Prop for 2012 187 w/4.3 I/O

NEboater28

Hello, I'm new to the forum and recently purchased a new (leftover 2012) SD 187 w/ a mercruiser 4.3 MPI i/o 220hp. I'm considering re-propping the engine for a better hole shot (skiing). I'm leaning towards a 4 blade stainless steel prop. I'm having trouble finding the current prop diameter and pitch for my engine. Are these dimensions standard on this engine? If so does anyone else have this engine that can forward me these specs? Also has anyone on the forum put a 4 blade on this engine/boat? If so, any suggestions? Thanks!

Ernest_T

I replaced the 3 blade prop on my boat with a 4 blade for better hole shot, but I have an outboard.  I went with a SS PowerTech prop.  They have a worksheet on their website that will help you find the right prop for your needs.  I used their worksheet to narrow down the choices, then called them and spoke to one of their reps. who further narrowed down the choices.  I've been really happy with their prop.  You might want to check with Mercury.  They make some excellent props, and I'm sure they could help you find a 4 blade.

In order for anyone to be able to help you upgrade props, there are a few basic things you will need to know, like max rpms of your engine, and current top speed, your current prop size, planning speed with your current prop, etc.. You will get an idea from the worksheet.  They don't have to have everything, but the more info the better.  The prop size and pitch should be stamped on your current prop.  There is not necessarily a specific engine and prop combination.  Each manufacturer props the engine to hopefully match their specific boat.  Here is a link to Mercruisers performance reports for that boat:  http://www.mercurymarine.com/engines/engine-tests/third-party/?ID=206&71290.52524297666

One thing I learned when prop shopping is that the whole thing is somewhat of a guessing game.  That is why it is a good idea to find a company that has a return policy.  You may find a couple of props that you have to try out to find the best fit for your boat and engine combination.

nquirk

Ernest T is right.  It's a bit of a guessing game.  If you check out the link he provided, you'll also see under Propellers a Propellor Selector. (http://www.mercurymarine.com/propellers/prop-selector/#)  This will give you a starting point of the ranges/options to consider in both 4 and 5 blade props suitable for you application.  It won't be perfect, but will narrow a range that you can work with.

You'll need some specifics on your engine and current performance to help narrow this down.

NEboater28

So I've had a chance to break in my boat and do some testing. 

With 2 people on board (myself and the driver), full tank, with smooth water, I'm showing the max RPM at 4800 and then over-rev protector jumps on.  There's still throttle left in the stick.  My speed is 48mph. 

I rarely go open throttle so loosing a few mph on the top end doesn't hurt me.  I'm looking for pick up and go for water sports.  Don't think i'm ready to drop $900 on a high5, so I think a 4 blade might be my fit.  I'm really not getting a ton of advice from the mercury site.  They recommend a few 3 and 4 blade props 15" with 15 pitch...  I know hurricanes are heavy boats, but that seems like a low pitch.  Am I wrong?? I know most of the forum members have OBs.  Any I/O's out there have luck with a certain prop??? 

nquirk

You certainly will notice the difference with a 4 or 5 blade prop so moving to a 4 blade will help with hole shot as well as maintaining speed (maintain grip) through turns if your doing watersports.

According to the link above on engine performance, 4400-4800 is the recommended top WOT range so minus a 1 degree of pitch either way, there isn't much room to play.  What is your current prop pitch? 

NEboater28

I wanted to follow up with my original post. I replaced my 19 pitch 3 blade aluminum stock prop with a 4 blade SS Stiletto 18 pitch per the recommendation of the online prop shop. It was a total slug... Hole shot was worse, top end suffered. I went to a local prop guy, he suggested I try an 18 pitch merc aluminum 4 blade. I tried it and the hole shot is about the same. Benefit is that my turning and water sports have better grip and mid-range acceleration is better. Unfortunately, I'm over reving a bit, and the rev limiter kicks in around 4900 rpms. The prop cut about 3 mph off my top end to about 46 mph. I'm still looking for the hole shot. The search continues... If anyone has suggestions let me know. Anyone interested in a Stiletto Bay Pro 2, 18 pitch for cheap $ used once, let me know.

nquirk

@NEBoater28.  Sorry to hear of the results.  Top end speed will always suffer at the expense of 4/5 blade props but as you've stated its they are ideal for watersports.

I'm surprised that the hole shot was worse.

cjjjdeck

I have a Bravo 3 drive, so I won't be of much help here.

Knowing that top speed will be affected further, with his continued "over-revving" condition still existing with a 4 blade 18 pitch prop, isn't he still under pitched?

It's always ends up being a "balance of compromise" when it comes to playing the prop pitch game.

avalanche

I just saw this. I posted to different topic (alarm triggered when under speed). My 2013 Hurricane 188 220 hp Mercury Alpha I/O came with a 23"pitch 3 blade prop. I could not get on plane until I reached 30-35 mph and had a hard time pulling tubers. But my top speed was 55-58 mph. we did not need that speed.My local Mercury dealer and I tried some other props (4 blades and 21"pitch. Slight improvement. Then we tried a High Five 5 blade with 19" and put on Smart Tabs SX80. What an improvement in hole shot and plane(now we et on plane at 17 mph). Our top speed dropped to about 45 mph at 4800. We also have to be careful not to over rev but boat is great now. Hurricane and dealers should spec more appropriate props. But we love the boat.

nquirk

@avalanche.  Thanks for the input.  I have the High Five 19" and I'm considering the SX80 for next season to allow me to stay on plane at lower speeds.  Good to hear the results on a 188.

ruwet2

Going from memory here but I think it is accurate....2010 202SS 4.3 Merc.

Replaced my 21p 14.25" alum Solas 3 blade (48 top end, poor hole shot, weak mid range - not sure on rpm's - this was with an empty boat) with a 19p 15.625 SS 4 blade Merc. Revolution 4. Now top end is lower 40's fully loaded - hole shot is good but mid range is excellent! Thinking the rpm's are now around 4450? 

NEboater28

Boat is back in the water The prop search continues. Thanks Avalanche, we have the same boat, so that's helpful. I added the trim tabs, and didn't see the best results (see my other thread). I hit up a prop guy from another site and he said for my boat, the high 5 was the way to go. Now I just need to gather some money one.

avalanche

NE Boater-. Do u have an I/O? As I said in my post from last Sept 2013, the High 5 19" pitch and the SX 80 smart tabs improved whole shot and ability to plane at lower speeds for my 188 220 hp alpha drive. We have set at middle setting. Let me know if any questions.

NEboater28

I do have an I/O, with the 4.3 220hp. So I'll def be looking for a high 5, thanks!