How can I make my boat a little faster?

**Spaceman Spiff** · 02-06-2023, 01:21 AM

Originally Posted by David - WI

$135 for a new 10-3/4 x 15... https://propcomarinepropellers.com/p...40209969184900

Oh shoot. I missed this post the first time.

**Jim Speros** · 02-06-2023, 08:43 AM

Make sure you get one with angled back blades. A high rake prop. The one pictured above is not. It is old blade design not for ventilating situations. Not all props act the same. Don't just buy the first one you see.

**FMP** · 02-06-2023, 09:40 AM

Well Aluminum isn't going to do everything you want, you know that.
SS at that 10.5" has pitch 14-16P. Ask him about the rake, and what he might have. Tell him everything, boat weight, running surface flat, length, motor height and rpm with current prop when deep and now. Personally I think if the motor is healthy all cyl psi solid, on tune , that motor will be more than you expected on that hull and good SS prop will make it safer ride. I'm sure if the motor is healthy a SS15-16P at height will have it spinning the rpm. Try a Bob's cav plate as well to help the low to mid hold or then drop the transom a half inch at a time if needed.
Pretty short boat, too much rake might upset things.

Hydro flipper is garbage

You're about the fastest ever to cut an inch from your transom and remount the motor.

Peter has been making props for decades, he's an accomplished offshore champion. Made Carl his props for the multi L6 offshore rigs, talk with him.

**Spaceman Spiff** · 02-06-2023, 07:31 PM

Well, I got it out today and hit 36mph with no vent plate. That's 3mph more than my best with this motor. Thanks to y'all. I started in the fourth trim hole and hit 36 at 5700rpm. Minimal porpoising in the midrange and no ventilation. Then I switched to the fifth hole and hit 36 at 6000 with a bit more midrange porpoise and some ventilation. So I'm thinking maybe I should give that 10 3/4 x 15 prop( again, mine is 10x14) a try. What do you think? I may try shoving a couple Miller paint stir sticks on top of the transom and see if I can squeeze out another 1 mph. Actually, when I tested it at 33 before, the water was like glass. Today there was a bit of chop in the Willamette. But not as bad as yesterday.

Stephen

**FMP** · 02-06-2023, 07:55 PM

You, gas, battery, controls, hull, ...+800lb without the 50hp?
Well damm, if that's a 2:1 gear that's the lowest slip% ever for a beat up aluminum running surface.

**Spaceman Spiff** · 02-07-2023, 03:01 PM

Originally Posted by FMP;[URL="tel:3377315"

3377315[/URL]]Call Peter Dean at Propco Propeller in GA and ask if has a 10 1/2x15SS or whatever you think pitch, he could press an 11 spline hub into.

I took your advice and talked to Peter Dean and he pointed me toward a cupped 10-3/4 x 13. He said it would have the effective pitch of a 15, but bite better. They didn't have anything in stainless. And it's only $139.🙂 Thanks for the tip.

**FMP** · 02-07-2023, 04:30 PM

Said he could do a ss 10.5 with 11 hub as mentioned but it would likely hurt that small prop shaft. He'd do what needs doing , weld and machine it to take the 11 but your lower probably won't take it.

**Spaceman Spiff** · 02-07-2023, 08:20 PM

That's pretty much exactly what he said. The prop shaft ain't strong enough to handle the stress of SS.

**FMP** · 02-07-2023, 08:34 PM

It's not the first time that's been said. Recall it now, strong motor but the issue was that. But what the heck, go break it !

**David - WI** · 02-07-2023, 08:35 PM

The new prop seems like your best bet. You could possibly send your old prop in and have the blades checked and then add "cup" or increase the pitch for a little less money?

**FMP** · 02-07-2023, 08:42 PM

Just hang a 77 Chrysler 90 on it with the one piece lower, that'll fix all this, good choice of Merc inline props.

**Jim Speros** · 02-07-2023, 08:46 PM

Originally Posted by Spaceman Spiff

I took your advice and talked to Peter Dean and he pointed me toward a cupped 10-3/4 x 13. He said it would have the effective pitch of a 15, but bite better. They didn't have anything in stainless. And it's only $139. Thanks for the tip.

Sounds like you should have one headed your way. Then you have a solid baseline for future fine tuning if needed. Its hard to accurately make a good choice with an old prop. Especially one that has seen better days or has be reconditioned.

**FMP** · 02-08-2023, 10:29 AM

Low water pick-up, 15 spline, big ci, not too heavy,
https://m.youtube.com/shorts/HGe-b8RKZ3c
You'll leave that Merc with it's crap lower hanging on the wall.

**Spaceman Spiff** · 02-08-2023, 01:56 PM

Originally Posted by FMP

Low water pick-up, 15 spline, big ci, not too heavy,
https://m.youtube.com/shorts/HGe-b8RKZ3c
You'll leave that Merc with it's crap lower hanging on the wall.

I have enough motors already. Well, that could never be true. But more than a few anyway.

I want to make this little 50 work on this boat if I can because it sips gas. I found another 15 pitch used prop on ebay for $60 shipped. Make have that one worked on. I may never get rid of this motor. It will probably end up on my next home built.

Stephen

**FMP** · 02-08-2023, 02:19 PM

Hope that prop works out
If you ever see a good example of that one in the vid have a look, if you're really lucky the Chrysler version had 17" mid available in the late 70s early 80s some where white some were black with that same lower unit.