Posted by f1loco on 10/16/17 - 11:00 AM
#1
So, currently I have a 9.8, 4 stroke, short shaft with a 8.5 x 7.5 prop. I run a pretty full load of 3-4 adults and it is only taching out at 4900-5000 rpms at WOT. Was looking for a bit more RPM and possibly a plane (I know a lot to ask for a 9.8). I feels like you are in 4th gear but really should be in 3rd, if you know what I mean? I did put a foil on it in hopes of "easier" planing - but no luck. Saw Tohatsu offers a 8.3 x 6 and a 8.0 x 5, 3 blade option. Was thinking the 2.5 drop in pitch would get me closer to the 6K range at WOT while the drop in diameter would keep slip resistance and strain down on the motor? Has anyone else run this or the 6 pitch set up and can offer some feed back.
Posted by EJO on 10/17/17 - 11:52 AM
#2
Like you said 9.8 with 3-4 adults in a 13 to plane is too much to ask. You can do the prop math and yes it would speed up your RPM but I doubt it would put you onto plane with 600+ lbs on board.
Posted by tedious on 10/17/17 - 2:36 PM
#3
Just from some quick math, you're looking for a 20% RPM gain and dropping to a 6-pitch from your current 7.5 is a 20% drop. So that's what I would try. Will it plane? I have no idea!