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Lagging silencer on air cooled HA2


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Hi

Just a quick question, I need to lag my new exhaust silencer. It is the type that goes straight up and out the roof.

I have lagged my flexible exhaust to near perfection, but embarrassingly my lagging fell off my silencer after a week! I think I may have done some thing wrong. Do I start at the top or the bottom?? I think I may have started at the bottom and worked my way up. I did wire the end up but I was greeted with a pile of lagging the other morning.

Funnily, when I told my other half, and to save embarrassment ( she knows how long it took me) I blamed our cats, saying they must have been using it as a scratching post again!

 

All help appreciated

 

Ps boat safety on Sunday :-(

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lagging!! I ran her for 6 months with just the pipe out the engine room door!! lol. anyway start at the top and wind it on tight with an overlap of 50% on each turn this will hold each turn in place, the hardest bit will be the silencer box (assuming it still has its original exhaust)

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I understood exhaust lagging was now an advisory for the BSS. the principle is wire to hold it all in place and anything up to 50% overlap. Doesn't matter which end it starts, sounds like your wire wasn't tight enough.

Unless it has been relaxed in the latest revision, no it is mandatory that every part is either lagged or fully shielded, except the manifold itself.

 

That includes every last internal inch and joint, so, for example, I was told that the couple of inches of pipe above the silencer but below the roof should really have been lagged, even though nobody can possibly touch it, (but was trusted I'd fix it afterwards!).

 

You don't currently seem to be able to download the individual parts of the very latest revision of the guide for private boats, so how you are supposed to see a guide that has the very latest revisions in I'm not fully sure though.

 

Personally I'd go for using a suitable sized Jubilee clip to tie the ends down - it doesn't move then, if wrapped tight enough

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In addition to what others have said - when you get to the end of the wrap, tuck the last turn undrneath the previous one and pull it tight. There's a technical name for it, used in whipping, but haven't a clue what it is.

Also you can wrap it with self-adhesive aluminium foil, on top of the lagging, should make it secure as well as more effective.

 

Tim

 

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Unless it has been relaxed in the latest revision, no it is mandatory that every part is either lagged or fully shielded, except the manifold itself.

 

That includes every last internal inch and joint, so, for example, I was told that the couple of inches of pipe above the silencer but below the roof should really have been lagged, even though nobody can possibly touch it, (but was trusted I'd fix it afterwards!).

 

You don't currently seem to be able to download the individual parts of the very latest revision of the guide for private boats, so how you are supposed to see a guide that has the very latest revisions in I'm not fully sure though.

 

Personally I'd go for using a suitable sized Jubilee clip to tie the ends down - it doesn't move then, if wrapped tight enough

I think Chris is correct, just changed as I understand it.

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Unless it has been relaxed in the latest revision, no it is mandatory that every part is either lagged or fully shielded, except the manifold itself.

 

That includes every last internal inch and joint, so, for example, I was told that the couple of inches of pipe above the silencer but below the roof should really have been lagged, even though nobody can possibly touch it, (but was trusted I'd fix it afterwards!).

 

You don't currently seem to be able to download the individual parts of the very latest revision of the guide for private boats, so how you are supposed to see a guide that has the very latest revisions in I'm not fully sure though.

 

Personally I'd go for using a suitable sized Jubilee clip to tie the ends down - it doesn't move then, if wrapped tight enough

 

 

I found the relevant bit in the new document. "Must be lagged" is now relegated to "advice" and then only in walk-through engine rooms. I think it's become much more sensible.

 

 

MP.

 

Check all structures and surrounding

surfaces near all exhaust system

components which can be seen for signs of

heat damage.

 

The structures and surrounding surfaces near all exhaust

system components must not show signs of heat damage such

as scorching, melting or burning.

 

Applicability – this check covers all types of exhaust system components including those on ‘wet’ or ‘dry’

exhaust systems including those parts of ‘dry’ systems that are lagged or shielded.

 

Advice to owners – ‘Dry’ exhaust systems, or those parts of ‘wet’ exhaust systems not cooled by water,

located in ‘walk through’ engine spaces or cabins/deck spaces or other areas where normal crew movement

about the vessel can be anticipated, should be effectively lagged, shielded or otherwise protected by craft

structures.

 

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Cheers every one, I suspect that wire wasn't tight enough as it was intact at the bottom. I will lag top to bottom with a tuck at the top followed by a very tight wire!

I had to chuck my bottoms away last week as they was covered in glass fibres! Looks like i will have to put some overalls on this time. :-)

 

lagging!! I ran her for 6 months with just the pipe out the engine room door!! lol. anyway start at the top and wind it on tight with an overlap of 50% on each turn this will hold each turn in place, the hardest bit will be the silencer box (assuming it still has its original exhaust)

I changed silencer for new one, but I kind of cheated, luckily the old silencer was rotten enough to allow me to snap it from the coupling in roof, otherwise I would of had to remove wood from roof to allow me to unscrew the silencer. The broken bit of the exhaust unscrewed with ease. I cheated with new silencer as I brought a coupling for the roof that allows the silencer to sit 3 inches lower than before, that allowed me to screw new exhaust into place without replacing tongue and grove wood on the ceiling.

If the silencers had top and bottom inlet and out-let's in the centre, all the myther would of been avoided.

 

Ps I had her running with just pipe and it sounded lovely :-)

Edited by Narrowboat Communicator
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I think Chris is correct, just changed as I understand it.

Yes,

 

I think you and Chris are right - it seems from the new check-list to be advisory.

 

I couldn't actually download the revised guide though, which seems a bit of a shortcoming.

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Examiners guide 2.15.2

is the section where examiners are looking for possible heat damage from exhausts says the following.

 

 

Advice to owners – ‘Dry’ exhaust systems, or those parts of ‘wet’ exhaust systems not cooled by water, located in ‘walk through’ engine spaces or cabins/deck spaces or other areas where normal crew movement about the vessel can be anticipated, should be effectively lagged, shielded or otherwise protected by craft structures.

 

 

Although this section is a requirement the "advice" above is just that, advice. I would like to add that I consider some weed hatchches to be an area of normal crew movement Where the exhaust passes near the weed hatch I would advise lagging, even when below deck. My logic? "In a hurry to clear prop through the hatch? That exhaust will almost certainly be hot and bare arms are exposed"

(This advice not for the OP but for semi trad or cruiser stern boat owners where this situation is very likely.)

 

The case of lagging was dicussed at a seminar I went to. Lagging that can be soaked in fuel is just as much a fire hazard as exposed exhaust pipe. The danger is from close combustables, and to persons.

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