Skin on frame: once upon a time all kayaks were skin on frame boats. The frame was made of driftwood and bone and the skin was actually skin, usually seal skin. SOF boats these days vary from home made ones using timber and polyurethane coated ballistic nylon, through to folding aluminium framed synthetic fabric skinned boats that fold up to fit in a backpack or golf bag. Just the thing for the jet-setting paddler.
SOF boats are usually very light. Home made ones can be constructed in a week or so for a few hundred dollars. They usually have no bulkheads or hatches so must be fitted with floatation bags and preferably a sea sock to minimise water ingress in a capsize. The traditional Greenland designs are narrow beamed boats with little freeboard and are very easy to roll. For paddlers with some skills these boats are an interesting proposition. However rescues and self rescues are more complex and these designs may not suit the absolute beginner.
Wooden core composite – Plywood, wood strip: These boats are also usually home built by enthusiasts. Timber is a superb core material for composite construction and these boats are usually light, strong and often are beautiful objects too. The build time for these varies from weeks to months for most home builders. There are a wide variety of designs to choose from.
Modern Composite Materials – Fibreglass, Carbon fibre, Kevlar: Fibreglass boats have been around a long time. They have some advantages over other construction methods. They are quicker to build on a commercial scale than wooden core boats. So are economically more viable. They are very rigid which means that the energy of the paddler is transferred very efficiently. The build quality varies greatly between manufacturers and the conditions they design the boats to withstand. They are usually lighter than traditional polyethylene boats and have a very smooth surface with little drag. They are however less impact resistant so if you like to play in the rock gardens or just haven’t learned those finer boat control skills, poly may be a better choice at first. Traditional fibreglass boats are easily repaired, but some modern materials while lighter and stronger can be difficult to repair.
Be wary of very light composite boats. Even with modern design and aeronautical vacuum bagging techniques, you still need enough material to make the boat strong enough to withstand surf landings on rocky beaches. There’s also a lot of experience required to get the best out of modern materials. Just because it says carbon fibre or Kevlar, it may not be as strong as you expect. Some designs are really barely disguised racing boats and while very light and very fast, they slow down rapidly once they’re in several jagged pieces.
HDPE: Modern HDPE construction methods are much better than the older ones. Boats with foam cores and welded in plastic bulkheads are available, these are stiffer, stronger and lighter than older single skin designs with foam bulkheads. Some manufacturers choose to use high molecular weight linear HDPE and use construction methods that make a stronger single skin boat than others. These boats are very tough too. The beauty of poly boats is their impact resistance. White water boats used to be fibreglass, now they are all poly. You can bounce them off rocks until the cows come home and you will rarely punch a hole in them. Experienced sea kayakers are coming back to poly designs to enjoy worry free play in rock gardens and surf, while often keeping a composite touring boat for longer trips. Poly boats should still be treated with care though as dragging them around on rough surfaces will roughen the surface or the hull resulting in greatly increased drag. Poly boats are also more difficult to customise as there are not many glues that will bond to the surface without some aggressive pre-treatment.
Thermoformed Plastic (Polycarbonate or ABS laminates): These are a newish type of construction. The material is light, impact resistant and has a smooth finish. These boats are becoming quite popular, particularly with people who have a high roof on the car. 17kg is a lot easier to lift on to the racks of your SUV than 23 kg. At this stage it’s too early to say how well these boats will last. Crash helmets are made out of very similar polymers and are pretty tough but they’re not made from a deck joined to a hull. Crack that seam in rough water and you’re in trouble. Good composite sea kayaks have the deck/hull joint taped on the outside and taped again on the inside making them very strong indeed. Time will tell how these boats compare.
In recent years, I have seen some thermoformed boats that are of similar weight to basic composite ones but the manufacturers marketing material still describes the boat as ultra light or light as a feather. So be aware that for all of these materials, the material is what it is, what the manufacturer does with it is important too. Don't believe everything you're told and ask around to see what other paddlers have. An acquaintance of mine says, "Cheap, strong, light; pick two ".
