1. SK101 Sea Kayak Design Presented by Greg Welker
Written by Greg Welker copyright 2009
Modified with permission and presented by Robert Golden 2011 and Ralph Heimlich 2012
Presented by
Greg Welker 1

2. Some Salty Terminology!
DECK
Day Hatch
Bow Hatch
Bow
Stern
Cockpit
Stern Hatch
Toggle
HULL
Keel 2

3. Deck and Grab Lines Deck Lines = bungee Grab Lines = non stretch
Deck lines for spare paddle, paddle float
Deck lines for pump, water bottle
Spare Paddle
You need to check you lines at the beginning of the season and the end.
You are going to need the Grab lines to hold your kayak while doing a real recovery – which is likely at the most inconvenient time and will be drastically more inconvenient if you are left holding a bit of broken grab line as you kayak floats out of reach
Deck Lines = bungee
Grab Lines = non stretch
Grab lines for grabbing your boat 3

4. Kayak Dimensions Beam water Waterline Length Overall Length
Kayaks are advertised by their over all length. However the waterline length is something to consider as we see in the following slides
Beam, or the width, of a kayak is directly related to the stability of the kayak as well as an effect on the speed.
water
Waterline Length
Overall Length 4

5. Tastes Great! Less Filling!
Long narrow boats go faster
Surf skis, racing kayaks
Sea kayaks:
Light touring: feet long
24-26 incheswide
Short wide boats turn better.
White water kayaks, recreational kayaks
16-18 feet long
22-24 inches wide
There is no Perfect Kayak – Its about finding the balance that works for you and your preferences – As an example, on the one hand Surf skis up to 21’ in length an 17” beam are just plain fast – but they don’t have a lot of cargo space and are not ideal for a leisurely outing or trip up a winding creek
A 14’ recreational boat is ideal for nice leisurely outing – maybe not so much for open water and not for any real distances
Between the two there are sea kayaks – Designed to handle open water – cover reasonable distances – and carry gear 5

6. Speed vs. Maneuverability
A long straight keel line increases tracking (go straight)
The kayak on top maximizes its speed and tracking, with almost no rocker and a long waterline length – It is ideal for flat water trips from point a to point b – However, as condition change its assets shade to liabilities – Its going to want to follow the waves and surf, and if your not going that way then its going to be harder to correct – also it will want to punch through waves rather then ride over them
The bottom kayak gains maneuverability by having increased rocker by sacrificing some of its water line length – The increased rocker makes this kayak easier to correct in rough or confused seas – and will want to ride over waves rather then through them. On a flat water day the reduced waterline will be more apparent from the extra corrective stokes, that slow you down a little more
With a set of golf clubs you pick a different club for each need – a driver for a 300 yard slice in the woods or a putter to miss that 2 foot giveme and there are several clubs in between to chose from
A kayak you pick 1 to satisfy several requirements, making tradeoffs along the way
Increasing “ROCKER” increases the maneuverability 6

7. A wide kayak is most stable in flat water
Primary Stability
Initial Stability
Primary / Initial stability
The perceived stability of a kayak on flat water – the wider the kayak – the more primary stability it has
However – as shown primary stability is not a benefit in rough water as the kayak will want to follow with the waves
Primary stability and the beginning kayaker – think training wheels – at first primary stability feels so right – generally a beginner will chose a kayak because it feels safe – and why buy a kayak that you feel will roll over any minute – However, very quickly you will outgrow the training wheels – but its kind of hard to narrow a kayak down
A wide kayak is most stable in flat water 7

8. A narrower kayak will handle the waves better.
Secondary Stability
Secondary or Final stability describes how readily a boat capsizes
Because it is more likely to tip – its less likely to follow the wave action, and as shown above will handle waves better then a kayak with lots of primary stability
A boat can’t have both good initial stability and final stability — you trade away one for the other
Generally – the kayak width is a primary factor in determining stability along with the hull shape and even the center of gravity of the paddler
Finding the right balance –
You have to determine what is right and feels best for you – my own lesson learned – choose not by primary stability – look for what feels on the edge of your limits and learn to control it so you avoided the need to quickly get a second kayak “which will happen anyways but you can forestall it a bit ”
Secondary Stability
A narrower kayak will handle the waves better. 8

9. Bulkheads Internal Bulkheads
Displayed – a kayak with a day hatch – typically having 2 bulkheads in the stern and 1 in the bow
A kayak without a day hatch may have a single bow and single stern bulkhead
The compartments are not just for keeping you gear mostly dry – its about floatation 9

10. Your boat must float! After you have managed to fill it with water!
The Right Way
Kayak stays level when flooded
Cockpit Rim is above water level when paddler is sitting inside
WHY?
The worse case scenario
You are going to have to pump out the water in rough conditions. The cockpit, with the paddler sitting in it full of water, has to be above the water line to have any chance of success 10

11. Rear Bulkhead Only Bow floods Cleopatra’s Needle
What about kayaks with no bow bulkhead
Some come with a bit of closed cell foam to help float the bow – its not enough to depend on – in addition the foam is typical held in by a screw or glue – not exactly a durable solution
Cleopatra’s Needle – not a solo recovery – and not a quick assisted recovery either
Bow floods
Cleopatra’s Needle 11

12. The Fix: Float bags Fore and Aft
No Bulkheads
The Fix: Float bags Fore and Aft
Cockpit flooded! 12

13. Float Bag Tips Tie them in place Do not over inflate
Check at the beginning and end of season 13

14. Weathercocking Weathercocking Leecocking (Boat turns into wind)
(Boat turns away from wind)
Steer with rudder
Pull up skeg
Sweep stroke left side
Weathercocking
(Boat turns into wind)
Steer with rudder
Put down skeg
Sweep stroke right side
WIND
Other Causes:
Unbalanced loading
Too much stuff on deck
Skeg
LeeCocking - adjusting the skeg up reduces the sterns resistance to change balancing out the bows tendency to turn away from the wind
Weathercocking – Adjusting the skeg down increases the sterns resistance to change and correcting for the bows tendency to turn into the wind 14

