Air outlet box

[Roxylass]

Has anyone got drawings of above mentioned for the SR2

had the canvas one that Sue makes but it’s deteriorated 

after a couple of years heard it can be made out of aluminium 

Wondering if anyone has made one at all 

[Tony Brooks]

Usually the fabric ones are tacked or sewn onto wooden rectangular fitting pieces at each end. You can use those as templates for flanges on the aluminium "tube". If yours are tubes held in place by large hose clips, then you may find aluminium heating or ventilating ducts that will fit.

 

I would be wary of using an aluminium sheet structure between engine and hull because I fear it will vibrate and eventually fracture.

[David Mack]

19 minutes ago, Tony Brooks said:

Usually the fabric ones are tacked or sewn onto wooden rectangular fitting pieces at each end.

My ST3 had flanges fabricated from small size angle iron, which clamped to the canvas fabric - no sewing involved. The flanges on the canvas transition piece were then bolted to corresponding flanges on the engine air manifold and the rigid steel duct which ran up to the vent on the engine room roof.

[Roxylass]

Sue has done an excellent making the rectangular shape 

Sadly there is not much ridgity in the canvas

possibly make one with half inch marine ply

thanks for mentioning possible fracture 

with the aluminium 

 

 

[Tony Brooks]

2 minutes ago, Roxylass said:

Sue has done an excellent making the rectangular shape 

Sadly there is not much ridgity in the canvas

possibly make one with half inch marine ply

thanks for mentioning possible fracture 

with the aluminium 

 

 

 

I am not sure that matters much because I would expect the big fan in the flywheel to "blow" the canvas ducting open if it needed it. If you don't suffer overheating (stalling when hot) I think you may be worrying over not a lot.

[David Mack]

My canvas adaptor was only about two inches long (between the engine flange and rigid ducting) so didn't need any rigidity to stay in place.

[Tony Brooks]

If the OP is worried and the canvas is in good condition, I expect one could bend you some steel wire (coat hanger material or thicker gas welding rods) into rectangles and sew them inside the canvas ducting. If the canvas flops between the rectangles, some straight lengths of the wire could be sewn between the rectangles and the canvas.

[Roxylass]

Engine doesn’t overheat Tony
Just looking to see if there was better alternatives 

I've seen a s/s one on an ST2

thanks for your help and good lnfo 

[Arthur Marshall]

I use a bit of flexible aircon ducting - a bit like the stuff you used to get for a tumble drier that you chucked out the window. I got a plate with the right size flange for it and bolted it to the outlet hole in the hull.

I did make an aluminium box originally but the angles were a bit complicated and it ultimately fell to bits.

[Roxylass]

Do you possibly have a picture of it Arthur 

[Tony Brooks]

2 hours ago, Arthur Marshall said:

I did make an aluminium box originally but the angles were a bit complicated and it ultimately fell to bits.

 

and I suspect those angles are likely to vary a bit from boat to boat.

 

I suspect a bit of chimney liner of eh correct size would be ideal.

[Arthur Marshall]

2 hours ago, Roxylass said:

Do you possibly have a picture of it Arthur 

Can't find one, but I'm down the boat Thursday so will take one then.

[Tony Brooks]

While you wait for Arthur, I think this is the type of thing he uses

 

 

 

The bottom one seems to have an overlarge box between ducting and engine.

 

Looking at the first photo, you would need a similar adaptor plate with the two "pipes stubs" on it to fix to the hull over the hull vent.

 

Edited Monday at 20:19 by Tony Brooks

[Arthur Marshall]

16 minutes ago, Tony Brooks said:

While you wait for Arthur, I think this is the type of thing he uses

 

 

 

The bottom one seems to have an overlarge box between ducting and engine.

 

Looking at the first photo, you would need a similar adaptor plate with the two "pipes stubs" on it to fix to the hull over the hull vent.

