I have a EPIC Malakai surfski with an EPIC mid wing paddle.
I paddle the same place alot.
I’m mid 60’s 5’6", 150 lb
I live in central Florida.
Two weeks ago on a windy day with some chop, I did a 10k course and then repeated it today – no chop.
I went a little slower than usual with the chop, but today did a lot slower!
Specifically 15% slower; 1.5% lower strokes per min; 15% ore strokes per mile; significant increase in heart rate even to keep that paces 105/min average max 120’s; today 121 average 140 peak.
The water is quite dark today, but it was very deep both days. Are there oils that get in water. There was no duckweed, nothing seemed to be stuck to the boat or plant material caught on the underside.
Bottom line is that I worked harder with nearly the same strokes/min, but 15% less meters/stroke, had better weather with less chop, but slower 15% . The only think I can think of is more viscosity.
Just a guess, but water current is likely the answer. After heavy rainstorms, currents are often stronger. This doesn’t necessarily correlate to surface waves.
It would take a huge amount of sediment to appreciably change the viscosity. Think liquid mud. Agree that is is probably current or you were just physically having an off day while still feeling fine.
What was the temp and humidity levels?. How much sleep the night before? Breakfast?
I’m thinking your engine was on low power.
Somedays a diamond, some days a stone…
I find that smooth, slick water feels “sticky” and slow to me. I almost never paddle with a GPS so I’m only going on feel and suspect that that there is nothing to it. When I do paddle with a GPS I am on a trip and those “sticky” days my GPS is showing a slightly slower cruising speed than I want to see but I attribute it to fatigue.
Something that I have wondered about, though, is if smooth, unagitated water passing over the hull actually is a bit slower. On wings trip strips are often installed to create micro-turbulence along the chord which reduces stall speed. Probably not applicable but when I do measure my speed I am slower when the water is not rippled.
Whatever. Not sayin’ nothin’. Just curious.
Dimples on a golf ball gives it more distance than a smooth ball. My understanding it’s because a slight bit of surface turbulence reduces friction. I have heard, but don’t know for a fact that a waxed boat is slower because the slick surface wants to “stick to the water”. The turbulence acts like a lubricant by reducing the friction. Perhaps someone knows if this is right.
A little turbulence reduces friction between the medium and the object. Laminar flow creates more friction.
I think that’s what I remember from the pipeline design course I took sometime in the early 80’s, complements of the US Army.
Like someone said, airplane wings have little doohickeys on the back edge to break up the laminar flow.
Tis true from what the sailors say. The top cat racers would sand their hulls .
Never heard of skiers roughing up their skis to go faster, water skis or snow skis. People racing tend to be fanatical about waxing these things to reduce friction.
I doubt that a boat plowing through or bouncing over waves would be faster than a boat gliding along on smooth water. According to my GPS that’s certainly not the case and it seems to take more effort to maintain the same speed. I’ve found that waves are the enemy of speed. A 15% improvement in speed, whether by kayaking in rough water or by roughing up the hull, would be pretty radical.
There have been some studies indicating that a roughed up surface, under certain conditions, can have reduced drag. However this effect is generally only seen at relatively high speeds and under very specific conditions. Not anywhere near the speed of a kayak and not the equivalent to a boat going through waves. And when was the last time you saw a dimpled aircraft or even a boat. I suspect that people racing boats back then were attempting to apply a poorly understood concept incorrectly.
Modern day serious racers won’t even use bottom paint, but wet sand down to 1200 or better and then treat the hull with products like McLube.
Water density is a function of the water temperature. Colder water is denser, scientifically.
Warm water can get dense because of algal growth, fertilizer runoff, and several other things.
The big problem with a rainy season, like we have here in Central Florida is the inflow of odd currents as that rain enters the Gulf.
Years ago I was diving for sea urchins in January and the temperature on my computer was reading
29 Fahrenheit in less than15 feet of water. I can truly state that water was dense. It was so cold on the surface that ice formed inside my dry suit when I got back on board the boat. I have also been told of waves smashing out boat windows in winter that would not have caused damage in warmer weather.
Where were you paddling? Like other posters, unless it’s a lake, I’d assume currents. In central Florida, for example, the St Johns River can either have a (local) negative current, or it can give you a 2mph or faster boost, depending on recent rainfall. We were doing 7mph in surfskis on the St Johns yesterday (near Blue Springs) without working hard.
Viscosity does not change with sediment load. What changes is the wind, the tides and the current.
I doubt that the water temperature changed appreciably over two weeks in a central Florida summer and certainly not enough to explain a 15% speed difference…
I’m pretty certain that Greg is right here and that my perceived increase in energy expended and measured decrease in speed is due to fatigue. It’s interesting that “stickiness” of glassy water is acknowledged by float plane pilots during takeoffs.
“Glassy water occurs when there is little to no wind. During takeoff, the adhesion of the water to the floats increases the drag making it more difficult to takeoff and requiring special techniques”.
“As smoother water creates more water drag due to the high surface tension of the water, the one float takeoff is a common technique to lessen this friction.”
From another source:
“Glassy water has very adhesive properties. The wavelets that occur in a normal takeoff, allow air to get under the floats thus reducing drag. In glassy water there is complete float water contact and thus more drag. It may be advantageous to circle first near the take-off point or step taxi
back and forth in your takeoff area to create some small waves on the water. Another option is to raise the right float (Left stick) out of the water reducing a large amount of drag. Raising the right float is the easier option due to torque”.
Now whether that stickiness has any effect on our hulls at our speeds I don’t know. Probably not, however, the conversation on this thread has created some really interesting comments that I have enjoyed reading.
The sea plane example would require that you were moving fast enough for an appreciable amount of the hull to be completely out of the water such that there was air under the boat. Very steep short period waves might have either a portion of the bow and/or stern out of the water but this would probably be more than offset by the resistance of the bow plowing through the waves and the loss of effective waterline length.
Hey Stevens, do you live here; are you an environmental scientist and hydrologist?
I answer yes to all of the above. Water density is a function of the water temperature. The colder the water is, the less dissolved oxygen it can carry, therefore the water atoms are packed closer together.
As it happens we had a front stuck over us for almost a week. We got over a foot of rain in Tampa and the rain was heavier further north, like Orlando.
That rain dropped the temperature of the Hillsborough River by 18 degrees. That will make the water denser.
A factor in water viscosity is the microscopic algae that blooms around this time of year.
I never worried about it because if it was a race everyone would be facing the same things.
Actually, cross-country skiers do put structure in their bases. Cold, dry snow requires fine structure, while warmer, wetter snow gets a coarser structure. Best done by stone grinding, but sanding works. Structure bars are also used for wetter snow. It’s all to battle a combination of static electricity, friction, humidity, water suction, etc. The structure goes lengthwise of course, never across the ski base. It’s pretty involved. And the base structure is just one piece of the puzzle - you also have to pick the right skis (flex, fit, etc) and the right wax for the conditions. And outguess the weather.