15. Rudder Pros Allows more efficient stroke Low Maintenance Cons
Adds to Cost
Adds drag
No cowboy reentries!
Operation
Typically have line to raise or lower
Foot Peg
Slide foot peg forward to adjust
Have to maintain position
Gas Peddle
Adjust with toe movement 15

16. Skeg Pros Cons Operation No clutter on deck Jams
Hard Foot Braces
Tips for fixing jams –
a butter knife available in gear bag to dig out debris
Putting a small through hole through the skeg and tying a small loop of fishing line to poll the skeg out when jammed
Cons
Jams
Adds Drag
Takes up storage space
Operation
Line or slide to adjust depth
Amount of skeg exposed
sets correction for
current conditions 16

17. Skeg and Rudder!
If you cannot make up your mind there is a kayak with both 
Have always admired the rudder system seen on Epic kayaks – last 8 to 12 inches of the hull is the rudder 17

18. Cockpit Styles Open Easy In and Out Poor Skirt fit – wet
Poor paddler fit
Keyhole
Compromise
Ocean
Very secure fit
Excellent skirt fit
Hard to get in and out 18

19. Have a seat! Keyhole cockpit Legs bent Feet on pedals Thigh braces
Legs bent – it should be a natural and comfortable position since you will be there a while – However – you also what to have good contact with your kayak - moving your hips and lifting your knees are part of balancing and control of your kayak
Feet on pedals - if you have a kayak with a rudder and sliding foot pegs then you will want to make sure you have full range of motion to properly control you rudder
Thigh braces – you will want to adjust your self so you thighs are comfortable AND have solid contact with the thigh braces if your kayak has them
Problems with back pain or leg numbness can often be corrected with a roiled towel behind the legs or some other method of support 19

20. (lower than cockpit rim)
Seat and Padding
Thigh Braces
Seat
Hip Pads
Closed cell foam is often the choice of materials for making ones own seat and pads
Back Support
(lower than cockpit rim) 20

21. What’s That Boat Made Of ?
Cost
Plastic (Low) Carbon/Kevlar (High)
Durability
Cloth (Low) Plastic (High)
Weight
Carbon/Kevlar (Low) Plastic (High)
Repairability
Thermoform(Low) Wood (High)

22. GO TRY OUT A LOT OF BOATS ON THE WATER!
Advice to New Boat Buyers
“All Boats are Compromises”
Corollary: No boat is the “best” at everything
Old boats rarely wear out—BUY USED
Buy the “BIGGEST” boat you think you’ll ever need.
Most of us have several boats – boats for different uses
You can take a “BIG” boat on small water, but do you want to take a “small” boat on BIG water? Like buying a bicycle.
GO TRY OUT A LOT OF BOATS ON THE WATER!

23. The Right Boat - Creeks, Ponds
Short feet
Manuverable
Larger cockpit
Durable - plastic
Floatation – 2 bulkheads

24. The Right Boat – Rivers, Bay
Longer ft
Tracking/Speed
Seaworthy –
Smaller cockpit,
Better spray skirt
Designed for waves
Floatation – bulkheads

25. Is this the right boat for here?
Big water, small boat (12 ft), no spray skirt, no floatation = WRONG BOAT!

26. Hatches Stern Hatch Bow Hatch Day Hatch Bow and Stern Hatches
Day Hatch - Pros
Nice place to store gear you want to keep handy but dry.
Keeps decks from getting too cluttered with gear.
Additional floatation if the back hatch floods.
Cons
You have to turn around to use it – can be tippy!
Keeps you from putting heavy camping objects near center of boat.
Not accessible in rough seas. 26

27. (Valley Canoe Products/VCP)
Rubber Hatches
Soft plastic Type
(Valley Canoe Products/VCP)
(Kayak Sport)
Pros
Most Waterproof
Replacements widely
available.
Cons
Can throw spray
Not animal proof
UV degradation
Pros
Most Waterproof – Considered by many to have the best seal
Replacements widely available. – hatches not vendor specific
Cons
Can throw spray – since it is raised above the deck waves washing over will generate additional spray
Not animal proof – any good hungry varmint will make short work of the cover
UV degradation – exposure to the suns uv rays will dry out and break down the material – maintenance with 303 Protectant will prolong life 27

28. Hard Hatches Hard Plastic or Fibreglass (Current Designs) (Epic) Pros
Animal Proof
Reduced Spray
Larger Capacity
Cons
Unique to each boat
Not as waterproof
Pros
Animal Proof
Reduced Spray – flush with deck mounting reduces spray from wave over wash
Larger Capacity opening is typical larger then a VCP hatch
Cons
Unique to each boat – must be available from original manufacturer if replacement is needed
Not as waterproof – constant compression of seals reduces effectiveness 28

29. Questions? 29

30. Hull Cross Section Rounded Hard Chine Soft Chine Composite Hull Shapes
Chine defines the transition from the hulls vertical side to the hull bottom
Soft Chine – typically has less wetted surface, making the hull faster. It trades away primary stability for more secondary stability
Hard Chine increases the wetted surface thus increasing drag – However it increases primary stability and the edge(s) can assist in surfing and turning / maneuvering the kayak
Multi-Chine kayaks are trying to reach a compromise between the two.
Examples:
My kayak 24.5” beam has a excess of primary stability. It was designed with a soft chine to improve its speed and secondary stability
Another kayak I had pondered had a 22” beam – making it fast with high secondary stability – it was manufactured with a hard chine to improve its primary stability 30