Gas installation query

[MtB]

Mike I am sure you know your stuff, but it is a pity you have to spend so much effort on pointing this out to everyone at the expense of not answering the questions fully and unemotionally at the first attempt. Sorry but I find the "knowledge is power" type of professional rather irritating.

 

Let face it, connecting some pipes between supply and appliances in a way that is leak proof at the moment and likely to remain so, is not really rocket science. It is the mystique that it is all wrapped in (in order to keep it inaccessible to non-gas-deities) that causes the problems.

 

Agreed about the rocket science. But the goal is not to achieve just a leak-free installation is it? It is to achieve an installation that complies with PD 5482-3 2005 and will pass future BSS inspections. It's taken as a given that the system will not leak. There are SO MANY ways in which a gas-tight installation can fail to comply, the only way to cover them all is to advise people in the first place to get it done by someone qualified. The requirement for isolation valves, for example, is nothing to do with avoiding leaks and everything to do with box-ticking.

 

Anyway you're never going to be convinced. I held the same opinion as you until I decided to get (then) CORGI registered, and it was only then I realised just how much I didn't know.

 

Mike

 

P.S. which questions do you consider I have not answered?

[nicknorman]

... the only way to cover them all is to advise people in the first place to get it done by someone qualified.

 

mmm, you clearly don't watch "rogue traders" etc! If only life were that simple. Present company excepted, there are plenty of people out there who are qualified but incompetant / lazy / dishonest. This type of forum is for those like me who don't blindly trust "professionals" but would rather understand the detail (which I still maintain is not that complicated). As I said I am sure you do know your stuff but sometimes you put a lot of effort into faulting other people's posts (which I agree are incorrect) rather than giving the correct answer first - and then maybe mentioning why other posts are incorrect, rather than just slagging them off in an emotional way.

 

 

P.S. which questions do you consider I have not answered?

 

OP questions:

1) can you get bubble testers in larger than 3/8 size? - not answered as far as I can see

2) is it ok to end pipe run at heater or would a stop end be better? -answered eventually in post #24, why not in post #4 (your first)?

3) would idolaters be better as close to appliance as possible? - not specifically answered as far as I can tell, though perhaps by implication

4) can I get the system installed by a qualified person? ( as have heard that they won't connect up the Morco as its not room sealed) - not answered

Edited July 29, 2012 by nicknorman

[bizzard]

Nor do I.

 

I have explained in full detail in previous threads why not, but broadly speaking I fitted one to my last boat and it showed the system was sound. My BSS inspector didn't spot it and did a conventional soundness test and revealed a fail! A bit of experimenting showed the bubble tester when used according to the instructions did not reveal the leak, I had to hold the button down for longer than the instructions said to get it to show a bubble.

 

 

 

Never heard of them. Got a link? Do Aquafax sell 'em?

 

More to the point, HOW do you know they are very accurate? Have you created a tiny leak just detectable using a manometer, then seen how the Gas-Low gets on spotting it?

 

Mike

My test of course was the simple basic test for soundness. Turn all appliances off, pressurise system by turning on at the bottle and then off and waiting, after a couple of hours the gauge started to enter the red ''empty sector'' so i new there was a slight leak. Testing all joints and appliance isolation valves with leak fluid revealed a minute gas leak from my fridges isolation valve the tapered plug cock type. I took it to bits re-lapped in the tapered plug to the tapered body with T-Cut clean off reassemble and refit, further test with the gauge, no drop at all in half a day. These gauges only have coloured sectors, Red-empty, yellow- about half empty and green-full.

Edited July 29, 2012 by bizzard

[MtB]

mmm, you clearly don't watch "rogue traders" etc! If only life were that simple. Present company excepted, there are plenty of people out there who are qualified but incompetant / lazy / dishonest. This type of forum is for those like me who don't blindly trust "professionals" but would rather understand the detail (which I still maintain is not that complicated). As I said I am sure you do know your stuff but sometimes you put a lot of effort into faulting other people's posts (which I agree are incorrect) rather than giving the correct answer first - and then maybe mentioning why other posts are incorrect, rather than just slagging them off in an emotional way.

