“It won’t be that much longer where molded boats will equal and surpass glass.”
It’s here: thermoformed plastic and triple layer plastic.
Summery . . .
So, there are performance differences, and red glass boats are a bit more efficient. However, these differences are not great, and when renting a boat, plastic will do just fine.
Thanks for all your advice.
Sometimes weight is the same
The current model Tempest 170 weighs the same in glass or plastic and is only slightly lighter in kevlar.
kevlar will soak up water like a sponge
and sink like a stone.
agreed jay
CD, I have to disagree that plastic has met glass. Triple layer still flexes a bit and thermoformed isn’t as durable/repairable (at least doesn’t localize damage like glass).
But it’s getting closer…
Some kevlar boats flex a bit, too.
Just being composite doesn’t have to mean being stiff.
Very true Yanoer
Kevlar is weak in compression and it needs to be used in conjunction with stiffer materials such as glass or carbon, or a core material such as Nomex, Divinycell, Soric, etc.
kevlar is plastic too 
and in some boats the difference in
weight between glass and plastic is less–only about 5-6 lbs
glass glides further
because after awhile the hulls on a plastic boat tend to get a furry textured type of surface due to repeated launchings off the beach.
Plastic can take more abrasion than
glass only because it is thicker. The outer surface of glass boats is very hard and withstands dragging quite well.
Renting
When renting, it doesn’t matter much. If there’s a skeg, it will be jammed. Glass coamings will be chipped. Plastic boats will be badly scratched from draggers, but glass boats may have been abused or dropped to the point of leaking badly (I rented one like that).
The difference between the same model in plastic vs. glass is NOT 10-12 lbs, as someone else posted. It’s often less than half that.
renting part II
– Last Updated: Mar-18-08 4:50 PM EST –
I'd go more by the outfitter's rep than whether the kayak was plastic or fg. Some outfitters replace their fleets much more often than others, and that's saying it diplomatically.
Also the make of kayak and how it would fit me would be way more important to me than what material it was made of.
The general kayaking public seems to feel more comfortable in a wider, plastic boat than a narrow fg one, and so the latter would see a lot less rental use and abuse.
Hopefully they don't charge extra for jammed skegs or messed up rudders LOL
Finally, a plastic boat may only weigh 6 lbs or so more, but it is funny how that feels like 12 or so lbs at the end of the day ;-) which is why i guess people pay to have the outfitter tote them....
Abrasion resistance ?
Not sure if hardness translates directly into abrasion resistance. I’m not an engineer but I have tried to sand plastic boats and it’s an impossible chore. You can scratch the surface but nothing comes off. Whereas if you sand a fiberglass boat, the dust starts and in no time you are cutting into the surface. If I had the chore of sanding into a surface as a challenge, I would rather sand into glass lay-up than plastic. I really don’t know the physics behind it but the plastic surface seems to be less prone to abrasion than glass. It must have something to do with the flexibility of the molecules? Their ability to bend rather than break? Maybe the plastic is kind of self-lubricating on some level?
But plastic is more UV resistant than
the resin in the bare composite (no paint because it’s been dragged off), isn’t it? But that probably matters more for boats that are transported upside down than boats that are transported right side up because the unpainted/abraided keel would be on the top in full sun.
People on this site are always commenting on how UV sensitive the resins are.
Yep, an aramid fiber
The difference between the same model in plastic vs. glass is NOT 10-12 lbs, as someone else posted. It’s often less than half that.
I agree with pikabike.
I’m not arguing that
it is… sometimes the difference is more than than, sometimes less. There are dozens of models out there offered in plastic and fiberglass, or blends - one could prove anything regarding weight spreads.
And, as a finishing touch, nearly all manufacturers understate the weights of their boats, or don’t use water ready weights.
Kayak weights are a moving target and it’s a pointless disagreement.
My QCC 400X is 45.2 lbs with rudder.
The basic kevlar boat is listed at 45 lbs, so my boat was less than the listed weight before the rudder was added.
Some manufacturers list their boats heavier than they actually make them so buyers will have a pleasant surprise.
Try 80 or 120 grit Adalox and random
orbit, and that poly will sand down fast. But real life abrasion occurs when the boat bottom is dragged over rocks or gravel. My poly WW kayaks certainly do “sand” down under those conditions, and they gouge more easily than my composite boats.