The following table gives a summary and typical price ranges for different materials.
| Material | Pros | Cons | Price Range |
| SOF | Light, can be packable. Cheap to build but commercial folders are dearer. | Need float bags and sea sock, not as rigid as composite designs. | $500-5000 |
| Composite | Strong, rigid, low drag, lighter than poly. Good Kevlar boats can be very light. | Can be holed although you have to work hard to hole Kevlar. | 2500-5500 |
| Thermoformed | Very light, impact resistant, smooth surface for low drag | Durability ? Not as rigid as composite. | $2000-5500 |
| HDPE | Very tough and impact resistant, better constructions can be nearly as stiff as composite boats. | Surface can be roughed up resulting in more drag. Harder to customise as glues are expensive. Bulkheads often aren’t completely water-tight. | $1500-3500 |
HULL SHAPE - or Swedish Fish aren't Neutral
What we’re talking about here is the shape of the boat as you look down on it from above. There are three types and you may have to look carefully to tell which some boats are, the difference is often quite subtle. All of these have their merits and you really need to paddle them to feel the difference. Below are some very general approximations and half truths. Not all comments will be true of all boats.
- Swede form: These boats have the widest part of the boat behind the centrepoint. In front of the cockpit they tend to be quite finely pointed. This allows a nice close entry for your forward stroke and lets you reach a little further forward on each stroke for increased efficiency. These boats tend to be fast.
- Fish form: These boats have the widest part of the boat in front of the centre. This is generally a better design if you want a playful and responsive hull with good manoeuvrability and good manners on a following sea. This is how fish are shaped and there are good reasons why.
- Neutral: A symmetrically balanced design of equal width front and rear.
KEEPING ON TRACK - THE SKEG VS RUDDER DEBATE
This is one of the most passionately debated topics on any sea-kayaking forum. There are also different paddling cultures in different parts of the world as the conditions vary and people tend to settle on a system that works for them in those conditions. As a bit of a stirrer, I confess to occasionally throwing a provocative “skeg or rudder” type comment into a forum and then sitting back for a couple of days of harmless entertainment as the fur and feathers fly.
Essentially, both of these systems do the same job. They help to keep the kayak tracking straight in windy conditions. Contrary to popular misconceptions, they are not really for turning and in close quarters manoeuvring, both of these gadgets tend to impede turning. So if that’s all they do, why the big brouhaha ?
Rudder fans point out that having a rudder deployed allows you to concentrate completely on your forward stroke, there is no need for correcting sweep strokes that break your rhythm and interfere with propelling the kayak forward as efficiently as possible. Rudders are found on all racing kayaks and ocean racing skis. If you’re doing marathon distances in straight lines, then a hard tracking boat with a rudder is going to do the job very efficiently. Rudders let you go hard and still change course to catch that next ride on a following sea.
I’m told that rudders are also more effective if you like sailing your kayak. This has been a popular addition to the paddling experience in Australia for many years and is gaining popularity overseas too. The over the stern flip down style of rudder was invented in Tasmania and most kayaks have some variant on this theme, although a few designs have build in integrated rudders which again offer advantages and disadvantages.
The proponents of the skeg argue that rudders are more complex, more prone to damage, inhibit paddling skills development, work against the shape of the hull for steering, make paddling backwards difficult and are downright dangerous during rough water rescues. I have personally lost significant amounts of skin to rudder related injuries and most of that was in fairly calm water self-rescue practice. But then I'm clumsy.
Skegs are simply a fin that drops down out of the hull of the kayak. They are adjustable and controlled by a single cable. They counteract the tendency of the stern to be blown downwind, (a phenomenon known as weathercocking where kayaks turn to face the wind). You can adjust the depth of the skeg to suit the wind strength and direction. You can then leave the skeg alone until the wind changes direction or you turn to a different course. In practice this lets you paddle on a hard track and concentrate on your forward stroke with very little interruption. The skeg is deployed further forward on the hull so it stays in the water doing its job, even when the boat is on a steep wave where a stern mounted rudder is hanging in fresh air. (Ocean racing skis have their rudder in much the same location as a skeg for the same reason). If you want to manoeuvre quickly or paddle backwards it is a matter of a second to raise the skeg.
Skegs work with the hull shape so paddlers learn to effectively steer and control their kayak by edging and leaning rather than relying on a rudder. Skegs are simpler than rudders with fewer components to break. There is no metal blade slashing around like a guillotine during rough water rescues. On the other hand skegs can be jammed by beach pebbles and landing with the skeg down can kink the cable preventing the skeg from going up or down.
So there are pros and cons for both. My personal preference is for skegs but this is largely due to my having two left feet and a tendency to overuse the rudder. For me skegs work better. I own both, but on my ruddered boat the rudder stays firmly on the back deck unless the wind gets right up at which point I tend to drop the rudder and then leave it alone unless absolutely required.
While rudders are preferred by many kayak sailors, skegs can also be used very effectively with a sail for directional control. A good understanding of how sails work and how the skeg works is required for best results though. You minimise edging and just raise and lower the skeg to fine tune your line.
