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Published byMarion Wilkinson Modified over 7 years ago
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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
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Some Salty Terminology!
DECK Day Hatch Bow Hatch Bow Stern Cockpit Stern Hatch Toggle HULL Keel 2
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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
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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
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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
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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
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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
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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
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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
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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
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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
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The Fix: Float bags Fore and Aft
No Bulkheads The Fix: Float bags Fore and Aft Cockpit flooded! 12
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Float Bag Tips Tie them in place Do not over inflate
Check at the beginning and end of season 13
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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
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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
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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
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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
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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
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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
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(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
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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)
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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!
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The Right Boat - Creeks, Ponds
Short feet Manuverable Larger cockpit Durable - plastic Floatation – 2 bulkheads
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The Right Boat – Rivers, Bay
Longer ft Tracking/Speed Seaworthy – Smaller cockpit, Better spray skirt Designed for waves Floatation – bulkheads
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Is this the right boat for here?
Big water, small boat (12 ft), no spray skirt, no floatation = WRONG BOAT!
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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
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(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
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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
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Questions? 29
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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
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