Speed and Stability of Greenland Kayaks

News

Note: You might need to shift+reload to see the current pages/graphs instead the older ones in browser's cache.

17th November 2008

Added KOG #27, 31, 33, 34, 36, 37, 43, 44, 52, 57, 70, 71, 88. That's all type IV kayaks except child kayak #35 and #38. I also fixed #75 a little and re-created #82 (Lc-148) from KOG book. #82 was previously made from museum offsets. New models are available for download.

Some non-Greenland kayaks are now available for comparison.

Click here to see old news

Backround

I ordered Harvey Golden’s book “Kayaks Of Greenland” some time ago. I thought I could make couple models in FreeShip (currently known as DelftShip) to compare freeboard, stability and maybe speed.

http://www.traditionalkayaks.com/AboutKOG.html
It started out from just two or three kayaks, but I found the stuff interesting and soon I had created over 20 kayak hulls. I decided I could put the results online for others. Kayaks have been selected my personal interest. At start I thought to find the fastest one, then I thought to find the next one to build.

Settings

Displacement

At start I needed to choose a displacement for the kayaks. I decided to use 90 kg (198.4lbs) of total weight, paddler 70 kg (myself) + light kayak 15 kg + gear 5 kg. It seems that original kayaks have been made for quite displacement. It’s possible - and much likely - that some kayaks in KOG are made for heavier or lighter load, also some kayaks must be heavier than others because the size differencies. But I wanted to use same displacement for comparison purposes.

Trim

The kayaks in KOG are not show in typical floating trim, but something close to that. After playing with some numbers I ended up thinking that center of gravity (and thus LCB, Longitudinal center of buoyancy) should be somewhere in front half of coaming. Example with kayak #46 (IV-A-483) below.

Larger image

Stability as Righting Arm

Stability came out from FreeShip’s cross curve calculation. I used 90 kg (198.4lbs) displacement. The tricky part is choosing the right CG height. Paddler is the largest weight and seat height changes things a lot. In reality kayaks with flatter bottom (like East Greenlander style) will allow lower sitting position and thus lower CG. It’s quite difficult to estimate seating height from bottom shape, so I just decided to use one constant CG for all the kayaks. After some fiddling with numbers I came up with 16.5 cm (6.5 inches).

Speed

I used Michlet to calculate speed. FreeShip has export function to Michlet. With so many models I could not compare kayaks by usual resistance vs. speed -graph. Example of that below (KOG 6, GMZ 700 and 77, L.9726). Also in this kind of graph the differences in lower speeds are usually difficult see. So I thought to make bar graphs of speeds at specific resistance. I chose the resistance so that average of all kayaks ends up in even number in km/h. Graphs will tell how much faster or slower each kayak will go with same resistance. The sample pic shows also frictional and residual resistances.

Larger Image

About Some Models

KOG 97

This model has a bit weird stern - not sure if I created it right. Also the trim was a bit of a question.

"KOG 72B"

This is the famous Illorsuit kayak that has been starting point for many commercial kayaks. Emanuel Korneliussen (also spelled as Emanuele Korneleisen) built both of these Illorsuit kayaks in 1959. The KOG 72 was made for John Heath and this 72B was made for Ken Taylor.

Download models

Can be done at http://personal.inet.fi/koti/tonivee/KOG/models.html

My Thoughts...

These numbers and graphs will give you only calculated values for a kayak in flat, calm water. In real life there will be waves and wind and most likely a bit different trim for different weight persons and gear. Also the numbers won't tell anything about the kayak really handles in different conditions.

And are the numbers right? Well for stability calculations, I believe it should be quite right, just remember the effect of CG. And the CG is assumed to be dead weight - in reality when the kayak is heeled, paddler will most likely shift, the CG moves sideways and kayak will be capsized more easily.

But the speed issue - I'm not so sure. Michlet uses only underwater body for calculations. However in higher speeds trim can change so that kayak's stern is submerged deeper and bow can raise higher. Also wave can climb up the stern and thus make the waterline longer. So the calculated speeds might not be exactly right in real world.

