Speed Odometer connection?

[frustratedboater]

I've just installed a Mercury 150hp, Optimax, DFI Saltwater... and noticed that the air hose for my odometer on the motor is very small (seen only when dropping the lower unit). My hose on the boat 1997 Wahoo, 19', that had a 1994 Merc. 115, 4-cyl air hose was larger at the motor. Where is this connection made to the Opti? Is there a special connector to the smaller hose that I saw in the unit?

 

[gm280]

Well I have to say that I have never seen an Odometer on a boat before. I've seen Speedometers but never an Odometer. But if you are talking about your speedometer, the tube running from the pitot pickup to the Speedometer gauge has little to do with the displayed speed. Because that tube only transfers the pressure to the speedometer gauge and nothing else. The actual pickup pitot is where the correction would be. But most every pitot pickup is set for such speedometers. So there isn't any correction factor you need to worry about. Your speedometer is actually a water pressure gauge. And as you go faster the pressure increases at the gauge and displays the relative speed. As far as true accuracy goes, it is close but not anything to bet on. And that is why a speedometer on a boat will usually display a different speed then a GPS speed readying... I attached a picture of a general aftermarket pitot pickup. You can see where the tubing attaches that goes to the speedometer gauge... JMHO

 

[MTboatguy]

What would an odometer be doing on a boat? I have never ever heard of anyone describing their boat with "This many Miles" I don't even worry about a speedometer, if I want to know how fast I am going I use the GPS on my fish finder.