Fuel tank inspection hatch - best design practice

[TandC]

What ho.  

 

My new boat is still unpainted and being fitted.   It has an integral fuel tank to the stern as per below - you can just see the filler cap in this ropey picture.

 

It does not have a tank inspection hatch, and I am now wondering whether this is an oversight... and while it's still unpainted, now would be time to cut a hole, do any welding etc.

 

Is it necessary first?  The filler cap is directly over the tank allowing me to pump out fuel for polishing etc - but its small. 

 

I obviously don't want to create another maintenance headache or something that will leak water into the fuel tank... 

 

What's the right size for an inspection hatch?  I surely needs to be big enough to be worth bothering with otherwise may as well just rely on the filler....  

 

Does anyone have a "good design" idea that they could share some photos of? 

 

 

 

 

 

 

 

 

Edited April 23 by TandC

[pearley]

We don't have a hatch on the propulsion tank but we do on the generator one as the fill pipe is offset.

 

Our hatch is about 10" x 5" with 2 hinges on one edge with the other secured by 2 M10 countersunk screws with a nitrile rubber seal under.

[Tonka]

27 minutes ago, pearley said:

We don't have a hatch on the propulsion tank but we do on the generator one as the fill pipe is offset.

 

Our hatch is about 10" x 5" with 2 hinges on one edge with the other secured by 2 M10 countersunk screws with a nitrile rubber seal under.

Can I ask how often do you use the inspection hatch

[Alan de Enfield]

The requirements for installation of a fuel system on a boat with fixed fuel tanks are given in the harmonised standard BS EN ISO 10088 Permanently installed fuel systems and BS EN ISO 21487:2012 Small craft - Permanently installed petrol and diesel fuel tanks.

The requirement for petrol fuel tanks to be ‘insulated from the engine and all other sources of ignition’ is deemed to be complied with if

a) the clearance between the petrol tank and the engine is greater than 100 mm and

b) all electrical parts on the engine which could create a spark, and any other electrical components in the engine/fuel compartment, are ignition protected. To ensure that these components are ignition protected the boat builder should use a petrol engine that complies with BS EN ISO 15584 Inboard petrol engines - fuel and electrical system components (the engine manufacture should provide this confirmation) and for other parts, e.g. blower fan or electric bilge pump, use only components that have been CE marked in accordance with Annex II 1. The clearance between a petrol tank and any dry exhaust components must be greater than 250 mm, unless an equivalent thermal barrier is provided. For diesel engine installations, the engines used should comply with BS EN ISO 16147

Inboard diesel engines – Engine-mounted fuel and electrical components to ensure that the fuel components fitted on the engine by the engine manufacturer are safe. The engine manufacture should provide confirmation that the engine complies with this standard.

Fuel hose used in the system must be fire resistant if used in the engine compartment and Where fuel hose is used the standard requires that only fire-resistant hose to BS EN ISO 7840 may be used in the engine compartment. Such hose should be stamped to indicate compliance

 

 

This appears to be a requirement in  BS EN ISO 21487:2012

 

If there is a drain in a diesel oil tank, it shall be fitted with a shut-off valve having a plug that can be removed only with tools.

Each tank shall have an inspection hatch of at least 150 mm diameter. The inspection hatch shall, as a rule, be located on top of the tank, but for diesel oil tanks it may also be on the tank side. There shall be access to the inspection hatch when the tank is in position.

 

[IanD]

45 minutes ago, Alan de Enfield said:

The requirements for installation of a fuel system on a boat with fixed fuel tanks are given in the harmonised standard BS EN ISO 10088 Permanently installed fuel systems and BS EN ISO 21487:2012 Small craft - Permanently installed petrol and diesel fuel tanks.

[snip]

 

This appears to be a requirement in  BS EN ISO 21487:2012

 

If there is a drain in a diesel oil tank, it shall be fitted with a shut-off valve having a plug that can be removed only with tools.

Each tank shall have an inspection hatch of at least 150 mm diameter. The inspection hatch shall, as a rule, be located on top of the tank, but for diesel oil tanks it may also be on the tank side. There shall be access to the inspection hatch when the tank is in position.

 

I wonder how many narrowboats with integral fuel tanks have such an inspection hatch? AFAIK mine doesn't -- but then it doesn't have a "diesel engine" as such, only a generator... 😉

[pearley]

1 hour ago, Tonka said:

Can I ask how often do you use the inspection hatch

Maybe twice a year to check for water and level.

