Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Drive Train / Propellers

Reply
 
Thread Tools Display Modes
  #1   IP: 70.20.35.146
Old 12-11-2019, 06:46 PM
Chica Chica is offline
Frequent Contributor
 
Join Date: Dec 2019
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Tartan 27 propeller

I replaced my old, chipped two blade with an Indigo 3 blade. Did not recognize an improvement. Furthermore, after light use over one season the three blade was evenly pitted on both leading and trailing edges, more pronounced on the trailing edge. I suspect serious cavitation. I think the prop is too close to the deadwood. Deadwood is 3" thick, Indigo blade is 4" long beyond a 1 inch shaft. 1 inch of the available 4 is directly behind the deadwood. My choices are:

1- Move the three blade aft by cutting the shaft and adding a spacer at the transmission, or...

2- Purchase a new two blade.

I want motoring performance above everything else.

What are your thoughts?
Attached Images
  
Reply With Quote
  #2   IP: 66.63.65.115
Old 12-12-2019, 10:17 AM
Chica Chica is offline
Frequent Contributor
 
Join Date: Dec 2019
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
i figured wrong with regard to what amount of the blades lay behind the deadwood but the principal is the same.
Reply With Quote
  #3   IP: 138.207.175.104
Old 12-12-2019, 11:34 AM
Administrator's Avatar
Administrator Administrator is online now
MMI Webmaster
 
Join Date: Oct 2004
Location: Chestertown, MD (Langford Creek)
Posts: 2,098
Thanks: 1,226
Thanked 243 Times in 136 Posts
Maybe it's no big deal, but is that jack stand chain stressing your rudder post?

Bill
Reply With Quote
  #4   IP: 97.93.70.7
Old 12-12-2019, 11:36 AM
Dave Neptune Dave Neptune is online now
Afourian MVP
 
Join Date: Jan 2007
Location: Lake Arrowhead Ca.
Posts: 4,075
Thanks: 433
Thanked 398 Times in 277 Posts
Careful proping

Chica, I assume you are a direct drive with the Indigo. There is not much room for the small diameter to bight on and what it bites on is disturbed water flowing around the deadwood. What was the original prop and crusing RPM's before?
And what RPM's are you getting with the Indigo? The Indigo runs at a higher RPM's to get to the power ccurve of the engine. Comparing speed at a given RPM is not what to look for. What you want is around 21~2200 RPM's for fast cruise. Choosing a 2 or a 3 blade is problematic for finding a flat enough pitch and diameter (usually larger) to achieve good power RPM's.

Before changing anything be sure of the tune of the engine. With the Indigo you should get to 24~2500 RPM's if the engine is tuned properly.

Dave Neptune
Reply With Quote
  #5   IP: 70.160.120.221
Old 12-12-2019, 11:56 AM
indigo indigo is offline
 
Join Date: Jun 2007
Location: Williamsburg, VA
Posts: 32
Thanks: 7
Thanked 22 Times in 12 Posts
Propeller Deterioration

The pitting you see on the prop is the result of Galvanic Activity. Since you do not have a zinc on the shaft, the prop is the sacrificial element. That is the concept behind the Indigo "No Barnacle" solution. The prop material has no zinc in it thus the pitting was very limited. The good news is that you had no barnacles.

To follow up on Dave's question, what was your WOT RPM and what boat speed did that yield. We have a least 20 Tartan 27s with our prop installed and no complaints.

Tom Stevens
Reply With Quote
  #6   IP: 66.63.65.115
Old 12-12-2019, 01:49 PM
Chica Chica is offline
Frequent Contributor
 
Join Date: Dec 2019
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Thanks all-

Bill, I'll check the stands and chain but I seem to recall the chain having some play...still not an ideal location.

Dave, i don't know the answer to these questions but I'll keep them in mind when i restart things. It had a 13"X8" and it appeared to work well.

Tom, I came to my cavitation conclusion because of the evenness of the deterioration and the shiny metal exposed, especially on the trailing edge of the prop. It looks like someone ran a 36 grit board over it. I did have the boat on a marina dock for the summer. Do you think the distance between deadwood and prop could be an issue? Is this prop still serviceable?

Thanks again-
Reply With Quote
  #7   IP: 70.20.35.146
Old 12-12-2019, 07:27 PM
Chica Chica is offline
Frequent Contributor
 
Join Date: Dec 2019
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Choosing a 2 or a 3 blade is problematic for finding a flat enough pitch and diameter (usually larger) to achieve good power RPM's.


