wrote in message
oups.com...

I'm looking for first hand experience if possible before buying
various props to find the best match for my 1988 Wellcraft Antigue
265.

I've used prop calculators and everything recommended for this boat
comes up as 14.5x15 to 23.

Currently I have a 14.5x17 on her. Top speed is about 30 in calm seas
and cruising speed is 26.

She seems to take a while to get on plane, but I'm used to a 20 foot
boat, this is a recent move to a 28 foot boat for me. Based on what
the previous owner told me, if there are 3 to 4 people on the boat he
would sometimes have to have them in the cabin to get on plane.

I'm wondering if I can use the trim tabs to assist in getting on
plane? I'm also wondering if I should increase the pitch?

My reasoning for that is with the 17 pitch top speed isn't to much
higher than cruising speed. So I wonder if it's possible the
additional weight reduces the speed from getting on plane.

The motor is a 5.7 with 260HP and it doesn't bog down at all when
throttling up. I'd also imagine with a higher pitch the engine could
be backed down to stay on plane and increase fuel efficiency.

Thoughts?



Is your current prop "cupped"?

Nope, not cupped as far as I know, it came with the boat. And yes, I
believe this boat had a big block option.

So I drove down to the marina yesterday evening and did some WOT
tests.

3800 RPM's @ 36 MPH. It was increasing slowly so I think I could have
hit 40MPH @ 4000 RPM's. The previous owner would hit 38MPH top speed
but the fuel flow meter would indicate 1.9MPG. I was pulling 2.15MPG
and that tells me she had more left in her.

I thought I had posted I think it's over pitched. Now that I have
these numbers and plugging them into prop calculators I'm seeing a
16x14 should be the best option.

I'm going to give that a try when I get a chance. I think the engine
is working to hard to get up to speed. This would cause carbon build-
up, pre-ignition, and may even score the pistons and cylinders.

Dropping to that pitch should increase RPM's to the 4400-4800 power
band and the increase in diameter should help with torque. The more I
think about it the more it sounds like the thing to do.

You can figure that each inch in pitch dropped will bring you about 200 rpm.
A 16 from a 17 may not be enough. Imho, if you tested alone you want to
shoot for the higher end of the range so that when you are loaded up with an
extra thousand lbs of friends and gear you're still in the ball park.
Dropping pitch will definately help with the hole shot. A cupped prop may
provide more lift but when comparing props consider that cupping is roughly
like an extra inch of pitch. So a cupped 16 is about the same as a
non-cupped 17.

wrote in message
oups.com...
Nope, not cupped as far as I know, it came with the boat. And yes, I
believe this boat had a big block option.

So I drove down to the marina yesterday evening and did some WOT
tests.

3800 RPM's @ 36 MPH. It was increasing slowly so I think I could have
hit 40MPH @ 4000 RPM's. The previous owner would hit 38MPH top speed
but the fuel flow meter would indicate 1.9MPG. I was pulling 2.15MPG
and that tells me she had more left in her.

I thought I had posted I think it's over pitched. Now that I have
these numbers and plugging them into prop calculators I'm seeing a
16x14 should be the best option.

I'm going to give that a try when I get a chance. I think the engine
is working to hard to get up to speed. This would cause carbon build-
up, pre-ignition, and may even score the pistons and cylinders.

Dropping to that pitch should increase RPM's to the 4400-4800 power
band and the increase in diameter should help with torque. The more I
think about it the more it sounds like the thing to do.

He's not going with 16 pitch...he's going with 16" diameter and 14 pitch.
Sounds right. I'd also have iot cupped.




"jamesgangnc" wrote in message
ink.net...
You can figure that each inch in pitch dropped will bring you about 200
rpm. A 16 from a 17 may not be enough. Imho, if you tested alone you want
to shoot for the higher end of the range so that when you are loaded up
with an extra thousand lbs of friends and gear you're still in the ball
park. Dropping pitch will definately help with the hole shot. A cupped
prop may provide more lift but when comparing props consider that cupping
is roughly like an extra inch of pitch. So a cupped 16 is about the same
as a non-cupped 17.

I missed the drive in the posts? If it's a merc I'd guess it's a bravo. 16
won't fit on an alpha. That's a noticable increase in diameter but I agree
14 pitch is a better place to start.

"Steven Vaughan" wrote in message
...
He's not going with 16 pitch...he's going with 16" diameter and 14 pitch.
Sounds right. I'd also have iot cupped.




"jamesgangnc" wrote in message
ink.net...
You can figure that each inch in pitch dropped will bring you about 200
rpm. A 16 from a 17 may not be enough. Imho, if you tested alone you
want to shoot for the higher end of the range so that when you are loaded
up with an extra thousand lbs of friends and gear you're still in the
ball park. Dropping pitch will definately help with the hole shot. A
cupped prop may provide more lift but when comparing props consider that
cupping is roughly like an extra inch of pitch. So a cupped 16 is about
the same as a non-cupped 17.

That's odd. The Mercruiser web site is the one that recommended the
16x14 prop after I plugged in all the specs. Are you sure it won't
fit?

I'll do some more research. I'm going to see if I can find anybody
local that can do a try before you buy toward a prop.

I/m pretty certain that anything bigger in diameter than a 14.5 inch is too
big for the alpha leg. Look at the clearance between your current prop and
the plate above it. On all the ones I've looked at a 14.5 is pretty close.
I think a 15 might fit but I'm not thinking a 16 will.

I don't know that I'd put much faith in web prop calculators. Most people
change based on what prop they have and what is wrong with it. In your case
you are overpropped and probably need to go down about 4 inches in pitch.

wrote in message
oups.com...
That's odd. The Mercruiser web site is the one that recommended the
16x14 prop after I plugged in all the specs. Are you sure it won't
fit?

I'll do some more research. I'm going to see if I can find anybody
local that can do a try before you buy toward a prop.