 

I think I get emotional about it because from my side of the fence, I can see the staggering amount of background knowledge involved in getting an installation right first time, and see this belittled by unqualified people who think it must be simple and then go on to give incorrect advice. Comments like yours ("its not rocket science") are irritating because agreed, it is not rocket science but it IS complex and you seem to think otherwise. It annoys me mainly though, because the OP is inclined to accept incorrect advice at face value and proceed to fit his/her gas system in a way that may be broadly safe, but will cost a lot of time/money to put right when the BSS next comes along.

 

Anyway I'm happy to answer specific questions on specific points, but not general questions like "how do I install my own gas system?" The time involved in explaining why the incorrect answers from all the guessers and bar-room specialists are incorrect is phenomenal - I'm not going to get involved in that any more (unless the poster of misinformation is a qualified gas bod!)

 

OP questions:

1) can you get bubble testers in larger than 3/8 size? - not answered as far as I can see

 

No. 3/8" is often large enough when the pipes are sized correctly in the rest of the system.

 

2) is it ok to end pipe run at heater or would a stop end be better? -answered eventually in post #24, why not in post #4 (your first)?

 

The OP did not ask this until post 20. Someone chucked it in as a suggestion earlier but not the OP.

 

3) would idolaters be better as close to appliance as possible? - not specifically answered as far as I can tell, though perhaps by implication

 

Yes. (I imagine you mean isolators?)

 

4) can I get the system installed by a qualified person? ( as have heard that they won't connect up the Morco as its not room sealed) - not answered

 

Yes. But as you point out, many qualified people may choose to decline due to fears (unfounded in my opinion) about being prosecuted for manslaughter should the user subsequently die.

 

Mike

[lexicon]

I think I get emotional about it because from my side of the fence, I can see the staggering amount of background knowledge involved in getting an installation right first time, and see this belittled by unqualified people who think it must be simple and then go on to give incorrect advice. Comments like yours ("its not rocket science") are irritating because agreed, it is not rocket science but it IS complex and you seem to think otherwise. It annoys me mainly though, because the OP is inclined to accept incorrect advice at face value and proceed to fit his/her gas system in a way that may be broadly safe, but will cost a lot of time/money to put right when the BSS next comes along.

 

Anyway I'm happy to answer specific questions on specific points, but not general questions like "how do I install my own gas system?" The time involved in explaining why the incorrect answers from all the guessers and bar-room specialists are incorrect is phenomenal - I'm not going to get involved in that any more (unless the poster of misinformation is a qualified gas bod!)

 

 

 

No. 3/8" is often large enough when the pipes are sized correctly in the rest of the system.

 

 

 

The OP did not ask this until post 20. Someone chucked it in as a suggestion earlier but not the OP.

 

 

 

Yes. (I imagine you mean isolators?)

 

 

 

Yes. But as you point out, many qualified people may choose to decline due to fears (unfounded in my opinion) about being prosecuted for manslaughter should the user subsequently die.

 

Mike

 

Thanks mike.

 

I fully intend to have the installation done by a qualified person as long as the morco issue won't prevent it.

 

Mainly checking the things that will affect the design of the gas lockers I will be getting built.

And the interior conduits etc I plan to build to conceal pipes from view in day to day use but allow easy inspection at a later date.

 

I am very grateful for the knowledge of others, and know my limitations as regard fit out and can't see anything but false economy in not getting the installation done by a professional.

[the grinch]

not put a bubble tester in for a while but its only a matter of changing the adapters to 1/2" ones as the slight difference in bore through the tester is negliable and unlikely to affect the overall resistance in the way indequate bottle or pipework sizing will

[the grinch]

as for niknormans we withhold info that is rubbish

 

just in this thread alone i advised that 13Kg would not allow enough gas take off and gave the calculations

in another i offered to pipesize if the appliance rates were given

Edited July 29, 2012 by hamsterfan

[alan_fincher]

I also think that you can only get bubble tester "off the shelf" in sizes up to 10mm or (harder) 3/8" imperial.

 

Southampton Calor (SoCal) used to supply the standard Alde item with metric couplings changed to Imperial, so worth checking what they now stock.

 

I don't think the fact it is resticted through a small length withh be a great problem - the issue, as has been said, must surely be that long lengths of undersized pipe are far worse.

 

I agree with MTB on most things, but not with the assertion it is hard to use a bubble tester in a well sited position in a gas locker. I neither need a torch to inspect mine, nor need to do any real gymnastics. All I need is one free hand to hold in the button, but clearly this depends a bit on the "geography" of an individual locker.

