Tach for outboard

Are the tachs offered on EBay for less than $15 adequate for checking the RPM of an outboard? I pick up a new project boat Friday and know the way to check if it has the proper propeller is to use a tach. I never worried about it before because there were very few props offered to fit my 25HP Evinrude, but the new boat has a 50HP and I noticed the choices are much greater. The OP has installed a Whale Tail and he said it comes up on plane faster with it. The fact he bothered to do that tells me the boat may be mis-propped.

I have one like this on mine. Works great. I use it to keep an eye on RPM's to see if my motor is running where it should be. This helps me determine if my jet impeller is in need of some adjustment. Have also used it to adjust idle speed.

https://www.amazon.com/gp/product/B00ACDP6YU?keywords=tiny%20tach&qid=1443644866&ref_=sr_1_1&sr=8-1

From the feedback I see on the e-bay models is the wire is not long enough
and "2 problems. #1- you can't turn off the meter when you are done boating
and #2 - the built in battery can't be changed or charged.
So 99% of the life of the battery will be used while the boat is parked with the boat cover on".

So I guess it would be wise to read the feedback of the ones found e-bay, amazon, etc.
If they can be turned ON/OFF, then that is a good deal.




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Given the difficulties referenced what is an acceptable alternative?
None of the other listed under "Others viewed these items" seem to be significantly different.
The motor is a 1985 50HP Evinrude so there is no factory unit listed.

Yes, there are several OEM or factory tachs for that engine!
Plus almost all the major players in the gauge industry make one for that engine.
If you have a dealer near you I will just about guarantee he will have one in stock.

Clint, is this for your tiller or remote steer ?
From what I read, nobody says how long the battery lasts.
and the common length of the wire is 6 feet.
also, one of the units I saw a few months ago had an optional
wire extension to reach the dash of remote steer boats for another $12.

My boats are remote steer - so I need at least 10 to 12' of wire.
so far, have not found one that suits my needs for a 40hp Johnson on one boat
and 50hp Force on the other.

I bought a real Tiny Tach in 2007 for around $40 or so for my f2.5. Display would stay on during non use. Lasted 6 years with same non replaceable battery. I bought a Tiny Tach in April 2015 from China for $10 or so with shipping, replaceable battery, turns off by itself and so on. Lasted 3 weeks, just long enough to learn the sound or pitch of my 15hp at 6500 rpm.

I think one can lengthen the wire as it is nothing special. My first one had 2 wires, one that was grounded. The knockoff had 2 also but did not need a ground.

Johnny said:

Clint, is this for your tiller or remote steer ?

Click to expand...

This is for the remote steer I pick up Friday. My tiller motor only has two props available so I never worried too much about it. But this boat - 1985 MonArk 1664V w/ 50HP Evinrude has MANY props available and as I said the OP installed a Whale Tail to make it come up on plane faster. I know they work but I would rather fix any performance issues by re-propping the boat rather than an add-on. I am going to do some major work on this one to build it the way I want it and hope to address all the challenges before they become problems.

I've had mine on my boat for 2 years. No issues. It doesn't have an on/off function and you cannot replace the battery. The battery is rated for 35,000 hours. That's 4 years with it being constantly on. An OEM tach for my motor is about $80. Aftermarket looks to be around $60. And that's just for the tach. If you need the wiring harness as well, it's going to be even more. Say mine craps out tomorrow only lasting 2 years. It would still take 10 years for an aftermarket tach to pay for itself compared to buying 5 tiny tachs, one every 2 years.

The wire can easily be extended. I extended mine about 8' so it reached up beside my control box. I have stick steer and the captains seat is close to the bow. I used 14 AWG, IIRC, tinned wire and all you have to do is butt connect and shrink wrap the connection.

Another nice thing about these tiny tachs is they can be mounted pretty much anywhere on a flat surface. A normal tach, I think, needs to be recessed in something to be mounted properly. I have mine mounted to the gunwale rib right beside my control box. A quick glance is all I need to check RPM's.

wouldn't it be a better idea of getting all your major work done first ?
then, match your prop to the weight and other balance issues of your finished boat?
It sort of seems like you are putting the horse before the cart, so to speak.

BigTerp said:

I have one like this on mine. Works great. I use it to keep an eye on RPM's to see if my motor is running where it should be. This helps me determine if my jet impeller is in need of some adjustment. Have also used it to adjust idle speed.

https://www.amazon.com/gp/product/B00ACDP6YU?keywords=tiny%20tach&qid=1443644866&ref_=sr_1_1&sr=8-1

Click to expand...

I bought the same one in the link but the "upgrade version" you can select. The new one has a replaceable battery and auto shuts off after 2 minutes of no fire on the spark plug lead. I used it on my mower for about 10 hours and had no issues. I having a timing light that shows rpm's and it was right on the money with the tach. My boat tach is now working, thanks to replacing the stator which had shorted charging windings, so I don't need it for rpm's but it also serves the purpose of monitoring any cylinder which you fear is losing spark. Which is exactly what I need because even after the new stator I think my switchbox is failing as my #1 cyl loses spark after 10 min or so of operation.

Right now, I am trying to extend the wire to use on the console of my boat but I am unsure of how exactly to do it. Maybe someone can chime in and if you decide to go with it it will help you too. The upgrade version has two 26awg wires wrapped in a shielded casing. I am unsure if both wires need to be extended to both be wrapped around the spark plug wire or just the positive one. The one tip I did find was that an old shielded transducer wire would be good to use to extend it.

Not sure on the upgraded version that you have, mine only has one wire. But it looks like the second wire needs to be attached anywhere on the engine/frame. Not sure if that means you can attach it to your boat hull or not? If it were me, I would extend both wires and wrap the correct wire around one of your plug wires and the other wire attach to a clean/bare nut/bolt on your engine.

I just bought one. Very satisfied. It also serves as hourmeter. Once you test the prop, you're not going to need it so much.

have used a REAL TinyTach on my diesel for four years. Incredibly, it senses the flex in the steel injection line!

BigTerp said:

Not sure on the upgraded version that you have, mine only has one wire. But it looks like the second wire needs to be attached anywhere on the engine/frame. Not sure if that means you can attach it to your boat hull or not? If it were me, I would extend both wires and wrap the correct wire around one of your plug wires and the other wire attach to a clean/bare nut/bolt on your engine.

Click to expand...

You would think so but it worked fine on my mower with both wires still in the shielding and wrapped around my plug wire on my mower (so neither grounded). Anyways, I am going to cut into an old transducer wire tonight and see if it looks like it will work to try to extend it. If so I will extend both wires and wrap both around the plug wire and see what happens. If that doesn't work I will run one to ground to see if that remedies it. I'll post my results so maybe it can help someone else down the road.