2-blade v. 3-blade

[OJ racer]

At some point I'm gonna get an x435 sized prop for my DF22, but I found out that OSE has a 3-blade prop with the same diameter and shaft size. Which would you reccommend for hydro, 2 or 3 blade prop?

[Steven Vaccaro]

Props are a very hard thing to recommend. One that works for one guy in the same hull, may not work as well for you. I know this isnt what you want to hear but the fastest guys have a range of props. Now obviously you don't need huge diameter props, but you might want to buy a few. One advantage of having a range will be changing speed and runtime. Its harder with a hydro, but for a mono, I can easily switch from a x646 in one of my boats for crazy speed but short runtime, to a x442 for more runtime and slower speeds.

[OJ racer]

At this point I'm running an x432, and I get about 5 minutes runtime. I would assume that 3-blades are faster but with shorter runtime?

[D. Newland]

This is some very general information as I don't know your setup.

3 blade props typically load the motor similar to a 2 blade prop that is a few sizes bigger. For instance: A 3 blade X435 may load your motor similar to a 2 blade X438. A 3 blade X440 may load your motor similar to a 2 blade X445.

Also a general statement: 2 blades are faster than 3 blades in a straight line, and 3 blades will hold the power in the turns better. 3 blades are more difficult to work on (balance).

The next size up in your case could be the X632 or X435 2 blade. If you feel your setup can be propped up, that would be the next step I'd take. If you've got more room after that, the Y535 is an option and the 3 blade X435 as well.

[OJ racer]

Thanks for the advice. I'm not racing at all right now so I'll probably stick to 2 blades.

[video200]

prop question

is there any of you gurues out there who can explane this to me ?
cmdi have a prop thats called 3861/4 were 38 is size. 61mm and 4 blades. but what do that realy work out to ? 61mm picth = 2,4 inches. but is that on all the prop with all 4 blades or on each blade ? figured maybe a 3861/4 could replace a X442 :D

tnx for all your help on all my wierd questions so far.

[Ub Hauled]

the this case (3861/4)
38mm = diameter of the prop
61mm = the pitch

pitch is identical on all the blades (or should be) and is measured by the distance that the prop moves forward, w/o slip, from the tip of the tongue to the end of the trailing edge furthest most tip.
Does that help?

[video200]

so the pitch = 2,4" but in all 4 blades so its twise as much to turn as a 2 blade of the same size ?

or roughfly 2X if this one ? X637 Total Pitch: 1.6x1.48=2.368"

[OJ racer]

Which prop is fastest: x632, or x435?