Aluminum to SS prop

**SeaRay** · 11-01-2019, 07:29 AM

My new 50 Tohatsu has a 15 pitch aluminum prop which runs out great. I know SS props have a better bite so a lesser pitch would probably be suggested.
My question is how much? I have access to a 13 pitch but I'm thinking a 14 pitch would be better match.
Is there a rule of thumb when making this switch?

**Cray** · 11-01-2019, 07:50 AM

May not be so in your case but I have always figured 1 inch less on stainless if your aluminum is running at proper RPM. I would certainly give the 13 a try before buying a 14. Check max RPM. On my 50 Yamaha 4 stroke I run a 13 on wareagle stick 17 ft and it’s perfect.

**trypman1** · 11-01-2019, 09:00 AM

I am with Cray, on this one. My 50hp Tohatsu, loves a 13.

**SeaRay** · 11-01-2019, 10:25 AM

Well that's good to know. Ironically the SS prop came off my 40 Yamaha 2 Stroke. Both are 13 spline if I'm reading correctly and diameters are same.
I sold it to a friend as a backup for his boat,so he's letting me try it.

**SeaRay** · 11-01-2019, 07:00 PM

Originally Posted by Cray

May not be so in your case but I have always figured 1 inch less on stainless if your aluminum is running at proper RPM. I would certainly give the 13 a try before buying a 14. Check max RPM. On my 50 Yamaha 4 stroke I run a 13 on wareagle stick 17 ft and it’s perfect.

Mine is a 16' Stick. Do you have a tach on yours? Can't figure best way to install one without a dash to mount it on. I have a Tiny Tach on it but it's at the back of boat and I have to get my buddy to holler out RPMs to know what I'm turning. Thinking I can splice a wire on the tach so it will reach front seat. The control box has tach leads if I could find a free standing tach to use.

**Cray** · 11-01-2019, 08:20 PM

Yes, I have a instrument panel in front of boat. Tach, fuel, voltage and trim gauge. Should be able to cut and bend a piece of aluminum to mount tach in and mount somewhere close to your controls.

**Atimm693** · 11-02-2019, 08:26 AM

I had a 13P SS 3 blade that was very close in performance to a 14P alum, with slightly better holeshot.

**SeaRay** · 11-02-2019, 09:34 AM

My concern is the stock prop is 15 pitch so I'm dropping 2" with the SS 13" I have. I'll get it on the water next week and see how it does.

By the way, if you want to turn a 5 minute job into a 30 minute job, just drop the cotter pin down inside the housing on the foot and see how long it takes you with a flashlight and bent clothes hanger to fish the dang thing outta there!

**Barnacle Bill** · 11-02-2019, 12:02 PM

Originally Posted by SeaRay

My concern is the stock prop is 15 pitch so I'm dropping 2" with the SS 13" I have. I'll get it on the water next week and see how it does.

By the way, if you want to turn a 5 minute job into a 30 minute job, just drop the cotter pin down inside the housing on the foot and see how long it takes you with a flashlight and bent clothes hanger to fish the dang thing outta there!

You should see 3-400 RPM increase. Depends on any differences in cup and or rake.

**Cane Pole** · 11-11-2019, 10:01 AM

Originally Posted by SeaRay

Mine is a 16' Stick. Do you have a tach on yours? Can't figure best way to install one without a dash to mount it on. I have a Tiny Tach on it but it's at the back of boat and I have to get my buddy to holler out RPMs to know what I'm turning. Thinking I can splice a wire on the tach so it will reach front seat. The control box has tach leads if I could find a free standing tach to use.

I extended the leads on tte tiny tach on my pondtoon about 8 feet. It didn't work right and interfered with my side imaging stuff. I am going to try rerouting the wire somehow. I use a the merc 4 blade aluminum performance blade on the 30hp merc, 11 inch pitch.

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