Another prop question

sixpacksummer

Just got a 212 captiva with 5.0L and alpha one drive. Had it out twice last fall and the boat ran at 5000 rpm and 52mph with a 21 pitch 3 blade prop. While the hole shot was fine for regular boating was a little lacking for skiing. Have contacted a reputable prop shop in Cincinnati, the only one. He recommends a four blade prop and gives me 2 choices. One four blade needs to drop the pitch to 19 to maintain overall performance. He claims for a little more money they have a Mercury four blade that will increase hole shot while maintaining wot performance and keep the pitch at 21. Assuming both of the above statements are true, my question  is is their an advantage to staying at a 21 pitch vs the 19 pitch when changing over to a four blade. Appreciate any feedback I can get as I am ready to make the change, just want it to be the right one.

212rowboat

there is a lot more to it than pitch, diameter, and number of blades... a prop with all those matching another may perform totally different than each other.  you can remove some elements of the crap shoot and get somewhat close, but you can't get solid data until you run various examples on your own rig... 

Handymans342

If you don't drop in pitch your motor will over rev

Cableguy Greg

I was told, which could be wrong, if you go to a 4 blade, drop 1 inch in pitch. So in your case, drop to a 20 pitch 4 blade prop. It should give you the hole shot without sacrificing your top end too much.

floater212

I have a 212 2005 with the rx1 package 350mpi, it came with a high five 21" prop which was ok but seemed slow on top end. after ALOT of searching I bought a Ron Hill ( California marina) pleasure prop 5 blade, larger diameter than the high five ( 14 1/4" vs. 13 3/8" high five) and in a 19" pitch, the Ron Hill prop has normal size blades as the high five are 1/3 skinnier than regular props, grabs more water. I would never change this prop, great hole shot for skiing, tubing and wakeboarding and top end is in the 45-48mph range. when we go skiing there are 10 people in the boat.

sixpacksummer

Thanks for the feedback. I have always heard you needed to drop the pitch going to a four blade. However, this shop is telling me the four blade from Mercury will perform at 21 pitch as the other at 19 pitch. My question is if that claim is true then is there an advantage of a 21 or 19 pitch if the performance is the same. So far consensus is that his claim is not correct.

nhsd

I also have a 212 with a 5.0 Alpha 1 Gen 2 drive. Mine is carbed so it is only 220 hp. I assume that yours is MPI given the speed and rev's. I use a 21 pitch Vengence SS prop and a 20 pitch Alpha 4 aluminum Mercruiser prop. The 21 Vengence gives slightly better top end (about 49) and the Alpha 4 is better at hole shot and, more importantly, holding plane. There are factors in a boat's performance that are at least as important as speed or hole shot. There is how slow can you still hold plane, best cruising speed, handling in turns and no-wake speed wander, among others. The relative importance of each of these is determined by how you use your boat. If you never tube or do water sports then I doubt that you would care much about slowest planning speed. If you have to idle through extensive no-wake zones then handling at that speed becomes important. While everyone wants to focus on getting that last MPH, very few people spend much time at WOT and spend far more time using the boat in ways that make other factors more important. For my use, the 20 pitch Alpha 4 usually is best. 

212rowboat

An an aside... The son of a friend just bought a new Monterey.. 22' and around 3500#... 5.0 mpi 260 up... 

Came with aluminum 19p 14.5" three blade merchant prop.  I let him try the pleasure five I run... We blew it out like it was nothing.. He's trying to stay away from wot until it's broken in with ten or so hours, so it's really hard to tell what it can or can't do, but the bow came WAY up and about 3/4 to plane the prop broke free and free spun until it bit again.   Too much power and too much heft for that prop.  Either that, or that Monterrey isn't much of a performer.  I would never have guess that prop was so much different on a similar boat as mine- which just drives this point home about different boats, different props, different uses and different conditions making huge impacts... 

I had a solas four blade in 23p I'm letting him have.. I forgot I had it.  He went back out today with his pops... I'm interested to see how it performs with that prop... I'm also thinking I may be prop shopping soon... 

sixpacksummer

As a follow up I purchased a Mercury Nemesis aluminum 4 blade prop, 21 pitch to replace my 3 blade 21 pitch. It was a rather inexpensive prop but the claim was no drop in pitch was required. Tried it out this weekend with two people on the boat and full tank of gas. 3 blade had decent hole shot with wot of 5000 rpm at 52 mph. New prop had significantly better  hole shot and wot of 5000 rpm at 55 mph. The hole shot was the important thing and it was noticeably better.

R_DAZE_OFF

SixPack - do you have all the specs on the Mercury Nemisis prop?  I know it says 4 blade 21p but what is the diameter?

randy56

@R_DAZE_OFF this guy has not been here for a long time, the post was May 2016

Cableguy Greg

@R_DAZE_OFF here is a place that sells it. According to the site, it isn't good for the 1.47:1 drive.

https://propshopinc.com/14x21rh-4-blade-quicksilver-nemesis-propeller-8m0055536-p691.html