Got my prop wrench (boating post)
 

I just got my brand new Yamaha prop wrench from an eBayer at a nice
discount. It's time for the painful (expensive) search for the perfect
prop. I know I need to drop the pitch by at least two inches. A cup
may be in order to improve the hole shot. The stock aluminum prop
doesn't "bite" quick enough and lacks in the top end by 750 rpm's.

The variables are endless - diameter, pitch, cup, venting, etc. so this
time I'm trying something new. I have a good idea of what the diameter
and pitch should be. I'll get a SS prop in that size and let the prop
shop tweak it for me. The one thing I know for sure is the F90 is best
suited for a three-blade prop rather than a four.

Once that is settled, I'm going to look further into the value of a
narrow jack plate. So far it looks like the hydraulic plates aren't
much more $$ than a manual.

Got my prop wrench (boating post)
 

On Thu, 12 Feb 2009 20:46:13 -0500, D K
wrote:

The one thing I know for sure is the F90 is best
suited for a three-blade prop rather than a four.

Three is always more efficient than four. Four blades is a way to get
the blade area in a smaller diameter, if you lack space.

Casady

Got my prop wrench (boating post)
 

Richard Casady wrote:
On Thu, 12 Feb 2009 20:46:13 -0500, D K
wrote:

The one thing I know for sure is the F90 is best
suited for a three-blade prop rather than a four.

Three is always more efficient than four. Four blades is a way to get
the blade area in a smaller diameter, if you lack space.

Casady


My admittedly limited experience with Yamaha taught me that the company
is pretty damned good matching up engines, props and boats, and that a
good dealer is also a valuable resource in prop selection. When I took
delivery of my 2008 model boat, the boat factory had just changed the
prop it spec'd for the boat and engine combo, upon a suggestion from
Yamaha. The factory sent me copies of performance print-outs for several
props. I was able to almost exactly duplicate the performance on the
factory print-out.

Almost every outboard boat I considered has performance sheets available
from the engine manufacturer, and those sheets specify props.

Got my prop wrench (boating post)
 

On Feb 13, 9:43*am, HK wrote:
Richard Casady wrote:
On Thu, 12 Feb 2009 20:46:13 -0500, D K
wrote:

The one thing I know for sure is the F90 is best
suited for a three-blade prop rather than a four.

Three is always more efficient than four. Four blades is a way to get
the blade area in a smaller diameter, if you lack space.

Casady

My admittedly limited experience with Yamaha taught me that the company
is pretty damned good matching up engines, props and boats, and that a
good dealer is also a valuable resource in prop selection. When I took
delivery of my 2008 model boat, the boat factory had just changed the
prop it spec'd for the boat and engine combo, upon a suggestion from
Yamaha. The factory sent me copies of performance print-outs for several
props. I was able to almost exactly duplicate the performance on the
factory print-out.

Almost every outboard boat I considered has performance sheets available
* from the engine manufacturer, and those sheets specify props.

Really? How did they know your exact requirements as far as weight,
loading fore and aft, etc.?

Got my prop wrench (boating post)
 

On Fri, 13 Feb 2009 11:03:39 -0500, wrote:

On Fri, 13 Feb 2009 14:32:34 GMT, (Richard
Casady) wrote:

On Thu, 12 Feb 2009 20:46:13 -0500, D K
wrote:

The one thing I know for sure is the F90 is best
suited for a three-blade prop rather than a four.

Three is always more efficient than four. Four blades is a way to get
the blade area in a smaller diameter, if you lack space.

Casady

Seagull has 4

I don't believe it is supposed to be a paragon of efficiency. That is
not it's strongest point, which is that the owner can fix it. Also, it
is built and used for low speed high thrust, that is, sailboats. For
the same horsepower, developing it at lower RPM will require more
prop. Within reason, a prop absorbs torque and is sized for it. It
doesn't know, or care, within limits, all that much about RPM. The
Seagull is a relatively low RPM motor if I am not mistaken. Evinrude
built a V-4 50 HP motor for the Navy during WWII. It was pretty basic,
like a seagull, and you started it with a rope. They used the blocks
for car racing motors after they were sold surplus.

Casady

Got my prop wrench (boating post)
 

On Fri, 13 Feb 2009 07:29:13 -0800 (PST), wrote:

On Feb 13, 9:43*am, HK wrote:
Richard Casady wrote:
On Thu, 12 Feb 2009 20:46:13 -0500, D K
wrote:

The one thing I know for sure is the F90 is best
suited for a three-blade prop rather than a four.

Three is always more efficient than four. Four blades is a way to get
the blade area in a smaller diameter, if you lack space.

Casady

My admittedly limited experience with Yamaha taught me that the company
is pretty damned good matching up engines, props and boats, and that a
good dealer is also a valuable resource in prop selection. When I took
delivery of my 2008 model boat, the boat factory had just changed the
prop it spec'd for the boat and engine combo, upon a suggestion from
Yamaha. The factory sent me copies of performance print-outs for several
props. I was able to almost exactly duplicate the performance on the
factory print-out.

