.My 3400 lb 206 came with a REV4 14.65x19 SS prop. I do not want to change performance much, WOT is just at 4600 with my 5.0mpi. But I want comparable performance from an aluminum prop. The Chain eats props so I would like to get a few spares. A prop shop sold me a Solas 4 blade 14.5 x17 aluminum. Said it would get close, possibly giving me a couple hundred R's at wot . which would put me midstream in Merc specs 4600-5000.
It jumps on plane great but blows past 5g's to fast for every day cruising, will use for tubing and other toy towing. What can any of you suggest as a replacement, Merc offers an Alpha 4 but no one can give me any info on size/pitch locally. I would rather not have to buy 3 or 4 different size props to test if not necessary. I know it's a real science, the REV 4 was probably added for performace reasons in the first place. Thanks to all.

On the chain, you really need to run a SS prop - allum does NOT hold up well, while SS holds up fine to the silty/muddy bottom.

Talk to Jim @ Fox Lake Propeller - he is very knowledge, great prices, and is a very nice guy to deal with.

What engine do you have LILGUY? (edit: sorry I see its the 5.0) Just for a reference point, I run the Merc Black Max alum 3 blade my boat came with. I have a 5.7L EFI and turn a bit over 4600 rpms w/ a 21p but the last few hundred rpms take a while. I also top out at 49 -50 mph so if the tach is correct I have a good bit of slip. I had similar numbers with a 20p 4 blade composite by Piranha. The Piranha blades didn't hold up to the stress of slalom skiing though so its my emergency back up now. The Piranha blade design was quite different than the Black Max...you can see pics of both online...but the Black Max blades are bigger and rounder.

If I were to get anything else I get a 4 blade in a 19 or 20p.

Another note, there is a another recent prop thread on here where a Solas Rubex HR4 is referenced. They appear to run high rpms relative to pitch vs. some others...just my impression from reading various threads/forums.

Please let us know what you end up with/test and how they perform. I've wondered about the Alpha 4 myself, but have never known anyone that actually had one. Good luck.

Thanks for the info, Doc where in FL is the shop ?

Alpha 4

Either 14 x 20 or 141/2 x 18, pick what you want based on current WOT rpm. Also made in a 15 x 16.

Expect to lose a little top speed with the Alum.

Ever un-plug one of the vent holes and maybe play around with different plugs sizes and combos?

Please explain the plugs, this prop weights a least twice an alumn. How do you determine which of the above three to get.I aready own one I cant use except for heavy loads.

A Rev 4 from Mercury has plugged up holes in the hub. To get max performance, these can be "played with" to adjust the slippage such that the engine revs to a higher torque rpm so the water and exhaust gas flow runs at less than 100% thru the hub at start-up type speeds. With a smaller plug, some exhaust goes over-the-hub at low speeds.

This should be "played with" until the fastest hole shot for that given boat and motor can give with your typical load. Merc sells low cost plug kits to do this.

Many I/Os do not benifit from this. Some O/Bs do. You have to play with it.

Note, all plugs in all holes do not have to be the same on any given "play with".

Note, if you slip too much now on take-off--you will not benifit from "playing with" the plugs. They can only increase slip at low speeds when one exchanges the full plugs with one or all smaller ones.

Merc calls this system PVS = Performance Vent System.

F.Y.I. Volvo makes a great aluminum 4 blade prop. Not too spendy either.

You didn't mention whether your RPM was with a normal load or a light load. If you are just at the bottom of the RPM range with a light load I would go to the 18 pitch to gain a couple hundred RPM.

Dealing with a prop shop is really worth it. They will get very close to what you want on the first try and usually will let you exchange them if you need something different. That way you can really dial it in.

http://www.foxlakeprop.com/

See above, also they are about a half-block north of Grand on the east side of Rt 12.

Prop shop will let me exchange props as long as I don't damage them
Trying a 14.5/19 this weekend. Thanks gentlemen on FLP, nice to know where to get them fixed and modified first hand.

If I may pursue the PVS system a bit. I have 3400 lb Bryant 21 ft bow rider that just reaches 4600 at wot w/ 3 on board and 1/2 tank fuel(25 gals). I have a 5.0 mpi/alpha( 4600-5000 range). I would like to get a little higher rpms. If I fully load the boat I cant get to wot range.What exactly happens when you pull the plugs on the prop? What is slippage and how to measure it? Thanks

Try Dan's the site has a chart of whats available. Not affiliated in any way, just used them in the past and was satisfied.

dans discount props

I have the Alpha 4 blade 14x20. It was right on with RPM and only lost a few off the top end, but hole shot was much better. I liked the prop for water sports, but now carry it as a spare due to a minor brush with the rocks. Main prop is a 14.25 x 21 alum 3 blade.

Plugs (PVS) do not effect top speed. They effect hole shot if the engine, prop, and drive bog down somewhat on a given boat with full plugs.

Here is a "prop calculator": Link

Slippage is the % less than full theoretical distance the boat should travel per rpm with a certain pitch prop. For example if you are using a 21p prop, one revolution of the prop should theoretically move the boat forward 21 inches...of course in reality since a prop is spinning in a fluid to push the boat forward the distance traveled per rpm will be less.

Plug your known numbers into the calculator...pitch, drive ratio, rpms and speed and the calc will solve for slippage.

BTW, when I posted above about my 206 I was thinking you had the same boat as me, I forgot you have a Bryant, hopefully still somewhat relevant.

If I remove plugs i will get a better hole shot but not lower top speed?