[Nick Flint Posts: 4853 Status: Offline]

Sorry if its basic, but have you the correct rotation? i.e. is the aerofoil section correctly orientated?
In the past this has been found- so mention in passing.

[A S T Posts: 18 Status: Offline]

Hi
   The craft is struggling for lift and forward motion,i dont know if the angle is correct and if increasing or decreasing would push more air. I wondered if you guys with experience might have had some thoughts on it.

[Philip Posts: 2436 Status: Offline 12" above the Earth's surface WWW]

I suspect the original angle was best so go with that.

[A S T Posts: 18 Status: Offline]

Hi yes original.

[Philip Posts: 2436 Status: Offline 12" above the Earth's surface WWW]

Hi What angle is optimum on blades for max thrust,at the moment,they are set at 32.5 degrees???.

Which blades did you fit? Same as original?

[A S T Posts: 18 Status: Offline]

Hi What angle is optimum on blades for max thrust,at the moment,they are set at 32.5 degrees???. 

[Ian Brooks Posts: 3550 Status: Offline]

Try here:

https://www.beatson.co.uk/industrial-fans/axial-impellers/

No-one uses these today, so I have no  details for them. But hopefully you'll be able to get replacements. I'd be tempted to replace the whole lot, the others may be old and have gone brittle.

Ian

[A S T Posts: 18 Status: Offline]

Hi i was working on Skima today,tried to up load pics but the file is to large,the blades are London Fan Company,310mm long x 62 tapering to 50mm set at 32.5 degrees,3 have been damaged.Have you come across the type of blade??.i will take a lower resolution pic to let you see the damage tomorrow.

[A S T Posts: 18 Status: Offline]

Your so right,ordered new drive belt tonight will take some pic's when we try to fit it.

[John Robertson Posts: 5121 Status: Offline WWW]

Yep - loose stuff is a problem when you've got a big fan sucking whatever it can (plenty people have made the same mistake!).

You'd need to check which type of fan it is - I've no idea what was fitted back then.  Maybe post a few pics (close up of the blades and any ID marks?).

[A S T Posts: 18 Status: Offline]

Hi John the cause was a loose guide rope drawn in, lesson learned,the reason we have the craft is to check the mooring,they are buried in very deep mud,are new blades available,this could 35years old?

[John Robertson Posts: 5121 Status: Offline WWW]

... and recovery - best to operate on water as recommended as it makes recovery much easier (tow to slipway, back trailer into water and float craft on - then rinse trailer thoroughly, unless you want to brake/hubs to seize solid ).

[John Robertson Posts: 5121 Status: Offline WWW]

Depends on how big a chip it is and how fast the fan runs.  Probably safer just to replace it (and carefully check the other (lift?) blades and hub for hairline cracks).  Any idea why the belt broke?

[A S T Posts: 18 Status: Offline]

Hi I was out on the mud with the Skima today,unfortunately the drive belt snapped and an out edge on one of the fan blades was chipped, its a 12 blade fan,can the blade still be used ??It was a challenge to get a 17ft craft out the sea and on a trailer with no power.