I have a dagger catalyst 13.0 @51 lbs.
The charleston 14.0 is 51 lbs.
The catalyst 12.8 is 45 lbs.
Which would you “upgrade” to for a faster boat?
I know length determines hull speed but how
does weight come into play?
FWY, I am a 5’11" 145 lb. male. doing lazy rivers
and small lakes…with overnighters.
For most purposes, not very
Weight affects acceleration, which is somewhat significant surfing a following sea and, I suppose, would have some marginal impact on the small accelerations and decelerations of the kayak from stroke to stroke, but for practical purposes the only time you’re going to notice a 5 pound difference is when you’re loading your boat.
Depends on how far you have to
carry it.
kAYAK WEIGHT
Odd thing about kayak weight. I was demoing the Catalyst 13.0 (51 pounds)and I had no trouble hoisting it on my truck and carrying it to the water. I then tried a 56 lb 15 foot kayak and I swear it felt 30 pounds heavier.
Maybe it was the extra lenght but those 5 pounds seemed to be magnified
Richard
Or maybe it WAS 30# heavier
Manufacturers tend to fudge weights.
fudge factor
you’re right, DL - i understand that many mfgrs list the hull weight, without fittings, hatch covers, etc - it’s difficult to check, unless you carry a good scale with you while shopping - - i also think that a longer boat “feels” heavier, as it tends to be more unwieldly than a comparable weight shorter boat
I don’t know anything about those yaks
…but it appears that the Charleston would be the fastest.
If it just speed that you are looking for than yes the longest and lightest would be the best, but you also want to throw into the equation the narrowest, and then the hull shape.
Cheers,
JackL
My Kayak
Always seems to gain 50 lbs when out on the water. At least it seems that way when I go to take it out.
That probably happened to you when you went to lift the “heavier” boat after demo ing the 1st one.
Longer is faster. Longer and narrower is faster yet. Smooth (glass) is faster than rough (plastic).
Though at those lengths, you will not be a speed deamon.
Weight and speed
When considering how weight will affect performance you have to look at it as a combined weight of paddler and boat. If weight was a significant issue, then a 150 lb. paddler would be significantly faster than a 200 lb. in the same kayak. Most of us could really reduce the weight of our kayaks by simply losing a few pounds. A kayak’s weight gets important when you’re putting on top of the car. Now, there 10 lbs. will make a big difference.
Also a greater length and narrower beam will “usually” result in a faster boat. The problem is that these are all gross generalizations. There are many more parts of the hull design that have a great amount of effect. There is V versus flat bottomed. There is also the question of how far forward the beam is taken. Or soft chined versus hard chined versus multichined. On the soft chines, what does the curve look like? On the multi-chined, how many chines are there, and what is the angle between them. On a hard-chined boat, how much of a V bottom is there and what angle is the chine? Are there any bulges or concavities? The sides of the hull, are they flat? concave? both? Many, many variables.
thanks for the replies,
I can relate to what DL was saying, I can tell a difference in acceleration from a standstill, an empty boat gets up to speed quicker than a boat loaded with gear, but once you get paddling the speed feels the same, only a little more work.
I will stop dwelling so much on boat weight, other than the loading/portaging aspects.
Some day I would like to know more about hull design, and how it comes into play, but it looks like you always have to look at the big picture and not just length,width,weight. Thanks to all, I am learning a lot hanging out here.
Weight does matters
Using the numbers for wetted surface at http://www.unold.dk/paddling/articles/kayakstatistics.html, I did some calculations.
The average increase in wetted surface for these 17 boats is 9% when paddler weight increases from 68kg to 91kg (addition of 23 kg).
Assuming there is a linearly relation between weight and wetted surface(big assumption!), this means every kg increase the wetted surface with around 0.39%.
John Winters gives the formula for the frictional resistance here: http://www.greenval.com/shape_part1.html
Rf = 0.97 x Cf x Sw x V^2 where:
Rf = Resistance in pounds
Cf = Coefficient of friction
Sw = Wetted surface
V = Velocity in ft/sec
0.97 = Constant for fresh water
In other words – there is a linearly relation between wetted surface and frictional resistance.
Below 4.5 knots it’s safe to ignore the residual(wave-making) resistance.
Conclusion: Below 4.5 knots one has to apply 0.39% more force for every extra kilo.
Does weight matter? Hell yes! 
More surface AND displacement
It’s worse than that. More weight = more displacement. That means more boat in the water and so more wetted surface and more friction as you say.
More displacement also means more water you have to move out of of your way (some to the sides - most under you). That takes work too. Yes, that’s more related to wavemaking - so the curve shoots up at higher speeds making it worse the faster you go - but it also takes a toll well below hull speed.
I estimated that if I lost 30# I’d reduce total displacement by 10-12% (me, boat, and all gear on normal day paddle), and so would have to push 30# less water out of the way (at any speed) and could shave off as much as 2-3 sq ft of wetted surface which should yield a noticeable drop in frictional drag too.
Side note for comparison: JackL is 60# lighter in the same boat. Total displacement closer to 215 vs. my 275. Given that huge difference in displacement/drag - it’s not really the same boat at all! My only hope racing him would be to improve my power to weight ratio by adding more power and/or losing weight.
