TOPIC: Information about propeller?

Hello,

Does anyone have information about this propeller? I found a Michigan Wheel spreadsheet online, but only the A1 prop was listed, not the A3 as indicated in the photo.

In case the photo is not easily readable, the number on the prop is

48-31452-A3-21

Thanks in advance,

Pete

No clue me, but for the life of me can't figure why they can stamp all kinds of crap on a prop but the damn pitch and diameter! Every time I run across a prop and know the dimensions? OUT COME THE STAMPS AND A HAMMER if not there!

mercury prop book has it listed for inline 6's. 650 4cyl in line. 650 thru 1500. 70-90hp 3 cyl above serial #A722297 and merc 700-800 Direct reversing with LH rotation.

The -21 tells you it's a 21P, and I think most of the 2 blade bronze Merc 6 cyl props (15 spline ?) were 13 1/8" dia.. It looks like a RH prop to me, but I'm still on some wacky meds!? LOL

I think the A1, A2, A3 designations were production runs or something to do with the amount of cupping? Also possible the pitch or cupping have been "adjusted" somewhere along it's life, only way to know is let a good prop shop check it out or bolt it on and run it. Looks pretty, did you get it from David P in MN?

Hey, thanks for the info guys. The prop belongs to a friend of mine, but he said I could have it to use on my '61 800 (if/when I finish building the boat!).

I haven't seen the prop in person, but it looks good. It'll be fun to try it!

Best,

Pete

make sure it is the correct rotation for your motor.
if it has full gear shift it will work. non shift in that rotation is rare. hope you have the motor on a very light boat with that much pitch.

Hi Dave,

Thanks for the advice. The motor is a FGS and the boat I'm building I expect to weigh between 700-800 lbs equipped (per the designer).

BTW will modern 3 eared props fit that motor?

Thanks again for the advice,

Best,

Pete

should.

I have a 63 1000 on a 900 lb hull. 21 is a bit too much pitch for it just with me in it. I prefer 19p. Also, I dont like the weight a stainless prop brings with it. BUT! If it's a free prop, give it a try!

Thanks Peter, yeah, I think you always have to try a free propeller!

One last thing, do any of you know what type of propeller will "lift" the stern rather than the bow?

I ask because this boat was designed for a motor weighing about 190lbs. This boat was designed before the advent of 4 stroke motors, mid to late '80s. Folks who have built this boat post 2000 or so, typically put a modern 4 stroke 60HP. weighing close to 250lbs. They porpoise.

The designer said to put a 5 deg wedge on the transom to increase the "tuck" for these motors and I did that, but thought maybe a propeller would help as well.

Sorry for all the seemingly naive questions - I just know enough to know what not to ask!

Anyway,

Thanks a bunch,

Pete

That's gonna be a lot of prop for an 800. Looks like it's chrome-plated brass to me, but my eyeballs ain't what they used to be, either!

You can use a modern-style prop with integral hubs on the old motors, by use of a spacer sleeve, Merc P/N 23-86918 (superceded to 23-86918T).

This sleeve goes up against the square-shouldered prop shaft. Then you use the "modern" Merc flat thrust washer and away you go!

One thing you can do is try the 21" prop, see how it performs. Then you'll have a baseline to help you figure out what pitch you really need.

If you don't have a tach, use an automotive tach on the 6-cylinder setting, and connect to one coil only. This will give you accurate rpm readings to help with prop selection.

HTH............ed

Thank you Ed for the advice, I wasn't aware of the need for the that part for modern props.

Still a little time before I'll be up and running, but it's never too early to get your ducks in a row! I'm hoping for June/July for the inaugural splash.

Thanks again,

Pete

In high performance boating, a cleaver style prop is a stern lifter, while the more common round ear, used on 98% of non-raceboats, is a bow lifter. Unless you are running 80+ mph, a cleaver will not help. The wedges are your best solution. BTW, I also believe that 21 is too much pitch. Be careful not to "lug" the motor if you do try it. (like trying to accelerate a stick shift car in second gear instead of first)

Hi Kerry,

Great information, thank you. I'll rely on the transom wedge to get the stern up - I'll be lucky to hit 50-55 mph I think.

I like the analogy about lugging the engine, I may take a few props with me to change out.

Than you very much.

Best,

Pete

The only way you hit 50 is when it's on the trailer. I have a 18' completely stripped out Starcraft aluminum with a 900 on it turning a 17" SS wheel and I would say maybe 40mph max.with PT&T.It does have floorboards and 3lbs of wood I used for a side console,but no seats,used for waterfowl hunting. I also have a freshly rebuilt 1500 turning a 20" SS jacked up about 2" on a 15' 425lb tunnel hull Power Cat and hit 53+ GPS on a good day,[ a bit of a ripple on the water,not flat calm]