[Alberg30] 2 blade prop

Mike Lehman sail_505 at hotmail.com
Wed Apr 9 19:29:55 PDT 2003


Jim brings up a great point. If you motor more than sail, the 3-blade will
always have a blade cutting the water. Whereas a 2-blade will have two
blades cutting; then two blades hidden behind the dead-wood. The 3-blade
will always have a least one blade cutting and have more power and control,
but you will sacrifice sailing performance. Like all things with a boat,
there are compromises, as John Birch stated earlier. You choose.


----- Original Message -----
From: <quest433 at msn.com>
To: "Alberg 30 public list" <public-list at alberg30.org>
Sent: Wednesday, April 09, 2003 7:24 PM
Subject: Re: [Alberg30] 2 blade prop


The real issue driving the 3 blade vs 2 blade trade is how much motoring
your going to do.  The 3 blade gives you driving power thru the waves and if
your more apt to be motoring than sailing then 3 it is.  It's remarkable the
difference in power you get into the water.  That's what I found after
changing to a 3-blader when I sold the boat.  The whole story goes that I
couldn't get the boat above 5 knots and when I sold it the surveyor told me
that the boats supposed to have a 13" propeller--which it had until I paid
someone $100 to re-condition the prop.  Did I tell you I owned the boat for
20 years so the prop change was dramatic.  You'll find that with a 3 blade
you can slow you engine down and go faster than with a 2-blader.   So this
is my spin on 3 v 2.

----- Original Message -----
From: George Dinwiddie
Sent: Tuesday, April 08, 2003 10:43 PM
To: Alberg 30 public list
Subject: Re: [Alberg30] 2 blade prop

Yves,

I would keep the old 2 blade.  In fact, I've done so.  The fact is, when
in reverse you've effectively got a large fixed rudder and a small
moveable keel, because the waterflow is reversed.  No prop is going to
change that.  Instead, you should learn how to use what you've got.

To make the boat turn well, you need water flowing past the rudder, and
that means the boat has to be moving.  Going forward, you can motor
slowly and the prop will add to the water flow.  In reverse, you need to
be moving faster, so give it a good jolt of gas.

Then, you don't want to be going too fast, so shift to neutral and let
the boat's momentum carry you.  In fact, I like to give a smaller burst
of forward, but not enough to slow the boat down.  It seems to help the
waterflow across the rudder.

It works, but because of the prop walk, you'll find the boat wants to
turn in one direction (bow to starboard, stern to port).  Use that, and
choose to turn that way, even if you have to turn further.

  - George

Yves Parenteau wrote:
> I'm a first time boat owner and just wondering if I should replace the 2
> blade prop for a 3 blade right away before the boat hits the water. It's a
> $600 dollars expense I could do without right now. any comments please( I
> concern about reverse capabilities )

--
  ----------------------------------------------------------------------
   Hope your road is a long one.                        George Dinwiddie
   May there be many summer mornings when,       gdinwiddie at alberg30.org
   with what pleasure, what joy,                 http://www.Alberg30.org
   you enter harbors you're seeing for the first time;
                                            from 'Ithaka' by C.P. Cavafy
  ----------------------------------------------------------------------

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