[mikeyt]

Note that these are general rules of thumb only and do NOT apply in ALL cases.

Whatever your recommended WOT (Wide Open Throttle) RPM range is, your best performance will be at the top end of that range. Having WOT rpms below the range causes your engine to "lug" (work harder) while going above the range causes excessive wear & fuel use. Going slightly over the range wont hurt as long you dont run the engine at WOT for any length of time.

Lower pitch = faster holeshot, better planing ability, increased rpms, lower top speed. (ie pulls tubers/wakeboarders/skiiers better)

Higher pitch = slower holeshot, slower planing ability, lower rpms, faster top speed. (ie better for cruising etc)

3 blades are generally the most efficient props. 4 blades provide extra bite but cause extra drag which usually results in a slightly lower top speed & slightly higher rpms when compared with the same pitch 3 blade. Depending on the application though (ie tubing/skiing/wakeboarding vs cruising) the extra blade is well worth it.

Cupped blades provide extra bite & reduce ventilation as well as allowing you to trim up just a bit more. They also reduce the effect of pitch change. For example: a 19" cupped blade should top out like a 20" or even some 21" non-cupped blades w/out the loss of holeshot/midrange performance. A good prop shop can also modify your prop to provide some cupping.

Aluminum is the least expensive prop material for general use and provides good performance.

SS props costs more but usually provides slightly better performance.

Composite props (IMHO) are good for spare "get me home" props only.

For most of our boats consider adding a pair of Nauticus Smart Tabs. Boats up to about 22ft can use the SX versions and anything over that should consider the metal versions. They are inexpensive to buy (under $150), reasonably easy to install yourself (if you can use a tape measure and a drill properly) and once installed provide benefits such as faster planing time, being able to plane at lower speeds, reduced (or even eliminated) low speed wander, eliminate porpoising and gain improved handling. Do a site search for "Smart Tabs" and see what many of our members have to say about them!




* Recommended WOT RPM Ranges for Mercruiser Sterndrives (note this is not a complete list for all model years, just a general guide).

Model HP WOT RPM Gear Ratio
3.0 L 135 4400-4800 2.00
4.3 L/LX 180/190 4400-4800 1.81
4.3 MPI 205 4400-4800 1.62
4.3 L EFI 210 4400-4800 1.62
5.0 L (A1) 220 4400-4800 1.62
5.0 L (B1) 220 4400-4800 1.65
5.0 L MPI (A1) 260 4600-5000 1.62
5 0 L MPI (B1) 240 4400-4800 1.65
5.7 L (A1) 250 4400-4800 1.62
5.7 L (B1) 250 4400-4800 1.65
5.7L EFI 260 4400-4800 1.47
5.7L EFI 260 4400-4800 1.65
350 Mag MPI (A1) 300 4600-5000 1.47
350 Mag MPI (B1) 300 4800-5200 1.50
350 Horizon 300 4600-5000 1.50
MX 6.2 MPI Horizon 320 4800-5200 1.65
MX 6.2 MPI 320 4800-5200 1.65
496 Mag 375 4400-4800 1.50
496 Mag HO 425 4600-5000 1.50


* Recommended WOT RPM Ranges for Volvo Penta Sterndrives

Model HP WOT RPM Gear Ratio Drive
3.0 GS 135 4200-4600 1.97 SX
4.3 GL 190 4800 1.66 SX
4.3 GXi 225 4800 1.66 SX
5.0 GL 220 4800 1.51 SX
5.0 GXi 270 5000 1.51 SX
5.7 GS 260 4800 1.43 SX
5.7 GSi 280 5000 1.43 SX
5.7 GXi 320 5000 1.43 SX