I posted a question about my beat up prop a few weeks ago and i have another question. I went on a fishing trip two weekends ago and my friend has what looks like the same exact Mercury Outboard that i do. His is a 2003 model and mine is a 2009 model. His is 50hp like mine and everything from the lower unit to under the cowl looks the same. Only difference is the stickers on the cowl are a little different color.

His boat is a 16ft alumacraft and mine is a 16ft Tracker PT 170. His boat came from the dealer with a 4 blade prop, mine came with a 3 blade prop.

I have read in the past that a 4 blade prop helps with hole shot where a 3 blade helps at top end, correct me if im wrong. Does that mean that if i was able to use a 4 blade like his that i would lose some top end? His boat was faster than mine but mine has lost some top end speed after having some of the blade missing from that stump i hit.

Im asking because im going to replace my prop with a new one and im going to keep my current one as a back up in case of an emergency. I plan on doing this in the next few weeks when i do all of my other stuff like fogging the engine, impeller replacement, lower unit oil change, spark plug change etc.

i think it depends on the hull and weight being carried.
if the boat is HEAVY then a lower pitch 4 blade will help the holeshot. And yes, the 4 blade (lower pitch) will be slower on top end.

i still like the 3 blade sst props on that rig. and your 09 motor will use the wide blade design. not the older style blade.

You are not wrong in your assumption on the 3 and 4 blade thing. As a rule of thumb you can get a 4 blade that will do 3 different thing. 1st increases the hole shot by lifting the stearn of the boat, 2nd prop will lift the bow of the boat, and 3rd the prop will lift the entire boat...
So lets review....
1st 4 blade prop would help for shallow water hole shots, that being like a boat used primerly in the flats.
2nd 4 blade prop is designed to hold the bow of the boat higher like that of a high prefromance bass boat. This style prop would increase speed by decreasing the amount of surface contact on the hull to the water.
3rd,,4 blade prop would be used where you need the entire boat lifted, like those of a ski boat. You need the boat to stay on plane at a lower rpm. You are not looking for high performance nor are you looking for tremendous hole shot but something that does both.

After this basic prop rendintion. You get into speciality props like those for extreme motor elevation, clever/chopper props for racing, cupping/double cupping/Texas cup/finger lay for really grabbing the water like a mud grip tire on steariods.
This is my rendition as to explaining the different styles prop. And even at that, I'm no expert.

You sound like an expert to me Good info!!

what is the wide blade design? is that a certain style of a 3 blade prop? I keep forgetting to look at my prop at home to get the numbers off of it

there are 2 versions of the 50hp + props.

one is the original blade
the other is a little wider and longer at the bottom of the barrell.
the wide blade won't blow out on the holeshot and cornering.

all the later model mercs need the wide blade. from about 05 and newer.