3 vs. 4 blade prop

[festivus]

so the brochure for the 2001 S22 says that the stock prop is the LH 13x13 3 blade.  I currently have a 4 blade fastened to the anus end of my v-drive.  The way I understand it is the 4 blade has a better hole shot and the 3 blade has better top end.  Is that true?  Does anyone run the stock 13x13 3 blade?  I am wondering because I have Bitzco's old 3 blade from his X22.  It is slightly damaged (Was that from launching at WIllard Bay) and I am considering having it repaired.  It would be nice to have a few more mph's at the big lakes-Powell, etc. The hole shot is more that enough for me anyways.
Pse Advise...

[Bitzco]

Man, you need all the hole shot you can get to get that big butt out of the water. Personally, I'd go with the ACME blade, but then you'd have to buy one.

[cyclone]

Festivus. For the rest of us. I love that screen name, always wanted to say that. Hey, on props, make sure that your V drive has the same prop rotation and shaft diameter as the  DD prop you have. From the literature I have seen, there were RH and LH drive props on direct drives. I assume they were all 1.0 in shaft dia.

As for Vdrives, off the top of my head I remember that one forum member (whiny David guy from Chicago who's since bought a Malibu) who had an SX, insisted that his prop shaft dia was 1.125. I've read that the SX and S22 used different transmission ratios, the SX had a higher ratio because it needed to pull weight. I do not know offhand the exact ratios, etc. It's probably on the Literature page but that doesn't mean it's accurate. 

 My orig Epic22 prop is LH 13x13 OJ 1 inch. I replaced it with an OJ 13x13 4 blade .080 (heavy) cup. It lost about 3 mph with a 4 blade, gained massive torque and driveability at low speeds and with weight.

Derek, you are the historian, wtf prop should Festivus use?


 My trans ratio is 1.23 It is a Hurth transmission, best you can buy. They used them in Detomaso Panteras, other exotics. 

[toyotafreak]

S22 is inch and an eighth. Don't know about SX. I do know that it's stamped on the prop, so look.

Spending one dollar on an OJ NiBral is too much. Wait till you want to spend the money, and get an ACME.

[Bitzco]

Just looking on the ACME prop site. They have a table with Nibral 3 and 4 blade specs, drive ratios, shaft diameters, etc for about every inboard boat maker. I'm too dumb to be able to read it, but there is info there if you want to convert to ACME or just need specs for your boat. Also, the SX drive is a one inch. I looked on my prop.

Here is the site for the table.

http://www.acmemarine.com/html/list.html

Here is the Toyota part of the table.

Toyota
Epic S 22 541 13 L 12 3b .080 C 209 13 L 12.5 4b .080 C 1" 1 - 1
Epic SX 541 13 L 12 3b .080 C 209 13 L 12.5 4b .080 C 1" 1 - 1
Epic X22 541 13 L 12 3b .080 C 209 13 L 12.5 4b .080 C 1" 1 - 1

[Bitzco]

Another bit from ACME's site.

Q: Which propeller should I choose, the Acme 3-blade or the Acme 4-blade?
A: Theoretically, a 3-blade propeller should always be more efficient than a 4-blade. However, in the past, two big issues have prevented the 3-blade from taking the lead in popularity. The first was a lack of manufacturing precision, which commonly caused 3-blades to vibrate more than 4-blades. When significant dimensional variation exists in a propeller, vibration is generally more noticeable in a propeller with fewer blades. The second reason for the 3-blade disfavor was an almost certain loss of blade area in the transition from four blades to three. Consequently, even though top-end gains were achieved, performance expectations on the low-end were diminished.
Through the implementation of precision manufacturing and design improvements, Acme Propellers are giving the 3-blade the reputation it deserves. Acme is consistently holding tolerances never before achieved in propeller production. This accuracy makes the Acme 3-blade incredibly smooth. In addition, the blade area of the Acme 3-blade has been expanded to equal that of the Acme 4-blade. The translation? The Acme 3-blade has raised the performance bar. From an awesome hole-shot to an unmatched top end, and all the smoothness throughout, the Acme 3-blade leaves nothing to be desired. We believe it has an edge that everyone will appreciate. On the other hand, please do not mistake our excitement as a lack of appreciation for the Acme 4-blade, a proven winner.
It should be noted that this choice might still be mildly influenced by application, because it is possible that the most perceptive users might be able to detect slight differences that cause them to prefer one prop over the other. Even still, the overall performance of either Acme Propeller is paramount, and is that from which dreams are made.

[toyotafreak]

Here's how it seems to me:


First, you must actually read the stamping on your current prop. Let's ASSUME that it says 13 x 13 LH and 1".

Second, what's your wide open throttle RPM with THAT prop at YOUR lake? Let's ASSUME you're at high altitude and your WOT RPM falls 500 rpm short of your engine's 6000 rpm redline. (Leaves you over-propped 500 rpm).

Third, do you want to correct for the over-propping/altitude? Let's ASSUME you do. (Just means that if you come down out of the hills, you'll be turning higher rpms and burning more gas - rev limiter will take care of your potential redline problem at lower altitudes and high speeds).

Fourth, do you want to prop for normal use or for pushing 3K out of the hole?


Based on these assumptions, here's what you do: "Hey ACME, I'm currently running a 3-blade OJ NiBral 13x13 LH 1" tapered bore prop. At my altitude, it's 500 rpm too tall because I can only reach 5500 rpm with my 6000 rpm engine."

Next, you add either, "I'd like to prop this to get my 500 rpm back so I can reach 6000 rpm at WOT", or.... "I'd like to correct for the over-propping, PLUS, I want to be able to come out of the hole with 2 to 3K in the boat."

When I finally make that call, I'll ask for them to figure out the first (get the 500 rpm back unballasted), THEN when they come back with an answer, I'll ask them how much change from that prop they'd recommend for the ballast adjustment. This way I'd know they weren't skipping/overlooking the 500 rpm.

That's just me. I'm anal like that.