Value of Tack on Jet Drive Outboard
pstrombe
Posted 11/1/2020 8:00 PM (#968612)
Subject: Value of Tack on Jet Drive Outboard





Posts: 191


One of my fishing partners is looking at a tunnel hull jet rig. Is there any value to having a tach on a jet drive OB. Given the way the drive pump works I can't see one.
Thanks
Fishysam
Posted 11/2/2020 6:43 PM (#968632 - in reply to #968612)
Subject: Re: Value of Tack on Jet Drive Outboard




Posts: 1209


Engine rpm, why not. Can help diagnose a change or issue if you can see it's 200 rpm off vs guessing it's low.
Windy City
Posted 11/3/2020 9:43 AM (#968654 - in reply to #968612)
Subject: RE: Value of Tack on Jet Drive Outboard




Posts: 93


A tachometer is important on a jet as you use it as a gauge to monitor wear on the pump. On a jet you have to maintain the tolerance or space between the impeller and the housing. As the pump wears from normal attrition or sucking in sand, etc., the tolerance becomes larger. To keep efficiency you have to shim the impeller down and keep tolerance between it and the housing so the pump creates the correct pressure to move the boat at max speed VS HP.