 

As an aside, I struggle with the suggestion people have had the "glass" in them break. It is very well protected, not "glass", and looks no more likely to failurethan the average bit of copper pipe!

 

Some BSS inspectors knock £15 to £20 off their fees if a bubble tester is fitted, (at least one forum member does this...), so whatever you think of them, if you keep the boat long enough, fitting one will ultimately see you "in profit"!.

[system 4-50]

I'm curious.

 

Just how much training would an intelligent, quite capable, person, with say quite a bit of experience with mechanical systems, perhaps automotive, and say, good experience of plumbing, need to be able to competently and reliably install typical, ie nothing exotic, LPG systems in narrowboats? Assuming that such a specialised course existed, one that did not include aspects of gas work not found in boats.

Would it be 1 day? 5 days? 1 month? 3 months? 6 months? More?

 

A second question. How long would the training have to be to enable the said person to be able to do any work on LPG systems in narrowboats, without turning a job down due to lack of capability?

[nicknorman]

The OP did not ask this until post 20. Someone chucked it in as a suggestion earlier but not the OP.

 

No, for the record the questions I pasted in were all from post #1

 

Anyway, I do have some sympathy with your points, however in my opinion it is always better to post correct answers as a priority over criticising other posters - the latter you can do or not depending on how much time you have on your hands.

 

Also, you cannot really blame questioners for not being too clear about which person to believe - this sort of thing tends to come out in the wash of post question discussion, but as I have said it is better to concentrate on giving correct answers than to justify (from a non-technical point of view) why you should be believed over others.

[Chris Pink]

I'm curious.

 

Just how much training would an intelligent, quite capable, person, with say quite a bit of experience with mechanical systems, perhaps automotive, and say, good experience of plumbing, need to be able to competently and reliably install typical, ie nothing exotic, LPG systems in narrowboats? Assuming that such a specialised course existed, one that did not include aspects of gas work not found in boats.

Would it be 1 day? 5 days? 1 month? 3 months? 6 months? More?

 

A second question. How long would the training have to be to enable the said person to be able to do any work on LPG systems in narrowboats, without turning a job down due to lack of capability?

 

I have done my own installations, 3 times now with a bit of research and reference to the BSS together with a bit of modification for appliance changes. They have always passed the BSS and given me no cause for concern but I would never fit a system for anyone else either professionally or otherwise though I would be happy to disseminate technique and knowledge.

 

Funnily enough I thought that was what this forum was for. Maybe it should be renamed "ask the professional", perhaps with a £45 per hour fee.

 

I would imagine if someone was using this forum to gather knowledge then sorting wheat from chaff is part of the territory.

 

As a matter of interest, do the training courses cover such specifics as why imperial rather than metric fittings are used and the specifics of marine LPG with regard to the BSS.

 

If an installation is done to the relevant BS then it will pass the BSS but not every DIY person can afford access to these and the BSS documentation offers a subset for free.

 

It may have changed since the last time I looked but an isolation valve wasn't necessary under the BSS for a fixed appliance though when I fitted my Morco I installed one for ease of servicing. I am happy to be corrected on this, again in line with my understanding of this forum.

 

The discussion about bubble testers is an illustration of how non-professionals contribute to such threads.

[Iain_S]

Some BSS inspectors knock £15 to £20 off their fees if a bubble tester is fitted, (at least one forum member does this...), so whatever you think of them, if you keep the boat long enough, fitting one will ultimately see you "in profit"!.

 

And, in the case of our canal society trip boat, it's an essential, as neither of the BSS inspectors up here are gas qualified, and are thus unable to do a manometer test on a commercial or liveaboard boat (I do struggle with the logic of this ). The alternative is having the test done by an suitably qualified Gas Safe registered person and observed by the BSS examiner, which would be a logistics nightmare!

 

The hire fleets "import" a gas qualified BSS examiner for their boats (and pay his hotel bill)

 

Iain

[Radiomariner]

Lex, I am surprised we did not talk about this when we met up a few days ago!!!!

For BSS test the bubble tester should be inside the gas locker, unless of course the bottles are stored in an "open" location. Nothing to do with the vulnerability of the "glass" (Its not glass anyway) but because the line between the regulator and the tester is not covered by the test. Any leak in the locker will drain outside the boat. The examiner should also test for leaks inside the gas locker. I have a gas sniffer for this which I find more effective/sensative than soapy detection fluid, especially inside a dark cramped gas locker.

