Today my Gaffrig II speedometer malfunctioned. It will only register up to 30 mph. Any ideas?
Today my Gaffrig II speedometer malfunctioned. It will only register up to 30 mph. Any ideas?
2009 Classic 16
NW Tampa Bay
More throttle.
GPS or pitot tube?
“Oh right, because you walked into strippers discount warehouse and said ‘Help me showcase my intellect.’” - Archer
Bill
Grand Rapids, Michigan
1985 Donzi Criterion SS
1967 Donzi 16 Ski Sporter, C16-409, Has a new home!
38' Carver Aft Cabin
1968 Sea Ray SRV 180 w/1975 70 hp Evinrude
10" RIB w/15 hp 1984 Evinrude
Non GPS -- I've been told to disconnect the tube from the speedo & force air through it - but the last time I tried doing this (not on a boat), the PSI was too high and caused more damage - so, what is recommended?
2009 Classic 16
NW Tampa Bay
Where is the pitot pickup? If it is on the drive, sometimes a small drill will break up debris right at the intake.
If worried about damage, you can disconnect the tube at the speedometer end as well.
"I don't have time to get into it, but he went through a lot." -Pulp Fiction
My experience is that when pressure type speedometers read too low there is a leak in the tubing leading up to the speedometer.
1971 Donzi 18' 2+3
1985 Eliminator 23' Daytona Offshore - Kevlar hull
1988 23' Donzi CC F-23 with 250HP EFI Mercury OB
1989 28' Team Warlock Offshore - single 548CID/600HP
1990 23' Warlock Offshore - single 525HP
Bill from Denison, TX - Lake Texoma
I have a 22C with a 454/385HP with the Volvo DPX drive. My boat came with the Gaffrig II gauge cluster with the 80 mph speedo. My boat ran 75 mph on the speedo but 71.6 on GPS.
In the spring of 2013 when I launched the boat the speedo was "pinned" at 80 mph and thats where it stayed for the season. I tried all that has been suggested in the previous posts to no avail.
I removed the speedo and took it to Florida for the winter and checked every marine supplier and salvage yard between Ft. Myers and Sarasota trying to locate a replacement speedo.( the Gaffrig II series had been discontinued and replaced by Livorsi branded gauges). Couldn't find one anywhere. The speedo is a sealed unit but does have a small hole on the back of the gauge.
As it wasn't working anyway, I thought that if I screwed it up completely it was no big loss. So I inserted a small screwdriver into the hole and kind of worked it back and forth until the speedo rested at "0". The speedo now reads a little slow... 65 mph. at WOT instead of 75 and returns to "0". It's worth a try.
Found I was getting water in my bilge too. Unhooked the speedo tube at the drive. No more water in the bilge so I'm 99% sure the speedo tube has a crack...
Thank you, Patrick
1994 18' Classic 350Mag Alpha
Previously owned Donzis -
1996 22' Classic, 502Mag Bravo
1987 20' Minx, 350Mag Alpha
1975 18' Classic, 350Chevy Volvo 280
Thanks all - I will try looking for clogs, if that doesn't work, I'll just leave it be till my next annual service and have it checked then.
2009 Classic 16
NW Tampa Bay
It's working again - used the 1/8" drill bit method & the compressed air method - don't know which one did the trick, but it's all good...
2009 Classic 16
NW Tampa Bay
These are all Bourdon Tube gauges. If you Google "Bourdon Tube gauges, you'll find they have a rather delicate linkage arrangement at the end of the tube and a tiny gear train.
Ideally, they should have a range of 20% higher than your planned maximum speed so the linkage never binds.
IMHO, 100 MPH speedos should be the minimum used in our boats.
George Carter
Central Florida
gcarter763@aol.com
http://kineticocentralfl.com/
“If you have to argue your science by using fraud, your science is not valid"
Professor Ian Plimer, Adilaide and Melbourne Universities
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