Prop question

[eggsuckindog]

Originally Posted by hugo

i have a 20 sf and 200 mercury, ive been running a aluminum blackmax prop 19p 14 1/2 diameter and it has always run pretty good, I have just fell into a quicksilver SS Mirage prop that is also 19p but the diameter is 15 1/4
would this be a good upgrade or not? any of you more experianced guys have any insight for me?

thanks.

you will probably need to raise the motor to let it work, they are pretty aggresive and have alot of dia

[hugo]

good point, i also just added a bracket to the boat. havent had it in the water yet but i did set the motor up 2 1/4 inches over the bottom of the hull with a 27 inch set back. i can up one more hole and be maxed out going up. think i should go up to the last hole or try it their?

[eggsuckindog]

there is a rule of thumb for bracket set back but I'm not sure what it is - I think its 1" per 12" - so probably. Like I said I'm not familar with setting up brackets

I did have a local memeber contact me about trying my prop, he has a 23 and tried a Mirage and he said he didn't like it at all, so they are not the instant panacia I guess

[hugo]

well i guess im just going to try it and see if i can see the cav plate above water and see how it performs, funny thing is befor the bracket i had treid a few diffrent props from freinds and none worked as well as the old beatup ugly bent aluminum one i got the boat with. i will try the mirage and if i dont like it i will try the old one again and maybe just by a new replacment. we'll see.

[eggsuckindog]

I have Merc Vengence 19" pitch that was on mine for 4 yrs I'm selling for $75 as its just collecting dust and I have seatow, cleaning out the garage as I'm moving - I also put up my Lee outriggers and bases rigged for $175 which are basically new work for gunnel mounts

I have a box to ship

[hugo]

what is the diameter of the vengance prop?

[eggsuckindog]

It doesn't say but I presume 14 1/2 best I tell - hard to measure I can get the part number though, the Mirage is a monster at 15 1/4 most everything else is 14 1/4 - 14 1/2. My 200 would get it to 5400/5600. Its not as agressive as the Mirage or the Stilletto - which are what they call progressive pitch - no sure exactly what that means but my Stilletto is a bear to swing and needs to be very high and I think its only 14 1/4

[DonV]

You are correct Dog, the Merc web site says 14.5" for the Vengance.

[Fr. Frank]

Originally Posted by eggsuckindog

...Mirage or the Stilletto - which are what they call progressive pitch - no sure exactly what that means

Progressive Pitch means the angle of attack on the blade increases from front to rear. It is essentially a slight cupping of the entire blade from front to back, not just the last bit of the trailing edge. It provides, in part, for greater stern lift at the hub, while retaining some bow-lifting properties at the tips.

Progressive Rake is an increase in the angle of the blade from inner to outer, that is, moving from the hub to the blade tips. It is also a cupping of the entire blade, but from hub to blade tips, rather than front to back. It provides a increase in surface tension, allowing the blade to run partially surfaced without ventilating.

Both the Mirage and Stilletto have dual progression, with the emphasis on pitch progression.

[eggsuckindog]

great explanation and to that extent thats why my Stilletto was harder to turn and wouldn't turn up until I raised