New Prop

[larr630]

Hi to All! I have a 94 Rinker 209 with a 4.3l i/o mercruiser. The prop that is on the outdrive is a 23 degree pitch mercruiser prop. I want to put a stainless prop on it with a lower degree pitch. I want a bit more power out of the hole and a bit more top speed. It takes quite a distance at 2000 rpm to plane up. I know the boat is heavy but does anyone have a suggestion on what degree prop to use? I cant find any charts or recommendations online. Any advice would be helpful ! have a great weekend everybody!:joyous:

 

[HT32BSX115]

Re: New Prop

Howdy,


Great prop question.......maybe a mod will move this to the prop forum!

In general, you want to have a prop installed that will produce an RPM at the TOP of the recommended max RPM range for your particular model engine.

If what you have doesn't give you max RPM, you're over propped. To find your recommended RPM range, have a look in your engine/drive owners manual. If you don't have one, someone here should be able to get the specs for your engine. (post the serial number of the engine)

Before you make any desicions though, you MUST verify your tach using a known or "shop" tach. They're frequently defective.......being off only 500 RPM at the top of the range can make prop decisions invalid.

Once you have a prop installed that gives you the 'right' wide-open-throttle RPM, it'll give you the best hole-shot possible for your engine.

Regards,


Rick


EDIT: now that was a fast "move" !!

 

[alldodge]

Re: New Prop

Hi to All! I have a 94 Rinker 209 with a 4.3l i/o mercruiser. The prop that is on the outdrive is a 23 degree pitch mercruiser prop. I want to put a stainless prop on it with a lower degree pitch. I want a bit more power out of the hole and a bit more top speed. It takes quite a distance at 2000 rpm to plane up. I know the boat is heavy but does anyone have a suggestion on what degree prop to use? I cant find any charts or recommendations online. Any advice would be helpful ! have a great weekend everybody!:joyous:

Agree with H32BSX115 but will add - I have a 232 rinker and I did what your talking about but have more cubes per weight. My 232 has a 7.4L and a 21 pitch prop on a bravo 1. I wanted to be able to pull more skiers at one time so I went to a 19 pitch. Tried 8 salomon skiers and 2 twin skiers and managed to get 7 and 1 up with the pull, what a great time, but I digress. The 19P worked very well but I could over rev in WOT. I knew this so I payed close attention when I was pushing it. So if your getting correct WOT with your current prop I would suggest getting a lower pitch prop and only YOU drive it when its on. Otherwise it is a whole bunch more money to get more HP. Your 20 footer should really have a 350 in it. A 350 makes it run like a banshee (another boat and time). It's all HP/weight ratio

 

[callen369]

Re: New Prop

A 23 is a lot of prop for that size boat/motor combo. Most 19-20 footers I have seen usually carry something around a 14-14.5 by 21. My 190 came with a 14.5x21, and was spot on for RPM's and had good pulling power. I switched to a turning point prop same diameter, but 4 blade, and dropped a few RPM, but still in range. They have a calculator on their site that lets you enter lots of info about your ride to spit out a size/pitch recommendation. Just punching in a few of your specs, it is spitting out a 14.25x21 stainless 3 blade. Your pitch recommendation will also depend on manufacturer as well, 21 pitch of one manufacturer can perform quite different than another's, so I'd suggest looking at a couple brands and using their respective calculators for selection. More power and more speed is quite a challenge, you usually sacrifice one for the other. I will tell you, I tried Turning Points Hustler Aluminum 4 blade, and picked up a little hole shot, and 1or2 top end. However, if your RPM's at WOT are a bit low, switching to a lower pitch prop will increase your hole shot, raise your RPM's, and will most likely keep your top speed since you will be spinning that lower pitch a bit faster.

 

[steelespike]

Re: New Prop

Depending on your present wot Rpm and gps speed you may be able to increase hole shot and speed but usually they don't go
together.

 

[callen369]

Re: New Prop

Too bad your not local, I'd let you slap on my old merc 14.5x21 3 blade just for kicks.

 

[jestor68]

Re: New Prop

According to the Mercury prop selector, the correct prop for your boat is a 19 pitch. There are plenty of SS props in that size.

The prop selector indicates that with a 19 pitch you should do about 43 mph @ 4600 rpm. Your rpm range is 4400-4800.

Google "Mercury Marine Prop Selector" to use their prop selector in the propeller section of the web site.

Your boat has a dry weight just under 2800 lbs. With 500 lbs of people/gear, and 35 gal of gas, it says 19 pitch. No need to guess. The standard engine is the 4.3L with a 1.81 gear ratio.

 

[HT32BSX115]

Re: New Prop

Most 19-20 footers I have seen usually carry something around a 14-14.5 by 21. My 190 came with a 14.5x21, and was spot on for RPM's and had good pulling power.

Of course it's ALL engine AND drive that determines what props you use.....

my "21 footer" Four Winns Liberator has 26P props and it will nearly jerk your arms outta the sockets if you can hold on!

But it's ALL BASED on the WOT RPM attainable. If your engine is running correctly and will make max RPM, you're propped correctly.

 

[callen369]

Re: New Prop

"1987 FourWinns 211 Liberator, 7.4L- Bravo III installed by ME, Formerly OMG 460 King Kobra powered
my "21 footer" Four Winns Liberator has 26P props and it will nearly jerk your arms outta the sockets if you can hold on!"

Yeah, well good for you, but this guy is asking about a 20 footer with a 4.3, and I highly doubt you run into many 26P props on such a setup, cause they would take all summer to get on plane.

 

[jestor68]

Re: New Prop

"1987 FourWinns 211 Liberator, 7.4L- Bravo III installed by ME, Formerly OMG 460 King Kobra powered
my "21 footer" Four Winns Liberator has 26P props and it will nearly jerk your arms outta the sockets if you can hold on!"

Yeah, well good for you, but this guy is asking about a 20 footer with a 4.3, and I highly doubt you run into many 26P props on such a setup, cause they would take all summer to get on plane.

I agree. :facepalm: That's not the only post in this thread that has nothing to do with a 4.3L powered boat.