I have two canoes. One a 10.5’ composite Hemlock Nessmuk (27 beam and 25 waterline)with weight of 16 lbs. The other a ABS Old Town 16’ Penboscot (34 beam, 33 waterline)58 lbs. weight. When I paddle the Old Town I’m usually 50 yards behind the last person in my club (all kayaks). I put a 5 gal jug of water in front for trim. I’m in bow seat facing backwards. Use a 260cm double blade paddle.
When I’m in the nessmuk I don’t get as far behind. Use a 240cm db paddle.
I would have thought the Old Town would have been faster. Does the shorter length of the Nessmuk not matter so much when you have lighter weight, narrower beam and more sophicated hull shape?
potential speed
of the OT is probably greater. You’re probably not going 100% effortwise?
you’re cruising
not racing. the cruising speed is easier for you to maintain because it requires less energy. theoritical hull speed of the tandem really doesn’t apply since you’d need to be super strong/fit to bring it up to speed or need a second paddler.
speed is really about power and resistance. the larger boat has much more resistance, and you always have the same power, so to speak.
the shorter boat is more efficient for you paddling solo than the tandem reversed. that’s a big boat for one person, and a whole lot of skin friction.
For your particular pace
and strength, there is an optimum boat length (assuming a decent hull design), where efficiency is maximized and it could be somewhere between the two boats you have.
If you bought a jon boat, you’d want an appropriate sized motor, you probably wouldn’t pick the same motor for a 40 foot luxury yacht.
In kayaking you have to think the other way around, with my strength and the pace I want to paddle, what boat length (and design) is appropriate. A petite female may be much more efficient in a 13 or 14 footer while a big strong guy may be better in a 20 footer. For those of us who don’t race, anything over 16 foot is often more length than we need and at a leisurely pace, 14 footers can be easier to paddle than a 16 footer.
Ultimately there are a lot of factors that affect how easy it is to maintain a certain speed and length is not always the dominant factor.
jim
Sometimes
Recently finished up a kayak I designed. I wanted to minimize the resistance in the 3-4.5 mph range since that is where most of us paddle. After a lot of experimenting (on the computer) I settled on a 15’ length for this boat.
Longer the and resistance went up at these speeds.
Shorter and the stability was hurt and needed to make it wider, which them made the resistance go up.
I can tell a big difference in this one and my 18’ boat. I can easily keep up with guys I was struggling to keep up with.
There is a lot of considerations but all things equal longer is not faster at the average paddling speeds (typically).
Making the Penobscot faster
I think you could make the Penobscot a lot faster. Get a single blade and some foot pegs and it will go much faster I think.
couple of thoughts
Lots of design variables at work here and I’m not an expert in exactly how they add up.
One shape factor is aspect ratio - length divided by width - they are about the same.
Another factor is wetted surface area - Nessmuk has way less than Penobscot.
Another is bow entry “sharpness” - again Nessmuk clearly wins.
Then weight - hmmm - Nessmuk lighter.
And the paddle - 240 easier to handle than 260.
==> does not seem too surprising if Nessmuk is faster and more efficient.
often thought about it …
– Last Updated: Jul-01-09 12:46 PM EST –
..... which boat has a greater wetted area ?? ... the Penobscot , but I do not believe this has anything to do with it's length or width . I believe it is simply because the Penobscot weighs 42 lbs. more .
An example : boat + paddler + gear = x ... The amount (volumn) or weight (lbs.) of water displaced must be X ... the wetted area required to displace X would be equal "if" both boats weighed the same (if X was the same) , regardless of demensions , or so I believe ??
So I see it like that , the Hemlock displaces less water weight/volumn because it weighs less .
If the Penobscot at 16' and the Hemlock at 10.5 weighed the same , although the displacement would be the same , the Penobscot by rights would ride higher in the water having less resistence to splitting the water (depth wise/dynamic resistence) , the Hemlock would ride deeper and require more force to split the water , displace it (depth wise) , while in movement of course .
In the overall picture , "if" both boats weighed the same , the wetted surface area (in square inches) should be the same , I think ... considering resistence of that wetted area , the higher riding boat (longer Penobscot) should have more linear resistence , but the deeper riding boat (shorter Hemlock) would have more dynamic resistence ... my guess is this dynamic resistence is a greater factor than linear resistence , there is probably a ratio or curve somewhere to be found that could prove or disprove this .
Now I don't really know what I'm talking about in the sense of fact by hydro engineering physics , but this is the way I see it in layman thoughts . maybe I'm way off base , maybe not ??
It’s getting deeper…
some interesting things to consider there.
The wetter surface is likely not the same, even though the volume/displacement would be the same with equal weight. A cube and a sphere with the same volume will have different surface areas – the cube maximizes the area and the sphere minimizes the area. If wetted surface area was the end all parameter, we’d all be paddling big hamster balls.
My gut says the wetted surface area of the smaller boat is generally smaller for common canoe shapes.
It is easy to get wrapped around the axle with entry sharpness, draft, and rocker. I think you can make inefficient designs by taking these to either extreme. A blunt entry is not good, but you also don’t see many kayaks with needle-like entry points – seems like there is a bow-wake issue as you build speed that makes sharper entries have a limit.
Getting a boat too deep in the water can make it hard to paddle and sometimes unstable, but you also don’t see fast kayaks designed to have a quarter inch of draft – this is obviously related to the wetted surface issue as it’s take a large flat-bottomed boat to only displace a quarter inch of water.
Rocker is more of a wildcard because you can find fast efficient boats with little or significant rocker – but these are often efficient for particular types of conditions. A kayak should have just enough rocker… whatever that is. You can certainly have more rocker than you need on a calm lake and you can have too little rocker in rough seas, so there is always a compromise for the average paddler.
jim
If you look at Hemlocks website
you will see that LDC and his wife trip in solos. He in a bigger solo she in a smaller solo. They keep pace with each other without one waiting for the other.
Partly this must be due to wetted surface and length of your arms reaching over the side for a sweepless stroke.
I know I do not have the horsepower to drive an 18 foot dedicated solo with a beam of 21 inches to its potential hull speed. A 15 footer with a width of 26-28 inches gives me a better chance, and the rounder the bottom the better.
The OP stated that the tandem was paddled with a double blade from the bow seat backward. This ensures a sweep with every stroke that is balanced by a sweep on the next stroke. The resulting course would be a zig zag.
That tandem needs a rudder!