Prop choices for RD-22

[FishMagnet]

My RD-22 still has the original prop on it. Unfortunately its got a lot of large nicks in it and I would like to replace it.<br /><br />What is the standard prop diameter and pitch that came with the motor? And what is a reasonable replacement choice? I use it mainly to get where I need to go for fishing, but occasionally like to punch the throttle for a little fun.<br /><br />Also, seeing as it is the original prop is there anything I should be wary of or should know before I pull it off?<br /><br />Thanks,<br /><br />Matt

 

[Paul Moir]

Re: Prop choices for RD-22

See if you can still read the numbers behind the thrust washer, which is just behind the drive pin.<br /><br />Off the cuff, I think a 13" prop would probably suit. But without some tach numbers, that's only a guess. A 12" might give more kick.<br /><br />The diameter is the resposibility of the prop designer. Brand new, I belive there's only two manufacturers; Bombardier and Michigan prop (Michigan Match propellers). Either-or.

 

[CATransplant]

Re: Prop choices for RD-22

Most of those 40hp motors came with a 10 3/8 X 13 prop as the stock prop. It's a pretty good choice in general and will give you a good hole shot, but may encourage too high revs on a light boat.<br /><br />I'm running that prop on an old 35hp motor, and it works very well, but I don't get quite up to the rated RPMs. No worries, for me, since I normally just cruise anyhow.

 

[FishMagnet]

Re: Prop choices for RD-22

Is it possible to grind the nicks out, or am I asking for trouble by messing with the weight (balance) of the prop?<br /><br />Matt

 

[CATransplant]

Re: Prop choices for RD-22

You can grind the nicks out, but try to balance the grinding. Best bet is to get a new prop and save the old one, with the nicks smoothed off, as a spare.<br /><br />They're not expensive. Click "Props" here on iboats and use their propfinder. They seem to be selling the aluminum ones for $6? or so. You can also watch eBay. I got a brand spanking new one there for my 35hp for $12, plus another $10 for shipping. Lovely.

 

[FishMagnet]

Re: Prop choices for RD-22

Propfinder brings up some at $71.99 that would work. They don't have the 10 3/8 x 13" prop, I suppose anything close would be ok right?<br /><br />If I were to search on eBay for one are there any keywords I would want to use to make sure I'm getting the correct prop?<br /><br />Thanks,<br /><br />Matt

 

[CATransplant]

Re: Prop choices for RD-22

Stick with the 13 pitch, at least, though. It could be 10, 10 1/2, or 10 1/4 diameter, though.<br /><br />On eBay, it's a tossup on these props. You need to look for the diameter and pitch you want, then look at the prop. It should have the brass extension with the holes for the shear pin. A lot of people selling these don't know what they're for, so you have to dig.<br /><br />I just passed on two grungy ones at a garage sale today. Too much edge damage to suit me, so I let 'em go.

 

[CATransplant]

Re: Prop choices for RD-22

Any of these below would work: The 10 3/8 x 13 1/2 would be ideal, in my opinion, as long as your boat is not a real heavy weight. I sort of think that's the standard prop. My 35hp has a 10X13 on it and it works really well. If your boat is heavyish, then the 13 might be a better choice. If it's a real lightweight, then you might like the 14.<br /><br /><br />10-1/2 x 13 Standard 3 $71.99 <br /> <br /> 10-3/8 x 13-1/2 Standard 3 $71.99 <br /> <br /> 10-3/8 x 14 Standard 3 $71.99

 

[FishMagnet]

Re: Prop choices for RD-22

Thanks for the quick replies.<br /><br />My boat is a fairly light 14ft. aluminum runabout. I'll keep my eyes peeled and see what I can find.<br /><br />Matt

 

[Paul Moir]

Re: Prop choices for RD-22

If you can locate your local outboard junkyard, they'll have plenty too. And they ought to be pretty cheap allowing you to pick up a couple different pitches to play with. I don't know if I would bother with ebay for what they charge me at the junkyard. And then I get to have a close look at it.<br /><br />A final note on dumpster-diving: The real old fashioned props have a 'big eared' look to them. I wouldn't bother with them if I were you.

 

[CATransplant]

Re: Prop choices for RD-22

Paul's right. An outboard junkyard will have tons of those old pin-drive props, and most people consider them worthless.<br /><br />Just do a good poor-mouth routine and you should get them cheap. You should be able to get them in pitches from about 11 to 14, and that would cover the range for your boat. I'm guessing that your light aluminum boat would call for a 14" pitch in the 10 3/8 to 10 1/2 diameter. I run a 10x13 on my old 14.5' glass trihull, and it works just about perfectly, so you could prop up a bit, I'd think.<br /><br />Sad thing is that you can't get things like stainless steel or other fancy props for your Big Twin. However, keep an eye out for a bronze or brass prop in the right size and pitch. They're pretty sweet, and have some of the good qualities of a stainless steel prop.<br /><br />Back in the day, there were a lot of props available, but those days are long gone, with these fine outboard being over 40 years old, now.

 

[CATransplant]

Re: Prop choices for RD-22

Paul,<br /><br />I don't know. I have one of those old original 10x13 "big-eared" props on my RDS-20, and it's terrific. Great hole shot and good top end on my ugly old tri-hull. I wouldn't discount them.

 

[Paul Moir]

Re: Prop choices for RD-22

I'll give the 'ol 12 and 1/2 a try. I had just assumed it was old technology. Thanks! <br /><br />(I've wondered about rehubbing a stainless prop to fit a Big-Twin. There's non-thru-hub-exhaust props for the (80s) 28hp but only in 12" and a mere 9.25" diameter. Would a thru-hub-exhaust prop look too weird?)<br /><br />I think I would pass on a brass/bronze prop. They were the "High performance" props of the 60s, but they're really hard on the gearcase.

 

[CATransplant]

Re: Prop choices for RD-22

I think it's worth a try. Old tech for old outboards, perhaps. Those Big Twins are torquey sorts of engines, and the broad cross-section of those old props might just suit them very well.<br /><br />I've had several folks on my boat, and all of them have commented on how quickly it planes off and how fast it actually goes at WOT.<br /><br />Some of that is pure surprise on their parts, I expect, but I think the prop design has something to do with the hole shot. It might not work as well on one of the modern 35hp outboards. I don't know.<br /><br />I do know that that old RDS-20 is rated at just 4500 RPM. Maybe that plays a role in prop design, too.<br /><br />My dad's old Fat Fifty has a brass or bronze prop on it. Worked a treat at jerking four teenagers up on two skis on his 16' Glaspar Avalon. So much for all these folks claiming that you have to have a huge motor to ski behind.<br /><br />Really, I suspect that prop designers were working to get the max out of those old engines, back when they were the biggest things available.<br /><br />I'd give that "big ear" prop a spin.