Low speed speedometer question

san dimas

Petty Officer 1st Class
Joined
Jan 20, 2012
Messages
369
My speedo has a range from 0-65 mph. It doesn't read anything untill I get to about 12mph. If I get a speedo that goes from 0-45 mph will it be more sensitive at lower speeds? My boat only goes about 31 mph so I don't need a 65 mph speedo. A lot of the lakes I boat on have 10 mph speed limit and I would like to know how fast I'm going.
 

smokeonthewater

Fleet Admiral
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Dec 3, 2009
Messages
9,838
Re: Low speed speedometer question

WHS.... Water pressure speedo's aren't precise and will never read at low speed
 

dan02gt

Chief Petty Officer
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Aug 30, 2012
Messages
463
Re: Low speed speedometer question

GPS or a paddle wheel speed sensor.
 

UncleWillie

Captain
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Oct 18, 2011
Messages
3,995
Re: Low speed speedometer question

GPS is the way to go.
There are also GPS speedometers available if you prefer reading a gauge. $$$
GPS Speedometers are Linear.

Pitot based speedometers are all going to have exponential scales. It is a square function.
50% Full speed is going to indicate at 1/4 of the dial. 71% speed at 1/2.

A 45mph Speedo will indicate 22mph at 1/4 of the dial and 32mph at 1/2 of the dial.
 

AChotrod

Petty Officer 1st Class
Joined
Aug 25, 2013
Messages
382
Re: Low speed speedometer question

You could get a fish finder with GPS and mount it on the dash like I did. Works perfect.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
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47,296
Re: Low speed speedometer question

pitot tube speedos are good to only indicate that you may or may not be moving. they are never accurate.

the GPS will tell you your speed with respect to the satellite (useful to know how fast you are boating). a paddle wheel fish finder will tell you your speed with respect to the water (useful for knowing how fast you are trolling)
 

Home Cookin'

Fleet Admiral
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May 26, 2009
Messages
9,715
Re: Low speed speedometer question

I see no need for a speedometer and I wouldn't buy a GPS or fish finder just to have one. But if you buy a fish finder to find fish, or a GPS for mapping, it's a good extra.

Your concern is not speed but no wake. So instead of looking at the dash board, look at the wake. That's what the cop will write you a ticket for; he won't know your speed either.

You can also ask another boat with a GPS to go 10 and you track him to feel what it's like.
 

BigDfromTN

Petty Officer 1st Class
Joined
May 16, 2013
Messages
268
Re: Low speed speedometer question

If you have a smart phone...
Download a speedo app. They have them in digital and analog dials.
Or the Navionics app has a gps speedo built in. App is free as I recall but maps with depth will cost $10-15.00.

If no smart phone. Do you have a mobile gps in your vehicle? Take it aboard. If not Just go no wake and be safe.
 

UncleWillie

Captain
Joined
Oct 18, 2011
Messages
3,995
Re: Low speed speedometer question

10 mph has to pretty close to the MAXIMUM Wake speed.
At 10 you are plowing about as much water as possible, and just on the verge of getting on plane.
Is 10mph another way of stating, "Do Not Plane?"
 

san dimas

Petty Officer 1st Class
Joined
Jan 20, 2012
Messages
369
Re: Low speed speedometer question

Thanks for your replys. I think I'll just leave well enough alone.;)
 
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