Boat Speedo

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Boat Speedo

Postby kwoffa » Sat Dec 30, 2017 4:57 pm

Hi Chaps,
I have just bought a classic speedo for my boat,however i have no idea about these things,it is not electricly powered,and does have a long tube coming out of the back,my questions are,What goes on this tube? and how does it work,i am really pleased with this unit..as it is from the same era as my boat,,anyhelp would be apreciated...TIA.Mel.
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Re: Boat Speedo

Postby floater » Sat Dec 30, 2017 8:19 pm

You have a pitot type speedometer, inside its a bit like a barometer working in the same way. The tube needs to be connected to a pickup on the back of the boat. The speedo responds to the pressure of the water rushing past the pickup. You can simulate the water pressure by blowing down the tube but you'll be surprised how much pressure is needed to move the needle. I checked mine using a conical adapter on a foot pump

See the lower half of this page:-
https://www.jamestowndistributors.com/u ... ?docId=836

Pickups are readily available from most chandlers.
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Re: Boat Speedo

Postby kwoffa » Sun Dec 31, 2017 8:45 am

Thanks a lot,,, thats what i thought i needed,,, but wanted to check......
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Re: Boat Speedo

Postby kwoffa » Wed Jan 03, 2018 7:37 pm

Hi there,
Can i trim the tube from the back of the guage,as there is a chance it maybe a tad long...at present it is not an open ended tube but has small slot and a hole...would i be changing the calibration by cutting shorter ?
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Re: Boat Speedo

Postby Woodwych » Wed Jan 03, 2018 7:42 pm

The length of the tubing from the pickup to the speedo doesn't matter- so trim away.
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Re: Boat Speedo

Postby kwoffa » Wed Jan 03, 2018 9:28 pm

Ah right,so i have a copper tube coming out from the guage,,,,thats what i am concerned about?....not the tubing from the pick up.
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Re: Boat Speedo

Postby Alacrity » Sat Jan 06, 2018 10:02 pm

I think there is some confusion here. I believe he has an different style speedo head which is NOT the style we are used to. I have one myself & have no idea what should be connected to it.

Please post a picture of what you have but DON'T cut the tube off until we know what you have. I don't think you should be cutting anything.
Mercs are like women, no 2 are exactly alike. That's what testing is about. In general it is safer to test motors and props than women!
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Re: Boat Speedo

Postby kwoffa » Sun Jan 07, 2018 9:17 pm

Thanks for the input chaps,i will take some pics tomorrow.
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