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Okie2
05-26-2009, 11:10 AM
So I must have picked up some debriss at AOTH (go figure) as my speedo no longer registers....Need a quick "how to" on on clearing the clog. Alpha drive & gaffrig speedo. Pull the water hose out of the back of the speedo & blow out with compressed air & then reinsert hose onto speedo? Any special requirement on reinstalling hose? Clamp? Thanks, Scott

Planetwarmer
05-26-2009, 11:21 AM
That's how you do it.

:)Or, you can find the pickup hole and use your mouth to suck the clog out. But that would probably would take special talent!

VetteLT193
05-26-2009, 11:23 AM
compressed air is definitely the easiest, as you described.

RedDog
05-26-2009, 11:44 AM
For a bad clog, I have had to run a drill through the pick-up hole to ream the wood out. Be careful, small drill bits are brittle

BigGrizzly
05-26-2009, 03:30 PM
Make sure the drill is the correct size or your speed will increase on the speedo. Me, My fix is take it off and use a GPS.

The Hedgehog
05-26-2009, 03:41 PM
I would drill it out a little more so it will say that you are going faster. That is what they do in Bajas

I picked up 15 mph in my X-18 one time by turning the back of the speedo!

BigGrizzly
05-27-2009, 08:01 AM
The owner of python new every drill size to make every boat read 72 mph

MOP
05-27-2009, 12:28 PM
You can help to soften the muck by disconnecting the tube at the drive, then add a piece of the same sized tubing a few inches longer. Fill it with 50/50 rubbing alcohol and water leave it be until you can see it either dripping or at least feel it is wet then try blowing it out. It is damn near impossible to blow out when hard and dry.

DonziJon
05-27-2009, 01:55 PM
I'm thinking that the entry hole diameter in the Pitot Tube pickup is irrelevant, as to what speeds the speedometer will indicate. I believe the small size of the hole is determined solely by the need to keep larger debris OUT of the orifice. After all, the tube running up to the dashboard only contains Air which compresses and puts pressure on the Borden Tube..OR Diaphragm, that moves the dial.

"X" PSI at the borden tube is still "X" PSI. I could be wrong. :nilly: John

PS: I would soak the Pitot Tube in Hydrogen Peroxide until it stops bubbling, then blow it out.....AND.. Best of all...according to my (NASBLA Approved) Safe Boating Course, Hydrogen Peroxide is the BEST thing to clean your boat stuff with and is Not Harmfull to the Environment....Which of course should be on everybodys mind, as it is mine. :) ................You Can't make this up. :lookaroun:

DickB
05-27-2009, 09:47 PM
Interesting Facts
Pitot tubes are used in many boats and planes to accurately measure speed. Its read out is completely independent of many factors, like the size of the hole on the front of the spine, the density of the water, or size of the column of water. The only variable that may decrease the accuracy is the height of the speedometer relative to the waterline. So for a given weight, the readings will be constant.


http://www.hobiecat.com/kayaking/speedo.html

The Hedgehog
05-28-2009, 06:29 AM
Interesting Facts
Pitot tubes are used in many boats and planes to accurately measure speed. Its read out is completely independent of many factors, like the size of the hole on the front of the spine, the density of the water, or size of the column of water. The only variable that may decrease the accuracy is the height of the speedometer relative to the waterline. So for a given weight, the readings will be constant.


http://www.hobiecat.com/kayaking/speedo.html

Ok, so it says that they are used in boats and planes. Well I can tell you for a fact that air density is a HUGE factor in planes. I bet that there are a whole list of members that fly that can back me up on this one. Air 22? Then they go on to say that water density is not a factor. How can that be true? Maybe not a huge factor but a factor none-the-less. This article may basically apply to sailors but as the equation moves on to bigger numbers I could see it losing validity.

You can't take factors that apply to sail boats and apply them to fast boats and visa versa. That would be pretty funny though. I could see the next generation racing sailboat with a step hull and pad. Or what about stopping by the pits of a OSS race and see the guys wetsanding hull at the waterline (yes I know it has been done).

BigGrizzly
05-28-2009, 08:28 AM
Actually even in a boat the air density is a really big factor. So if a hole size doesn't matter then we can put a funnel on the pitot and it won't make a difference. One thing I will tell you is if I put the Teleflex pitot on my Keller spedo it will Not read the same, If I reverse the situation same thing happens. Of course I am getting old and my eye sight isn't what it use to be, but I think I can still see 12 mph. Now I only use Lowrance speedos, read that GPS. The Criterion does not even have a speedometer or pitot on the boat.

MOP
05-28-2009, 08:29 AM
Enlarging the orifice will increase readings, for the non technical types in our group try a very simple test! At 60 mile an hour stick one finger out of your car window not the force, then stick you hand out the window note the force. The same applies to all media flow wet or dry! The method I mentioned is one of several that can help, I wait for the muck to soften then break off one bristle from a wire brush and work it into the hole. Once flow starts it is easy to blow more water through the tube back out of the orifice. I do not like using drill bits as they may enlarge the orifice riding on hard bits of debris, but then again that is my opinion.

P.S. Speed odometers are strictly for passenger thrill use your GPS!