Prop discussion

Designs for inboard or outboard power

Moderator: BruceDow

User avatar
Bill Edmundson
Posts: 12152
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Prop discussion

Post by Bill Edmundson »

Matt

I'll get the calculator out in the morning. At some rpm, blade tip cavitation plays in. A 12" prop. starts having issues at about 4000 rpm. A really good prop. shop can get you above that. (Yes some will disagree with me.)

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

benpetre
Posts: 88
Joined: Tue Apr 21, 2009 7:53 am
Location: Annapolis, MD
Contact:

Re: Prop discussion

Post by benpetre »

https://www.mercuryracing.com/propeller ... lator.html

good tool to use

1.23 ratio
5000 pm WOT
assume a 15% slip

Given all the above variables, the 14 gets you to 46mph at WOT
the 12 gets 39mph as long as you dont cavitate above 4k like bill said.

Prop slip may be different between the 3 blade and 4 blade. 15% assumed for discussion
__________________________________________________
Ben Petre
Annapolis, MD
https://www.facebook.com/barrelback19
http://drpetre.com

Building the barrel back 19 ever so slowly.

Hercdrvr
Posts: 1517
Joined: Mon May 11, 2015 12:52 pm
Location: McKinney TX

Re: Prop discussion

Post by Hercdrvr »

I mounted the 14x14 3 blade prop. It has 2.75 inches clearance from the bottom of the hull, is this sufficient?
Matt B

User avatar
Roberta
Posts: 7182
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Prop discussion

Post by Roberta »

That should be fine.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

User avatar
kens
Posts: 5258
Joined: Wed Nov 12, 2003 5:25 pm
Location: Coastal Georgia

Re: Prop discussion

Post by kens »

2.75" is a rather generous clearance, that prop should breathe nicely. run smooth
Oak..........the juice ain't worth the squeeze :D :shock: :o :)

denbrlr
Posts: 733
Joined: Sat Sep 18, 2010 10:06 am
Location: Peoria, IL

Re: Prop discussion

Post by denbrlr »

Matt,

A 2.75 inch clearance should work well. I am curious, what is the drop of your strut?

Lee
YouTube channel: Boat Builder Lee
Monaco build YouTube playlist: https://www.youtube.com/channel/UCP4Edb ... /playlists

Post Reply

Return to “Power Boats”