 

Vey similar, except on my engine at least there's just one vent for the cooling air so I've just fitted a single outlet with that kind of tubing, and an equivalent plate at the hull vent. I was worried that it might be too small (presumably why the photo has two) but as the original canvas sagged so much it cut the capacity right down I thought it would be ok. Engine hasn't overheated since I did it.

[alan_fincher]

I would have thought that even if the canvas tube was "floppy" once the engine was started the air being pumped through would cause it to swell out, and not be an impediment.

 

That said, neither of our boats currently have any ducting whatsoever and pump out their hot air in a manner that must mean a  lot of it just gets recycled into the inlet fan on the flywheel.

 

Clearly less than  ideal, but so far never a  problem.  And these a full sized deep draughted working boats.  A shallower leisure boat would be less likely to have issues.

[David Mack]

1 hour ago, alan_fincher said:

That said, neither of our boats currently have any ducting whatsoever and pump out their hot air in a manner that must mean a  lot of it just gets recycled into the inlet fan on the flywheel.

Your engines are in voluminous engine rooms, and you probably have the side doors open most of the time the engine is running. Recirculation of hot air might be more of a problem in a closed-in cramped below-deck space on a cruiser or semitrad stern.

[Tony Brooks]

7 hours ago, David Mack said:

Your engines are in voluminous engine rooms, and you probably have the side doors open most of the time the engine is running. Recirculation of hot air might be more of a problem in a closed-in cramped below-deck space on a cruiser or semitrad stern.

 

Certainly was on our SL4s in wide beam wooden cruisers with larger than typical narrowboat inlet and outlet vents in the hull, plus canvas ducting. In the worst cases, I ducted the engine inlet air from the inlet vent and that seemed to cure the problem of the cast in steel inserts in the pistons coming out, but I don't think the SRs have those so maybe not so much of a problem.

[Roxylass]

Where would I be able to get one of those especially the one with the single circle then I could connect the chimney liner to that 

[Tony Brooks]

6 minutes ago, Roxylass said:

Where would I be able to get one of those especially the one with the single circle then I could connect the chimney liner to that 

 

I got the impression that they were a Lister part, but nowadays I expect that you would have to get a local firm to make one from steel sheet. I think @Arthur Marshall may have either made his or had it made.

[alan_fincher]

8 hours ago, David Mack said:

Your engines are in voluminous engine rooms, and you probably have the side doors open most of the time the engine is running. Recirculation of hot air might be more of a problem in a closed-in cramped below-deck space on a cruiser or semitrad stern.

 

Yes, fully accepted.

[Arthur Marshall]

56 minutes ago, Tony Brooks said:

 

I got the impression that they were a Lister part, but nowadays I expect that you would have to get a local firm to make one from steel sheet. I think @Arthur Marshall may have either made his or had it made.

It was off the shelf part, made for some kind of ducting connection. I just picked the one with the right diameter hole. Then I just bolted it to a plate the right size to fit to the Lister outlet and the hole in the hull. I had to cut those myself. I have no idea where I got the connecting doofers from, I'm afraid, or what they were called. I do know it took me a while on Google to find them!

[Tony Brooks]

29 minutes ago, Arthur Marshall said:

It was off the shelf part, made for some kind of ducting connection. I just picked the one with the right diameter hole. Then I just bolted it to a plate the right size to fit to the Lister outlet and the hole in the hull. I had to cut those myself. I have no idea where I got the connecting doofers from, I'm afraid, or what they were called. I do know it took me a while on Google to find them!

 

So, probably from a heating and ventilation supplier, such as may be used for industrial ventilation. A suitably sized tube stub with a flange at one end.

 

Something like these https://www.ventilationland.co.uk/en_GB/roof-terminal-slab/1547/

[Arthur Marshall]

3 hours ago, Tony Brooks said:

 

So, probably from a heating and ventilation supplier, such as may be used for industrial ventilation. A suitably sized tube stub with a flange at one end.

 

Something like these https://www.ventilationland.co.uk/en_GB/roof-terminal-slab/1547/

OK, so you found it quicker than I did! That's exactly what I used. Probably took me longer because I didn't know what I was looking for in the first place.