Dave, Could you either elaborate on this or put it in terms a carpenter can understand?
Reply With Quote
  #8   IP: 70.160.120.221
Old 12-12-2019, 09:58 PM
indigo indigo is offline
 
Join Date: Jun 2007
Location: Williamsburg, VA
Posts: 32
Thanks: 7
Thanked 22 Times in 12 Posts
Indigo Prop

Since I have had no negative feedback from other Tartan 27 owners with the Indigo prop, I can only assume that the clearance you have from the deadwood is sufficient.

You should hand dress the leading edges especially to restore decent performance. Try to create a nice parabolic leading edge, not something razor sharp.

You can probably get a zinc of some sorts on either the shaft (a thin "Donut" model) or one of the "Nut" types on the threads. The addition of a zinc will prevent the Galvanic Action on the prop, however you will get barnacles which make a mess of performance as well.

Tom
Reply With Quote
  #9   IP: 66.63.65.115
Old 12-13-2019, 10:17 AM
Chica Chica is offline
Frequent Contributor
 
Join Date: Dec 2019
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Thank you Tom.
Reply With Quote
  #10   IP: 32.211.28.40
Old 12-13-2019, 11:14 AM
Al Schober's Avatar
Al Schober Al Schober is offline
Afourian MVP
 
Join Date: Jul 2009
Location: Uncasville, CT
Posts: 1,555
Thanks: 9
Thanked 223 Times in 179 Posts
Chica,
The prop in the photos is corroded, and shows impact damage on the leading edges at the tips. The corrosion can be due to an engine/battery grounding issue. I've seen a 12" propeller reduced to 9.5" by stray ground current!
Your best powering performance will be with a 3 blade prop (more blades gives you less vibration), as big as you can fit in there while maintaining adequate tip clearance to the hull. As diameter increases, you have to reduce pitch so the propeller performance curve matches the engine power curve.
The performance of a propeller can be adjusted somewhat. Diameter can be reduced by machining the tips of the blades, and pitch can be adjusted somewhat by twisting the blades. These are both jobs for a good propeller shop. A bronze propeller has limited ductility and will only stand so much 'adjustment'. River tug boats frequently damage their propellers, but select stainless propellers that can be beat back into shape numerous times.
I recommend you consider a DriveSaver https://www.globemarinedirect.com/pr...01-12-0020.htm
This unit will stop any stray currents in the shaft/propeller, as well as moving the propeller aft bit, giving room for a zinc forward of the propeller hub.
Reply With Quote
  #11   IP: 67.175.33.159
Old 12-14-2019, 10:42 PM
HOTFLASH HOTFLASH is offline
Senior Member
 
Join Date: Oct 2004
Location: Chicago
Posts: 206
Thanks: 27
Thanked 20 Times in 15 Posts
Cool Room for thin anode on a Tartan 27

Chica,

There is very little room for an anode, other than a thin donut collar type on the 1" shaft of a Tartan 27. Boatzincs.com carries "LC-3 Micro Thin Collar Zinc Anode - 1" Shaft" which is 11/16" thick. Install it on the shaft just forward of the prop leaving a margin on both sides. But it could be your new prop takes up more space on the shaft that the original prop, leaving no room for even a thin anode.

I have a Tartan 27 in fresh water with original prop and I have not found a magnesium nor an aluminum thin (11/16") anode for a 1" shaft, so I have to use a 25mm one designed for a Beneteau. It only comes in zinc or aluminum. I use the aluminum, and the 25mm one fits fine. Boatzincs.com has those too.

Mary

Last edited by HOTFLASH; 12-14-2019 at 10:47 PM. Reason: clarification
Reply With Quote
The Following User Says Thank You to HOTFLASH For This Useful Post:
sastanley (12-15-2019)
  #12   IP: 66.63.65.115
Old 12-19-2019, 10:13 AM
Chica Chica is offline
Frequent Contributor
 
Join Date: Dec 2019
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Thank you Al and Mary. Very helpful.
Reply With Quote
Reply

Thread Tools
Display Modes

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
propeller question Hymodyne Drive Train / Propellers 34 03-23-2014 09:46 PM
Tartan 30 Exhaust jacques debauche Tartan 8 07-02-2010 04:42 PM
Prop fouling s/v Dearbhail Drive Train / Propellers 21 01-05-2009 06:25 PM
Stuck #4 Exhaust Valve: A special Tartan 30 problem? jellisfeingold Tartan 7 12-09-2006 04:11 PM


All times are GMT -4. The time now is 12:10 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2020 Moyer Marine Inc.

All Rights Reserved