloration is not
uncommon in structural cloth, and often has no significance. I just bought a few yards of S-glass, being warned by the supplier that (a) it was not “washed” for appearance and that (b) the adherance of epoxy resin would actually be better.

Wenonah will probably 'fess up, but I doubt the discoloration indicates weakness. There’s a solution for splotchy cloth… gelcoat.

Location of discoloration
"Is this discoloration always adjacent to a rib, float tank etc?"

No, not really. It is certainly more prevalent at the bow and stern (adjacent to the float tanks), but it happens at what appear to be random spots all over the boat. There really doesn’t seem to be any particular pattern to it.

Could be.
That could be it - “unwashed” cloth or something. That’s about what it looks like.

Does anyone from Wenonah frequent this forum?

UV changes
I wonder if some things show changes to UV but can have no structural consequences.

Splotchy Kevlar
I’ve seen some of my Kev boats darken in certain areas faster, giving them the ‘splotchy’ appearance you spoke of. Have no fear… the rest of the hull will eventually catch up and be a uniform ‘swarthy’ color in due time. Regular use and cartopping (read: exposure to sun!) will speed the darkening process up, though I’ve seen boats darken hanging from the ceiling of my shop. Can also happen (splotchyness) when the hull spends too much time in its shipping plastic, say in a dealers storage. Don’t ask me how I know.

Wenonah’s Response
The folks at Wenonah were kind enough to respond to the email I sent them with the question above. They got back to me within 3 or 4 hours. It’s nice to do business with a company like that! Here’s their response:

Thank you for contacting us with your question on your Voyager. What you are experiencing is that the areas that are turning a bit darker are resin rich. Resin rich refers to more resin in those areas in comparison with others. This is completely natural and you should not experience any problems other than the esthetics. Please feel free to contact us with any additional questions or concerns.

Happy Paddling,


Wenonah Canoe & Current Designs Kayaks

Sounds like a good explanation. The
surest way to avoid that would be vacuum bagging, which removes more resin and puts more even pressure on the laminate. Also increases cost, and probably not worth it except for whitewater applications.

Vacuum bagging
While vacuum bagging does a great job of removing excess resin, it’s virtually impossible to remove all excess resin in all areas of the hull. As an aside, Wenonah does vacuum bag all their composite hulls.

Same spots on another kevlar brand
I experienced the same dark spots on my kevlar canoe, and thought something was defunct or wrong with the kevlar. It’s only a cosmetic thing.

They do not claim to vacuum bag,
and Bluewater claims to be the only open canoe manufacturer to routinely vacuum bag.

I think Grasse River and Savage River both do some sort of vacuum process on all of their boats. If I remember correctly, Savage River is a vacuum infusion process (assuming I understand the terms correctly - they bag the boat, then inject the resin).

I thought Bell was doing some sort of vacuum process with their lightning tech stuff, but I could be mistaken.

I have always operated under the assumption that Wenonah bagged their ultralight layups, but when I look at their website, it says vacuum cured. That sounds the same to me, but I don’t claim to be any sort of expert.

They do…
I watched them do it years ago on a factory tour, vacuum bagging that is!

Another bagger
Millbrook canoes are just about all vacuum bagged. There are a few that aren’t, but thats maybe 10%.