Speedo not working

[Colliemcc]

I have a Faria speedo in my glastron its says 1668-60-6
last year it stoped working i only got round to taking it out today.
I checked the pipe from the back up to the front its there is notting in it.
if i blow into the bacl ok the gauge notting happens, what could this be, can i take it apart. or is there any thing i can do.
for me to buy a new one in Ireland it is over 100 euro.

 

[Brewman61]

Re: Speedo not working

Ignore the speedo and use a GPS. More accurate, and possibly less expensive.

 

[QC]

Re: Speedo not working

I always chime in on these to remind that GPS measures speed over the bottom, not the water. With current your boats speed over the water and the speed by GPS are off by the affect of the current, so judging your boats performance is not always accurate with GPS.

Annnnd, despite a lot of experience that counters this, I have found my "pitot" style (actually an air pressure gauge calibrated for MPH) speedos to be very accurate. Within 1% of GPS with no current.

Collieemcc, if blowing directly into the gauge doesn't do anything, I am pretty sure your are f'ed.

 

[tboltmike]

Re: Speedo not working

Agree with Mariner. My 35 year old Airguide is within 1 or 2 mph of the GPS and is more steady.

Might check for holes in the tube or pinched points. I would guess that the gauge uses a bellows, something like an barometer. A hole in the tube or the bellows should shoot water out. Based on what you said, it may be the linkage between the needle and bellows. If you can get to it, may be an easy fix. What do you have to loose?

 

[emilsr]

Re: Speedo not working

Just about every spring I have to clean out the debris from the pitot in the drive....perhaps that's your problem?

If not, Faria will fix it for US$ 18. Contact them directly....good customer service.

 

[Silvertip]

Re: Speedo not working

I always chime in on these to remind that GPS measures speed over the bottom, not the water. With current your boats speed over the water and the speed by GPS are off by the affect of the current, so judging your boats performance is not always accurate with GPS.

Annnnd, despite a lot of experience that counters this, I have found my "pitot" style (actually an air pressure gauge calibrated for MPH) speedos to be very accurate. Within 1% of GPS with no current.

Collieemcc, if blowing directly into the gauge doesn't do anything, I am pretty sure your are f'ed.

And I disagree. Anchor in a 5 mph current (for example). GPS will show 0 MPH while your pitot or paddle wheel speedo will indicate 5 MPH (if it can register at that speed) because the water is passing under you. In relation to forward motion, the boat is standing still. Current has zero to do with a GPS measurement. The speedo however would indicate what the "speed of the current is" but it does not indicate how fast the boat is going.

 

[QC]

Re: Speedo not working

You just confirmed what I said, not refuted it In relation to the water the boat is moving at 5 MPH (water going under) . . . So when I boat in 3 MPH current (very often for me) my GPS shows 45 MPH down river, but the propeller is pushing the boat at 42 MPH "through" the water, and Upriver the GPS says 39 and the propeller is pushing me 42 "though" or "over" the water.

Think about this way, if I give you WOT RPM and MPH for propeller selection under the scenario above, I get really good slip numbers downriver and really bad upriver if I use the GPS. If I use the pitot speedo I should basically have the same slip numbers assuming that the increased wind resistance downriver doesn't hurt me.

Or another example is trimming sails against current in a sailboat, if I am running downwind and say to myself "there is something wrong here. I usually run 7 knots with a 12 knot breeze and this spinnaker and flyin' the main, but I'm only making 6 knots on the GPS, WTF?", and then my first mate says "but sir you're heading into a 1 knot current." Are my sails OK?

Wait a flippin' minute . . . Does your avatar tell me you're a pilot? How is this different than the relationship between indicated airspeed and GPS? Same issue, right?

 

[Colliemcc]

Re: Speedo not working

well tonight I took it out of tho cluster. cleaned it. At the back where the hole is for tho pipe I got a fine piece of metal like a large needle and cleaned it out. now when I blow into it, it will move up to about 12mph is this normal for pressure that I would be applying by my mouth or should the speed be higher.

 

[Brewman61]

Re: Speedo not working

well tonight I took it out of tho cluster. cleaned it. At the back where the hole is for tho pipe I got a fine piece of metal like a large needle and cleaned it out. now when I blow into it, it will move up to about 12mph is this normal for pressure that I would be applying by my mouth or should the speed be higher.

