Adding speedo to boat.

[77Saturn620]

1977 Galaxy Saturn 620 w 76 Merc 500 Thunderjet.

I know how car speedos hook up....how do they on a boat?
( imagining a little paddle wheel on bottom of boat...lol)

Any other gauges besides water pressure I can have on this engine?

 

[ziggy]

Re: Adding speedo to boat.

i had a yamaha pwc that had a paddle wheel type speedo sender. more usual on a boat is a pitot tube that works on water pressure the compresses air and moves the needle. these types of speedos are generally not real accurate.

or

just get a gps. very handy to have on a boat + they have speed on them. very accurate speed even.


i don't know ob's at all. but surely ya could have a tach too.. that would be a more important gauge than a speedo too.

fwiw, my boat don't have a speedo. it does have a tach.. i do have a gps...

 

[NW Redneck]

Re: Adding speedo to boat.

( imagining a little paddle wheel on bottom of boat...lol)

Actually, that IS one of the types of speedo sending units! The other (and more common) is called a pitot tube. It is a rigid tube that mounts to the transom and sits in the water and a small tube connects it to the gauge on the dash. While underway the pressure of the water pushing into the pitot compresses the air in the tube and causes the needle to move.

You can have gauges for: Amps, water temp, oil pressure, rpms, trim, hours, and maybe more!

 

[vegasphotoman]

Re: Adding speedo to boat.

ok the boat speedos work like this for the most part

a thing called a PITOT...it mounts to the bottom at the back transom....has a little hole in it ....a small tube connects....it goes all the way to the dash...the speedo works from the pressure of the air inside the tube...the water comes into the tube a little bit...and pressurizes the air...causing the speedo to show speed etc...FYI it is definitely different than a car speedo....


a volt meter is super dandy....shows battery and charging voltage etc

engine water temp VERY GOOD TO HAVE!

a tach is even more useful than a speedo...shows RPMs...so you dont blow up yer motor! lol speed is relative! ( I do like to know my speed tho)

an oil pressure gauge is good to have.....or atleast an idiot light....

some people have trim gauges, though it is handy its not necessary...you can feel trim once you get accustomed to boating......shows the angle of the outboard or I/O outdrive....

mebbe a compass if you go out in big water...(ocean/great lakes etc)

GPS is handy...your cell phone might have one too...works! (Iphone-etc)

fuel gauge....should have for med to large boats....little tiny boats dont need em...they mostly use 5-10 gallon tanks with primer bulbs etc....

 

[Eric 3.7LX Alpha 1]

Re: Adding speedo to boat.

I have a speed o and never hooked it up. It's coming out this winter and gonna put something else in it's place.. I get speed readings from both my GPS(chartplotter), and fishfinder (which has the wheel type sender), both work well sometimes alittle off from each other depending on the current I am in.

GPS is better will let u know if you pulled the anchor while tied up somewhere, don't think any other type of speedo will do that.

 

[kenmyfam]

Re: Adding speedo to boat.

Easiest is a GPS. No drilling the hull.

 

[jaxnjil]

Re: Adding speedo to boat.

Easiest is a GPS. No drilling the hull.