Dumb Prop Question...

[hoowahfun]

Okay so here's what may be a dumb prop question. My existing prop on my project boat is mangled so I removed it to replace it. It has a removable hub that looks like it's in good shape. Is it a bad idea to use a fixed hub prop as a replacement? Found a used Michigan prop in good condition for pretty cheap, but it has a fixed hub. Also not sure if it's possible to convert from fixed to removable or not....I think not, just not sure how the term "fixed" is really used here.

3.0 motor w/ Alpha One Gen 1 outdrive.

Any help is appreciated. Thanks!

 

[Bt Doctur]

just make sure the thrust collar is correct and bolt it on. Fixed hub/ Runner hub VS the plastic Flo-Torc inner hub that is owner replacable

 

[hoowahfun]

Here's my existing prop:

 

[hoowahfun]

Here's the one I'm looking at

 

[harringtondav]

Hub choice is up to the owner. Each mfg. makes their own claims for value, but they're all designed to slip and protect the drive under severe impact. Removable hubs offer a cheaper replacement, or spare propeller cost. But you're stuck with that brand. I've found fixed, pressed in props are less expensive than the replaceable prop + hub kit. And the prop shop doesn't care which.

My prop pro said Merc's new design has a removable hub with break-off fingers. It's claimed to deliver full torque, but give up sooner under impact, possibly saving the prop. Then you just buy a replacement hub. I'd carry a spare hub in my boat. You can limp home with a spun rubber hub. Once Merc tabs are gone, I suspect you're just spinning.

 

[hoowahfun]

Does it look like the new one will work as long as I swap over the thrust washer from my old prop? Looks to be the same fit. I don't really care on the type of hub as long as it works, and I'll keep the one I have just in case.

 

[harringtondav]

I basically repeated Bt Doctur , and he said yes. So do I.

 

[hoowahfun]

Sorry. If that was the case, then I missed it. I'm new to some of this stuff. Thanks for the help.

 

[jimmbo]

The michigan is probably going to need a different thrust washer, one that is totally flat. Mercury had a few variations of its hubs and thrust washers, and prop nut washers over the years. Wrong thrust washers can lead to poor performance and/or gearcase housing damage.
As for the type of hub, what you are calling Solid is more than likely a rubber cushioned hub, Your original prop had the Merc Flow-Torq hub system. Is one better than the other, well with the rubber hub, you will probably be able to get home, with the flow-torq, maybe, maybe not. If the plastic parts of the hub kit shatter small enough, you won't be going anyway as the prop will not do much as the propshaft turns. So unless you carry a spare hub kit, having a spare prop aboard really doesn't mean much. As for which protect the prop better?, That is not their intent. The rubber hub is really designed to absorb the sudden load placed on the gears and drive train when the clutch dog engages. Zero rpm to whatever rpm in a millisecond is quite a strain on the parts, especially with some of the heavy stainless props. Those Hub kits really offer little or no cushioning

 

[hoowahfun]

The michigan is probably going to need a different thrust washer, one that is totally flat. Mercury had a few variations of its hubs and thrust washers, and prop nut washers over the years. Wrong thrust washers can lead to poor performance and/or gearcase housing damage.

If the previous thrust washer provides the same or a little larger clearance between prop and gear casing is that really going to be a big deal? I can see it being a problem if it's too close. What is the recommended gap supposed to be anyways? Might be able to fabricate something if I know the final dimension.