[blackrose]

Mine doesn't have an inspection hatch. As the OP says, one downside of any external hatch is that it may actually increase the risk of leaks and water getting into the tank which sort of defeats the purpose of a installing a maintenance hatch in the first place.

[pearley]

1 minute ago, blackrose said:

Mine doesn't have an inspection hatch. As the OP says, one downside of any external hatch is that it may actually increase the risk of leaks and water getting into the tank which sort of defeats the purpose of a installing a maintenance hatch in the first place.

Ours is on an internal tank. I have to lift a floorboards to access it.

[blackrose]

11 minutes ago, pearley said:

Ours is on an internal tank. I have to lift a floorboards to access it.

 

Then the risk I highlighted obviously doesn't apply to you.

 

My boat is coming up for 20 years old and touch wood I've never had a problem with fuel contamination. I've dipped the tank a couple of times with a clear tube but there's nothing untoward I can see at the bottom of the column of fuel. So for me the fuel tank is basically "fit and forget", except that I didn't fit it of course!

 

If you do need to clean your tank then a hatch is obviously invaluable - but it must be large enough to gain full access otherwise it's a complete waste of time. On the other hand like the vast majority of canal boats, you may never actually have to clean the inside of your tank .

Edited April 23 by blackrose

[pearley]

I dip mine with water finding paste. Never had any in the propulsion tank but the internal generator tank had around 30 litres in due to poor installation of the filler. Removed by Pela pump.

[GUMPY]

 Never had an inspection hatch on any of my boats but have always had a decent drain at the lowest point of the tanks.

Never had much water in the tanks either. Maybe pint or so in 30 years.

[TandC]

So what do you actually use the hatch for, that you can't do with a straight-down filler neck?  I can dip the tank to the bottom - and that the filler is located close to the stern it is probably not far off at the lowest point. 

 

I'm still not convinced it's worth the faff - especially on a widebeam 10ft where you'd need go-go-gadget arms to be able to reach all areas within the bottom of the tank (i'm thinking that what - you may need to extract all the fuel, and maybe hoover out any infected gunk, etc?  What are you actually DOING through that hatch that makes it so useful?)

 

 

Thanks for the BS extract Alan - that's interesting, although I note that the vast majority of boats don't seem to have one...  is it another one of those where depends on what standards your applying for your RCD compliance etc? 

 

 

 

Edited April 23 by TandC

[ditchcrawler]

3 hours ago, Alan de Enfield said:

The requirements for installation of a fuel system on a boat with fixed fuel tanks are given in the harmonised standard BS EN ISO 10088 Permanently installed fuel systems and BS EN ISO 21487:2012 Small craft - Permanently installed petrol and diesel fuel tanks.

The requirement for petrol fuel tanks to be ‘insulated from the engine and all other sources of ignition’ is deemed to be complied with if

a) the clearance between the petrol tank and the engine is greater than 100 mm and

b) all electrical parts on the engine which could create a spark, and any other electrical components in the engine/fuel compartment, are ignition protected. To ensure that these components are ignition protected the boat builder should use a petrol engine that complies with BS EN ISO 15584 Inboard petrol engines - fuel and electrical system components (the engine manufacture should provide this confirmation) and for other parts, e.g. blower fan or electric bilge pump, use only components that have been CE marked in accordance with Annex II 1. The clearance between a petrol tank and any dry exhaust components must be greater than 250 mm, unless an equivalent thermal barrier is provided. For diesel engine installations, the engines used should comply with BS EN ISO 16147

Inboard diesel engines – Engine-mounted fuel and electrical components to ensure that the fuel components fitted on the engine by the engine manufacturer are safe. The engine manufacture should provide confirmation that the engine complies with this standard.

Fuel hose used in the system must be fire resistant if used in the engine compartment and Where fuel hose is used the standard requires that only fire-resistant hose to BS EN ISO 7840 may be used in the engine compartment. Such hose should be stamped to indicate compliance

 

 

This appears to be a requirement in  BS EN ISO 21487:2012

 

If there is a drain in a diesel oil tank, it shall be fitted with a shut-off valve having a plug that can be removed only with tools.

Each tank shall have an inspection hatch of at least 150 mm diameter. The inspection hatch shall, as a rule, be located on top of the tank, but for diesel oil tanks it may also be on the tank side. There shall be access to the inspection hatch when the tank is in position.

