Prop recomendations 290 drive Rt or left cupped etc

"looking for just some more th

"looking for just some more thoughts recomendations or possibly just your experiences on props/
I have a 86 Sunrunner 210 with the Volvo aq151 and the 290sp drive 2:15 ratio. long hub.
the boat came with the wrong prop when I got it, it now has a left handed 14x19 aluminum (michigan)short hub prop, yes it has a short hub prop on the long hub shaft. at 3/4 throttle it will peg the tach at 6k. my max rpm should be 5500.
now I grabbed a nicely priced right handed michigan stainless SSV prop on ebay but it is a 14.5 x21 and it is a cupped prop (what ever this means) I figured this would be too much for it and I was looking for a 14x21 but this was cheap. and yep it is too much, it now will max out at 4800-5k rpm but is real slow out of the hole. my assumption is I need a 14x21 but what does Cupped blades do and does anyone have any experience with the design of the long and short hubed props? it looks like the short hubed prop has much less blade area then the long hubed props? so could a long hubbed 14x19 be ok even though what I have now is too small?"

"on another note, with the lef

"on another note, with the left handed prop the boat will not ride level, with the rt handed it does, althought the rt handed prop steers a bit harder over all handling was much better, the boat tends to tip real bad with the left handed."

"Short hub/long hub:
The long

"Short hub/long hub:
The long hub was introduced to handle the torue from V8 and diesel engines. In Your case not importance.
Left/right rotation:
Depends normally on doat design and configuration. Boats with steering on starboard side normally runs straighter with a right hand prop. To compensate for steering forces, adjust the trim tab behind the propeller. Loosen the screw and turn it the same side as the boat pulls.
Cupping: The rear end of the blades are bent 'up'. It makes the prop hold better to the water and not spin out to easy in turns or if the installation is mounted to high. In Your combination probably non effect at all except that You may loose some 50 - 100 rpm and top end speed.
If You have the 'old' small bladed 14 x 19 I would rather go for the newer long hub with wider blades and same dia and pitch."

"thanks,

so my thoughts are

"thanks,

so my thoughts are probalby right the same pitch and diameter prop in a long hub version will likely drop the rpms. but by how much, I need to drop probalby 700-1000 rpms, the 14.5 x21 in stainless dropped it too much about 1500-1700. do you know or have any experience on just changing diameter and rpm changes?? if I stay the same pitch what will diameter changes do to rpm? basically I know this is a touogh question, but I would hate to get a 14x19 and still over rev, but then again going a 14x21 may also be too much?? I guess its a trial and error choice. Ideally I want to pick up some speed but don't want to kill the hole shot.
I did adjust the trim with both right and left props, I can get the boat to trim ok but with the left prop it will not ride level, it tilts"

"Similar design (area/cupp

"Similar design (area/cupping etc) change the rpm 200/inch pitch, and 100rpm/inch diam. I suspect You have the small blade short hub and it is next to impossible to give a straight answer. However if we use the SST 14,5 x 21 as refference, You would probably gain about 500 -700 rpm compared to that."

"Jshick,

The stainelss ste

"Jshick,

The stainelss steel propeller blades do not "flex" as much as aluminum when the boat is running. This explains why you obtain more speed from a stainless propeller than from an aluminum propeller of the same pitch and diameter, and why changing from aluminum to stainless brings a drop in engine RPM.

When it comes to propeller diameter, more diameter increases thrust and efficiency (cuts down slip) but does not necessarily increase speed.

Small blade area and large blade area are independent of the long or short hub. Propellers with larger blade areas are for applications where thrust is more important than speed, and the opposite happens to props with small blade areas.

Cupping a propeller is "bending" the blades at the end of the trailing edge. This reduces cavitation and as a rule of thumb it virtually increases the pitch by 1" or 5% when compared with an identical uncupped propeller. Cupped propellers are far more efficient at higher speeds than uncupped propellers.

The maximum speed for your engine is 4800-5500 RPM, so your current stainless steel prop is correct from the perspective that will not overload the engine. However, you must keep in mind that a propeller giving you the best top speed will normally not give you the best hole shot. There is a trade-off. If you want better hole shot you will have to go for less pitch or for a different blade shape. It is a matter of experimenting until you find a propeller giving the performance you want. Many times it is a matter of going to a propeller shop or a dealer and borrow a few used propellers so that you can find which one works best in your boat by trial and error."