2005 SX 19 4.3l 190hp Prop Selection

adamsrrl · 09-14-2010, 07:17 AM

Hi,

We have just purchased an SX 19 with 4.3L Mercruiser and what I believe is a Bravo leg. I am looking to purchase a stainless steel prop. We use the boat mainly for waterskiing and wake boarding, as the boat has been anti fouled I cannot retrieve any numbers from the prop so have no idea what pitch I need. I would be grateful for any help on determining the best pitch for our use of the boat.

Many Thanks
Ross

***indykoch*** · 09-14-2010, 03:02 PM

First, I'm doubting you have the Bravo One outdrive. They're usually coupled with engines above 300 hp. Of course, I could be wrong - but I think you have the Alpha One.

There are a few prop selection tools on the internet, but they aren't perfect in helping select a prop. Depends on what you're looking for. Do you want great hole shot for watersports at the expense of top speed? Do you want better efficiency and higher top speed at the expense of hole shot? Do you want good all around? Another thing is your elevation. Are you high in the mountains where there's little oxygen?

My suggestion would be to take notes of your performance with the existing prop. What are the RPM's at WOT? What's the speed? How's the hole shot? Then examine the prop for any stampings that would let you know what size it is. Even if the prop is painted (?) you should be able to see the stampings somewhere around the hub or even inside the hub on one of the ribs. Knowing what you currently have and what you're looking to accomplish would help tremendously. I usually see 19 pitch props on that size boat/engine, but you may want a 17 for hole shots, 18 pitch 4 blade for hole shots and a little all around performance, 19 for speed and economy???

I wouldn't suggest the expense of a stainless prop until you know exactly what you have/want in size.

adamsrrl · 09-14-2010, 03:38 PM

Thanks for the reply Ryan,

I have checked the prop again and it is a 21 pitch, I think the rpm at WOT was around 5000. The reason I wasn't happy with it was I didn't feel the boat was pulling the skier out of the water with ease. We usually use the boat at sea level or not far over, would you suggest a lower pitched prop?
Also I have been looking at 4 & 5 blade props would this affect what pitch I need opposed to a normal 3 blade?

***mikeyt*** · 09-14-2010, 03:57 PM

You need to know exactly what your rpm's at WOT are before we can give you an exact answer but i really dont suspect you are at 5000 rpms with a 21" pitch prop on there now. The recommended range for your engine is 4400 - 4800 rpms at WOT. As Indykoch pointed out, I would suggest you confirm your rpms first but the likely scenario to improve holeshot with a skiier/wakebarder etc would be to install a 19" - 3 blade or 4 blade prop. The 4 blade will give a little extra 'bite' at the expense of a couple of mph off your top speed.