the importance of trim in a flat water canoe is something I’m wondering about. I’m somewhere in the middle of understanding the design and benefits of an asymmetrical canoe, and would like to hear anyone’s input to help better understand it. So far, I know that asymmetrical canoes are supposed to have the same forward momentum effects in water as well designed cars have when moving forward in air. Water dynamics and air dynamics. This makes asymmetrical canoes typically better than symmetrical canoes, in that they are much more efficient for paddling. So the front half is shaped somewhat differently from the back half. This applies primarily to the water surface area, as well as the entire canoe. This also applies to kayaks, as well as canoes.
As far as trim goes, I know that when going into the wind, the front should be slightly lower than level to help keep on track. I think this is reversed when the wind is coming from behind, meaning to keep the stern a little lower then. So far, so good.
Then consider the affects of trim with regard to the asymmetrical hull. Because the asymmetrical hull is shaped differently from front to back, it is unbalanced also in water surface area, somehow, from front to back. In a symmetrical canoe, the shape and water surface are balanced from front to back, so the effects of trim somehow seem to make sense.
My dilemna of understanding is how the asymmetrical design responds to changes in trim, since the asymmetrical design is probably based upon a level trim assumption for its effectiveness. Does an asymmetrical hull go banannas if it is not kept at level trim? If anyone can contribute to this, I would greatly appreciate it. Happy paddling! and keep trim.
Seesaw leverage
My tandem tripping canoes are asymetrical, with the exception of the old Grumman. Trim becomes more important as the wind speed increases. In calm to moderate winds and as long as the full waterline is in the water, my experience is trim isn’t that fussy a deal. But I do mark a 4" waterline on the inside of my canoes for a quick bowman/sternman reference after everything is loaded. Think of the center of a symetrical canoe as the fulcrum for a seesaw. A lighter load is able to trim a heavier load by placing the heavier load closer to the fulcrum. The lighter load has a leverage advantage. In an asymetrical canoe the fulcrum is to the stern of the center. There is even more leverage advantage to a lighter load in the bow, and this can be increased with a sliding bow seat. That same fulcrum point is also the pivot point for lateral force (wind). The longer bow portion of an asymetrical canoe (pivoting seesaw) has more wind resistance than the shorter stern portion. The stronger the wind, the more leverage. The more the trim is bow light, the more the wind resistence difference and the lighter the wind speed to make paddling difficult. Hope this helps.
running downwind
When running downwind in a stiff breeze my “fishform” Bell Morningstar can be a handfull as it is overly lively and eager to broach, much like an over-canvassed sailboat.
On windward and reaching tacks I’ve not noticed any real difference in handling vs. a symmetrical hull.
Asymetric does go banannas, then,
when it is trimmed stern down in a downwind. I have two hi-tech “fishform” hull canoes and have noticed the same disappearing act of control and stability in that situation. One of them is a relative of your canoe, but I’ll try to keep this conceptual. I would think that since the “fishform” has most of its design up front, then that half must be kept well in the water to make the design work, no matter what the circumstances. This apparently is a characteristic of hi-tech asymetric “fishform” canoes that I wish I had known about earlier. Thank you. A way to test the directional difference - try solo paddling from a drop-in box seat just behind the middle thwart from both directions. Should be kind of like driving a car forward, and then in reverse, with consideration to overall control.
Asymetrical boats ??
There are Asymetrical boats ??? when I look at my Pamlico 140 , it is perfectly symetrical. Does anyone have a pic of an asymetrical canoe or kayak ??
morningstar
is not “fishform” The only thing assymetrical about the morningstar is the rocker, with more rocker in the bow than the stern.
When running downwind, especially if your canoe is lightly loaded, you need to make sure there is enought weight toward the stern to keep it deep enough in the water to act like a skeg and the bow light enough that it doesn’t plant itself in a wave trough and give the boat something to pivot around.
Not just rocker
I don’t know about the Royalex MorningStar, but on my composite version the tip of the stern seems to be noticeably sharper and narrower than the bow. I don’t use it solo, but paddling tandem we have had much less trouble with it wanting to broach in a following wind than we did with the Malecite we used to paddle.
LMAO
Fishform and Swedeform further
clarified - I borrowed this from another site, and it helps describe the asymmetrical difference somewhat:
Symmetry: Kayaks are either symmetrical, which means that the front half and the back half of the kayak have the same shape, or asymmetrical, which means that they don’t.