If you are planing to build a new kayak, don't forgot your skills and usual paddling. If you tend to paddle at speeds 5-7 km/h do not look for the kayaks that have least resistance at 15 km/h. Remember to think if the kayak fit's to your paddling area - long and low kayaks might not to be so great in steep lake chop.

Comments, suggestions? Send an email:
toni(dot)vakiparta(at-mark)pp(dot)inet(dot)fi

Draft with 90 kg Load

Larger Image

Kayak and Waterline Properties

Total length and waterline length of kayaks. (90 kg displacement and chosen trim)

Larger Image

Total width and waterline width of kayaks. (90 kg displacement and chosen trim)

Larger Image

Waterline length / waterline width ratio.

Larger Image

Speeds in km/h

Each graph represent certain resistance value. Each kayak’s speed is shown at this resistance. Graph will tell how much faster or slower would a kayak go compared to other kayaks. I left only three images, but clicking will show speeds from 5-15 km/h in 1 km/h increments like before.

5 km/h 6 km/h 7 km/h

8 km/h 9 km/h 10 km/h 11 km/h 12 km/h

13 km/h 14 km/h 15 km/h

Speeds for Each Type

These graphs will give a bit more detailed information about speed.

Type I
Type II
Type III

Type IV
Type V
Type VI

Type VII, VIII
Type IX, mix
Type X, XI, XII

Stability

Stability of all kayaks.

Larger Image

Stability for Each Type

Tilt angle in X-axis, righting arm in Y-axis as metres.

Type I
Type II
Type III

Type IV
Type V
Type VI

Type VII, VIII
Type IX, mix
Type X, XI, XII (Note different scale for righting arm)

Non-Greenland kayaks

Here's some graphs from non-Greenland kayaks. Models have been made the same way like the Greenland ones. These kayaks do not affect on the average values or misc graphs. I included kog #8 and #77 to graphs for comparison.

Rec. Sea Kayak

Fiberglass round chine sea kayak. Waterline length about 16 feet and total beam 21 inch

Rec. Racing

Fiberglass training racing sea kayak. Waterline length about 16 feet and total beam 19 inch

Competition Sprint K1

This is true competition sprint k1 racing kayak. Waterline length about 17 feet and waterline beam about 14 inch. No stability data for this one.

MAE 593-76

Aleutian baidarka from 1845 Akun island. Created from David W. Zimmerly's survey 1975. Kayak length is 581cm (19 ft) and beam 43.4cm (17" 1/16). Waterline length is almost same as kayaks length and waterline beam is about 41cm (16").

Ainalik

Original built by Ainalik at Ivuyivik. Hudson Strait kayak of ca. 1959, from Dr. Eugene Arima's "Notes on the Kayak and its Equipment at Ivuyivik, P.Q." (1963). This kayak is 734cm in length (24 ft) and 63cm (25") width. I must say using 90 kg displacement is not fair for this kayak. I would guess this kayak is relatively much faster with more load. Harvey Golden has made a replica:
http://traditionalkayaks.com/Kayakreplicas/IVB767.html

S&G HV

This is a commercial high volume stitch&glue sea kayak. Length about 17 ft and width about 60cm (23").

Schulz F1

Skin-on-frame kayak designed by Brian Schulz. It's quite short - 430cm (14 ft) and 58cm (23") wide. Brian has made this design available at his web page:
http://www.capefalconkayak.com/f1.html

S&G 1 and 2

Commercial stitch&glue sea kayaks. S&G 1 is about 17 ft in length and about 53cm (21") in width. S&G 2 is about 18 ft in length and about 51cm (20") in width.

Waterline length / waterline beam of Non-Greenland Kayaks

Graph showing LWL / BWL ratio.

Larger image

Speed of Non-Greenland Kayaks

Graph showing speed vs average Greenland kayak speed.

Larger image

Stability of Non-Greenland Kayaks

Graph showing stability.

Larger image (Note different scale for righting arm)

Misc Graphs from Greenland Kayaks

Average speed for each types

Times visited after 11/2008

Type I	Type II	Type III
Type IV	Type V	Type VI
Type VII, VIII	Type IX, mix	Type X, XI, XII