Re: 1966 Mercury 500 / opinion on Hydrofoils
Interesting Ed. I will try drilling the holes out. I have thought about a new prop and have been doing some research about them and learning about pitch. I guess I can relate it to changing gear ratios on a car. Do you have any advice for what pitch or prop i should be looking for? Where is a good place for me to purchase one for my older outboard. Thanks for the info.
Best thing to do is to see what pitch you already have. Check the body of the prop, if it's an OEM Merc prop it'll have a string of numbers like "47-######A12". The last number is the pitch of the prop. I expect you wouldn't have more than a 12" pitch on it now, 'cause a 50hp probably wouln't pull a steeper pitch on that size of boat.
If it's an aftermarket prop, pull the propnut and thrust washer, usually right on the face where the thrust washer sits, will be a string of numbers, most times ending in pitch but sometimes just the mfr's part # for the prop. That can help you look up the prop pitch.
My good friend used to slalom ski on a small boat with a 50hp, if I recall he told me that he had a 10x10 prop (that is, 10" diameter and 10" pitch). Said the motor was screaming at its max rpm but would pull him just fine.
Probably you're gonna have to do something like that to get the max performance out of your motor.
Question, how does it take off with just you in the boat? Does it still struggle to get on plane, and does it sound like it's making good rpm at full throttle?
It'd be great if you had a tach, since that's the most accurate way of telling what's happening. The thing is, if you're already "overpropped" even with minimal load, that's gonna skew the prop selection.
In other words, you potentially may have to drop down 4" in pitch to get the performance you want.
But maybe it just runs out adequately as is, with light load. Then, perhaps the 2" drop in pitch would do.
If you are propped pretty close already, the "Holey Prop" trick will definitely make a difference.
It's a great way to gain more hole-shot performance with a marginally-powered boat.
Heck, I've even used the trick on my old 1350 Merc, you shoulda seen the way it took off! :0
Not to mention the old Merc 700-Six Dockbuster (Direct Reversing) I had almost 30 years ago, on a 13-1/2' Sea-King runabout.
With a Holey Prop it would rip my buddy out of the water on single ski and still go 35 mph. Not bad for a $25 motor!!! Hard to find 'em like that nowadays! Motors were cheap and gas was cheaper! But we sure had a lot of fun for little $$$.
The sport is more expensive now but the old motors just keep on running. Congrats for keeping one of the Classics alive!
Cheers........ed
