Speedometer help

[99 Regal]

Can somebody out there explain how a speedometer works and what the likely cause would be why it is not working now? I have a 99 Regal 19' bowrider. the pitot looks ok to me but I'm no expert. Thanks

 

[Don S]

Re: Speedometer help

You should find a pitot tube pickup similar to the one pictured below on your transom. Some times they get kicked up, or plugged up or the small hose that goes to the speedometer broke off.

 

[99 Regal]

Re: Speedometer help

Thanks for the response Don. I do have that pitot tube on the transom next to the outdrive its pointed straight down and will fold upward/backward if I pull on it. Does that movement drive the speedometer when the boat is moving through the water?? Again no expert here..

 

[PrinceValium]

Re: Speedometer help

There is air in the tube that goes to your speedometer, as the water rushes underneath your boat it tries to enter the tube which compresses the air in it and the pressure moves your speedomoeter. The tubes can plug or get kinked or something might have gotten into the pilot fitting that was shown to you in the previous post. Tubes can also come off the back of the speedometer or be cracked or split Lastly there are times when there is a mechanical failure with the speedometer, however usually it is one of the above issues. Also the pilot fitting should be locked in the lowest position or it will not build up the pressure sufficiently.

Hope this helps.

 

[Oshkosh1]

Re: Speedometer help

Does that movement drive the speedometer when the boat is moving through the water?? Again no expert here..

No...That motion is meant to save the Pitot if you ground the rear of the boat. Rather than breaking the plastic, it will simply "pop" up.

It uses a measurement of pressure to indicate the speed. Aircraft use almost the same arrangement to measure airspeed. There is a rubber tube which connects the instrument with the pitot, many times this will be plugged with dirt/debris. Mine was plugged, so I simply disconnected the tube at the speedometer and the pitot and blew a little compressed air through it. A big "plug" of mud shot out...and everything was good.

If the pitot itself looks to actually be broken, they are easily replaced and cost around $10 or so.

 

[99 Regal]

Re: Speedometer help

Thanks guys for the response. Thats what I needed to know, I will take a look at tube and the pitot this weekend and see if i can find a blockage, break or just a bad connection. I'll check back and let you know what I find. Thanks again.

 

[PrinceValium]

Re: Speedometer help

Ok let us know how it went.

 

[Silvertip]

Re: Speedometer help

If the tube is broken anywhere inside the boat the floor or your feet would be wet. This is a captive air pressure system and as such nothing flows through the tube UNTIL or UNLESS it breaks at which time air will be expelled and water will have a free path through the break.

 

[Philster]

Re: Speedometer help

Yeah, it's the most common reason why people ask, "Why is there water coming out from under my helm?"