I’ve been renting a few canoes lately (trying to decide which to purchase) and it seems that some of them are very prone to weathercocking and others are not bothered much at all. I would have thought that added depth, especially at the stern, would have been the likely culprit but the canoe we had the most trouble with was the MNII which was the shallowest of the bunch. That got me wondering, what aspects of a canoe’s design make it more susceptible to weathercocking?
Trim and load.
In a canoe similar to a Minnesota II, we were blown around when paddling empty, even though trim was only slightly down at the stern. When paddling the same conditions with all our gear aboard, the boat was almost indifferent to wind angle. So maybe what you are noticing has to do both with the load carried and how it is trimmed.
Load and Trim
I know that load and trim play a big role but in this case we had several canoes on a trip to the BWCA and were swapping them so we could all evaluate the different models. The tendency to weathercock seemed to follow the canoes rather than the paddlers and gear. In other words, my partner and I were paddling one model that really wanted to weathercock badly. We switched canoes (brought our gear with us loaded approximately the same) and had no issues. The paddlers we switched with, who had no problems before, then reported the same issue of weathercocking.
It was kind of strange because we tried 4 different canoes - 2 of them seemed to want to weathercock no matter how we trimmed them, and the other 2 didn’t seem to be affected nearly as much.
hull shape
– Last Updated: Sep-23-08 10:30 PM EST –
Swede form, delta hulls resist squatting in shallow water. That full, flat bottomed, aft section also blows downwind pretty easily.
In the end, tracking, or yaw resistance is affected by Block Coefficient, length to width ratio and lack of stern rocker, in that order.
Forward speed also increases weather cocking. Google "peripatetic pivot point".
Tripping gear, balanced fore to aft in almost any hull sinks it's footprint into the soup and makes the boat track better.
Can’t explain that, though you might
examine what load each canoe was carrying when you played musical canoes.
It is true that some canoes will blow sideways more easily than others, with equivalent load. However, to weathercock, the canoe has to turn into the wind, and it is hard to see why that should happen if the canoe is in reasonable trim.
From a little experience in several
different canoes; the lighter the canoe is the more it will weathercock.
Our 29 pound Comp Cruiser weathercocks easier than our 39 pound Jensen, and that weathercocks more than my heavier Penobscot.
My heaviest barge, the OT discovery at about 80 pounds weathercocks the least of all our canoes.
In last weeks ADK 90 miler in one of the lakes we had to keep all 4 paddlers on one side several times in our C-4 to keep straight.
On those same lakes, there were several 19 pound C-1’s that went swimming.
Cheers,
jackL
One thing I haven’t seen mentioned …
– Last Updated: Sep-13-08 11:53 PM EST –
... so far is that even though some canoes apparently weathercock more than others and this can be adjusted with trim, a perfectly symetrical canoe that is in perfect trim WILL weathercock when underway, and the tendency to do so increases not only with wind velocity but also with the boat's forward speed. The reason for that, as I understand it, is that there is less water pressure against the sides of the hull on the trailing end of the boat than at the bow, which makes sense if you figure the bow is wedging its way into the water and pushing it aside, while the stern is doing the opposite and the water is falling back into place there. This is why a canoe coasting through the water in an uncontrolled manner will turn by having its stern go into a skid (the more maneuverable the boat, the more quickly this will happen: my Supernova will rapidly spin-out in one direction or the other within about three seconds after I stop paddling, while an extreme straight-line cruiser that's just coasting will only go into a very gentle turn that gradually gets a little sharper). The the bow will never intiate this turn on its own; it's always caused by skidding of the stern. Paddle backwards and it will be the bow that has a tendency to skid, as it always is the trailing end that wanders to the side more easily.
Blackhawk made a series of canoes that are exceptionally low-slung at the stern, and I've been told that the reason for this was to make them behave better in the wind. Someone here recently said that these Blackhawks are a fishform design, but he was wrong (I looked closely at some Blackhawks owned by friends after reading that comment so I know for sure that the widest point is NOT forward of center, but if anything, might be a bit toward the rear). If you figure a normal canoe will have some tendency to weathercock just due to normal hydrodynamics, it makes sense that providing less of a "sail" for the wind to hit at the stern than at the bow would help counteract that. You might be able to replicate this action by putting any taller packs you have in an upright position forward of center, but my inclination in windy weather would be to pack everything below the gunwales.
Incidentally, I've verified this idea with my guide-boat, which is perfectly symetrical and usually pretty close to being in perfect trim when rowed solo. The stronger the crosswind, the more the boat tends to turn into the wind. When sitting still, it will turn exactly 90 degrees to the wind and stay there, but once you start moving, it wants to turn into the wind. It's not much of an inconvenience, but it's very noticeable. However, in an extremely strong wind (30 mph or more), the little bit of differential pressure that causes weathercocking becomes insignificant in relation to the very strong force of the water on the whole downwind side of the boat that results from being pushed sideways, and for practical purposes, weathercocking ceases and the boat ends up being turned crosswise to the wind and being "pinned" there, so that great effort is needed to "un-do" that process. I imagine that if I could row fast enough in that situation, the weathercocking forces would increase to the point of being noticeable again.
Not to change or steal the thread,
– Last Updated: Sep-15-08 9:41 AM EST –
but since you mentioned "Guide Boat"
I have to make a comment. - You guys seem to be the happiest paddlers on the water!
In the recent 90 miler the Guideboats started in the second or third wave, and naturally the faster boats were in the later waves.
In about the middle of each days race, we would catch up and start to pass them, and every single one whether it be solo or otherwise would have a big smile and a pleasant comment for us as we went by.
At one occasion, while I was thinkin that I would love to row one, my wife who was up in our bow, turned and said to me; "When are we getting one?"
Both of us got our love of paddling from rowing old skiffs when we were kids growing up near Boaton Harbor.
OK, I'll return the thread now!
Cheers,
JackL
adjust your paddling to the conditions
True…some aspects of design may leave something “to be desired”, but adjusting your trim and paddling to the conditions goes a long way.
$.01,
SteveD
MN 2
I own a Minnesota 2. When running empty, it weathercocks easily. It’s a very light boat for its size. However, I have never had any problem adjusting the center of buoyancy to compensate.
My wife is close to my weight so the sliding front seat usually does the trick. If the wind is strong enough so that is not enough, I can kneel to get the last little bit.
CEW speaketh the truth
– Last Updated: Sep-24-08 3:46 PM EST –
http://clydewinter.wordpress.com/2006/08/06/ithe-peripatetic-pivot-point/
But he spels as gud as I.
But does the pivot point move due to reduced pressure on the stern or because of some other factor?
Jim