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Author Topic:   Soliciting Propeller Opinions for 15' Classic/ 70 hp Yamaha
Peter posted 07-27-2003 12:25 PM ET (US)   Profile for Peter   Send Email to Peter  
I'm looking for opinions on a good propeller for a 70 hp Yamaha on a 15' Super Sport. I currently have a 13 x 19 Yamaha aluminum propeller that achieves a WOT speed of about 43 mph at 6000 rpm. I am wondering whether it would be worthwhile to move up to a stainless steel 21" pitch.
Sal DiMercurio posted 07-27-2003 02:40 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Is that engine a 4 stroke ?
Isn't it rated at 6,000 max rpms.
If you go to a 21p your rpms will drop to 5,600, you will loose top end speed, plus your hole shot will suffer, plus your engine will have to work harder, plus your fuel economy will go down.
Still feel you want to go to a 21p ?
Leave well enough alone.
prj posted 07-27-2003 11:50 PM ET (US)     Profile for prj  Send Email to prj     
'90 70 hp Johnson with 13x19 stainless prop achieving 42.3 mph on a gps.

You won't do much better than the prop you have unless you are looking for specific improvements, i.e. hole shot or ...

skred posted 07-28-2003 08:14 AM ET (US)     Profile for skred  Send Email to skred     
My 15 originally had a '85 70 Yam with SS 13 x 19, and lightly loaded would run over 45 - and I felt barely in control. Seems you're extracting just about max efficiency from your combination already. Any more speed with the 15 could be hazardous to your health...
VMG posted 07-28-2003 08:38 AM ET (US)     Profile for VMG  Send Email to VMG     
Went through the same drill back in '84 when I bought my 15SS CC w/ Johnson 70. I stuck with a cupped SS OEM 19 because I needed the hole shot for water-skiing. After the 19 ws stolen off of the boat, I used an uncupped non-OEM 21 that I'd found for virtually nothing -- it performed about the same as the 19.

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