Last article update: October 2nd, 2021 (10:59 pm)
If you want your inflatable boat performing at its best, you need to keep it inflated at the correct air pressure.
But as with many things in life, the answer isn’t simple.
Read this entire article to find out what the correct air pressure is for an inflatable boat, be it a dinghy, kayak, SUP or a pontoon boat.
Recommended air pressure for the different parts of an inflatable boat
The table below contains the average recommended air pressure for inflatable boats and SUPs. Mind you, these are averages. Be sure to read the rest of the article as well.
|Main tubes||1 – 3.5 PSI|
|Keel||4 – 4.5 PSI|
|6 – 11.5 PSI|
With that said, keep in mind that the recommended PSI for your dinghy, kayak or pontoon boat may vary slightly.
Read the instruction manual provided with your boat, or search google for the specifics of your inflatable.
When and how to adjust the air pressure of your boat
The air pumped turns into compressed air inside your boat’s tubes.
This compressed air is never at a constant PSI, it changes based on the:
- weather and air temperature
- and even water temperature
You may recall this from elementary science class:
- Cold decreases the PSI by decreasing the volume of the compressed air
- Heat increases the PSI by increasing the volume of the compressed air
Modern, quality inflatable water crafts are manufactured to be able to handle the effects of changing air pressure without noticeable effects. For now.
But over time, the lifespan of your boat might be affected.
Knowing when to adjust your air pressure is vital to keeping your inflatable boat at top performance. You will need to top off the air, or let some out as needed.
The effect of air temperature
The weather can change slowly over the course of the day, or dramatically over a shorter period.
Here are some tips on when to adjust the pressure in your tubes based on changes in weather:
- If you pump up your boat in the morning hours when the temperature is still cooler, you should account for the rising daytime temperatures. You can do one of 2 things to compensate. Either pump the boat to the lower range of the recommended PSI band and let the warmer temperature increase the PSI of your boat. Or my preferred method, let a bit of air out of our tubes as needed during the day.
- Vice versa, if you were at full PSI during the hottest hours of the day and the temperature starts cooling down in the afternoon, your boat’s air pressure might fall and you might need to top it off.
I always have a K-Pump Mini with me for this.
The effect of sunlight
The most dramatic change in the pressure of the compressed air in your inflatable watercraft will be as a result of direct sunlight.
- Direct sunlight can quickly heat up the air inside your tubes, causing over-inflation. You will need to let some air out if this happens.
- Vice versa, if it becomes cloudy after a day of sunshine, your air pressure will drop and you might need to top it off.
As I mentioned, strong sunlight can increase the air pressure in your chambers very quickly.
Be aware of this phenomenon, as it can quickly lead to over-inflation.
The effect of water temperature
Many people wonder why the pressure of their correctly inflated boat drops all the sudden, as they put the boat onto the water.
It is probably because the water is much colder than the air.
The cold water will lower the temperature of the compressed air inside your chambers, thus cause the PSI to drop.
You should always have a reliable hand pump in your boat to be able to top off the pressure as needed.
What happens if your boat’s PSI drops?
If the air pressure inside your inflatable boat’s chambers drops, you will feel like your boat is very hard to propel.
It feels sluggish when you paddle an inflatable kayak or dinghy with low air pressure, everything becomes harder.
On boats that are otherwise capable of planing on the water, planing might not be possible any longer.
Is a drop in air pressure dangerous?
It depends on the circumstances.
If you are out floating in your dinghy on a lake, than no. Your boat will become sluggish, but that in itself is not dangerous.
However, if you are in a whitewater raft or a kayak, not being able to propel and steer the boat efficiently might become dangerous.
What happens if your boat’s PSI increases?
As the air pressure in your boat’s tubes increases, the compressed air expands.
This will lead to over-inflation, which is a phenomenon that occurs when the actual air pressure in the tube is above the recommended air pressure.
What happens when you over-inflate a rubber balloon?
Just kidding 🙂
I’ve never seen an inflatable boat pop due to over-inflation alone, but I have seen what over-inflation can lead to.
Read on to find out.
Is an increase in air pressure dangerous?
Yes, it can be, depending on the circumstances.
Firstly, over-inflation can put extra stress on the seams of your boat, shortening its life span. You do not want your seams to ever fail, especially not when you’re out on the water.
Secondly, an over-inflated kayak or white water raft is prone to puncture when hitting a sharp rock in the water. Such a blow-out puncture will lead to the quick deflation of the given air chamber.
On a lighter note, check out how these guys over-inflate their boat:
What does a correctly inflated boat look and feel like?
When a tube is properly inflated, it is hard and has a bloated feel to it.
You can use what is known as the thumb deflection test to gauge the operating pressure as well.
Here is how:
- Place your thumb on the top center of the tube, and press down using just your thumb.
- It should depress about 1/2″ (1.2 cm).
- If you can’t press down that far, your boat may be over-inflated.
- Vice versa, if you can press down way further, your air pressure is still low.
Air pumps with pressure gauges
The foot pumps inflatable boats come with are very basic.
If you want to avoid overinflation/underinflation, and know exactly how much pressure is in your tubes when pumping, you should get a pump that has a pressure gauge.
Here are the ones I use, click for my reviews of each.