Have you ever gotten (is that even a word?) cocky while puttering around in your kayak, only to come to a screeching halt on a sandbank or pile of rocks?
Or, have you ever considered working some bait over a particular stretch of river, but worried about whether the water was too shallow to support your kayak? Then you didn’t.
In this article, we discuss how to kayak in shallow water. For those kayak anglers in the mix, we also discuss how one particular pedal-kayak handles shallows with ease.
To kayak in shallow water, ensure the water depth is at least 5 inches. Calculate the depth at which your kayak will sit using the equation below (2-3 inches). Paddle harder to make up for the downward suction from squeezed water between the hull and bottom. Use a paddle you don’t love, or consider the Hobie MirageDrive.
**PaddleGeek.com is reader-supported. I may earn a commission for purchases made through links in this post.**
Table of Contents
How much of your kayak floats below the waterline?
The simple answer is that you don’t need a lot of water to paddle a kayak. 5” is usually quite sufficient for a non-pedal kayak to happily putter around without running aground.
There are several elements that combine to determine how much of your boat floats below the waterline.
Waterline length
Your kayak’s water line length (LWL for short) is the length of your boat at the level where it sits in the water. The overall length of your kayak is longer, but the LWL is the portion that sits at water level.
In simple terms, the longer the LWL, the more weight a kayak can hold without sinking.
Beam
The beam measures the width of your kayak.
The ‘waterline beam’ (BWL) measures the maximum width at the waterline. Simply, the ‘beam’ measures the widest part of the boat.
Depending on the design of the kayak, it is conceivable that a design focused on primary stability could see the widest portion of its hull at the water level.
The wider the waterline beam (BWL), the more weight a kayak can hold without sinking.
Water density
Saltwater is incrementally more dense than freshwater. This means that your kayak won’t sink quite as far down in saltwater as it will in freshwater.
For fun, the water density of saltwater is 65lb/ft3, whereas the water density of freshwater is 62.4lb/ft3.
Hull shape
The shape of the hull, be it rounded, v-shaped, flat or pontoon does have an impact on how far down your kayak sits in the water.
Similarly, the chine, be it rounded or hard, as well as the rocker, also impact your kayak’s buoyancy.
However, these hull shape considerations actually have more impact on speed, stability and maneuverability than the depth at which your kayak sits in the water.
Block coefficient
This is the ratio of the underwater volume of your kayak to the volume of a rectangular block, expressed as a decimal. Without getting deep into the technical weeds, it’s common to use a number between 0.60 – 0.65.
Calculating how much of your kayak sits under the water
Here is a simple equation for you to determine how much of your kayak will sit underwater.
LWL x BWL x Weight x Water Density x Block Coefficient = Sinkage
Let’s consider the following example of a recreational kayak setup:
Kayak waterline length (LWL) = 10’
Kayak waterline beam (BWL) = 2’
Weight (kayak, paddler and gear) = 250lbs
Paddling on freshwater.
10 x 2 x 250 x 62.4 x 0.64 = 0.308 feet <or> 3.7 inches (0.308/12).
Under this scenario (without taking into account the exact hull shape), this kayak can be expected to sit about 3.7 inches under the waterline.
Let’s consider another example of a fishing kayak. As we know, fishing kayaks are typically heavier and wider than recreational and touring kayaks.
Kayak waterline length (LWL) = 11’
Kayak waterline beam (BWL) = 2.85’
Weight (kayak, paddler, gear) = 360lbs
Paddling on freshwater.
11 x 2.85 x 360 x 62.4 x 0.65 = 0.283 feet <or> 3.39 inches ( 0.283/12).
So, even though the fishing kayak plus gear is significantly heavier than the recreational kayak above, because its waterline length is longer and waterline beam is wider, it can be expected to sit slightly higher in the water than the recreational kayak.
Remember that this is an equation on paper (or screen). In the real world, your kayak might sit higher or lower than what we calculated above as well as what you might calculate on your own.
Nevertheless, as they say, in the land of the blind, its good to have one eye.
So, why do kayaks need at least 5” of water underneath them?
Many long, wide kayaks with lightweight paddlers can operate on less than 5” of water.
However, in a previous article, we calculated that the average kayak weighs 63.2lbs, is 12.47’ long and 30.5” wide.
If we reduce these dimensions to get to LWL = 11, BWL = 2, Weight = 250 lbs (paddler: 175 lbs, kayak: 63 lbs, gear: 12lbs), that results in 3.33 inches of expected inches floating below the waterline.
The bottom of the average kayak can be expected to sit 3.33 inches below the waterline.
When I suggest 5” of water, that simply allows for a slight margin of error that always exists when you take esoteric equations and apply them to real life.
How do current and waves impact a kayak in shallow water?
Difference between waves in deep water and shallow water
Waves are more troublesome in shallow water.
When the depth of water beneath your hull is less than about half the length of your boat, the fundamental character of the waves around it begins to change.
The speed of a wave is a function of the depth of the water, the wavelength, plus a few constants.
When water is deep and greater than the wavelength, the speed of the wave is principally determined by its wavelength.
However, when water is very shallow, the speed of the wave has nothing to do with the wave’s wavelength and everything to do with the depth of the water (and little bit to do with the gravitational constant.)
