Speedo Probs.....84 Rider

[brack]

OK guys help me out here.....i did a search and couldnt find another thread about it.....took the boat out yesterday and it ran great ....problem is that neither speedo work..... Not to sound to stupid here but i understand how speedos work in a car....but how do they function in a boat...

thanks in advance

[rludtke]

The Speedometers feature a device called a "bourdon tube", which senses pressure, and converts it to a dial reading via a coiled tube in the gauge that tries to uncoil when pressurized by the water pressure generated by boat speed. Pitot (pronounced pito) tubes mounted at the stern hang down into the water stream, and transmit water pressure to the gauge by run of plastic tubing or hose.

There are not many failure modes for the pitot system. The pitot probes have a small hole in them, which could be plugged by spiders or daubers. The tubing could become blocked, severed, or disconected, or the gauge may simply fail. If the speedometers fail to register at all, try disconecting at the speedometer, and blow air from the speado end to remove blockages by back flush the system. If you have confidence of the integrity of the pitot system, then the problem must be the gauge.