Inflation guide for your semi-rigid inflatable boat
Inflating the tubes of your RIB correctly is essential to preserve its performance, stability, safety and the lifespan of its tubes.
A properly inflated RIB has stiffer tubes and behaves more evenly on the water. On the other hand, under-inflation or over-inflation can affect how the boat handles and speed up wear on the fabric, bonds or valves.
But what pressure should you use? Should you inflate more on land? How does temperature affect pressure? Which pump and pressure gauge should you choose? And how do you know whether a tube is properly inflated?
In this complete guide, Orca Retail explains how to inflate a RIB, how to check its pressure and what precautions to take before going out.
What inflation pressure for a RIB?
The first rule is simple: the pressure recommended by your boat's manufacturer is always the reference. It can vary according to the model, tube diameter, material, number of compartments and design of the boat.
So there is no universal pressure that suits every inflatable boat. A value of 0.20 bar (200 mbar) is common on some models, but other RIBs or tenders may need a different pressure.
For example, some manufacturers' documents give values of around 0.19 to 0.25 bar for the main compartments. Highfield, for instance, gives a maximum pressure of 0.25 bar / 3.63 psi on some of its models, while some Zodiac manuals specify different pressures depending on the compartment and model.
So never choose a pressure just because it is "generally recommended" for a RIB: check the manual, the builder's plate or the markings on your boat.
Bar, mbar and psi: how do they compare?
Pressure gauges can show pressure in bar, millibar (mbar) or psi. Here are some useful conversions:
| Pressure | Approximate equivalent |
|---|---|
| 0.19 bar | 190 mbar / 2.76 psi |
| 0.20 bar | 200 mbar / 2.90 psi |
| 0.22 bar | 220 mbar / 3.19 psi |
| 0.24 bar | 240 mbar / 3.48 psi |
| 0.25 bar | 250 mbar / 3.63 psi |
These conversions help you read a pressure gauge correctly, but they are not pressure recommendations. The target pressure always depends on the model.
Where can you find the recommended pressure?
Depending on the boat, the information may be:
- in the owner's manual;
- on a plate or label on the boat;
- in the technical documents supplied with the boat;
- available from the dealer or the manufacturer's after-sales service.
If in doubt, it is better to ask the manufacturer for the exact value than to judge the pressure by feel.
You can, for example, check the information available from Zodiac Nautic, Zar Formenti or Highfield before inflating your boat.
How to inflate a RIB correctly?
Beyond the final pressure, the way you inflate matters. A RIB generally has several separate compartments so that it keeps reserve buoyancy if one of them has a problem.
For even inflation:
- Place the boat on a clean, clear surface.
- Check the condition of the valves and make sure they are in the right position.
- Identify the different compartments.
- Start inflating the compartments gradually, alternating between them.
- Avoid bringing one compartment straight to full pressure while the others are still completely deflated.
- Finish by checking with a pressure gauge once the compartments have taken their normal shape.
- Close the valve caps properly before launching.
This method spreads the stress on the internal baffles gradually and lets you check that each compartment behaves normally.
How does the outside temperature affect inflation?
Temperature is one of the main factors that can change the pressure in an inflatable tube. When the air in the compartment warms up, its pressure rises; when it cools down, it falls.
The change can become significant when the air or fabric temperature varies a lot during the day. Direct sunlight in particular can heat a tube strongly, especially a dark-coloured one.
As an order of magnitude, a change of around 3 to 4 mbar per degree Celsius can be seen in some configurations. The exact value, however, depends on the conditions and the boat.
It is therefore best to check the pressure when the boat is in conditions close to those you will be boating in, and above all to follow the manufacturer's instructions.
In strong sunshine, check the pressure regularly. Don't try to compensate in advance with an arbitrarily low pressure: an under-inflated tube can also lose handling and stability.
This is also why it is important to cover and protect your RIB when it is stored outdoors.
How does water temperature affect inflation?
Water temperature can also change the pressure measured in the tubes. If a boat has been inflated somewhere warm and then launched into much colder water, the air in the compartments can cool down and the pressure can drop.
The effect is especially noticeable when there is a big difference between the air temperature, the temperature of a tube exposed to the sun and the water temperature.
In some situations, you may therefore need to check the pressure again after launching. Here again, the right approach is to follow the pressure range recommended by the manufacturer rather than apply a universal rule.
How long does it take to inflate a RIB?
Inflation time depends directly on the size of the boat, the volume of the compartments and the type of pump used.
- Manual foot or hand pump: generally slower, but simple, self-contained and reliable.
- Electric pump: much more comfortable for a full inflation, especially on larger boats.
- Electric pump with pressure gauge and automatic stop: makes checking the pressure easier, as long as the pump's maximum pressure and operation are compatible with the boat.
Estimates of 15 to 25 minutes with a manual pump and 5 to 10 minutes with an electric pump can serve as an order of magnitude for some boats, but they vary widely with the volume of the boat and the actual flow rate of the pump.
Which pumps should you use to inflate a RIB?
Several types of pump can be suitable:
- Manual pump: light, inexpensive and reliable, it makes an excellent backup even if you normally use an electric pump.
- Electric pump: handy to save time and physical effort during a full inflation.
- Pump with built-in pressure gauge: particularly useful for checking the pressure without extra handling.
For regular use, we recommend keeping a manual pump on board as a backup, even if your main equipment is electric.
Warning: do not use a compressor or a compressed air cylinder without equipment specifically designed and suited to inflating the boat. A pressure rise that is too fast or uncontrolled can damage the compartments.
How do you check the inflation of the tubes?
