Power Tech OFS4 15.5 X 17

[Vezo, Part II]

I'm aware that Denny has advised that he is getting best results with identical SeaFari 20 (yes, now sold) and Etec Gen 1 150, using a PT OS4 15 X 15. I have an opportunity to buy a used 15.5 X 17 for about half the money. Ironically from a SeaCraft 23 looking to go up to an 18 on a Gen 1 300. How close is this to a new 15 X 15? Is Denny still amongst us?

Vezo, Part II

[Bigshrimpin]

I have experience running a 15p 4 blade powertech OFS. I lost about 3mph compared to my enertia 15P on the top end and it was slower at cruise too. 15P OFS has good sternlift. Rev4 has more sternlift (IMO) than the OFS and is usually a bit faster in my experience. Both Rev4 and Powertech OFS are slower props but have great bite (large surface area). Propping hulls requires a bit of voodoo magic, so make sure the engine height is set correctly (cavitation plate clearly visable . . . out of the water when on plane) before you start messing with props.

See post from June.
http://www.classicseacraft.com/commu...t=28644&page=9

Originally Posted by Bigshrimpin

Tried a powertech 15P four blade OFS and lost 3.5 - 4mph on the top end . . . could only turn 5250rpm @ 35.5mph. 15p enertia is WAY better. Terry the 17P is packaged up and will go out tomorrow.

[Bigshrimpin]

From Denny's greatest hits album!!

http://www.classicseacraft.com/commu...t=28361&page=2

Originally Posted by Vezo, Part II

. . . The OFS 15x15 SS was $269. Are you saying that I should be researching newest models of BRP props rather than the Power Tech?. . .

Hey Michael, the PT web site says the OFS series is similar to the Merc Mirage +, which is a pretty good prop. However I tried a 3B 15.5 x 17P version, and it wasn't as good as my 4B 14.125x20P Michigan Apollo, but neither one would turn over 5200 rpm. A 4B version of the Mirage + and the 4B OFS would probably be a little better. BTW, PT's web site lists all OFS4 props as 15.25" diameter, so I'm not sure you could turn a 15P version up to at least 5300 rpm.However the $269 is a dynamite price for a 4B SS prop! My 4B Apollo was $360 in 2007. Most 4B SS props are in the $400-500 range nowadays!

My choices if I were picking 4B SS props at this time, would be:
1. 14.5 x 15P BRP Cyclone
2. 14 5/8 x 16P Michigan Apollo
3. PT OFS4 15.25 x 15P
4. PT ELE4 15 x 15P

Both the Cyclone and ELE turn 5400 rpm on my boat with a heavy load but the Cyclone is 2-3 mph faster and at least 10% more efficient. Don't know what the Apollo and OFS would turn. If I were you, before I spent that much $, I guess I'd check with Ken at Prop Gods to see what he recommends. I think he's in the Tampa area near you, and I believe he'll exchange props till you find the best one.

I'll email you my prop test spreadsheets tonight. Denny

[Vezo, Part II]

Thanks BigShrimpin! Just found the 15 X 15 Powertech elep Denny originally suggested on eBay at $329 but hubless, and new. Probably need to pull the trigger. I am quite certain I have the engine at correct height. How's the weather in Onset? Never understood Onset being on the Cape, yet opposite side of canal. Or Wellfleet considered lower Cape. Haha

Have family and friends in Wellfleet since 1938. Have visited almost every year of my life, but have not been back since 2010. Would you happen to know the (Roger) Keys family of Onset? He is my neighbor here in SC. His Mother passed just about a year ago, and he still has the home. Roughly 60-65 years old and a great guy.

Thanks,
Michael.

[jtharmo]

Denny passed on all his prop data with the Seafari along with a box of props. I haven't dug through it yet but I can look through it tonight and pass along anything relevant. I can confirm Bigshrimpin's comments though. There is definitely plenty of bite with this prop. It takes a delicate touch coming off throttle or you will bust your teeth on the windshield frame.

Capt Terry and I had dinner a few weeks ago and discussed props a little. The one on Denny’s, (now mine) was originally Terry’s. He also has a 150 G1. Below is a link to one of his prop test posts. Terry was after speed stability for wake boarding and the bite on the Cyclone wasn’t giving him that. I hope I'm not putting words Terry's mouth.


http://www.classicseacraft.com/commu...52&postcount=7

[Capt Terry]

SSPBill had it about right.

I tried Denny's 15P PT awhile ago, It did not spin up fast enough, however this may have been before my last engine height change (now at about 1.5" above the keel and 2' above the transom) and my ETEC 150 HO wants a higher WOT RPM than Restless Lady. In my prop testing, the 15P Cyclone was one of the strongest performers. However, even with PerfectPass speed control it did not hold wakeboarding speed as steady as the 17P High Five. For overall speed versus RPM across the RPM range the Cyclone was one of the best indicating it was an efficient prop. Even though the Cyclone was not as smooth at wakeboarding speeds as the High Five, I would have kept it for cruising, had it achieved the recommended 5500-5600 (5800 lightly loaded) WOT RPM for my ETEC 150 HO. Denny’s, now Bill’s, ETEC 150 had a lower recommended WOT RPM; therefore the Cyclone was a good choice for Restless Lady.

Last summer Bigshrimpin loaned me an Enertia 17P to test as my cruise prop. It held wakeboarding speed equivalent to the High Five, Plotting the results revealed like the High Five it is not efficient at the lower RPMs which is helpful with wakeboarding to get above the steepest part of the RPM curve. Therefore, Enertia was not what I wanted as a cruising prop. I need to try my 17P Black Diamond again (don’t think I have run it since the last engine height change), which initially provided good speed across the RPM range on the ETEC.

I provided a word document with tables and graphs to Bigshrimpin of the Enertia versus other props if anyone is interested and I can figure out how to get it in here.

[Bushwacker]

Originally Posted by Vezo, Part II

I'm aware that Denny has advised that he is getting best results with identical SeaFari 20 (yes, now sold) and Etec Gen 1 150, using a PT OS4 15 X 15. I have an opportunity to buy a used 15.5 X 17 for about half the money. Ironically from a SeaCraft 23 looking to go up to an 18 on a Gen 1 300. How close is this to a new 15 X 15? Is Denny still amongst us?

Vezo, Part II

The first PT prop I tried was an ELE4 17” pitch prop, and I couldn’t turn in much over about 5000 rpm with a full cruising load, so I traded it for the 15” prop. I believe your motor is the same vintage as mine was, so it needs to turn 5300-5500; newer models like Capt. Terry’s want to spin a couple hundred rpm faster. The ELE prop supposedly had the same blade profile as the old OMC SST prop which I ran with my 115 and was a very good performing prop. Don’t know what the difference is between the ELE and OFS props are, but the PT guys should be able to tell you. The 15” PT ELE4 prop is an ok prop with good stern lift and hole shot, but it’s not as good as the 15”P Cyclone, which was 2-3 mph faster and easily exceeded 4.0 mpg at cruise vs 3.7-3.8 for the PT prop! Although the PT props might be a little cheaper, if you really want the best prop look for a 15P Cyclone. Also make sure you’re running the right thrust washer to make sure it fits the taper on the prop shaft correctly. There have been some prop shaft failures when guys were running Merc props because the thrust washer didn’t properly match the shaft taper.

[Bigshrimpin]

Hi Michael - I sent you a PM.