Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 25-08-2016, 16:41   #1
cruiser

Join Date: Nov 2015
Boat: 1984 Sovereign 28 CC
Posts: 77
Images: 6
name that prop..

My prop needs replacing and I have a few questions. The prop is starting to chip apart and it looks like rust on the inside. I am wondering if this is typical of 20-30 year old props or if it's a possible indication of the PO not being on top of sacrificial zincs. My main reason for asking this is because I am not familiar with prop issues and I want to avoid having to buy another prop soon. The million dollar question is what is supposed to go back on there and where should I buy it from? The old one has some obscure looking marks/numbers and I have not been able to wrap my head around all the numbers involved in online prop calculators. As always, all of your help is appreciated.

84' SOVEREIGN 28 (LWL 23', Beam 8.3', Displacement: 6800 lbs)
Yanmar 2gm (Freshwater cooled) 3,600 rpm, 16 HP, Gear Ratio 2.62:1

The prop I pulled off is about 14" in diameter with a 1" tapered shaft (I believe it is a Clockwise rotation.)
Attached Thumbnails
Click image for larger version

Name:	IMG_0380.jpg
Views:	56
Size:	412.0 KB
ID:	130088   Click image for larger version

Name:	IMG_0382.jpg
Views:	62
Size:	441.1 KB
ID:	130089  

Click image for larger version

Name:	IMG_0383.jpg
Views:	59
Size:	427.3 KB
ID:	130090  
__________________
BravoVita is offline   Reply With Quote
Old 25-08-2016, 17:13   #2
cruiser

Join Date: Nov 2015
Boat: 1984 Sovereign 28 CC
Posts: 77
Images: 6
Re: name that prop..

Quote:
Originally Posted by BravoVita View Post
84' SOVEREIGN 28 (LWL 23', Beam 8.3', Displacement: 6800 lbs)
Yanmar 2gm (Freshwater cooled) 3,600 rpm, 16 HP, Gear Ratio 2.62:1
I now believe this is actually a 2GMF with 15HP.
__________________
BravoVita is offline   Reply With Quote
Old 26-08-2016, 11:03   #3
Registered User

Join Date: Nov 2014
Posts: 581
Re: name that prop..

Using the info that you have given, my prop program says:

Top speed - 6.2 kts
Theoretical best 3 blade prop:
15.6 X 8.8 X 3

Next best in descending order:
15 X 9.4 X 3
14 X 10.5 X 3
13 X 11.5 X 3 but this prop will suffer from cavitation at high loads due to inadequate blade area.

Theoretical best two blade prop:
16.3 X 9 X 2

Next best in descending order:
16 X 9.25 X 2
15 X 10.2 X 2
14 X 11 X 2 with cavitation problems as mentioned above

Things to remember when buying props in the US:
- Normally sold in whole inch sizes on both diameter and pitch, but a prop shop will adjust pitch for you.
- Although larger diameter props are more efficient at displacement speeds, you should maintain blade tip clearance of 15% of the diameter between the blade tip and the hull. Anything less may be noisy and give some vibration.

Your existing prop is indeed a RH turning prop. It was made by Radichi (?) an Italian builder, and because of that you should check carefully and make sure it is a 1 " shaft and not a 25mm shaft. Metric shafts normally have a different taper angle than SAE and they are not interchangeable.

Hope this helps....
DougR
__________________
DougR is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Name this prop noise... AndDavRos Propellers & Drive Systems 39 11-01-2015 20:44
Name of City and State, or Name of Country ? Tori Off Topic Forum 11 15-05-2011 13:44
Engine Bolted Straight to the Steel Hull ! Engine Name ? Windlass Name ? surfmachine Engines and Propulsion Systems 15 14-02-2011 16:08
Anchors - Brand Name vs Non-Brand Name outdoor Anchoring & Mooring 30 01-04-2010 07:41
ssullivan, What was her name? What is her name? Woodsy Multihull Sailboats 1 06-05-2008 18:50



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 11:48.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.