Re: sea hunt
The most common speedo works of of a combination of water and air pressure. As the boat moves through the water water is forced into a small hole in the pitot pick up or a small hole in the leading edge of the lower unit of the motor. This in turn forces the air in the hose and gauge to compress, giving you your reading.
Follow the tube from the back of the gauge. Make sure it is not cut, kinked or closed from a too tight wire ty.
Follow it to the back of the boat. Take the tube off of the pitot pick up or disconnect it from the lower unit use some GENTLE compressed air to blow in the hose going to the gauge, the needle should move. If not the gauge is probably bad if the tube is intact. If no compressed air try your lung power! Have a helper watch the gauge.
Make sure the Openings in the pitot or lower unit is clear, blow back with compressed air to clear out.
The #1 cause is some debris caught in the pitot.
