Adding a speedo

[captmello]

I'm considering adding a speedo to my pontoon motor in my sig.

Is there a pickup on my outboard that I can use or would I have to add one of the pickups that sits down in the water?

I don't think I'd bother with the type in the water, but If I can hook into the outboard I may go ahead with it.

Thanks.

 

[ziemann]

Re: Adding a speedo

If you are referring to your '01 90HP Johnson, yes there is a pick up. You might have to find the fitting to the lower unit, but the '01 90 V-4 does have a pickup. You would just need the speedo kit with the tubing. Do a search for a parts diagram online for that outboard- it is easier to look on a picture to see where it is versus me trying to describe it here... (hmmm, I tried look at the parts diagram and I couldn't find a picture).

FYI- OMC introduced the gearcase mounted pitot with the 1982 model year. There is a small hole in the leading edge of the gearcase and then there is a plastic barbed fitting on top of the gear case just in front of the motor's pivot point. You simply stick your speedometer hose onto it instead of drilling holes into your transom and mounting a conventional pitot tube.

 

[captmello]

Re: Adding a speedo

thanks ziemann, thats just what I needed to know.

 

[will941s]

Re: Adding a speedo

FYI: My cheap little pitot tube, with my cheap auto vacuum line running to my Faria Speedo reads right on with my GPS....dead on the money running with or against the current. And thats hitting strong current pockets along the way.

 

[Silvertip]

Re: Adding a speedo

FYI: My cheap little pitot tube, with my cheap auto vacuum line running to my Faria Speedo reads right on with my GPS....dead on the money running with or against the current. And thats hitting strong current pockets along the way.

I'd like to see that speedometer. GPS provides speed over the face of the earth and is not impacted by river current. Pitot speedometers however are indeed impacted by river current since the pitot moving through the water is what makes the speedo work. So -- it is impossible for a pitot speedometer to read identical to a GPS going up and down stream. In fact if the GPS is showing 30 MPH going up OR downstream, you are indeed going 30 mph over the face of the earth regardless what the current is. If your speedometer is showing 30 MPH going downstream (say with a 5 MPH current) the actual boat speed is 35 MPH since you have to overcome the 5 mph current to make the speedo read 30. Conversely, going upstream at an indicated 30 MPH your speed is only 25 MPH. GPS would show 30 MPH under either condition.

 

[will941s]

Re: Adding a speedo

Interesting......Maybe the speedo it doesnt pick up as fast (not sure how fast my GPS updates), but everytime I looked at it, and the speedo they were the same thing (except for the .2, or .3 the GPS was picking up. Current pockets did'nt really move the speedo needle at all, the the GPS never flinched, even though you could feel the boat move. At some points the speedo would pick up a MPH or the GPS would but 99% of the time they were dead on. I think unless you are running in a small creek with tide rolling out, the current isnt strong enough to really impact a pitot tube or the boat. Or at least the river where I was running did'nt impact it. Next time I go running the creeks I will run the GPS to see if the tide running effects readings. Current in those creeks will pull a anchor out of the mud. I have thrown a line with a 1 ounce egg sinker and actually seen it come back to the surface when I locked the bell on my reel.

 

[will941s]

Re: Adding a speedo

Then again 13,000 CFS coming from the hydro station into the Cooper river really is'nt alot. I would say the water may me moving 5 mph at the dam, but maybe 1 or 2 down river. I am going to do a Speedo vs. Gps test on the lake...gather that info, then do it again in Goose creek (8' at high tide, 2 1/2' at low and about 40' wide) which equals alot of current. If it will get thrown off, that creek will do it when the tide is going out. Im guessing every pitot type speedo is about the same, so the info I gather should be good use to someone.

 

[Silvertip]

Re: Adding a speedo

To determine current, anchor in the stream with the bow upstream. Read the speedo. That's the river current. Turn on the GPS. Since the boat is not moving it will read zero. So much for being dead on. Since pitots are not very accurate (and may not register) at slow speeds, you might not even see 5 MPH current on the speedo and certainly not a 1 or 2 MPH current. A paddle wheel speedo for a locator would provide a reading however.

 

[will941s]

Re: Adding a speedo

I went out this morning and did a test...got the data on this forum under (speedo vs. GPS). I think the Teleflex tube begins to read at about 10-20 MPH but there are some that will pick up at 5 (OMC pitot) I think. I read current speed by drifting in neutral running the GPS. Speedo would'nt pick up til I at least hit half throttle.