The most reliable way is to use a pressure gauge compatible with your boat's valves. Checking by feel can give an indication, but it does not tell you the pressure precisely.
Without a gauge, a properly inflated tube should feel firm while keeping a slight give. The traditional rule of thumb, "hard under the thumb, soft under the knee", can give a general idea, but it is no substitute for measuring the pressure.
Signs of under-inflation
- excessive creases or deformation of the fabric;
- tubes that are visibly soft or not stiff enough;
- less precise handling;
- slapping or more movement in the waves;
- excessive deformation of the tube under load.
Signs of over-inflation
- tubes that are unusually hard;
- pressure above the recommended value;
- the pressure relief valve opening;
- an abnormal rise in pressure after strong sun exposure.
For greater accuracy, the best option is therefore to buy a pressure gauge. This inexpensive accessory can prevent inflation mistakes and lets you track the pressure from one outing to the next.
Which pressure gauge for a RIB?
The pressure gauge must be compatible with your boat's valve and pressure range. Models designed for low-pressure inflatables are generally graduated in bar, mbar and/or psi.
A pressure gauge is particularly useful if you want to:
- reproduce the recommended pressure exactly every time you go out;
- compare the pressure before and after launching;
- spot a gradual loss of pressure;
- check a boat exposed to large temperature changes.
If you notice the pressure dropping regularly between two checks, don't just keep topping it up: look for a possible leak at a valve, a join or an old repair.
What are the risks of over-inflating a RIB?
Over-inflation can put excessive stress on the fabric, joins, valves and bonds. Heat and direct sunlight can push this pressure up further.
Boats fitted with a pressure relief valve have extra protection, but this should not be seen as permission to exceed the recommended pressure.
An over-inflated tube can also absorb some impacts less effectively. On the other hand, an under-inflated tube can deform significantly and lose stiffness.
Good practice is therefore to follow the manufacturer's pressure and check it regularly, rather than trying to make the tube as stiff as possible.
If you notice a bonding or seam problem on a tube, also see our guide on seams coming unstuck on RIB tubes.
Why check the pressure relief valve?
The pressure relief valve fitted on some RIBs releases some of the excess pressure when it gets too high.
- If the valve hisses regularly, check the pressure with a gauge and look at the temperature conditions.
- If it leaks all the time, no longer works properly or shows signs of wear, it should be checked or replaced.
- Also check that the valve and its cap are clean and correctly fitted.
A pressure relief valve is a safety device, but it does not replace regular pressure checks.
Should you reinflate a RIB every time you go out?
You don't necessarily need to start from scratch every time, but checking the pressure before each outing is a good habit, especially if the boat has been stored for several days or the temperature has changed a lot.
If you go out very often, you will quickly learn your boat's usual pressure and be able to spot an abnormal loss.
After a long period of storage, always check the tubes, valves and any repairs before setting off again.
How do I know if my RIB is losing air?
A slow loss of pressure can be hard to see with the naked eye. If one compartment seems softer than the others, or you have to top it up regularly, look for the source of the leak.
The areas to inspect first are:
- the valves and their seals;
- old repairs and patches;
- the joins between different parts of the tube;
- areas exposed to heavy rubbing;
- any small holes in the fabric.
A leak can sometimes be found by applying soapy water to a suspect area: a steady stream of small bubbles can reveal an air leak. A major repair, or a leak in a structural area, should however be left to a professional.
7 mistakes to avoid when inflating a RIB
- Inflating without knowing the pressure recommended by the manufacturer.
- Relying only on feel instead of using a pressure gauge.
- Leaving a well-inflated boat in full sun without monitoring the pressure.
- Inflating one compartment fully while the others are still completely deflated.
- Using an unsuitable compressed air source or one without pressure control.
- Ignoring repeated pressure loss and just topping up.
- Forgetting the backup pump on a trip far from shore.
FAQ: RIB inflation and pressure
What pressure should you put in a RIB?
There is no universal pressure. A value of 0.20 bar is common on some models, but the recommended pressure depends on the boat. Always follow the value given by the manufacturer.
How many psi for a RIB tube?
0.20 bar is about 2.90 psi. But if your manufacturer recommends 0.19, 0.22, 0.24 or 0.25 bar, the conversion will be different. Use the pressure specified for your model.
How do you inflate a Zodiac RIB?
Use a pump and nozzle compatible with the boat's valves, inflate the compartments gradually and check the pressure with a gauge. Zodiac models can have different pressures depending on their design: the manual for your model is the reference.
Should you under-inflate a RIB in summer?
You should not apply a general rule of under-inflating the boat in summer. Pressure rises when the air in the tubes warms up. The right approach is to follow the recommended pressure and check the boat, taking into account temperature changes and sun exposure.
Why does the pressure drop when I put my boat in the water?
If the water is colder than the air or than a tube warmed by the sun, the air in the compartments cools down and the pressure can drop. A check after launching may therefore be needed when the temperature difference is large.
Which pressure gauge should you use for an inflatable boat?
Choose a gauge compatible with your boat's valve and with a measuring range suited to the low pressures of the tubes. A model showing bar and/or psi is particularly practical.
How often should you check the pressure?
Checking before each outing is good practice, especially after a period of storage or when the temperature has changed a lot. Repeated loss of pressure should lead you to look for a leak.
Valves and parts for your tubes
- CEREDI NEWTON inflation valve: replacement valve for tubes
- CEREDI TWIST inflation valve: screw-in valve for tubes
- CEREDI pressure relief valve: prevents over-pressure when the tube heats up in the sun
- All inflation and pressure relief valves
- Neoprene glue + hardener kit: everything you need to glue a patch onto Hypalon
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