How can I make my boat a little faster?

**Spaceman Spiff** · 02-12-2023, 11:11 PM

Originally Posted by Jim Speros

Its only worth raising if and when your willing to buy a Stainless prop designed to run raised. IMO

I imagine there has to be a lot more availability on SS props for this 1983 motor than my 1968 Merc.

**Spaceman Spiff** · 02-15-2023, 07:36 PM

Well, I got my "new" used ebay 15" prop and it looks to be in pretty good shape. I slapped it on there to give it a try before my new propco cupped prop comes in.

However, my new tach doesn't work any better than the last one. I tried moving the signal wire to the other brown rectifier wire and still nothing. I put my multimeter on the signal wire and then crank it and does change value from constant to jumping. Any thoughts on where to go from here?

**David - WI** · 02-15-2023, 07:55 PM

Is your tach reading 1/2 the actual rpm... or zero... or what's the symptom?

**FMP** · 02-15-2023, 08:07 PM

Originally Posted by David - WI

Is your tach reading 1/2 the actual rpm... or zero... or what's the symptom?

Symptom is 3% slip with a beat old aluminum running near surface.

**Spaceman Spiff** · 02-15-2023, 08:12 PM

Originally Posted by David - WI

Is your tach reading 1/2 the actual rpm... or zero... or what's the symptom?

The symptom is no reading whatsoever. Needle doesn't move off of zero.

**David - WI** · 02-15-2023, 08:49 PM

Originally Posted by Spaceman Spiff

The symptom is no reading whatsoever. Needle doesn't move off of zero.

Do you know if the system is putting out 12v when the engine is running? I think when a diode fails in these chintzy regulators or rectifiers you lose part of the AC sine-wave the tach relies on?

**Spaceman Spiff** · 02-15-2023, 10:25 PM

Originally Posted by David - WI

Do you know if the system is putting out 12v when the engine is running? I think when a diode fails in these chintzy regulators or rectifiers you lose part of the AC sine-wave the tach relies on?

I don't know. I don't know where to test it.

**David - WI** · 02-15-2023, 10:33 PM

You could just put your.voltmeter on the battery (+) and (-) posts before and after you start the engine... if it's charging the voltage should be higher when it's running.

**Spaceman Spiff** · 02-15-2023, 10:35 PM

Originally Posted by David - WI

You could just put your.voltmeter on the battery (+) and (-) posts before and after you start the engine... if it's charging the voltage should be higher when it's running.

Thanks. I'll test before and after tomorrow's run.

**FMP** · 02-15-2023, 11:14 PM

Don't think that is regulated, just a rectifier which if failing will lead to more.
Over charging will likely be part of norm but when you spin even higher rpm. You need a good dual purpose or marine type battery, not just a thin cheap maintenance free or deep cycle.
I'd get a new rectifier regulator on it before anything. I don't think that produces more than 10A , CDI has a piece for it that is common to used on L6 Mercs as the fix. Actually a OMC piece for small motors too. But a cheapo type brand could also be available.

**Spaceman Spiff** · 02-16-2023, 11:57 AM

Wtf

**Spaceman Spiff** · 02-16-2023, 11:57 AM

This is the rectifier isn't it? That red wire there has worked for for several runs as my tach signal wire. I should mention that when i got this motor, the original tach was running off of the signal wire from the controller. I read somewhere you move wires on the switch box if you want to wire it different. But I don't understand that.

**Jim Speros** · 02-16-2023, 02:03 PM

Hard to see in pic. A rectifier is triangular in shape. Has 2 mounting screws usually in slots on either side. the two terminals that appear in a pair together get a yellow wire each. The other terminal, the one that stands a bit further from the other two gets a red wire.
It appears a red wire got connected in error to a yellow wire.

**Spaceman Spiff** · 02-16-2023, 02:14 PM

The red wire connected to the yellow lead is my tach signal wire. It worked fine there for several runs.

The rectifiers i find online as replacements for my motor look nothing like what i have here.

**Jim Speros** · 02-16-2023, 02:15 PM

Click image for larger version.

Name: IMG_0327.jpg
Views: 7
Size: 431.0 KB
ID: 515564

This is a rectifier. The lower terminal is marked with a + for the red wire. the other two get a yellow wire each. The gray tach lead can connect to either one.
If one side does not offer a tach signal you can switch to other. If a yellow does not offer a tach signal the rectifier is bad. A rectifier with just one yellow with a signal will run. However, it will not charge. Connecting a red wire to a yellow lead likely damaged the rectifier. A loose battery connection will also damage a rectifier.