 

I just knew you would post that. All this about RCD on self fit outs 

[GUMPY]

Don't forget the fuel tank needs pressure testing and having a hatch that will need a good seal is going to make this more difficult.

[IanD]

59 minutes ago, TandC said:

So what do you actually use the hatch for, that you can't do with a straight-down filler neck?  I can dip the tank to the bottom - and that the filler is located close to the stern it is probably not far off at the lowest point. 

 

I'm still not convinced it's worth the faff - especially on a widebeam 10ft where you'd need go-go-gadget arms to be able to reach all areas within the bottom of the tank (i'm thinking that what - you may need to extract all the fuel, and maybe hoover out any infected gunk, etc?  What are you actually DOING through that hatch that makes it so useful?)

 

Thanks for the BS extract Alan - that's interesting, although I note that the vast majority of boats don't seem to have one...  is it another one of those where depends on what standards your applying for your RCD compliance etc? 

 

 

Including mine, and many others I've been on. Does that mean they're all illegal, or is the inspection hatch not actually required? I know which I think is more likely... 😉 

[blackrose]

14 hours ago, IanD said:

 

 Does that mean they're all illegal, or is the inspection hatch not actually required?

 

Both... probably 

[IanD]

52 minutes ago, blackrose said:

 

Both... probably 

Schrodinger's inspection hatch, then... 😉 

 

Methinks there are also two possible meanings for the acronym in "Thanks for the BS extract Alan"... 🙂 

[Tacet]

21 hours ago, Alan de Enfield said:

The requirements for installation of a fuel system on a boat with fixed fuel tanks are given in the harmonised standard BS EN ISO 10088 Permanently installed fuel systems and BS EN ISO 21487:2012 Small craft - Permanently installed petrol and diesel fuel tanks.

The requirement for petrol fuel tanks to be ‘insulated from the engine and all other sources of ignition’ is deemed to be complied with if

a) the clearance between the petrol tank and the engine is greater than 100 mm and

b) all electrical parts on the engine which could create a spark, and any other electrical components in the engine/fuel compartment, are ignition protected. To ensure that these components are ignition protected the boat builder should use a petrol engine that complies with BS EN ISO 15584 Inboard petrol engines - fuel and electrical system components (the engine manufacture should provide this confirmation) and for other parts, e.g. blower fan or electric bilge pump, use only components that have been CE marked in accordance with Annex II 1. The clearance between a petrol tank and any dry exhaust components must be greater than 250 mm, unless an equivalent thermal barrier is provided. For diesel engine installations, the engines used should comply with BS EN ISO 16147

Inboard diesel engines – Engine-mounted fuel and electrical components to ensure that the fuel components fitted on the engine by the engine manufacturer are safe. The engine manufacture should provide confirmation that the engine complies with this standard.

Fuel hose used in the system must be fire resistant if used in the engine compartment and Where fuel hose is used the standard requires that only fire-resistant hose to BS EN ISO 7840 may be used in the engine compartment. Such hose should be stamped to indicate compliance

 

 

This appears to be a requirement in  BS EN ISO 21487:2012

 

If there is a drain in a diesel oil tank, it shall be fitted with a shut-off valve having a plug that can be removed only with tools.

Each tank shall have an inspection hatch of at least 150 mm diameter. The inspection hatch shall, as a rule, be located on top of the tank, but for diesel oil tanks it may also be on the tank side. There shall be access to the inspection hatch when the tank is in position.

 

BS EN ISO 21487:2012 has been withdrawn https://www.iso.org/standard/57087.html#:~:text=ISO 21487%3A2012 establishes requirements,installation requirements%2C ISO 10088 applies.

 

The new ISO might contain similar standards in this regard - I don't know.  But the more important point is that meeting the ISO standards is not obligatory for the RCR or BSC.  They might be good practice - and meeting all the relevant standards might gain you an automatic pass for the RCR, but there is no binding requirement to have an inspection hatch in a narrow boat diesel tank.

 

Whether an inspection hatch is a good thing is open for discussion.  It is handy for extracting muck if/when it builds up.  On the other hand, a hatch in the vertical face is an increased risk for leaking diesel.  And a hatch in the horizontal face is a possible route for rain etc ingress. Personally, I would settle for a nice big drain at the lowest point.

