nice repair
Hi, I am a chemist (more or less)
though not an organic one, but can`t for the life of me understand how blow molding might PRODUCE longer chain molecules?
I guess, blow molding might permit longer molecules to be USED; the high pressure pushing longer, ‘stickier’ molecules in mold cavities that would not we filled by mold rotation alone.
What type of rivers?
If you’re not planning on doing any white water, thermoformed will be fine. Anyone who owns a thermoformed kakak, including myself, occasionally goes pretty hard against or over a rock, with no damage.
If you have limited funds, I would look for a used Eddyline or Delta. This material keeps its good looks for years.
Do you ever go camping by boat?
– Last Updated: Aug-16-12 10:58 PM EST –
If you do, surely you've noticed that after hours of hauling your gear, paddling the boat is almost magically easier once you have unloaded your cargo. I do this a lot. I'll go upstream with camping gear, stash the gear where I intend to camp and then continue farther up the river before returning to my chosen camping spot. I can see more miles of river with much less effort if I do it this way than if I keep the gear on board for the whole trip. It doesn't matter which boat I use - the difference in required effort between the loaded and unloaded condition is impossible to overlook.
Now, if the extra effort needed to carry a 40-pound cargo is impossible to miss, the effect of a 20-pound load (in the form of unnecessary hull weight) would be present too, even if a bit less obvious.
A boat that sits lower in the water has more surface-area drag. Also, part of the water resistance you are thinking of is simply the inertia of that water. Water must be put into motion as your boat moves, and accelerating anything with mass requires force, and YOU supply that force. The more weight you carry, the greater the mass of water you mus push aside as you travel, and therefore the more work you must do. I suppose for an ideal streamlined shape, the water "falling back" into position at the rear of the boat would cancel-out the effort needed to push water aside at the front end, but since there IS turbulence associated with all boats, and since nothing is 100-percent efficient, it's easy for me to believe that moving aside more water while on-the-go requires more "horsepower".
That is correct
– Last Updated: Aug-16-12 10:52 PM EST –
My Supernova spins like a top compared to my Odyssey 14, but the Supernova weighs a lot more so the effort needed to INITIATE a rapid turn is about the same with either boat. The more weight there is out near the ends of the boat, the harder it will be to initiate any kind of swinging motion (you can feel this for yourself in any single boat by noting the difference between a centrally located payload and a similar load that is spread out more), and a heavier boat has heavier ends. Of course, the ends are where the effect of excess weight really shows up, but extra weight at any location still must be put in motion when initiating a turn. Excess mass near the center of the boat accelerates less than excess mass near the ends, and that means less force is needed, but it's still an extra amount of force that wouldn't be needed at all if the excess mass were not there.
camping
Yes, I’ve camp out of my boat and everyone in the group talked about how easy it will be once we drop our gear at the camp site. But our average speed doesn’t change much before and after according to the GPS. And I personally don’t notice that much of a difference. Granted, I don’t carry the kitchen sink on camping trips like many others. Most of my gears do double duty with backpacking so it’s mostly pretty light weight stuff.
I’m almost to believe it’s more psychological than real! In other words, I do FEEL it’s quicker to get up to speed, but the GPS said we weren’t going any faster over a set distance!!!
That said, I do see your point of having to push more water out of the way since the boat sits lower in the water. Except as you also pointed out, a lot of that water we push away are falling right inline. So we’re really not pushing ALL the extra water that’s equating the extra weight. I don’t know how much that 20 lb extra weight translate to… 5 or 10 lb extra water to push away?
physics
"I’m almost to believe it’s more psychological than real! In other words, I do FEEL it’s quicker to get up to speed, but the GPS said we weren’t going any faster over a set distance!!!"
It’s not psychological. Physics will tell you it takes less energy to accelerate something that is lighter/lower mass than it takes to accelerate something that’s heavier/higher in mass.
But once you get up to speed, weight isn’t going to matter nearly as much. So your GPS is not lying to you either, avg speed over a set distance is going to be pretty similar between a light boat and a moderately heavier one.
Acceleration and average speed = largely two different things.
Though if one wishes to be particular about it, you could say that your boat de-accelerates slightly between paddle strokes, and then accelerates slightly during the stroke.
Mostly responsivenes
Someone already mentioned it - any quick maneuvering that you do is easier with a lighter boat. But, if the maneuvering is not quick and not done all the time for long periods of time, the difference is not enough to matter in practice. Lighter boats feel more stable for this reason too - more affected by small waves and wind gusts as well as the paddler’s body motions… Of course, for kayaks like these, the main difference is at the take out 
You’re quite right
"Acceleration and average speed = largely two different things."
Quite! I was waiting to see if that got spotted. 
“Though if one wishes to be particular about it, you could say that your boat de-accelerates slightly between paddle strokes, and then accelerates slightly during the stroke.”
Well, the “particular” being the heavier boat would DE-accelerate less too! So that pretty much cancels out the sluggish acceleration.
The advantage of light boat would ONLY matter if one is doing a lot of short burst maneuvering like in rock garden etc.
So basically, our “feel” of a lively boat is just that, lively. It’s not traveling faster but quicker to change speed and direction.
HOW ABOUT…
…a Hurricane Tracer (or perhaps is was a Phoenix 140) dropped from a cartop to the concrete apron of a boat ramp several years ago? All was OK, except the ego of the dropper, of course, and a bit of abrasion where the hull met the road…
Apparently little worse for the wear, the fellow just got into his boat to
PADDLE ON!
-Frank in Miami
Waterbird, do you know how to choose
an appropriate reply button so that your comment shows up where it belongs? It doesn’t belong under a comment about severe cold and thermoform brittleness.
Yes, thank you for inquiring
– Last Updated: Aug-17-12 6:57 PM EST –
Although RavenWing's topic was "Brittle in cold water," he or she raised two topics in the post above. One was: "As long as we are talking strong, Prijon's blowmoulded plastic is far stronger and more impact & scratch resistant than thermoform and the usual rotomoulded plastic used in non ww kayaks."
I was replying directly to that. OK?
rotomolded material bends
Take a piece of each, and bend it until it breaks. Come back and confirm for us which one broke first.
Sorry, must have had my eyes crossed
when I read the post you responded too.
Prijon plastic is a bit harder and stronger. That’s their ww kayaks often do not have support walls. I have been bothered about seeing some thin spots in the plastic on their cockpit rims, but I haven’t heard anyone report a failure due to such.