Tach recommendations

I would like to mount a tachometer somewhere on the rear end of a Jon boat and wanted to see if anyone has any recommendations on a tachometer for use on a outboard with a steering tiller.

Any cheap inductive tach will work.

Sounds good.... figured that since it's Amazon Days, I found one and ordered it. Now that I know the standard prop size and will get a tach. set up, I will look at purchasing another prop.

Although I in the break-in period on my new Tohatsu 20 hp outboard, just over 1/2 throttle, the High Speed ESG light comes on. Since the boat planes nicely, and the antiventilation plate is at the correct height, the next thing to check is the rpm reading.

Appreciate the answers. I will no doubt post about prop size to get once I know the tach. reading, as well as stainless vs. aluminum.

Assuming MFS20E? I have the same engine, MFS20E EFTS 15" shaft. I'm on stage 3 break-in, 6-hrs on the engine. You need the tach to break it in correctly. I have the Hardline. 1-wire real simple. Tough finding a spot to mount it and I don't like where it is now, back by the tiller trunnion. Pain to see, but I'm figuring out RPM by sound now. That light should not be coming on, sure it's not blowing out? I mounted mine per instructions, about level with the bottom with engine trimmed vertical. At WOT I can barely see the anti-vent plate. Max RPM I'm getting is 5700. At this stage I'm only allowed to run the engine WOT for 10-minutes. Maybe after break-in, and tweaking the trim I can get 6100RPM. The stock prop is 9-1/4" X 10. I believe most aftermarket limit to 9-1/4" diameter but go up to 12 pitch. If I can't achieve max RPM, I probably drop down and inch in pitch with a stainless prop. Shallow water here, nice sand bottom, but everyone bumps bottom once in awhile. The aluminum props loose trueness very easily.

Yes, I have a new MFS20E, long shaft that I picked up during a outboard motor clearance. Needed to go with the long shaft due to the transom depth, and ended up raising the motor via a jack plate.

I have a tach coming in on Saturday, so it will be interesting to see where the rpm reading is sitting.

You mentioned that the light should not be coming on- sure it's not blowing out? I was a bit surprised to see the light come on, and the motor run rough when it does, but with not knowing what the rpm is at, I figured that checking the rpm reading would be a good place to start. Can you explain what you meant with regards to "blowing out"?

I am running in lakes, but will still consider a stainless prop. Figure that i would look at props after seeing how the rpm reading is sitting.

By blowing out meaning the prop ventilating. I just re-read your first post and you said the light is coming on at 1/2 throttle. I initially thought you were hitting the rev-limiter (6400 RPM). You have something going on and should probably find a dealer for warranty repairs. You sent in you warranty card right? That light comes on for more things than high revs, it's like a check engine light.

25Johnny said:

By blowing out meaning the prop ventilating. I just re-read your first post and you said the light is coming on at 1/2 throttle. I initially thought you were hitting the rev-limiter (6400 RPM). You have something going on and should probably find a dealer for warranty repairs. You sent in you warranty card right? That light comes on for more things than high revs, it's like a check engine light.

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I did send in the warranty card, but will take a look at common causes of prop ventilating too. Once the tach comes in, it should at least give me an idea on where the rpms are sitting when I am at half throttle.

After looking into ventilation, I may lower the motor height a little and see if this changes anything.