Want to cup - ?'s, and good shop in WA?

[55Crestliner]

I have a real nice Bronze 2 blade, (with rubber hub), and it has no cup. This is on a '55 Johnson 25 horse.<br /><br />I'd like to have it cupped. Is there anything I should know ahead of time to ask a prospective shop? You know, sort of like an interview to make sure they know what they're doing. This prop was a good chunk of coin to me, and it's in very nice shape. I don't want it messed up.<br /><br />Are all "cuppings" the same?<br />I am in Western Washington State.<br /><br />I'm wanting to cup it because it's the most pitch I seem to be able to find, and RPM's are slightly high, and I get ventilation when trimmed out, with a pretty slight turn.

 

[Dhadley]

Re: Want to cup - ?'s, and good shop in WA?

Cupping is like most other prop terms. It's a general statement that can cover a lot of specific area. With most good prop shops or prop builders you tell them what it's doing and what you want it to do and they work it accordingly.<br /><br />Cupping is looked at in several ways. Now in this case we're only going to talk about cupping an existing prop, not different ways to build cup. And we'll only talk about round ear props, assuming that's what you have vs. a cleaver type prop.<br /><br />The trailing edge is bent to grab the water better or hold it longer for more forward thrust. The amount of thet bend depends on a lot of things. And more cup towards the hub does one thing while more tip cup does another. <br /><br />Then you get into cup placement. Where do you stop it? In the middle of the tip? Around the end of the tip? How far past the tip?<br /><br />It all boils down to the fact that the term cupping is a general statement that can get pretty involved.

 

[55Crestliner]

Re: Want to cup - ?'s, and good shop in WA?

Wow. That's kinda what I thought - lots of choices of how much, and where to put it. <br /><br />So, do I just trust what the shop does is best? Or should I say I want this and that specs?<br /><br />I think I know your answer - since I don't know what I want, take what I get.<br /><br />btw, you're right, it's a round prop, not a cleaver, but it is raked back some, compared to the regular 3 blades I have.

 

[Dhadley]

Re: Want to cup - ?'s, and good shop in WA?

It's good if the blades are raked back. That will add lift. As for a good shop that's a tough one. About the only way to know is to try one. Or at least talk to them. If they kinda blow you off either they don't know or don't want to get into it. Either way you can figre it's probably not a good idea to send it to them. <br /><br />I'd start by telling them what you have and what it's doing. And what you'd like it to do. Then ask them what they'd recommend. You'll know right off if they're shooting from the hip or not.

 

[55Crestliner]

Re: Want to cup - ?'s, and good shop in WA?

Ok, thanks, good info. I'll see what I can find.

 

[Tail_Gunner]

Re: Want to cup - ?'s, and good shop in WA?

I see your from the NorthWest, are you close to portland or?

 

[55Crestliner]

Re: Want to cup - ?'s, and good shop in WA?

I'm closer to Seattle/Tacoma.<br />I've got 2 shops in mind, one is Tacoma Propeller, the other is SeaWay, in Seattle. I've bought from both of them. I'll do what Dhadley said, approach them about it, and see who's more interested.

 

[496 Cubic Inches]

Re: Want to cup - ?'s, and good shop in WA?

The Prop Shop in Mukilteo does good work.

 

[Uniflite32]

Re: Want to cup - ?'s, and good shop in WA?

I've heard good things about the Prop Shop also. You can also try Krueger and Sons, he's done good work for me.<br />I highly recommend Northwest Propeller in La Conner. I have twin 5.7 MPI's in my 32' Uniflite. I needed 300 more RPM's at WOT. Tom took out 2 inches of pitch and added more cup including tip cup. I got my 300 RPM's at WOT but lost NO speed at my 3200 RPM cruise. (18.2 KN) Fuel economy should also improve due to less load on engines.