Indigo and RPM question

[fullkeel]

I have recently decided to put an Indigo prop on my Bristol 29. The prop shop was very against the idea but I have read a lot of good things about it on this forum and others and think that the shop is just behind the times. My boat lacks a tach, any suggestions on how I will know if I am over revving the engine? I suppose I could get the boat to within half a knot of hull speed and if its not shuttering or producing some other sign of distress I could assume I am at or around the advertised 1900 rpm cruise setting.


Any idea on how challenging it is to install a tachometer? is this an easy weekend job or even necessary?

thanks.

[roadnsky]

Any idea on how challenging it is to install a tachometer? is this an easy weekend job or even necessary?

It's an easy job! The hardest part is just figuring a place to put it.
(If you have a spot picked out, it's a half-hour job)
MMI sells a good one on this site. It's really nice to have...

[sastanley]

fullkeel...I agree with Jerry. The tach is nice to have. I am cheap, and bought a $30 automotive tach. My engine is mounted under the galley so I mounted my tach underneath the counter top pointing at the cockpit.

most tachs have four wires. red-power (+), white-light (+), black-ground (-), & green-pickup (connect to (-) terminal on coil)

I add tachs to my cars that don't have one. Actually the tach I have in the boat is the same model I had in my Honda..It goes to 8,000 RPM!!, so I lose a little bit of accuracy than a marine unit designed to only read up to 4,000 or so, but it was $30.

I think it is an excellent instrument for tuning & troubleshooting, plus it is just plain cool! :cool:

[Dave Neptune]

Fullkeel, you shoukld be safe even without the tach :o although it is a good gage to have. The I-prop was designed for the A-4 exclusively and in a fresh engine it will still only give you about 2600 maximum RPM's unless yuou have a bad cavitation problem develope.
I installed mine a few years ago and have been very happy with the overall performance especially being able to back out of my slip which any of the 4 two blades I tried over the years (26) just wouldn't allow me to do in any wind at all!!!!

You'll be happy and I'd try another prop shop!

Dave Neptune:cool:

[sastanley]

Dave,
How about the sailing performance? They claim only a 9% increase in surface area over typical two-blade props, although with two-blade you can also hide the blades vertically behind the keel (or strut in my case) for added drag reduction. I know it is a cruising boat, but I still don't like to go slow! ;)

[Dave Neptune]

Shawn, I used 3 different diameter 2-blades 14, 13 & 12" before and I could tell the light air performance was off with the two larger diameters however not much. With the Indigo 3-blade I could tell very little differance in fact if anything I think it has less drag than any of the above since the blades are very narrow. I really didn't notice any sailing performance differance with the Indigo however everything is MUCH better while motoring especially in reverse and there is almost no wobble in the tiller like with the two bladed props!

I wish I'd found the Indigo 26 years ago when I started playing with props. I used the 3 diameters above and each one was re-pitched a few times as well. The 13" was actually the 14 cut down.

Dave Neptune:cool:
Volador E-35 MkII 1970 original A-4 still ticking!!!!!!!!

[Jesse Delanoy]

I switched over to an Indigo 3-blade prop from the original 2-blade on my Catalina 30 about five years ago. I'm a cruiser, and I don't cut my performance numbers too fine, but I haven't noticed any particular decline in performance under sail. Backing into the slip is much easier than it was.

Jesse Delanoy
s/v Off The Grid,
Baltimore

[Dave Neptune]

Shawn, there clasims of the 9% are against a 10" diameter if memory serves me right, although I was raised in the sixties!:eek:

David:cool:

[fullkeel]

Thanks for all the great info.

Can someone give me a brief overview of what it might take to install a tach? Do the units that Moyer sells come with a sending unit? How/where does the sending unit get attached? Will I need to calibrate the unit; does this require any specialized equipment?

[67c&ccorv]

Don't think the units Moyer sells require a sending unit like say, the old Sun tachs from the 60's & 70's had.

I think they sense the rpm from the pick-up line that attaches to the coil.

[Dave Neptune]

fullkeel, you wil need a hole saw and some wire lugs. Most tach's today do not use a sensor, as the unit is solid state. Some are switced on the back of the tach for the number of cyl's or it is just a matter of which wire to hook to the coil. They're no big deal to install after you have the hole which is the hardest part. However getting through the instructions can be frustrating:mad:!

Good luck David:cool:

[keelcooler]

Keep in mind the Indigo wheel needs clear water in front. Could be a problem if your full keel has fat dead wood at the cutlass base like my Triton. Call and talk to Tom at Indigo about other Bristol owners results.

Sastanley,
Can you tell us how to wire up the Sun tack? Red power to starter or panel?

[roadnsky]

Can someone give me a brief overview of what it might take to install a tach? Do the units that Moyer sells come with a sending unit? How/where does the sending unit get attached? Will I need to calibrate the unit; does this require any specialized equipment?

fullkeel-
The MMI Tach (Product No. - GAUG_08.1_322) doesn't use a "sending unit".
It "reads" from the coil. The gauge comes with instructions for installation. Very simple to install. 30 min tops.
Call Ken at MMI and he can read you the instructions if you want...
-Jerry

[sastanley]

In my case, I wired the SunPro tach red power (+) to the coil, since mine is mounted near the engine. If you ran it out of the panel, you could wire the (+) the same way the other gauges are wired (using Don's diagram that is purple, which gets its power from the coil as well), so that you have power to it when the key is on.

This does tend to stack up the (+) terminal of the coil...I think I have 5 wires running to it right now, including the light for the tach. If/when I ever re-wire the bird's nest behind the boat's electrical panel, I would wire the tach's backlight to the steaming light switch.

[jlroberts280]

I installed the tach sold by Don this spring. I had a hole already so the job took maybe 5-10 minutes. Very simple.