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I am repowering my 1970 Katama with new Yamaha F70 . I see on Whaler Central that I should get a 13.25 x 14 . Out of stock everywhere I checked for OEM prop and will not have any until June ! Is there a substitute for same ? I have tried to go aftermarket , cannot get that size .

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Check with Tom Clark.

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Check with the Yamaha prop selector online
http://www.yamahapropselector.com/pro...ector/web/

Also see prop 101 article on the Yamaha website
http://yamahaoutboards.com/propellers...s/prop-101

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There are lots of options besides OEM, almost all of which are significantly cheaper, too. On my 15/F70, I use a PowerTech SCD-3 in 16 pitch, with excellent results. You'd probably want to go down an inch or two in pitch for your Katama, but the good news is that if you get a PowerTech, you can trade in for a different pitch prop of the same model for a relatively small fee. It sometimes takes a bit of trial and error to get the pitch right but I am confident you'll be happy with the performance of the SCD-3.

I got mine from Dan's Discount Props - have dealt with them many times over the years. The SCD-3 is not shown on Dan's website, but if you call them they are happy to order any of the PowerTechs and what they order gets drop-shipped to you - special order does not create any additional delay. Mine arrived in 3 or 4 days from the time of order.

Tim

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I presume you are talking about retailers being out of stock? Most retailers keep low inventory.

Contact Andy at SIM Yamaha. I highly recommend him for Yamaha service and selection. They have it in the Performance Series.

https://www.simyamaha.com/Yamaha_Prop...-v4-14.htm

I also 2nd Tim's advice. He set the standard for testing the Power Tech props on his boat with an F70.

http://dansdiscountprops.com

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Thanks for responses . SIM Yamaha is out of stock . All the dealers I contacted are oos and the size I need (13.25 x 14 ) is on back order till June 2017 !. The Powertech prop only comes in 13 or 15 pitch . Everything I have researched states the 14 pitch is ideal . Motor is scheduled to be installed this Friday . Looks like I need a sail .

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Warning- Prop size is not universal across brands or even models. It is not like the size of a tire.

Each make and model of prop has a different blade design and that affects performance.

A Yamaha Performance (stainless) prop in 13.25x14 will not behave the same as a PowerTech 13.25x14.

Tim did testing on several props to dial in which prop was better. He stated in the past he was a bit overpropped with 16" so the SCD-3 in 15" reads spot on.

If I were in your shoes (10+ yrs of Whaler experience) I would call Dan in a heartbeat for a 15".

BTW - Make sure they mount the motor 3 holes UP. Do not let the dissuade you. See:
http://www.whalercentral.com/articles...cle_id=106

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Just to clarify, what Phil means is that a 14-pitch in one prop will not perform the same as a 14-pitch of another model. I used a 15-pitch Stiletto originally, and it was too much pitch. I switched to the 16-pitch PowerTech, and it is slightly too little (Phil, you remembered wrong, I'm slightly underpropped with the 16) but I like it that way.

Every model of prop is different, and every boat performs slightly differently. Even two Katamas are unlikely to perform the same way - one may weigh more, for example. It all adds up to prop selection not being an exact science, which is why trial and error is needed.

I don't remember precisely as it has been a couple of years, but at the time I bought my SCD-3 I certainly had the impression they were available in 1 inch pitch increments. You could call their customer service and ask - they are very helpful.

Tim

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Tim-

Thanks for correcting me. I actually didn't remember, had to look it up. Too bad I flipped the terms.

cf:http://www.whalercentral.com/forum/vi...ost_138856

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Oops , ordered the 13.25 x 15 . Should I call back and change to 16 ?

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Absolutely not, your boat is bigger and heavier than my 15, so it won't go as fast or need as high a pitch. 15 is where I would start if I were in your situation.

Think of pitch like the gears in a car with a manual transmission - if you have a heavier load, you need a lower gear!

Tim

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Update ; Got motor installed , told installer to go the three holes up diagram . Was emphatically told that mounting three holes up went against everything that he knows about installing , and was joined by a couple of other service guys who said the same thing , all the while looking at me as if I believe everything I read on the internet . I remember reading in Whaler Central that " whatever the installer says , DO NOT let them talk you out of mounting 3 holes up , which I quoted that quip to the installer .
The 13.25 x 15 prop from Powertech was a perfect match . After break in hours , I ran it up to W O T for a couple of minutes ( 300 lbs of me , gas , and gear in boat ) I hit just a hair above 6300 rpms . Boat planes really quickly and tracks straight as an arrow all the way up rpm scale . Thanks tedious .

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Wow, good for you in insisting on having it done your way after doing your research. Sounds very much like the argument I had with the Evinrude dealer service manager when I had my engine installed. One week later he was all smiles and commenting on it being the "fastest" 17 Montauk they had ever run... Can't imagine why! Whaler Central members know their stuff, great resource for us vintage Whaler owners. (FYI, Tedious was very helpful when I was doing my repower research as well.). Congratulations on the new engine, hope it gives you many years of enjoyment.

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Awesome result, and great story about the installer - good for you sticking to your guns! I trust you'll go back and tell them that the boat performs absolutely perfectly? It would be fun to see their faces. Prop technology has improved greatly, and these installers are still stubbornly applying rules of thumb from 40 years ago. My guess is they'll probably think you don't understand how the boat is performing - maybe they're so used to poor acceleration, torque steer, and porpoising that they think it's supposed to be that way.

Glad it worked out so well for you - it'll help you enjoy your classic for many more years!

Tim

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I have read this thread with interest and one of the final posts seems to indicate that prop selection will effect steering torgue. I have a 1974 Outrage 21 with twin Yamaha 90s ( non-counter). I get substantial torgue which I can trim out to about zero torque. Am I correct to assume that this torgue could be partially caused by the current props, and that improvement could come by changing props. Thanks in advance.

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Reel, I meant that motor height will affect steering torque, not the prop so much.

You may wish to open another thread with you question - I suspect people here may be able to help you.

Tim

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Thanks Carom: I misunderstood however I do not believe I am 3 holes up. So you are saying hole choice effects torguing? Thanks again.

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Carom: Sorry--forgot to ask, does 3 holes up hold for twins as well or is that a different story?


Please start a new thread on twin engine mounting height/