Edited April 24 by Tacet

[Alan de Enfield]

12 minutes ago, Tacet said:

The new ISO might contain similar standards in this regard - I don't know.  But the more important point is that meeting the ISO standards is not obligatory for the RCR or BSC.  They might be good practice - and meeting all the relevant standards might gain you an automatic pass for the RCR, but there is no binding requirement to have an inspection hatch in a narrow boat diesel tank.

 

 

The title of the thread is :

 

Fuel tank inspection hatch - best design practice

 

which is the question I answered by quoting the size and preferred location.

I did not mention the RCD / RCR and I did not suggest that it was a legal requirement.

 

Edited April 24 by Alan de Enfield

[Tony Brooks]

7 minutes ago, Tacet said:

 Personally, I would settle for a nice big drain at the lowest point.

 

I agree with that, except the way most narrowboats trim (stern down) and the way the tanks are constructed I think the tank would need a sloping bottom to bring any water and muck to the front f the tank where the drain would be. That means more costs.

[David Mack]

2 hours ago, Alan de Enfield said:

I did not suggest that it was a legal requirement.

The document you quoted starts off with the words "The requirements..." and goes on to quote British Standards. The average reader could be forgiven for thinking that there is a legal obligation to comply with these 'requirements'.

[IanD]

Just now, David Mack said:

The document you quoted starts off with the words "The requirements..." and goes on to quote British Standards. The average reader could be forgiven for thinking that there is a legal obligation to comply with these 'requirements'.

 

"The requirements for installation of a fuel system on a boat with fixed fuel tanks are given in the harmonised standard BS EN ISO 10088 Permanently installed fuel systems and BS EN ISO 21487:2012 Small craft - Permanently installed petrol and diesel fuel tanks.

[snip]

Each tank shall have an inspection hatch of at least 150 mm diameter. The inspection hatch shall, as a rule, be located on top of the tank, but for diesel oil tanks it may also be on the tank side. There shall be access to the inspection hatch when the tank is in position."

 

If that's not suggesting this is a legal requirement, I don't know what is -- average reader or not... 😉 

[TandC]

I wasn't being snide when I thanked Alan for the BS extract - but all it does is highlight what a mess the whole thing is.  The lack of clarity on what is required and what isn't is why you get such a diversity in approach and frankly, people give up and this creates the room for dangerous or poor practice.   I've resigned myself to doing everything I can that is practical, high quality and safe - but given up trying to make sense of the rest of the vague and conflicting standards etc. 

 

Mounting a drain on the side of the tank inside the engine bay is an option - but as Tony says, the stern slopes back and realistically the drain wouldn't work to drain the real layer of sludge/water on such a large tank area. 

 

And as for an inspection hatch - in my situation, with a 10ft wide fuel tank, I can't see it offering any real practical benefit vs the risk of leak, additional maintenance task, etc .   So in short, this has been a useful debate but I've decided I won't be bothering with an inspection hatch.  

 

And I think in my situation, if I ever want to empty the tank, I'll have greater success draining it via suction through the fuel filler, as opposed to a drain on the side.  I may need to add some additional ballast to tip the boat to get fuel over to the side of the filler, but being so close to the stern it would be the lowest point.  

[blackrose]

55 minutes ago, TandC said:

... but all it does is highlight what a mess the whole thing is.  The lack of clarity on what is required and what isn't is why you get such a diversity in approach and frankly, people give up and this creates the room for dangerous or poor practice.   

 

I don't really agree. It's easy to take one bad example and try to make a generalisation about a lack of clarity, but when I fitted my boat out to BSS standards it all seemed pretty clear to me. Of course there may be differences between the BSS and RCD because they're different sets of standards.

[Alan de Enfield]

5 minutes ago, blackrose said:

 

I don't really agree. It's easy to take one bad example and try to make a generalisation about a lack of clarity, but when I fitted my boat out to BSS standards it all seem, and based only on those they beleiev rekevant to the types of boats and waters a Ned pretty clear to me. Of course there may be differences between the BSS and RCD because they're different sets of standards.

 

 

There are some differences between the two, but generally the BSS is just 'watered down' RCD requirements based on what a canal boat is likely to need, or to be subject to on Cat D waters.

 

The BSS cannot make something required in the RCD a BSS Fail, otherwise a brand new, compliant boat would be refused a BSS and a licence, and, likewise the BSS does not require everything specified in the RCD.

 

A boat can easily pass the BSS and yet be an RCD failure requiring a PCA.