Elements of Hull Design for Small Watercraft

 

 

 

 

 

Hull Design Primer for Single or Double Paddle

Here is a very brief overview of elements involved in hull design for paddling with a canoe or kayak paddle. Boat design and construction is a delicate balancing act influenced and often dictated by the essential laws of physics and finances.

In order to extract performance in one area, performance in another area will have to be sacrificed. Each element implies a specific behavior and often these features conflict with each other. In all cases, when it comes to selecting a boat, the ideal solution is a design that will meet a majority of your needs most of the time. No boat can successfully meet all your requirements all the time. When your requirements change, you would do well to consider a different solution.

“You can never have too many boats,” my buddy Chris once noted. There’s plenty of truth to that statement, especially if you enjoy boating on a variety of levels.

I enjoy whitewater paddling however my designs are not suited for whitewater. I don't take my boats down fast, rocky rivers. I have no qualms about renting the right canoe for when I’m going whitewater which I don't do often. A majority of my paddling consists of throwing a boat on the truck after work and taking a quick paddle after work. My next priority is camping so I want my boats to hold a comfortable amount of gear.

The fact you're considering a canoe or kayak means you've already settled on some variables. Ideally it will be light and portable, yet strong and some what seaworthy; it must be of the smallest dimensions possible to good paddling and possibly sailing qualities yet roomy enough to serve as transportation for you and all your gear.

There are many scientific principles and esthetic variables to canoe and kayak design that I won't go into much detail here. However understanding some fundamental design elements affecting a boats performance can help you narrow the range of alternatives. This outline applies primarily to canoes and kayaks.

Kanoe or Cayak?
There are so many hybrid hulls on the market today that the features historically distinguishing a canoe from a kayak blur. A common example are the short fat kayaks often called play boats. In my humble opinion their only benefits include stability and low price. They aren't particularly light, they don't look fast and they can't hold much.

Canoes generally refer to wide stable, double-ended, open boats allowing easy entry and exit of people and gear. Seats in a canoe tend to be elevated off the floor. They are ideal for inland lakes and rivers. Kayaks tend to be long narrow decked boats with a cockpit one sits in and are ideally suited for large open water, big waves and wind. In a kayak, one sits very close to the floor.

Large wilderness tripping canoes hold lots of gear and expedition kayaks will do the same. Racing canoes in the Olympics look like open kayaks and there are wide open kayaks with tiny decks which look more like canoes. There are decked canoes used for sailing and you sit on the floor to paddle it with a double blade paddle, and un-decked kayaks so you can tan your legs.

A Broad Distinction
In the BWCA (the Boundary Waters Canoe Area), where I expect to load and unload gear frequently for portaging my preference is a canoe. In the big water like Lake Superior, I feel safer in a kayak. Portaging a kayak is difficult because gear is packed in small sacks to fit through the hatch. It’s also difficult to see the trail ahead of you with your head in a kayak cockpit. A special portage yolk is needed here but the problem of many small sacks of gear remain. Kayaks are ideal for camping in situations like big water which have potential for large wave action due to wind or where you plan to go long distances but stay at one camp site. Campsites on Saganaga at the end of the Gunflint Trail, Voyager's National Park and anywhere on the Great Lakes qualify. I keep a slender ultra light kayak for a really quick paddle.

Canoes are generally wider than kayaks. People sit elevated above the floor in canoes, much less so in kayaks. Sitting higher increases the center of gravity and to compensate a canoe is necessarily wider. The added width allows increased stability in a canoe where the paddler’s center of gravity is significantly higher than someone sitting in a kayak. The wider hull has more surface compared to a slender hull of the same length. More surface area translates to added resistance and means either a slower boat or one that requires more work to go faster.

Both canoe and kayak are ideal for occasional or frequent use. For many day trips, I take the wood kayak; it’s fast, responsive and lighter than my Kevlar tandem canoe. My composite wood solo canoe is ideal for BWCA trips where there is one more person in the party than seats in available tandem canoes. It’s fast enough to keep up with the longer boats, especially when using the kayak double paddle. It is much easier to portage and fish out of than a kayak in the BWCA.

It’s a matter of preference and where you expect to paddle most often. Regardless, I prefer a lighter boat than a heavier boat, if for no other reason than it is easier to get on and off the car myself. The lightweight wood boats I build will generally weigh significantly less than a fiberglass or aluminum model. This doesn't apply however to wood tandem canoes which may weigh less but not so much that I would brag about it. The joy of a lightweight boat is that it’s more likely to get used because carrying it to and from the car is not such an issue.

Tandem or Solo?
If you only plan to paddle with two people all the time and your budget is small then a tandem, which holds two will suffice. Larger tandems are ideal for small families as children and pets can sit in the middle and they hold plenty of gear for extended wilderness trips. Tandems are ideal where one paddler is less experienced than the other. A small tandem which can be paddled solo is a fair compromise for occasional use by one or two people, but it's not good for two adults on an extended trip with lots of gear.

If the budget allows, always consider two solo boats for two people. My experience has been that many couples buy a tandem boat fully expecting both to use it. More often than not, one person wants to paddle more frequently and a partner is not always available so the tandem boat is used infrequently. This applies to canoes and kayaks.

Solo boats give owners the freedom to paddle whenever one wants. Two solo boats give each person a degree of freedom and control on the water unmatched in a tandem. Frustration between paddlers evaporates. Given a crew of paddlers in the BWCA with mixed tandems and solo boats, the solo boats will be in the highest demand. Once other paddlers try the solo it’s difficult to get it back. Finally, you can't pull alongside your sweetie and give him or her a kiss in a tandem. If your honey doesn't rate a kiss you'll be glad you have solos.

General Rules of Thumb
The joy of a boat is inversely proportional to size.
It starts declining at the point you can't carry it in one hand and a paddle in the other and continues to decline until your docking fee rivals your mortgage
Large boats typically hold more than a small boats
Wider boats will be more stable than narrower boats of a given length
Less experienced paddlers will feel safer in a stable boat
Experienced paddlers tend to prefer a faster boat
Longer boats will be faster than shorter boats of a given beam or width
Decked boats take on less water in rough conditions than un-decked boat
Bigger boats,require more material and weigh more
Lighter boats are easier to carry than heavy boats
Given the same design, sturdy construction will withstand more punishment than lightweight construction.

Historically canoes and kayaks have been measured by length, width and center depth, so we will start with these basic dimensions.

Design Page, continued. .