[Public-List] Public-List Digest, Vol 3998, Issue 4 Two blades prop

[aldworthfamily at cogeco.ca]

The prop will “windmill” with the engine in neutral. The vessel is moving forward under sail and water is flowing past the prop. With the 3 bladed prop, there will always be enough prop. surface area exposed to keep it spinning. I think with a 2 bladed props, they tend to lose thrust when in the shadow of the keel. 
I have a larger motor vessel and if we shut down one engine, that prop will windmill when we are underway. 
Does this sound right Gord?
Greg 

Sent from Mail for Windows 10

From: Greg Hounsell via Public-List
Sent: April 26, 2020 6:49 PM
To: Alberg 30 Public List -- open to all
Cc: Greg Hounsell
Subject: Re: [Public-List] Public-List Digest, Vol 3998, Issue 4 Two blades prop

I don't understand how a prop would cause rotation when in neutral. Is
there a strong tide or current?

Greg
#592

On Sun, Apr 26, 2020, 6:06 PM Daniel Swords via Public-List <
public-list at lists.alberg30.org> wrote:

>     The PO of my boat had replaced the original two blade prop with a
> three blade prop, but fortunately had saved the original. I disliked the
> three blade so much that I paid to have the boat hauled just to replace it
> with the original two blade.
>
>
>
>     If left in neutral the three blade spun continuously and noisily and
> created enough turbulence to feel through the tiller. If left in gear
> (something Yanmar recommends against) the transmission would lock-up with
> even the slightest forward motion such that the safety interlock would
> prevent starting the engine.     As far as I can tell the two blade prop
> does not spin in neutral and typically parks vertically behind the keel.
> Also, I did not notice any significant advantages with the three blade prop
> so I gave mine away and have never considered going back.     Currently
> sailing on Lake Pontchartrain, winds 15 gusting to 19 knots, double reefed
> main and 110% jib. Daniel SwordsSolitude, Hull #525Mandeville, Louisiana
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