Depends on weather or not you're walking into the wind, standing still (or sitting), or walking with the wind.

Seriously, just hook it up and try it out.

 

[Silvertip]

Re: Speedo not working

Your are not comparing apples to apples here. the discussion is about speedometer vs GPS accuracy. Using a speedo for prop calculation is very different than determining actual speed over the earth. If you are a wakeboarder, then what you are contending has merit because it is the size of the wake and the "indicated" boat speed that makes the ideal wake. Doesn't matter if you measure speed in feet/minute, MPH, Knots or whatever (or how accurate the speedo is since). If you are interested in what your speed is over the face of the earth then GPS is more accurate than the pitot or paddle wheel because current has no bearing. Yes -- you will travel faster with the wind than against it or downstream faster than upstream, but again a pitot cannot compensate for head or tale wind. I agree that the boat passing over the water in either direction will read differently but that is NOT speed over the earth. Obviously a boat (powered or sail) will go faster downwind or with current than it will upwind or against current. Again -- if you were able to measure the distance accurately between your dock, as the the crow flies, to your destination and were able to travel in a straight line, you could travel at say 30 MPH and calculate to the second how long it would take to get there. If you run against current or wind, you will find that calculation woefully wrong using a speedo. But if you used GPS to measure speed, that calculation would be correct. And yes, pilots do have a pitot to measure air speed, but they also know winds aloft and must compensate. They also have compasses which must account for magnetic deviation. Which is why modern airplanes also have GPS and rely on it for navigation.

 

[QC]

Re: Speedo not working

There has been no disagreement in any of our posts, yet you claim I'm messed up. Exactly like our GPH discussions . . .

 

[Silvertip]

Re: Speedo not working

You Said: I always chime in on these to remind that GPS measures speed over the bottom, not the water [THIS IS TRUE]. With current your boats speed over the water and the speed by GPS are off by the affect of the current [THIS IS ALSO TRUE], so judging your boats performance is not always accurate with GPS [THIS IS NOT TRUE]. The statement should be -- your boats performance is not always accurate with a "pitot or paddle wheel speedo" because of currents. You will still see faster (accurate) downstream speeds as well as somewhat slower (but still accurate) upstream speeds with GPS. This is opposite and therefore inaccurate with a speedo. The difference is the speed of the current. The long and short of this was and still is accuracy or true speed. Your true speed upstream or downstream will NEVER be the same as GPS and therefore very inaccurate. They can be dead on where no current is involved. I stand by my example of anchoring in a stream with a current of any speed. Your TRUE speed is zero by GPS because the boat is not moving. The speedo however would indicate speed of the current. While we agree in the physics, we do not agree in how the concept was presented (which just happens to be why our elected officials can't seem to get anything done).

Peace

 

[emilsr]

Re: Speedo not working

well tonight I took it out of tho cluster. cleaned it. At the back where the hole is for tho pipe I got a fine piece of metal like a large needle and cleaned it out. now when I blow into it, it will move up to about 12mph is this normal for pressure that I would be applying by my mouth or should the speed be higher.

Don't know, but you should be getting a reading now unless the pitot is clogged (which is common if there's any debris in the water).

 

[justchecking]

Re: Speedo not working

If you are management when you blow into the speedo the speed should be a lot higher. If you are a working man then about 12MPH is about right. You should also be able to blow into the end of the tube disconnected from the speedo and blow air all the way through the motor or pick-up (which ever you have). Most often it is plugged up right where the water pressure enters at the motor (or pick-up).

 

[bellhop]

Re: Speedo not working

There has been no disagreement in any of our posts, yet you claim I'm messed up. Exactly like our GPH discussions . . .

Let me see if I can make this anymore confusing. Considering the relative motion of the water or as I'll put it in terms I'm more familiar with, relative wind. Just take out wind and add water.

You're flying at 90 knots at a given power setting downwind. Airspeed indicator shows 90 knots and gps ground speed is showing 100 knots.

Do a 180 degree turn and using the exact same power setting the airspeed indicator will still read 90 knots but the gps ground speed reads 80 knots. That is due to the relative wind. The aircraft (boat) is using the same amount of power and will give the same indicated speed but the groundspeed will change. Airspeed indicator measures pressure only and that pressure will remain the same if the same power setting is used. (we won't consider changes in the temperature or barometric pressure.)

Don't know if that helped any.