The real world effect of this esoteric nugget of knowledge is that shallow water becomes much more difficult to paddle in. As you paddle harder, you create force that tries to make the water move faster than it wants to.
The result is wave resistance.
When the water below your kayak is a mere 2”, the wave resistance that you meet when trying to paddle your kayak is significant.
Shallow water and downward suction
Another challenge with kayaking in shallow water is the suction that occurs when the water beneath your kayak hull becomes squeezed between the bottom of your boat and the bottom of the body of water.
This is a real-world example of Bernoulli’s Principle, but it happens under water instead of in the air.
The water underneath and around the kayak hull accelerates. This results in a downward force on the hull, the impact of which is compared to the paddler suddenly gaining weight.
Clearly, as you negotiate shallow water, forces that are different than those found in deeper water combine to make paddling challenging – requiring more physical exertion.
(If you really nerd out on this kind of stuff and want an in-depth treatment of the principals and the math from a fellow with a PhD, then regale yourself with Shawn Burke’s work here.)
How to use a kayak paddle in shallow water
If your intent is to spend the day in shallow water characterized by a rocky bottom strewn with other assorted ‘treats’, don’t bring your performance paddle. Unless, of course, your plan is to engage in some performance paddling.
Using your paddle as a wizard staff
Here’s the thing, in shallow water with a rocky bottom, you will spend just as much time pushing off rocks and debris as you do paddling – if not more.
Your paddle will become a wizard staff.
“You shall not pass!” Thanks Gandalf.
In other words, while bobbing around in the shallows, that paddle will become a veritable multi-tool. At the end of the day, it will get chipped, scraped and scratched. Hopefully it will still be in once piece, but maybe not.
So, unless you are h*ll-bent on hitting a run of rapids that requires a performance paddle to keep you safe, leave the $300 Werner at home and bring the $75 whatever-is-left-over-in-the-garage paddle instead.
Shallow paddle strokes
While it’s likely not even necessary to highlight the fact that your strokes need to look different in shallow water, I’ll say it anyway.
If it hasn’t occurred to you that shallow water doesn’t allow for deep kayak strokes, you will be quickly reminded by the very ground that doesn’t allow it.
Paddle strokes that are as shallow as the water in which you’re paddling are necessary to propel your kayak forward (or backward).
The bad news is that shallow paddle strokes are slower because you can’t insert as much paddle blade in the water.
The good news is that shallow paddle strokes are drier because the shaft remains more horizontal, keeping the dripping paddle blade from soaking your head.
Should you be planning on spending a significant amount of time in shallow water, you’ll might benefit from learning how to select the right paddle for the job.
How to use your (Hobie MirageDrive) pedal kayak to fish in shallow water
If you are an angler that enjoys fishing from a kayak then this could be of interest.
A great many fishing kayaks are pedal-driven. This pedal mechanism frees up an extra hand fish.
Conventional thought has typically been that a fishing kayak equipped with a pedal drive can’t operate in shallow water.
In some cases this is correct, pedals drives that spin propellers aren’t usually appropriate for shallow-water fishing.
However, the Hobie Mirage (Pedal) Drive is different.
(My intent was never to make this article into a Hobie commercial. However, their technology is so compelling, yet mis-understood as it pertains to shallow water, that I felt it worthy of some real estate.)
Fins tuck up against hull
This pedal drive is equipped with fins that sit beneath the hull of the kayak and propel it forward as the angler presses the pedals.
If water becomes particularly shallow, one of the pedals can be pushed forward and held. This motion serves to tuck the fins up against the kayak hull until the super-skinny water has passed.
If the water remains shallow for awhile, then the pedals can be ‘feathered’ while still in the forward position, providing propulsion from the fins while remaining tucked up against the hull.
Kickup feature
If the fins are down but happen to impact a rogue rock or other obstacle, the kick-up feature literally kicks the fins up to avoid damage.
When the kayak is clear of the obstacle, the fins redeploy, continuing to propel the kayak.
Easy drive removal
If you are zeroing in on a particular location and its shallow, the MirageDrive lifts right out of the bottom of the kayak in a couple of seconds.
This will give you all the clearance that you need under your boat and not require you to hold a pedal forward to keep the fins tucked against the hull.
Use that crappy shallow-water back-up paddle you brought to position your kayak for that perfect cast.
When its time to depart, take another two seconds to re-engage the drive mechanism and be on your way.
Again, in the interest of being comprehensive (and at the risk of this looking like a commercial, which it isn’t), Hobie manufactures a forward-only model (MirageDrive GT), a forward and reversing model (MirageDrive 180) and a full-circle navigation model (MirageDrive 360).
If you have a Hobie kayak and are curious about the MirageDrive GT, check it out on Amazon here. (For clarity, this is an affiliate link.) And by the way, it’s about as expensive as a cheap kayak.
Kayaking in shallow water – Parting Thoughts
In summary, the average kayak requires at least 5” of water to sit and operate without grounding. I strategically jammed a few numbers together to explain why.
However, shallow water creates other paddling difficulties that simply make it harder to move around. You still can, it’s just harder.
If you are a kayak angler that enjoys a good pedal-drive, Hobie manufactures the MirageDrive that actually executes in shallow water very well, leaving your hands free to reel in that whopper. (The bass, not the burger. And certainly not a bass burger. Gross!)