Almost every outboard boat I considered has performance sheets available
* from the engine manufacturer, and those sheets specify props.

Really? How did they know your exact requirements as far as weight,
loading fore and aft, etc.?

They give you one in the middle of the range of props that are
individually ideal for one of the varying conditions. My sprint car
has a quick change rear axle. You can change the gear ratio in a
couple of minutes. There are three brands around, and they all have a
magnesium case. Stuff is brittle, but there are no impact loads. They
have variable pitch props for ships and planes.

Casady

Got my prop wrench (boating post)
 

On Feb 13, 1:24*pm, wrote:
On Fri, 13 Feb 2009 18:17:35 GMT, (Richard





Casady) wrote:
On Fri, 13 Feb 2009 07:29:13 -0800 (PST), wrote:

On Feb 13, 9:43*am, HK wrote:
Richard Casady wrote:
On Thu, 12 Feb 2009 20:46:13 -0500, D K
wrote:

The one thing I know for sure is the F90 is best
suited for a three-blade prop rather than a four.

Three is always more efficient than four. Four blades is a way to get
the blade area in a smaller diameter, if you lack space.

Casady

My admittedly limited experience with Yamaha taught me that the company
is pretty damned good matching up engines, props and boats, and that a
good dealer is also a valuable resource in prop selection. When I took
delivery of my 2008 model boat, the boat factory had just changed the
prop it spec'd for the boat and engine combo, upon a suggestion from
Yamaha. The factory sent me copies of performance print-outs for several
props. I was able to almost exactly duplicate the performance on the
factory print-out.

Almost every outboard boat I considered has performance sheets available
* from the engine manufacturer, and those sheets specify props.

Really? How did they know your exact requirements as far as weight,
loading fore and aft, etc.?

They give you one in the middle of the range of props that are
individually ideal for one of the varying conditions. My sprint car
has a quick change rear axle. You can change the gear ratio in a
couple of minutes. There are three brands around, and they all have a
magnesium case. Stuff is brittle, but there are no impact loads. They
have variable pitch props for ships and planes.

Variable pitch props and adjustable pitch props are two different
things.- Hide quoted text -

- Show quoted text -

Um, and adjustable pitch prop IS variable.

Got my prop wrench (boating post)
 

Got my prop wrench (boating post)
 

Got my prop wrench (boating post)
 

On Feb 13, 2:37*pm, HK wrote:
wrote:
On Fri, 13 Feb 2009 14:30:01 -0500, HK wrote:

wrote:
On Fri, 13 Feb 2009 11:02:00 -0800 (PST), wrote:

On Feb 13, 1:24 pm, wrote:
On Fri, 13 Feb 2009 18:17:35 GMT, (Richard

Casady) wrote:
On Fri, 13 Feb 2009 07:29:13 -0800 (PST), wrote:
On Feb 13, 9:43 am, HK wrote:
Richard Casady wrote:
On Thu, 12 Feb 2009 20:46:13 -0500, D K
wrote:
The one thing I know for sure is the F90 is best
suited for a three-blade prop rather than a four.
Three is always more efficient than four. Four blades is a way to get
the blade area in a smaller diameter, if you lack space.
Casady
My admittedly limited experience with Yamaha taught me that the company
is pretty damned good matching up engines, props and boats, and that a
good dealer is also a valuable resource in prop selection. When I took
delivery of my 2008 model boat, the boat factory had just changed the
prop it spec'd for the boat and engine combo, upon a suggestion from
Yamaha. The factory sent me copies of performance print-outs for several
props. I was able to almost exactly duplicate the performance on the
factory print-out.
Almost every outboard boat I considered has performance sheets available
* from the engine manufacturer, and those sheets specify props..
Really? How did they know your exact requirements as far as weight,
loading fore and aft, etc.?
They give you one in the middle of the range of props that are
individually ideal for one of the varying conditions. My sprint car
has a quick change rear axle. You can change the gear ratio in a
couple of minutes. There are three brands around, and they all have a
magnesium case. Stuff is brittle, but there are no impact loads. They
have variable pitch props for ships and planes.
Variable pitch props and adjustable pitch props are two different
things.- Hide quoted text -

- Show quoted text -
Um, and adjustable pitch prop IS variable.
Um, you are confused. "Variable Pitch Prop" is a technical term, not
common usage. It does not mean adjustable.

Just to step around the pile of Loogy**** left here, while my boat was
still being manufactured, I contacted the manufacturer and was put in
touch with the tech guys, who emailed a few prop-performance data sheets
to me, sheets from Yamaha and from tests they had run. Then, I had a
couple of phone discussions with Parker. In the end, I picked the prop
that most closely matched *my* parameters.

You shouda picked the prop that fit your BOAT'S parameters.

All the "possible" props fit the boat. They weren't *that* different.
One was a bit better match than the rest, producing a higher cruise
speed at my preferred RPMs.- Hide quoted text -

- Show quoted text -

snerk Is there a specific prop for a boat that stays on the hard all
season?