Propeller

[dmr]

6 minutes ago, David Mack said:

If the OP has a LH prop rotating RH the boat will be going backwards. Surely the effect you describe could only arise if the prop was fitted back to front. And that could only happen if the manufacturer has bored the taper from the wrong end of the boss. Unlikely I think.

 

There used to be an ongoing joke at the Southampton Ford Transit factory about "Friday Afternoon Vans" so maybe you can also get a Friday Afternoon Prop  😀

[MtB]

18 minutes ago, dmr said:

A very few engines rotate backwards

 

Ahem, modern engines rotate backwards!

 

The Gleniffer, viewed from the helm and looking forwards along the length of the boat, rotates anti-clock and has a LH blade, as does my Samofa. The kelvins, being a forward-looking company rotate clock though, as does your JD3 IIRC. 

 

Anyone here know which way a Gardner LW rotates? It's not easy to tell just by looking at one, as the flywheel is enclosed.

[dmr]

3 minutes ago, MtB said:

 

Ahem, modern engines rotate backwards!

 

The Gleniffer, viewed from the helm and looking forwards along the length of the boat, rotates anti-clock and has a LH blade, as does my Samofa. The kelvins, being a forward-looking company rotate clock though, as does your JD3 IIRC. 

 

Anyone here know which way a Gardner LW rotates? It's not easy to tell just by looking at one, as the flywheel is enclosed.

 

But the front pulley is exposed 😀 (or is this your joke in retaliation to mine?)

I think I read that Kelvins were available both forwards and backwards?

Honda engines always went backwards, bloke I used to work with had a little Honda sports car (a mgb gt type thing), the engine failed so he put a morris minor engine and gearbox in, guess what happened?

[Split Pin]

3 hours ago, MtB said:

 

Ahem, modern engines rotate backwards!

 

The Gleniffer, viewed from the helm and looking forwards along the length of the boat, rotates anti-clock and has a LH blade, as does my Samofa. The kelvins, being a forward-looking company rotate clock though, as does your JD3 IIRC. 

 

Anyone here know which way a Gardner LW rotates? It's not easy to tell just by looking at one, as the flywheel is enclosed.

LW'S were available in handed pairs if required so it all depends on where it originated from.

Normal roation is clockwise when viewed from the non flywheel end

Edited October 3, 2021 by Split Pin

[MtB]

2 hours ago, Split Pin said:

Normal roation is clockwise when viewed from the non flywheel end

 

Which of course depends which end the flywheel has been fitted! Or did you mean for the Gardner LW specifically?

[Split Pin]

24 minutes ago, MtB said:

 

Which of course depends which end the flywheel has been fitted! Or did you mean for the Gardner LW specifically?

I was answering your question about LW's

[Maudesmaster]

7 hours ago, Loddon said:

What reduction is the gearbox? 

They come in four different ratios:

Model.     Ratio

500D1.5   1.459:1

500D2     1.935:1

500D2.5  2.565:1

500D3     2.904:1

 

A 500D3 will spin the prop at half the speed of a 500D1.5

 

With a 21x18 I would think that a  500D2 or a 500D1.5 would be required.

D2 pretty sure will check Wednesday when back on boat the prop is Left hand the boat goes forwards when gear box is in forward 

[ditchcrawler]

12 hours ago, MtB said:

 

Even then, no it couldn't. If you turn a fan blade (or propeller) around on it's shaft it still blows the same way if you think about it. (You will have turned the blades through 180 degrees.)

But the leading edge would trail and the trailing edge lead

[MtB]

35 minutes ago, ditchcrawler said:

But the leading edge would trail and the trailing edge lead

 

And????

[ditchcrawler]

5 minutes ago, MtB said:

 

And????

It probably wouldn't work so well as the blade leading edge is designed different to the trailing one unless its an Axiom or whatever they were called.

[blackrose]

On 03/10/2021 at 23:30, ditchcrawler said:

It probably wouldn't work so well as the blade leading edge is designed different to the trailing one unless its an Axiom or whatever they were called.

 

Yes, a propeller blade is not generally symmetrical either in shape or cross section. The leading and trailing edges perform different functions.