So, how much speed would dropping 30# buy me? Depends on what percentage of that 30# is fat! Better plan - drop 40# of fat and put on 10# more muscle!
My gut feeling (pun intended) is that a 10% reduction in displacement could translate to as much as a 10% increase in speed for same effort. There would have to be a curve though - as 50% less displacement would not yield 50% more speed, and even JackL’s 20% less is not likely to give him 20% more speed (even if all else was equal).
There is math for this displacement change/speed ratio somewhere. Sculling maybe. Hull design and paddler output cannot be ignored, so too simple of a formula would be a wag, but some idea of the relationship would be interesting (to me at least).
For most of us - it matters little. We and our boats weigh what they way. Better to focus on the power to weight ratio than displacement.
Funny thing though - if I really have to work harder to paddle in my current somewhat overweight state, shouldn’t the extra work be helping me to drop the weight! Funny how the vicious circles in life only spiral toward the negative!
So, does boat weight matter? Sure. but I weigh more than 4x what my boat weighs - so for me that’s literally the bigger issue. Not that shaving a few pounds off the boat wouldn’t be nice too…
since mine weighs 83 pounds
(aside from the technical posts above which I will read when I get a chance)
I am going to say it FEELS like weight makes a big difference.
… in required effort.
My (inexperienced uneducated) theory on this is …
… the heavier boat displaces more water (so it sits lower IN the water) … then to accelerate it … you have to ‘push it’(with muscle power) through that deeper ‘wall’ of water in front of its displaced shape.
which means more resistance … which your muscles have to overcome 100% of the time …
… now maybe a more efficient hull shape might allow the boat to ‘plane out’ on top of the water ? … and increase efficiency when ‘on plane’ ?
But hull for hull … more weight to me means more resistance … more effort … less speed per amount of effort expended.
By my ‘feel’ … my 83 pound (weighed) “barge” takes a heck of a lot of effort to maintain a set speed … and … to accelerate those pounds each time you want to.
whew !
- but for general fiddling around recreational use for fun - weight probably doesn’t matter very much … if you had fun - it doesn’t matter.
Kayak weight/speed
Then another Question Would a 250 lb. paddler riding low in the water in a boat rated for 270 lbs. be slower than in a similar hull shape by the same mfg. rated at 300 lbs that is 2 ft longer?
Hey Chris…
Thanks for using me in your comparisons.
I am no mechanical or nautical engineer, and my math is probably the worst in the world, but I can attest to the fact that weight loss equals faster paddling.
In the past two months I have lost 22 pounds, and in the race last Saturday I had my fastest times yet in both the kayak and C-2 races. Nanci has also lost a couple of pounds.
Holds true in cycling also. My times in the senior games time trial qualifiers were faster this year than last.
My equation:
Low fat diet+ light weight boats (or bikes)+ training = Faster + happier than a pig in sh-- !
Cheers,
JackL
Wow…
That math hurts my head but a little sunk in.
For anyone interested, I ordered the Charleston
from an online dealer for 20.00 more than the cost of the other boat and saved about 200.00. I will have a boat the same weight as my old one, (51 lbs), a foot longer,(14ft.) and an inch and a half narrower…should be faster but I dought I will notice much of a difference…I hear you have to go a few feet in length before it’s noticeable.
The last few posts made me think of something else…“rocker”, on a yak with a lot of rocker, would probably track/turn differently with heavier/lighter paddlers? More waterline with a heavy guy vs. less with a lighter person.
Careful Greyak…
Your boat may go shopping for a new hi-tech lighter paddler…
and I’m not letting my boat read this thread… GH
L My Q700 will have to get in line!
My ski needs a lighter faster and much better paddler even more!
Something just not right about a short fat middle aged guy on a 21’ long needle of a racing ski! At least sometimes “on” it anyway! I made it 3/4 of a mile before dumping yesterday - on glass flat water of course! Only dump of about 3 miles total for the day. Sunday was good for maybe a dozen swims. Maybe I’m improving (I still consider it a miracle I can stay on it at all!) but just haven’t had the time. Limited time and long breaks between paddles do not really work learning a ski.
That of course has nothing to do with the thread. Wait, it weighs about 30# - and is faster (or would be if I wasn’t working so hard to stay upright) than my 48# boat. There - back on topic.
You will notice a difference
The 1.5" less beam can make more difference than the 12" more length. Together - you’ll notice the difference.
Longer = more POTENTIAL SPEED, as in higher top speed IF you have the power and paddle at a decent clip.
Narrow = less effort for same speed, at ANY speed. At same power, narrower is faster.
The only drawback is narrower and longer BOTH increase wetted surface (at any given displacement). Both make the kayak less round. A sphere has the least surface are of any shape. Surface area relative to volume or displacement increases as the shape gets elongated. All else equal, narrower will also sink deeper (but narrower boats are usually longer too - so usually don’t sink deeper).
More wetter surface = more frictional drag, so you need a little more energy (usually very little) to move longer kayaks than shorter ones at lower speeds. Where they shine is when you speed up and their lower wave drag lets you go much faster (assuming you have the power).
OK, enough. Getting to much like math again.
Rocker? Yeah, just as you say. Impacts waterline length and turning/tracking. Beyond that it gets into all sorts of variables and conditions and gets complicated.