It is OK to install a bubble tester outside the gas locker for your own peace of mind, but if it is to be used by the examiner for a tightness test it and the line to it must be in an "open area"

 

The difficulty of operating this device in a locker is appreciated. I find that reflective foil or white paint around and behind the bubble tester helps considerably. One boat I have seen has a small angled mirror making viewing easier.

About isolating valves. The BSS recommends the use of isolation valves for each appliance but only insists upon it when there is more than one appliance and hoses are used. On the practical side, as somebody mentioned, should there be a gas leak in the system isolation valves can speed up it's location.

 

The test nipple can be anywhere in the system. Having it after one of the isolating valves however can make detection of the leak slightly less straightforward. I personally prefer the test nipple to be near an appliance, because as an examiner I need to carefully reduce the pressure in the line for the tests by lighting and usually quite rapidly turning off a small burner while looking at the manometer (gauge).

Certain gas bottle gauges are currently available, and it may be possible to check for gas tightness using these. BSS are I believe currently looking into this, but at this stage it is NOT an approved method of tightness testing by them

 

It is true that BSS recommend as few joints in the gas line as possible. You would need a hell of a lot of them I think for a BSS examiner to fail you. This regulation in the main applies to fittings such as adaptors from one pipe size to another which should not be made up of an excessive number of pieces, ie two adaptors when only one is necessary. It is appreciated that sometimes that if an already bent pipes can not be fitted into a space then probably neither will a pipe bending tool and an elbow joint necessary here and there.

 

Now, the Morco. Gas-Safe registered fitters I believe are instructed to fit only devices that the manufacturers state is suitable for fitting on boats, and nowadays for instant water heaters that means "room sealed". Although they recommend room sealed heaters the BSS still allows these heaters because as yet nobody has come up with a suitable affordable replacement, and much to my amazement have a fairly good safety record All the room sealed ones I have seen to date have been expensive and required AC mains to run fans, pumps etc. Finding someone to do it for you might be difficult. I should expect that any fitter who agrees would ask you to sign some sort of waiver. (I dont know if this is allowable within the law). The other route is that of "compitent person" that is a can of worms I really do not wish to go into.

(Just spotted in time that I typed "compitent PARSON", now that would have had the forum buzzing!

 

Apologies if this post has been dealt with already by others, I had to do a bit of "emergency shopping", only three cans of beer in the fridge and SWMBO down to her last bottle of Gin with 15 more days of Olympics!

Edited July 29, 2012 by Radiomariner

[bizzard]

Gone are the days when people simply plonked a gas bottle down next to their gas cooker in their galley, connected it up with a couple of feet of rubber tube ''two joints'',lit up the stove, put the kettle on and boiled up a lovely stew for dinner. As the bottle was there ''on the spot''within reach of you it was always turned off without fail after use.

I don't think any more folk blew themselves up then than they do now. And its almost certainly still common practice with some DIY'ers with old sea boats.

Edited July 29, 2012 by bizzard

[nicknorman]

... I personally prefer the test nipple to be near an appliance, because as an examiner I need to carefully reduce the pressure in the line for the tests by lighting and usually quite rapidly turning off a small burner while looking at the manometer (gauge)...

Excellently informative post thanks. Out of interest, why do you have to reduce the pressure for gas tightness tests? One would have thought that testing at max pressure was the way to go, or is the reduced pressure in case there is a leak which "self-seals" at higher pressures?

[Radiomariner]

And, in the case of our canal society trip boat, it's an essential, as neither of the BSS inspectors up here are gas qualified, and are thus unable to do a manometer test on a commercial or liveaboard boat (I do struggle with the logic of this ). The alternative is having the test done by an suitably qualified Gas Safe registered person and observed by the BSS examiner, which would be a logistics nightmare!

 

The hire fleets "import" a gas qualified BSS examiner for their boats (and pay his hotel bill)

 

Iain

 

Yes, I struggle with the Logic of this also. Although I am qualified to inspect Commercial craft, I can not touch the LPG system All boat examiners are trained and tested in tightness testing of LPG systems by Gas Safe but are not registered with them as fitters. To work in "commercial" premises any work on a gas system must be carried out by a registered person. Unscrewing, and putting back the screw on the gas nipple is considered as "work" . This comes up frequently at meetings but it seems nothing can be done about it. To me it reeks of "jobs for the boys"

(When working for the Government abroad, I was responsible for all maintenance, repair and servicing of electronic equipment at my post. Yet, when I came home where there was a resident engineer, I was not allowed even to replace a fuse!)

