Prop spacing question......

[skatermike24]

Has anyone moved there prop back on the prop shaft with positive results?????

[W. Tripp]

I use custom thrust washers to adjust the prop's position relative to the tip of the nosecone in 1/16th inch increments on all of my gearcases. 1/8 of an inch can make a big difference on a light hull.

Moving the prop forward usually allows the prop to slip a bit more - especially out of the hole. This can help increase tail lift.

Moving it back will unshroud the prop and feed it more water. This can help a prop hook up more at speed. In some cases this can reduce pourposing or lift the bow a bit more.

With multi-engine set ups, a small bit of spacing can really afect the way a hull holds the bow at speed, but cleaver type props show less change than a full blade round ear prop.

Use this as a tuning trick to find out what work to add to your prop.


I hope this helps,

[Jay Smith]

I have seen on my 1/4 mile race boats as much as 5 MPH in the quarter BIG end numbers ( from all the way forward to all the way back ) and on twins 3 MPH moving the prop back on the shaft with custom spacers and machining a prop nut in half just enough where 1 thread of the shaft is past the nylon lock nut then torque the nut to 100 FT LBS.

Been there and done it !

BTW. It does put some undue stress on shaft and bearings but when a win or a mph goal is needed ( wanted ) its no holes bared.........FYI... Also ATF for a couple of passes will find 50 to 100 rpms + over the thicker oil too , BUT I don't suggest it for your Summer long gear case lube !

Few tricks of the trade....