Go Back  Offshoreonly.com > General Discussion > General Boating Discussion
My pitot tube speedo is accurate >

My pitot tube speedo is accurate

Notices

My pitot tube speedo is accurate

Old 05-12-2015, 11:33 AM
  #1  
Registered
Thread Starter
iTrader: (1)
 
Join Date: Jun 2012
Location: OK CIty, OK
Posts: 1,449
Received 0 Likes on 0 Posts
Default My pitot tube speedo is accurate

I've always heard how inaccurate these things are, typically on the high side, with members saying discrepancies can be as high as 15mph. Well, not mine. I was out playing a couple weeks ago and and decided to check them against each other.

My Gaffrig pitot tube speedometer from 1997 is within 1-2mph from 35mph to 72 mph, the highest speed I saw that day. The batteries were dead in my Garmin so i had to use a speedo app on my Galaxy S4 and couldn't get any pics. I can see why the Gaffrig is accurate, the scale isn't linear but has a decreasing rate.

That saved me like $500.
Cole2534 is offline  
Old 05-12-2015, 12:35 PM
  #2  
Gold Member
Gold Member
 
Dave M's Avatar
 
Join Date: Oct 2000
Location: Hollywood, MD, USA
Posts: 5,651
Received 122 Likes on 77 Posts
Default

With my last boat, I was always hitting chit in the water and bending the pitot tubes. When the tube was brand new and straight, It would read high. Then it would end up getting bent a little and read right on with my GPS. Then it would get bent more, and start reading low. Bought a GPS speedo and never looked back.

My current boat does not even have a speedo. I just use the GPS.
Dave M is offline  
Old 05-12-2015, 01:27 PM
  #3  
Registered
 
Join Date: May 2010
Location: Red Oak, Texas
Posts: 987
Received 177 Likes on 87 Posts
Default

My old Norskog was usually within a MPH across the board, but as Dave said, bent tubes and messed up brackets made GPS the best choice in the long run. I haven't run a manual speedo in years.
CDShack is offline  
Old 05-12-2015, 02:06 PM
  #4  
Registered
Thread Starter
iTrader: (1)
 
Join Date: Jun 2012
Location: OK CIty, OK
Posts: 1,449
Received 0 Likes on 0 Posts
Default

Originally Posted by CDShack
My old Norskog was usually within a MPH across the board, but as Dave said, bent tubes and messed up brackets made GPS the best choice in the long run. I haven't run a manual speedo in years.
Mine just uses the pitot built into the Bravo
Cole2534 is offline  
Old 05-12-2015, 02:11 PM
  #5  
Registered
iTrader: (3)
 
Join Date: Jul 2004
Location: chicago
Posts: 11,332
Received 70 Likes on 38 Posts
Default

I had a liquid filled gaffrig in my boat when I bought it, with transom mount pee tote. Metal gaffrig one.

Speed readings were close to GPS, very close.

Another buddy has same setup, speedo readings way off. Low actually. He probably has some chit clogged in his pee tote though.
MILD THUNDER is offline  
Old 05-12-2015, 04:10 PM
  #6  
Registered
 
Join Date: Oct 2000
Location: Lakewood, NY, USA
Posts: 3,476
Received 315 Likes on 172 Posts
Default

Originally Posted by Dave M
With my last boat, I was always hitting chit in the water and bending the pitot tubes. When the tube was brand new and straight, It would read high. Then it would end up getting bent a little and read right on with my GPS. Then it would get bent more, and start reading low. Bought a GPS speedo and never looked back.

My current boat does not even have a speedo. I just use the GPS.
I agree no speedo just a GPS. I think we are in a minority but I think the GPS is easier to read then a guage and it gives more room on the dash for things like oil temp and water pressure.

Padraig
Padraig is offline  
Old 05-13-2015, 12:01 AM
  #7  
Registered
 
Join Date: Jan 2005
Location: Pasadena, MD
Posts: 3,567
Received 121 Likes on 39 Posts
Default

I used to have a paddle wheel speedo with a trolling mode switch. From 0 (and I mean zero, if we were anchored and the current was moving in troll mode you could see it) to 55 mph it was dead on. But like others have said a couple debris whacks and it was never the same. Nowadays the only time I use gps is prop testing besides that it rpm's are all that matter to me.
f_inscreenname is offline  
Old 05-13-2015, 06:27 AM
  #8  
Registered
 
Join Date: Sep 2013
Location: Southeast Michigan
Posts: 1,879
Received 7 Likes on 6 Posts
Default

Without a speedo, you cut down significantly on gawkers looking at the speedo and debating from the dock whether the boat can reach the big number....
Speedracer29 is offline  
Old 05-13-2015, 09:08 AM
  #9  
Registered
iTrader: (3)
 
Join Date: Jul 2012
Location: indianapolis
Posts: 1,248
Likes: 0
Received 2 Likes on 2 Posts
Default

I didn't hook my speedo back up after I did the transom in my scarab. It's a liquid filled gaffrig it was fairly off. I played with the pilot tube but could never make it better.
indysupra is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.