Prop selection??? Mercruiser 4.3LX/Alpha One Gen 2/ Gear 1.81

[rhillman75]

So I have "combed" the internet to find out what prop was "intended" for my 1996 Sylvan V196 with a Mercruiser 4.3LX and a Alpha One Generation 2 outdrive with I believe is the 1.81 gear ratio. I simply cannot find anything! It had a 4 blade, 19P, 14.75" diameter last year that my wifey "smoked" in shallow waters. I had a back up which was a 3 blade, 19P, 14.75" diameter that I used, then I noticed one blade had a "through" crack (couldn't be repaired), that went to the scrap yard. Now I am left with the dilemma... "what the ???? do I use now? I know with the 4 blade, 19P, 14.75" diameter I was close to WOT rpms, operating at about 35 pmh, but if I wanted the most MPH (regardless of mpg), but within "safe" operating rpm range, where do you start? I have no marinas in the aea that offer the "try it before you buy it" oncept, so now I have a drive without a prop. Almost all of the "internet" prop selectors steer you towards a "lower" and sometimes a "higher" pitch prop at different blades and different diameters. Is there anyone that has the same setup as mine below? And if so, what is your starting point?

 

[smokeonthewater]

Re: Prop selection??? Mercruiser 4.3LX/Alpha One Gen 2/ Gear 1.81

the reason that you can't find "the intended prop" is that there is no such thing....

A 3 blade prop will usually be good for a couple more mph than a 4 blade but you will also gain a few rpm... my BET is that the 19" ptch 3 blade is a good speed prop.... 99% of the time you will get more top speed from a stainless prop than an aluminum prop.

I have used mercury's online prop selector several times and it has been VERY accurate for me on several boats.

http://www.mercurymarine.com/propellers/prop-selector/

 

[rhillman75]

Re: Prop selection??? Mercruiser 4.3LX/Alpha One Gen 2/ Gear 1.81

So my next question (maybe dumb!), but is mine a clockwise or counter rotation? I'm a little "new" in this category, since I come from building auto engines, so please be "soft!"

 

[smokeonthewater]

Re: Prop selection??? Mercruiser 4.3LX/Alpha One Gen 2/ Gear 1.81

clockwise

 

[Willyclay]

Re: Prop selection??? Mercruiser 4.3LX/Alpha One Gen 2/ Gear 1.81

Is there anyone that has the same setup as mine below? And if so, what is your starting point?

My son has a 1995 Ebbtide 192SE with 4.3LX and Mercruiser GenII. Dry weight listed as 2650lbs. He uses the Mercury aluminum three-blade 19P prop for cruising, tubing and skiing plus it runs 45+mph at WOT. Hole shot is not great but it is a good compromise. Hope this helps!

 

[Tail_Gunner]

Re: Prop selection??? Mercruiser 4.3LX/Alpha One Gen 2/ Gear 1.81

http://boatpropellers.iboats.com/Me...19.00-Pitch_Propellers/765/?*******=513212324


4 blade amita great prop.


Heres what you do..Get on the water with a normal load of people....Get a gps unit...run the boat at wide open throttle...take a note of rpm and gps speedpost back and everyone will comment with gusto..


Here's the ideal one gear in that boat so you gear the prop to the engine...the idea is to run a prop that allows your engine to run at 4800 at wide open throttle...From there one reads the gps speed to determine the actual slip going on...8-12 % slip is a good range....

Prop selection comes in several different form's..3 blade generally provide the best top end speed...4 blades generally provide the better hole shot and midrange performance....90 % of you boating occurs between 600 and 4000 rpm.

Then there are bow lifters and stern lifters..again most i/o's will benefit from stern lifting prop's which are 4 blades...It can be a very subjective topic and while those rules generally apply there always are exceptions.

 

[Whitey72]

Re: Prop selection??? Mercruiser 4.3LX/Alpha One Gen 2/ Gear 1.81

My 2 Cents Worth, I have just replaced my 3 blade stainless with a 4 blade Turning Point "Hustler" that I bought from here on IBoats. I have a 2006 Tahoe Q4 Ski/Fish with the 190 hp 4.3l v6. Same leg as yours with the same ratio. My previous 3 blade was a 13x19p and top end was 47mph but she was red lining and being rev limited at 5100rpm. I asked the question here and was pointed at the hustler and am extremely happy with it. I bought a 14x21p and my top end is now 45mph with the revs at 4800 and the boat is alot happier. The hole shot is also "awesome" as it drags my old fat body out of deep water on a single ski with now worries. Very happy with it and at only $100 plus postage is great. Hope this helps. Cheers from Australia, Whitey.