colb
Full Member
Posts: 21
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Post by colb on Jun 4, 2020 22:39:18 GMT -5
This is my first boat so kind of dumb on whats what. Today I noticed that my speedometer was only reading 20 mph when it should be reading 28 or 30, and then it started not reading at all. So I googled problem and I came up with the pilot tube could be plugged on the sterndrive, since my boat has two motors and two stern drives, which hole are they talking about, port or starboard. I assume the pilot hole, is the one I see on the backside of the drives lower unit facing the stern of the boat. I also noted that I have a black plastic paddle wheel on the back of the boat, is that for the speedometer? It was knocked up a bit and I snapped it back in place, or is the paddle wheel for a different instrument, not sure what is what. I read in the manual that you can stick a wire in the pilot hole to possible unclog if it is plugged. Does the speedometer use both pilot holes in the port and starboard stern drives. Confused here. Thanks
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Post by 3060blue on Jun 5, 2020 6:23:42 GMT -5
The term is actually a "pitot" tube, not pilot - do you have a pickup like the one in the video below attached to the boat itself? If you search the term on Google "pitot tube speedometer" you will see the exact part and some videos on YouTube on how to repair. I am not familiar with the 2015, if you do not have that part at all you may have GPS speedometer or perhaps on the newer outdrives there is a hole as you mention. Here is one of the YouTube videos about this subject:
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Post by gofast24 on Jun 5, 2020 9:30:18 GMT -5
Assuming you have a smart phone, download a GPS location/speed program that will show you the actual boat speed (make sure what units is indicating, knots or MPH) . Regarding the water wheel and (only one) of the stern drive lower units would be sending water pressure to you speedo via water pressure or if electronic speedo that signal would come from the water wheel.I suspect you just have a plugged inlet on the lower unit or in the rubber tube sending the pressure to the speedo.. Best procedure to fix the plugged passage is blow it out from the speedometer to clear out all junk in total system.
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colb
Full Member
Posts: 21
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Post by colb on Jun 5, 2020 12:13:12 GMT -5
thanks going to give it a try today, I have located the water inlet, I think the water wheel I have is probably for my garmin.
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Post by gofast24 on Jun 6, 2020 11:32:38 GMT -5
So, what does the Garmin say for MPH or Knots vs. the speedo gage at the helm? You will finally get to the point that you cant trust or believe any mechanical/water wheel speed readings and just use smart phone GPS app to be sure of what your actually doing. If you actually have a pitot tube inlet on either the front of the lower unit or a separate pickup that just dips into th water at the transom suggest you blow out the line from the speedometer gauge inlet hose to fully push out any obstructions.
FYI= Pitot tubes are also used on almost all aircraft to indicate relative air speed (not ground speed), admin will know a lot about this as well!
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Post by gofast24 on Jun 8, 2020 9:46:44 GMT -5
Can you advise what you found out, it always helps when a problem is posted and after some diagnosing that problem was solved by .....
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Post by gofast24 on Jun 9, 2020 9:51:12 GMT -5
Addendum = Please list your model/ year/ propulsion system(gas/diesel/Inboards/I-O's) / location in your salutation. Makes it a lot easier to determine what we are talking about here.
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colb
Full Member
Posts: 21
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Post by colb on Jul 2, 2020 20:32:05 GMT -5
sorry for the late reply, been a bit busy with Covid stuff. I did find out the problem, my speedometer works off the water wheel for my Garmin. It was out of alignment and not in the correct position to measure the stream of water flow, fixed position, all good. thanks
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