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Message 5 of 5
Posted by member Peter Davies on Wednesday 5 June 2024

Thanks Kate. I follow the correct drills re refilling and vent closure that I adopted on my previous boat. So am reducing risks.
I intend to fit a bilge blower but it seems sensible to locate it in a position above the top of the fuel locker in order to ensure that petrol vapour does not leak past the fan.
If anyone thinks this is OTT I am interested. Also some Hardy Pilots have their tanks in the cockpit. Vapour could collect in rear bilge. Owner's view welcomed.
Pete D

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Message 4 of 5
Posted by member Kate on Wednesday 5 June 2024

Hi Peter,
I found the following information which is informative:

The vent on your fuel tank is necessary to prevent a vacuum block which would prevent fuel from being pumped from the tank to your motor. It needs to be open when operating your motor.

During storage, the vent must be kept closed to prevent evaporation and loss of your fuel as well as to prevent dangerous fumes from escaping, which could cause an explosion. This is especially true if your tank is stored in a locker or holding box. Petrol vapours are heavier than air and can collect in a closed locker. When the right mixture of fumes and air are present, any source of ignition can cause an explosion. With the right fuel air mixture, 1 gallon of petrol has the explosion power of 20 sticks of dynamite. Although it’s difficult to get the right fuel, air mixture, it’s not impossible, so always err on the side of safety.

Plastic fuel tanks are designed and built to allow for expansion and contraction. That’s why fuel should only be carried, transported and stored in containers certified for that purpose. Even petrol and diesel have different containers.

When you open the vent on an expanded tank, fuel vapours will escape. If the tank is sucked in, opening the vent will allow air into the tank to equalise the pressure. For safety reasons, opening the vent should be done off the boat on a level surface with good air circulation in the area and no ignition source present, even mobile phones. Some boats will have explosion proof exhaust fans to vent the area prior to starting the engines and others will have proper ventilation built into the locker design. If in doubt, take the tank off the boat to open the vent and make sure that there are no fuel fumes on the boat prior to starting the motor.

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Message 3 of 5
Posted by member Peter Davies on Tuesday 4 June 2024

Interesting. Our bilge pump is in port locker. Starboard fuel locker is vented but upwards! My confusion comes from our previous yacht. Outboard fuel tank was in cockpit locker. Safety examiner advised change in safety rules. But I was confused. Do I keep fuel line connected to engine and do I close breather? Can anyone give more understanding to use of petrol on a cruiser with outboard. There are many of them about.
Pete D

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Message 2 of 5
Posted by member Kate on Tuesday 4 June 2024

Our Pilot 20 has the port locker floor fibreglassed in and sealed and she was previously on the rivers with a BSC- assuming that port locker was for the fuel tank(?)
Our starboard locker has a removable base and a manual bilge pump within and our fuel tank sits in the recess under the outboard engine well.

I open the tank vent when using and then close of at all other times- it’s just what I learned years ago (hope I’ve not been doing it wrong all these years ????)

Hope that info helps.

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Message 1 of 5
Posted by member Peter Davies on Saturday 1 June 2024

My Pilot 20 has fuel tanks located in the starboard cockpit locker. As she had a safety certificate when I bought her I assume this location is fine. Comments please. Also is it preferable to leave the breather open when boat not in use? Comments please.
Pete D

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