Symmetry affects not only the efficiency of the boat as it moves through water, but also its ability to turn. Symmetrical boats are better for quick maneuvering, as in negotiating small streams or whitewater. Asymmetrical boat designs usually lengthen and streamline the bow for more efficient and faster passage through the water. Directional control is increased, but turning ability is decreased.
There are two types of asymmetrical shapes: fishform and Swedeform. Fishform boats have more volume fore (ahead) of the midpoint, and Swedeform have more volume aft (behind) of the midpoint.
I’m posting this because I think most canoes and kayaks that are asymmetrical are fishform, except for those that are designed specifically for racing. The fishform is noticeable about 1’ to 4’ back from the bow, and that area will have more water surface than the same area in the stern. I understand it much better now. I still think that the fishform area needs to be well within the water for the design to function as it should. Thanks to all for your contributions.
not many canoes are fishform
There are probably quite a few fishform kayak designs, but very few canoes. A few of Pat Moore designed solos from the 1980s were fishform, but none of the big canoe companies have ever had any in the model line.
amen
i ran downwind with the big spirit sail rig in 25 knots in a bell rob roy and it was all i could do to keep the nose from burrying. lean back, sweep stroke, lean back, nearly flip, switch sides, sweep stroke, lean back, etc. this is a great post, btw.
questions beget questions
As you seem pretty sure about this, I went out and measured my Morningstar and more width is carried forward of the center thwart, so I’m a little confused here.
One can definitely see the fishform shape of a New England catboat, but if the same shape is put into a narrower hull with a higher length to width ratio – while not as dramatic as the aforementioned sailboat – would it not still be fishform, albeit on the skinny side?
It looks like we’re comparing flounder to sardines and debating whether they are both fish.
more questions
did you measure at the waterline?
Excellent point about the waterline
shape. I believe several modern designers make all sorts of subtle differences between bow and stern shapes below the waterline while keeping the shape at the waterline relatively symmetrical. I’ve owned several canoes which were officially asymmetrical, but the only one which was obviously so at the waterline was a Reflection 15, which had a (relatively) long narrow bow with soft chines and a blunt stern with sharp chines. (Hardest boat to back up I’ve owned.) The MorningStar is not so obvious, and I never was able to see any difference between the bow and stern of the Malecite by just looking at it, although the factory says it is asymmetrical.
Morningstar Crossover
I see that the Morningstar is called a Tandem/Solo crossover and that the bow and stern rocker are different. What does the crossover mean?
CedarEater
assuming you are correct
As I don’t have the time nor inclination to take on a project of science-project proportions to map my waterline hull shape, I’ll assume you are correct.
Which now leads to the question, if most asymmetrical canoes aren’t built for extra speed, why do they exist?
Are there special handling characteristics or is it all just a marketing angle?
Not very scientific, but
based on our experience the short answer to your question about special handling characteristics is “could be”. According to Mad River the Malecite has slightly more rocker in the stern than the bow, and for us it always wanted to broach in tailwinds, even with added ballast in the stern. The MorningStar, with the same paddlers and no ballast, has much less tendency to broach in the same conditions, which I’m sure Bell would attribute to its having less rocker in the stern than the bow. Works for us.
hey seumas
I think you’ve left us high and dry here.
You were sharing your knowledge and experience and now you’ve dropped off the radar.
Radio check, please?
Pics of fishform and swedeform to
help portray the difference. Here is an example of a swedeform canoe, with the widest part being behind the center of the boat, and the front half of the craft having no fishform to push the water away from the front of the craft:
http://www.uscanoe.com/ResultsNationals2004/Pictures2004/SundaySet1/pages/PICT1086.htm
Here is an example of a fishform canoe with the front half showing the typical fishform area:
http://www.uscanoe.com/ResultsNationals2004/Pictures2004/AdultSprintsSet1/pages/PICT0026.htm
The examples are somewhat extreme, but the differences are shown in their visible shape. Thing is, the same differences exist, although more subtle, in the wetted surface area of asymmetrical crafts. However we call it, if the wetted surface area is mainly up front, and if paddling in a downwind, the trim should not be adjusted to lift the frontal wetted surface area to the point where it does not contribute to the control of the craft. In that situation, the “tail” part of the fishform is then put into control of the craft, and it is not designed to do that with efficiency. The tail part of a fishform is designed to be more of a rudder than anyting else. Hence, the asymmetrical fishform goes banannas in a downwind when trimmed stern low. I guess that’s the end of it.