What propeller should I use??

[MTECHMARINE]

Regarding propellers for Mercury "classic" racing motors over the years ~~

I know this is a pretty generalized request. I have a box full of propellers from over the years, but have no clue where to assign them. Is there anywhere I can find a pitch/diameter range for older Merc applications? Ron, can you help?? Anyone??


Hydro / Runabout
KG4H
KG7H
MK20H unconverted 1:1
MK20H conversion 1:1
MK20H conversion 16:21 ( same as 40/55H?)
MK30H (as I recall) 7x10 / 7x9
MK40 /55H

As a rule of thumb, when using a 3 blade lower the pitch 1 inch?

THANKS FOR YOUR COMMENTS!! :cool:

[DeanFHobart]

Hey Bill, call me. Dean Hobart... 425-503-1882.

[zul8tr]

Regarding propellers for Mercury "classic" racing motors over the years ~~

I know this is a pretty generalized request. I have a box full of propellers from over the years, but have no clue where to assign them. Is there anywhere I can find a pitch/diameter range for older Merc applications? Ron, can you help?? Anyone??

Hydro / Runabout
KG4H
KG7H
MK20H unconverted 1:1
MK20H conversion 1:1
MK20H conversion 16:21 ( same as 40/55H?)
MK30H (as I recall) 7x10 / 7x9
MK40 /55H

As a rule of thumb, when using a 3 blade lower the pitch 1 inch?

THANKS FOR YOUR COMMENTS!! :cool:

Here is some prop info on the 20H 1:1 and 16:21 with and without conversion

http://johnsoldmercurysite.com/phpBB3/viewtopic.php?f=7&t=8297

Also I recall drivers would use a D stock 1:1 wheel on a 20H with 16:21 gears.

[champ20B]

Regarding propellers for Mercury "classic" racing motors over the years ~~

I know this is a pretty generalized request. I have a box full of propellers from over the years, but have no clue where to assign them. Is there anywhere I can find a pitch/diameter range for older Merc applications? Ron, can you help?? Anyone??


Hydro / Runabout
KG4H
KG7H
MK20H unconverted 1:1
MK20H conversion 1:1
MK20H conversion 16:21 ( same as 40/55H?)
MK30H (as I recall) 7x10 / 7x9
MK40 /55H

As a rule of thumb, when using a 3 blade lower the pitch 1 inch?

THANKS FOR YOUR COMMENTS!! :cool:

It depends on boat. Old utility (wider beam, more wind drag for open hull)? Or is it an older shovel-nose hydro? If so, what class hull? These worked well with the older two blades that ran a bit deeper. If your running a modern up to date hull of either type, a proper designed and cupped two blade would work. One could be made up from one of the old props if necessary. It can be run high like todays props with good top end, but if turning characteristics is what you want, a three blade is probably better. Pitch can stay the same in most cases. Grab depends on overall combined prop area more so than how many blades when running straight in my experience. You might be surprised at how close the old stock engines can run to the newer ones on a newer style hull, if everything is tuned right or at least close enough to cut it to start with. The mark 30H props sound about right for originality.