Need advice regarding prop.(SC19, 190HP)
 

Hello!

I own a 2005 SC19 with the V6, 4.3L, 190HP. I want to change the original prop. to a Michigan Ballistic steel prop. My problem is that I don`t know witch to choose. The boat does 39,40 GPS knobs with one or 6 persons, and the engine always engage the safetysystem regarding the rpm of the engine(lack of a better word). The instrument shows 5000rpm when this occurs.

I guess the prop. is standard. What pitch, diameter and number of blades should I choose?(I use the boat for cruising, and a little bit of wakeboarding. I want a boat that uses a little less gas(less rpm?) and posibility of tilting the Alpha One more than 90 degrees without a spin.(curved blades?)

Thanks in advance, guys!

Kyn

hi Kyn

I'm not sure what prop you already have installed on the boat but the fact that you are hitting 5000 rpms at WOT indicates that you do not want to lower the pitch any or your rpms will increase. I'm pretty sure the recommended rpm range for your engine is 4400 to 4800 so you are already above the limits.

I'm going to assume you have a 19 pitch 3 blade aluminum prop? You could go to a 4 blade, 20 pitch prop, preferably S.S., which would drop your rpm very slightly but give you more "bite" out of the hole and a little more mid-range 'oomph' which will help with wakeboards / tubers / skiiers etc. It shouldn't affect your top end either as the increase in pitch will offset going from 3 blades to 4 blades.

Let us know what prop you have installed on the boat now.

I checked the size of prop. today. It says 14.5 X 19P, it`s a black alu Mercury(Black Max?)

Do I need RH or LH prop.?

Ok. So the 4 blade, 20 pitch prop is a good option. You could also go with a 21 pitch 3 blade. The advantages will be a higher top speed (2 mph or so) and a lower rpm (around 4600 - 4700 at WOT). The disadvantages will be that it is slower coming out of the hole & it will have a little less mid range kick. I believe all single prop drives are RH.

As said earlier, a SS prop will outperform an equivalent aluminum prop. If you can find a prop vendor that will let you test run a prop then you have everything you need to sort her out quickly.

I have searched for Ballistic 4-blade, but no luck:-(
I see that the Ballistic 3-blade comes in these sizes: 14 3/8 x 21, 14 1/2 x 19 and 14 1/4 x 23. Witch one?

I have no possibility for trying these out as our(Norwegian) distributor/stores sell them for 1100-1300$/pice!!! So I buy from US:-) So: No chance to try!

Go with the 21 pitch prop then if you cant find a 4 blade - 20 pitch. I bought a Michigan Wheel "Apollo XHS" SS 14.25 x 20" pitch 4 blade thru IBoats.com for mine and it performs very well.

Thanks! I did a search on IBoats.com, but all they had in Michigan 4-blade was 14 1/8 x 20, so I think I buy the Ballistic 3-blade, 14 3/8 x 21P from http://www.deepblueyachtsupply.com/ (338$) Do you know of a better deal?(they have to ship to Norway)

Do you know if it is true that the Ballistic do not need a hub-kit?

All props need a hub kit. Michigan Wheel may supply hub kits with the prop, which is why they say you don't need one. This is very confusing, so make certain it has the hub kit!

From your explanation of everything, I think the 14 3/8 x 21p will be a great match. As Mikeyt stated - you'll lose a little response out of the hole, but should be a good compromise between hole shot and top speed. Let us know how you like it!

oops. The Apollo prop i bought was a 14 1/8" diameter not 14.25

Either the Apollo prop or the Ballistic will improve matters for you. The Apollo may split the difference between the 19" you have now and the 21" Ballistic. The Apollo comes with the proper hub kit.

Ok, then I found it at the deepblue-site for a little over 200 $. Do I have 4-3/4" Gearcase? It was not listed for Mercruiser/mercury engines, just as a standard dimention. (didn`t include hub-kit, costs 33 $ extra:-)

Will the 4-blade make my boat use less fuel? Or is it just for the akseleration-matters? What about those curved blades on the Ballistic vs Apollo? Any advantages/disadvantages? I really want to tilt my boat higher up at WOT/or near without getting spin.

Just for the confusion:-) This is cut from their site: Ballistic propellers have a pressed in hub, so you do not need the XHS Hub Kit with this propeller.