You should not go down in pitch from the 19 to a 17 by going to a 4 blade.
The 4 blade should be a smaller diameter (13.5 or so). This compensates for
the extra blade in terms of top end rpms. You will loose a couple mph on
top end w/ a 4 blade due to extra drag but the overall acceleration and
handling make up for it unless you are really into top speed.
You will notice a big drop going to a 17 from the 19. Sounds like the prop
shop has a 14.5 x 17 x 4 that they want to get rid of. You want a 13.5 x 19
x 4 SS in your application assuming your rpms are within 300 of max for your
engine.


--
Tony
My boats and autos - http://t.thomas.home.mchsi.com



"Rich" wrote in message
...
If you want the boat to run at optimum performance thru out the entire
operating range - go w/ a good 4 blade SS for your application. You
won't
believe the difference.

I've been talking to a prop shop about changing from a 14.5 X 19 X 3 alum.
to a 4 blade SS prop. The shop recommended a 14.5 X 17 X 4 but said that
I
would loose 3-5 mph from the top end, I guess because of the drag of 4
blades. Is there any other size 4 blade that won't cut the top speed?

TIA
Rich