 

My local Hire boat Co. have bubble testers on all 38 boats. They still need a gas test every year part of the "hotel" inspection. Having the bubble tester makes it easier for them to find a BSS examiner that does not charge extra for doing the gas. Unfortunately for me, I am not that examiner!

[MtB]

I also think that you can only get bubble tester "off the shelf" in sizes up to 10mm or (harder) 3/8" imperial.

One can buy any size bubble tester and unscrew the nickel-plated metric adaptors to reveal 3/8" BSP female threads into which you can screw your own adaptors to 1/2" imperial pipe, or 3/8", or whatever it needs to be.

 

 

Southampton Calor (SoCal) used to supply the standard Alde item with metric couplings changed to Imperial, so worth checking what they now stock.

8mm is virtually identical in size to 5/16" tube. 8mm and 5/16" compression fittings are effectively fully interchangeable with 8mm and 5/16" tube. 3/8" tube will fit into a 10mm fitting and can be made gas tight but it is a loose and baggy fit to start with and not right from an engineering POV. I doubt most BSS bods would notice if this has been done though.

 

 

I agree with MTB on most things, but not with the assertion it is hard to use a bubble tester in a well sited position in a gas locker. I neither need a torch to inspect mine, nor need to do any real gymnastics. All I need is one free hand to hold in the button, but clearly this depends a bit on the "geography" of an individual locker.

 

Indeed. It was easy on my last boat with a tug deck but try getting your head inside the gas locker on a modern boat with cratch in the way. You have to balance about on the (usually tiny) foredeck and get your head down through the hatch whilst being careful not to fall in. Not easy when I tried it and murder on the knees. Isn't there a cratch on Chalice? Do you not find it difficult?

 

Mike

[the grinch]

Excellently informative post thanks. Out of interest, why do you have to reduce the pressure for gas tightness tests? One would have thought that testing at max pressure was the way to go, or is the reduced pressure in case there is a leak which "self-seals" at higher pressures?

 

because a 2 Mbar leak could be hidden by a 2 Mbar let by at the gas bottle valve, that is why we have let by tests in both LP and Natural Gas as let by should be visible by a rise in pressure on the "U" Guage.

[MtB]

To me it reeks of "jobs for the boys"

 

It might look like it from your side of the fence, but not from mine. Parliament and the HSE have scant regard for the lowly gas technician. Our financial interests are not taken into account in any way in the drafting of the safety legislation (as you would expect).

 

Quite the reverse in fact. How easy do you think it is to charge someone for an hour or two labour establishing their appliance is dangerous and finding one is legally obliged to disconnect it from the gas supply? When they say "Its been fine for the last ten years mate, sling yer hook", do you think they then follow through with, "Oh and by the way, how much do I owe you for disconnecting it and leaving me with no heating or hot water?"

 

As it is, we are required to isolate or disconnect or otherwise make safe whether or not we get paid. Not a very good implementation of the 'jobs for the boys' principle in my view!

 

Mike

[the grinch]

I'm curious.

 

Just how much training would an intelligent, quite capable, person, with say quite a bit of experience with mechanical systems, perhaps automotive, and say, good experience of plumbing, need to be able to competently and reliably install typical, ie nothing exotic, LPG systems in narrowboats? Assuming that such a specialised course existed, one that did not include aspects of gas work not found in boats.

Would it be 1 day? 5 days? 1 month? 3 months? 6 months? More?

 

A second question. How long would the training have to be to enable the said person to be able to do any work on LPG systems in narrowboats, without turning a job down due to lack of capability?

 

to do Core plus 1 element (boats) as a novice i would expect 5 days to cover everything you need to know, with basic understanding you could probably complete in 2 days. But you would not be qualified to work on any appliances

 

it takes approx 4-5 days to do the LPG modules including Assessments depending on how many you do (i have 3 elements plus Core changeover from Natural) but i have NG boilers and cooker so no need to do those LP elements as covered in CONGLP1

[Timleech]

Yes, I struggle with the Logic of this also. Although I am qualified to inspect Commercial craft, I can not touch the LPG system All boat examiners are trained and tested in tightness testing of LPG systems by Gas Safe but are not registered with them as fitters. To work in "commercial" premises any work on a gas system must be carried out by a registered person. Unscrewing, and putting back the screw on the gas nipple is considered as "work" . This comes up frequently at meetings but it seems nothing can be done about it. To me it reeks of "jobs for the boys"

(When working for the Government abroad, I was responsible for all maintenance, repair and servicing of electronic equipment at my post. Yet, when I came home where there was a resident engineer, I was not allowed even to replace a fuse!)

