Can we talk about propellers?

[Daniel1980]

I am a new boater. I have an 18' Sea Ray. She's a gem. Little rough visually, but I like the visual character with phenomenally working mechanics.

So I replaced the prop with a 21" aluminum new propellor. Out of box, it's not sharpened but I am assuming balanced?

Tops out at 38mph with 3 people and gear. Claimed is 42mph new with 1 person and empty.

I used to race gas powered RC boats. Lot of fun! Number ine performance upgrade was a worked prop. Once you got thw right prop size that gave you the hole shot and didn't bog your motor, you would balance and sharpen it. It was a real art.

Question is, does the same hold true for full size boats? Also, can you tell me what would happen if I went with a smaller prop, say 20 or 19" versus the factory spec 21"? I really like to squeeze out performance. Yes I understand there is definitely a point of very dkminishing returns from a Mercruiser 3.0L 4 cyclinder motor, but I was hoping to gain some understanding on props. Please and thank you

 

[Strecker25]

Generally your measure of a good match is to ensure your engine can reach rated WOT while loaded up how you normally use the boat. You mention the bogging of an RC engine and the same principle holds true in full size boats except it’s usually not noticeable that you’re bogging the engine but if you can’t reach wot you’re running overloaded at all cruise Rpms.

the first move should be to verify your tach is accurate then go for a wot run to see where you’re at. 1” of pitch will either raise or lower your wot by 150-200 rpm usually

I used to run rc boats too. We had 1/8 nitro hydros, some big gas boats, and small nitros. Fun stuff

 

[Daniel1980]

Thanks Strecker. I appreciate the feedback. I miss my RC Boats. Had a nasty Aeromarine Sprint Cat gasser...did about 60mph and handled on rails. I have a feeling the propr that I have is probably the right one. Don't think I'm going to try and out think the folks at Sea Ray here. It just looks so dull....edges. Wasn't sure if sharpening and balancing a prop out of box was something that people did.?

 

[Strecker25]

Thanks Strecker. I appreciate the feedback. I miss my RC Boats. Had a nasty Aeromarine Sprint Cat gasser...did about 60mph and handled on rails. I have a feeling the propr that I have is probably the right one. Don't think I'm going to try and out think the folks at Sea Ray here. It just looks so dull....edges. Wasn't sure if sharpening and balancing a prop out of box was something that people did.?

balancing, absolutely. Sharpening, not so much aside from the really high end go fast guys.

I’d make sure you can get into the proper WOT range and just go boating. The only change the smaller bow rider guys usually go for is a 4 blade instead of a 3 so you get a better hole shot for pulling tubes and such. 4 blades will generally be a little slower on the top end

I do know where you’re coming from on the sharpening though. I can distinctly remember tiny files and wetsand paper shining up those octura propellers on our little boats

 

[Daniel1980]

Ok, I will look into balancing. Mower blades or boat props, performance gains and smoothness must be had here. Thanks Strecker.