Working on boat/prop comination

[jrampey]

I'm a new owner of a 2007 Q6. Previous owner had less than 30 hours on the boat and had to sell as part of a divorce settlement - bummer for him. Anyway, I've had the boat out three times now and still need some more time to calculate the correct props to purchase. First time out I had the original aluminum 21 pitch prop. Did not have a GPS so couldn't get an accurate calculation. RPM's were 4500 and 43 - 44 mph. Second time out I borrowed 2 ss props, a 19P 4 blade, and a 24P 3 blade turbo. The 19P is obviously too little pitch - I hit the rev limiter at 5200 easily! The 24P worked great... still did not have the GPS, but hole shot was ok, and top end was 48 - 49 mph at 4800 rpm. Was only me and the dog on a 2/3 tank of fuel. This prop is ventilated - about 1/4 in hole behind each blade.
After reading numerous posts I bought Smart Tabs and put them on last week...
Third time out was yesterday... for a party. With 4 in the boat, 24P prop and the smart tabs - pulled 1 skier up easily. but a little slow with some revving before the prop finally hooked up. Later I took 7 people for a cruise and the boat was slow to pull up on plane but once up cruised at 35 - 40 easily. I didn't have an opportunity to wind it out...
My observations sofar -

Tahoe Q6 4.3l carburated 190 hp
1.81 ratio
smart tabs
typical load 4 people pulling 1 or 2 skiers

I'm going back this week to get some more numbers with the GPS, smart tabs and tach... I'll fill in some blanks and ask some advice next week.

 

[Paul DuLaney]

Re: Working on boat/prop comination

From the looks of your numbers how about a 21p ss?

 

[jrampey]

Re: Working on boat/prop comination

OK, here's more data...

21P aluminum 3 blade, 2 people, 30 gals fuel... 5000 rpm's GPS 44 mph - Good holeshot with smarttabs added since last try. By the way - speedo indicated 48. Smarttabs increased topend 4 mph by speedo and improved holeshot significantly!

24P SS 3 blade same load 4600 rpms GPS 46 mph - holeshot OK with 2-but from experience Saturday (7 people really slow to plane and overrevving)

I need something different. I'm thinking loose the vent holes, 22P SS - maybe 4 blades? The prop slip calculators show both of these props at approx 20% slip! I had a bassboat with 4 blade 19P 150HP outboard ventilated - great holeshot with 8% slip... can I get close to this?

 

[Paul DuLaney]

Re: Working on boat/prop comination

I beleave that you gain about 200 rpm for every 1 deg of pitch. I'm running a Merc 150 hp ob turning a Trophy Plus 21p vented four blade that Jay Martin from bassboatmagizine.com tweked it to get rpm up to 5600-5650.I know that were talking two diffrent beasts here but the basics are the same.If you have a GOOD marina that you trust get three props and try them out if you want to buy it from them. If not go to mercury.com,their link on props put in your info and it will get you real close.In my case Trackers info has mine at 51-53 mph tops,It's running 55-59 depending on load and hope to break the 60 mark when I take all my gear out & run it later this fall.Hope this helps a little good luck and have fun.

 

[mandopickr]

Re: Working on boat/prop comination

I went to a SS Mercury Laser 2 13 7/8X21, and it gave me 5200 rpm. I haven't pulled skiers yet, but have pulled two tubers, with two people in the boat, full tank and of course have had four people in the boat cruising.

As I remember, I think it was 50 mph (gps) at 5200 w/ four, and 30 mph at 3200 (my normal cruising rpms). HOle shot was fine, though a skier may have made a difference.

I'm sorry I can't remember the exact details, since I normally run by myself. I do remember that I considered this prop to be the correct setup for my boat (06 190 q6sf).

 

[Paul DuLaney]

Re: Working on boat/prop comination

It sounds as though your in the top of your rpm range so when you add skiers this should be the right combo. If your hole shot is not that goog try moving 1-2 people to the bow of boat/trim tabs or vented prop. Have heard that KN air filters is making a marine app.havent heard if it helps or not. At times boats can seem to be a never ending money pit, it can be if you let it. Just know your limits if not your better half my know theirs before you.Good Luck I'm a moderator on bassboatmagizine.com stop in and check it out.

 

[mccownk]

Re: Working on boat/prop comination

I have the QL 14.5 dia 19P aluminum amd it performs great. I just installed smart tabs and will let you know the final numbers next time out. With this prop the boat has a great hole shot and plenty of power at top end. With four peole and a full tank it cruised at around 3200 rpm and WOT was around 4500. I will try and get MPH and more accurate numbers next time out.

 

[jrampey]

Re: Working on boat/prop comination

Thanks guys for your input... I bought a 4 blade solas 21P... weather's been lousy and I've been swamped with work... so I haven't seen the lake. I'll let everyone know my results when I finally get back on the water.

 

[Q6SFRuss]

Re: Working on boat/prop comination

You all appear to be pretty happy, but I'm not there yet. I have a 3 blade, 21 pitch, SS prop that I bought, and I'm not happy with hole shot. I have carburated 190 HP engine. Hole shot is fine with skiers on two skis, but too slow with me (220 lb) being pulled out on one ski. Perhaps God is telling me to stop skiing, let my kids do the skiing, and go to just fishing. Not sure yet.

I'm thinking of going to a SS 3 blade prop, 19 pitch. From what I've read above, it looks like I might have to be careful not to over-rev on NON-skiing hole shot. Did someone say that there's an RPM limiter, or is it strictly a driver-imposed limit?

 

[mccownk]

Re: Working on boat/prop comination

I've got the Q6 with the 220 hp MPI motor. You can check out my post on the smart tabs install and it's got all of my performance data. I've got the 19p aluminum and it performs excellent. No problems with over revving. Not sure of the difference with your 190 hp model. The smart tabs made a big difference in performance, especially the hole shot.

 

[jrampey]

Re: Working on boat/prop comination

Boy, this lousy winter is really getting on my nerves... I haven't been able to get this boat in the water since getting the new prop back in October. I gonna need prozac if we don't get some boating weather soon!

 

[jrampey]

Re: Working on boat/prop comination

Finally got back on the water... I tried out the 4 blade 21P Solas aluminum prop... 46.5 mph by GPS at 4600 rpm. Great holeshot with 2 people and dog, full fuel tank and 200lbs of batteries. This may be the one! This equals the 24P SS with better holeshot!