How can I make my boat a little faster?

**Spaceman Spiff** · 02-08-2023, 07:22 PM

Originally Posted by FMP

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.

Well, I literally look on craigslist and offerup every day for boats, motors, and parts. So if there is one around, I will see it quick. But haven't seen many Chryslers for sale. And when they are, they are usually small.

**Spaceman Spiff** · 02-08-2023, 07:26 PM

Back out on the Willamette today and it was smooth as glass. I put 1/2" back on the transom and now I'm reaching 38 at 5900

still on hole 4. Not sure if it's the smoother water or higher motor. But happy nonetheless. But it does vent pretty good on hole shot. I should have some rpm room to spin a bigger cuppier prop. Can't wait to try it.

**Jim Speros** · 02-08-2023, 09:20 PM

Its probably the height, ripples or little chop is generally faster than glass smooth. If you are tempted to adjust height more adjust at 1/4 inch now you are nearing its sweet spot. Might as well wait for your new prop though. It will act a little different and you'll find yourself tweeking height a little more.

**FMP** · 02-08-2023, 09:32 PM

How are you measuring speed?

**Spaceman Spiff** · 02-09-2023, 09:59 AM

Originally Posted by FMP

How are you measuring speed?

I have a GPS speedometer and my iphone. They are always the same.

**Spaceman Spiff** · 02-09-2023, 10:04 AM

Originally Posted by Jim Speros

Its probably the height, ripples or little chop is generally faster than glass smooth. If you are tempted to adjust height more adjust at 1/4 inch now you are nearing its sweet spot. Might as well wait for your new prop though. It will act a little different and you'll find yourself tweeking height a little more.

I think I'm just going to wait for the prop. My tach just crapped out and I'm going to install my temp gauge and clean up all the wiring.

**FMP** · 02-09-2023, 12:42 PM

Originally Posted by Spaceman Spiff

I have a GPS speedometer and my iphone. They are always the same.

Have you calculate prop slip % with that old Alum...
36 at 5700
38 at 5900
14P
2:1

**Spaceman Spiff** · 02-09-2023, 01:51 PM

Originally Posted by FMP;[URL="tel:3378013"

3378013[/URL]]Have you calculate prop slip % with that old Alum...
36 at 5700
38 at 5900
14P
2:1

3-5%

**FMP** · 02-09-2023, 03:06 PM

Really,
At 14P and 2:1 at 5600
Absolute best is 37.1mph..
((((5600×(1/2)×14P))÷12")÷5280)×60=37.1mph at 0%
So...
5700 is 37.7mph
5900 is 39.1mph

Maybe you're spinning more than you think, pretty low % for AL

**Spaceman Spiff** · 02-09-2023, 04:45 PM

I'll have to double check rpms when I get my new tach.

**FMP** · 02-09-2023, 05:37 PM

How's the Larson, power?

**Spaceman Spiff** · 02-09-2023, 06:07 PM

Originally Posted by FMP

How's the Larson, power?

That does pretty well. 17', 82" beam, 1100 lb hull weight, 300lb 115hp Mariner w/13-1/4x17 prop, 44mph at 5500rpm with just my 250lbs. I can trim it up until it vents. I couldn't ask for much more for the $600 I paid for this thing. I went out there thinking that the motor needed work based on their ad. But after I had it hitched up and ready to go, they said it probably just needed some new gas to run. And sure enough!

**FMP** · 02-09-2023, 06:41 PM

L6 ADI 115 Mariner, good motor, either way. Sounds like well spent $

**Spaceman Spiff** · 02-12-2023, 02:39 PM

Well, speaking of the Mariner.

. How many holes up should I try on this one? Bearing in mind, I can only trim it so far because it will start to vent. Prop shaft is 6" below the bottom of the hull. Yeah, it has a Merc lower.