Prop Search

[croSSed]

I have a 17' Cee Bee Avenger Mach II w/ an '87 Merc 2L XR2 150. With a jack plate and the prop shaft about 3" below the pad (no lwpu) I'm getting 70-72 mph at around 5800-6000 rpm (depends on the day). Over the winter I'm dropping on a 2.4L 175 power head. The Laser II (oddly) is the fastest prop I've tried on my set-up, and I tried at least a dozen speed props - Choppers, Trophy's, a Power Tech Tempest copy and others. That 175 is going to be turning up 6400-6600 rpm with the same set-up. I don't want to rev it that high, if I can avoid it. These older stainless speed props are getting hard to find, and 27" of pitch is the tallest Merc ever made in the Laser II. I'll still be running the 150 2:1 lower. What other suggestions do any of you have? Thanks, and Merry Christmas!

[LakeFever]

Have you tried a small ear chopper?

[croSSed]

Have you tried a small ear chopper?

Yes. I forgot to mention, with all the speed trials I've done with my boat one of the things I discovered is that my boat needs BOW lift to get best top speed. The small ear chopper couldn't carry the bow well enough, and because I'm running with one blade on the surface (instead of two like a chopper needs to really run like it's supposed to) it wasn't as fast. One prop I've not tried is a straight-up big ear chopper.

[OnPad]

I'm impressed at the speed your getting with your laser prop! What pitch?
Not sure about prop advice for your gear ratio, running at that depth. Tempest works well on my bass boat at 3" down, but I have a faster gear ratio, and am only running 70.
I guess if I had any advice it would be to think about a 1.87 gear case, or lwp, or both.

From what I've read, the closer you can be to 1.5×diameter of propeller, with your pitch, the more efficient it is. Seems like the drag race guys have this figured out. Doesn't work out for the guys using fishing engines to run light weight boats, without revving em up.

[croSSed]

I'm impressed at the speed your getting with your laser prop! What pitch?
Not sure about prop advice for your gear ratio, running at that depth. Tempest works well on my bass boat at 3" down, but I have a faster gear ratio, and am only running 70.
I guess if I had any advice it would be to think about a 1.87 gear case, or lwp, or both.

From what I've read, the closer you can be to 1.5×diameter of propeller, with your pitch, the more efficient it is. Seems like the drag race guys have this figured out. Doesn't work out for the guys using fishing engines to run light weight boats, without revving em up.

Yeah, I know! I did all of this testing between 2008 and about 2012 when I first picked up the XR2. I had a Garmin hand-held gps, and at the time I was running a small dia. 26" Laser II. The motor was turning up almost 6400 rpm. I thought it might be prop slip, but when I looked at the gps it said 72.3 mph. I thought that couldn't be right, so I reset the gps and ran again...Same result. I tried a different gps since then...same result. The boat is maybe 2 cases of beer heavier than 800lbs, so there's that.
I'm kinda thinking comparing drace boats with this is a bit like comparing apples to oranges, and yes we're talking about a fishing motor. Another thing that seems to be true with this little boat is that small diameter props (aka, Laser II) tend to run faster. Back when I was first doing these tests there were dozens of props for sale out there and that's why I could try so many. Now-a-days the used prop market has seemed to have dried up.
What about these new Pro Max props?

[OnPad]

I hear the promax props are decent, don't have one. I've got choppers, cleavers, e.t's, drag, trophy, tempest, laser, mirage, fury, mazco's, and a few more. I do the best with 28p 4 blade over the hub props on my bullet and ltv. Running fishing engines with lwp, and 2" above pad.
3" down is a different world.

[Tomanytoys]

Raise your motor and watch your temperature & water pressure.
When your temp starts to climb & your pressure starts to fall block off the top half of the factory water inlet.
Depending on how much setback you’re running you’ve probably got at least 1-1.5” you can go up before you’ll start to have any issues.

[LakeFever]

Tomanytoys is right. My Vandal does not have a lwp either and i raised it with above method and ended up going down one hole further. I ran the scoops on on water intake. I tried a lot of props but a small ear with extra trailing edge cup was the winner.

[OnPad]

There's a weird zone between even with the pad, and 2 1/2" down. Seems like you lose bow lift. Probably because your no longer bringing water over the centerline of bullet, and it starts pushing the bow down. I've also had some extreme cavitation and slippage in that zone. Particularly with trophy, and drag prop.

Often think a transom mounted water pickup would be a good way to go. Cheaper, lighter, and faster. The Bobs cones I run, add a good 20lbs to your lower. You will need to think about a torq tamer if you start running much faster.

[LakeFever]

That must be what happened to me too. I lifted to a point where no prop seemed to bite on launch, at all. I had to attempt a few launches to get it to go. Dropped down a hole and its been there since. All good

[David - WI]

I think you should start with the Laser II that you know works on the boat... then go from there.

[David]

What about a small manual jackplate? A bit of setback will help carry the bow, and of course you can go up or down.

The usual suspect props for bow lift would be big ear choppers, Trophies, Tempest, Mazco RE4, Hoss Hyperdrive. Any of these could be sent to a prop shop to be worked for more lift, if needed.

you could also buy a new prop from Hydromotive, They can tune it for your needs.

[OnPad]

If you would like to take a road trip. Your welcome to try what I have, when the snow melts.

[croSSed]

To address a few comments here...I have a CMC hydraulic jackplate, and I have tested pretty extensively how high I can go before sucking air. It's at what I think is the best height - still taking in enough water to cool, still has enough of the prop in the water for it to bite and lift, and gives best top speed. I also have the top 4 holes plugged.

[OnPad]

Once you get the prop shaft above the bottom of the boat, (lwp) you start getting your bow lift back. It really becomes dependent on prop design at that point. It also requires alot bigger prop, or more blade surface.