Speedometer not working, where to check first?

[nmucowboy]

Good day, I have a '95 Rinker 180. It is powered by the 3.0L mercruiser with the aplha 1 outdrive. I am relatively new to the boating world as this is MY first boat. The boat runs great but it would help a lot with towing the kids around the lake, if my speedometer was working. I am not sure how they work, but even when i turn the key on, the speedo does not even jump. Where are the areas I should be checking that foul most often for these speedometers? Thanks for your help!

 

[JASinIL2006]

Yor best bet, especially for measuring accurate speeds when not going fast (like when you're pulling a tube) is to use a GPS-based speedometer. Lots of fishfinders have them built in, but you can even find free smartphone apps that will be way more accurate than yout boat's speedometer.

If you really want to fix the boat's speedometer, try Googling "pitot speedometer" and you'll find all kinds of info.

Good luck!

 

[R055]

Check the tube that the pressure runs through to the speedometer where it connects at the outdrive. It's under the bellows.

 

[Scott Danforth]

your pitot tube may be connected to the outdrive, or to a pitot pickup. the speedo is a purely mechancial gauge using water pressure to operate.

most of the time there is dirt in the pickup. if you have water entering the boat, it could be a broken tube.

 

[roffey]

Speedometers on boats are incredibly inaccurate. My boat is fairly new so every thing works as it should, my speedometer reads accurate up to about 40 mph after that it goes down. WOT my reading is 25 MPH. I use the tachometer as a gauge. I can normally guess with in a mile per hour how fast I am going by the RPM. As stated above I would get a cell phone app and compare it to the tachometer. For what ever its worth, when pulling skiers or tubers I go with what they want and don't even looks at the tachometer or speedometer and its the spotter that tells me go faster or slower.

 

[jkust]

All of the above but that these speedo's don't jump when you turn the key so don't be alarmed by that.

 

[roffey]

All of the above but that these speedo's don't jump when you turn the key so don't be alarmed by that.

exactly, they are pressure sensitive and that is why they really don't work.