 

My local Hire boat Co. have bubble testers on all 38 boats. They still need a gas test every year part of the "hotel" inspection. Having the bubble tester makes it easier for them to find a BSS examiner that does not charge extra for doing the gas. Unfortunately for me, I am not that examiner!

 

I don't know about the current production, but early test points used a fibre washer which could easily be split by overtightening, but they could work loose if not tightened enough. I think that has a lot to do with the requirement to be gas qualified to do the tests.

 

Re the metric/imperial sizing thing, I did a gas installation course about 25 years ago, before CORGI had even heard of boat installations. Someone asked the instructors (Calor employees) the same question. Their answer was (true or not) simply that they had never got round to changing.

It does have the incidental benefit now that most Imperial sized pipe & fittings is suitable for LPG, because that where the main market lies now that everyting else has gone metric.

 

Tim

[MtB]

to do Core plus 1 element (boats) as a novice i would expect 5 days to cover everything you need to know, with basic understanding you could probably complete in 2 days. But you would not be qualified to work on any appliances

 

it takes approx 4-5 days to do the LPG modules including Assessments depending on how many you do (i have 3 elements plus Core changeover from Natural) but i have NG boilers and cooker so no need to do those LP elements as covered in CONGLP1

 

I'd have thought the path would be to do Core Gas Safety (the biggest module of by far), elements for each class of appliance the OP wishes to install, then LPG changeover for the whole lot along with LPG for boats. I'd imagine this would take in the order of two to three weeks depending on how fast the OP is at soaking up the training, and how fast the other candidates are on the course too. The big benefit here is that the OP would be qualified to work on NG too (albeit unpaid).

 

I'm not sure there is such a thing as standalone LPG Core Gas Safety.

 

Mike

[the grinch]

 

 

I'm not sure there is such a thing as standalone LPG Core Gas Safety.

 

Mike

CCLP1 is Core LPG

CKRLP1 is cookers LPG

HTRLP1 is fires

LEILP1 is leisure Appliances

and there are several other individualn appliance ones

 

WATLP1 is water heaters

CENLP1 IS boilers up to 60Kw

these two are now covered in 1 module think its CENWATLP1 but not 100% on that ones code

 

I'd have thought the path would be to do Core Gas Safety (the biggest module of by far), elements for each class of appliance the OP wishes to install, then LPG changeover for the whole lot along with LPG for boats. I'd imagine this would take in the order of two to three weeks depending on how fast the OP is at soaking up the training, and how fast the other candidates are on the course too. The big benefit here is that the OP would be qualified to work on NG too (albeit unpaid).

 

 

 

Mike

 

unless you want to do NG as well, just additional expense as to do my last lot NG core, 4 elements, LP changeover and 3 elements cost £1,500!

 

I don't know about the current production, but early test points used a fibre washer which could easily be split by overtightening, but they could work loose if not tightened enough. I think that has a lot to do with the requirement to be gas qualified to do the tests.

 

Re the metric/imperial sizing thing, I did a gas installation course about 25 years ago, before CORGI had even heard of boat installations. Someone asked the instructors (Calor employees) the same question. Their answer was (true or not) simply that they had never got round to changing.

It does have the incidental benefit now that most Imperial sized pipe & fittings is suitable for LPG, because that where the main market lies now that everyting else has gone metric.

 

Tim

 

yes some still have that silly little washer, some don't

 

you can use either metric or imperial so long as the wall thickness is correct both are available.

[Timleech]

 

 

you can use either metric or imperial so long as the wall thickness is correct both are available.

 

Yes I'm aware of that, but my point was that it's easy to find metric stuff that is not suitable (and many people would be unaware that it's not suitable). If you stick to Imperial, and buy it from recognised chandleries, it'll be a fairly safe bet that it's suitable.

 

Tim

[alan_fincher]

Isn't there a cratch on Chalice?

No cratch - easy access to gas locker from front well deck!

 

Do you not find it difficult?

No, but I accept that is probably because of the answer given above!