Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Troubleshooting

Reply
 
Thread Tools Display Modes
  #1   IP: 47.16.178.29
Old 11-03-2019, 07:39 PM
Wisakedjack's Avatar
Wisakedjack Wisakedjack is offline
Senior Member
 
Join Date: May 2015
Location: New Jersey
Posts: 118
Thanks: 19
Thanked 29 Times in 16 Posts
Low boat speed troubleshooting

My boat is 1976 Catalina 30 with 3 blade Indigo prop. At the start of the season I was able to get 1900 RPM at full throttle and slightly over 5kts boat speed. Towards the end of the season few issues have developed:

1. I could barely make more than 3 kts at full throttle.
2. There was noticeable vibration when I increased RPM, which seemed to come from under the cockpit.
3. Tachometer stopped working: its jumping between 0 and reasonable RPM, while staying mostly around zero. I don't think issue is related to the first 2, but just adding it here for completeness. I suspect this is just the case of bad connection... But because of this I don't know what was the engine exact RPM.

So, long story short the boat was hauled out this weekend and I was curious to see the state of the prop (hopefully a big garbage bag wrapped over it). There was some barnacle on the blades and some on the shaft. The later was behind the strat and kinda asymmetric. But I don't think this could explain such a loss of boat speed. The hull was mostly clean. I check the prop shaft for play and did not find any. So, obviously I will have to wait until next season to see what my boat speed will be with clean prop. But in the mean time I wanted to ask few questions:

1. Should I expect to see higher RPM with Indigo prop. I think max 2300 is advertised.
2. What else should I check in spring to explain loss of speed? Could it be ignition timing, for example, or anything else?
3. Can growth on shaft case vibration? What else should I check? Engine mounts, alignment come to mind as obvious candidates.

Any advise would be greatly appreciated.
__________________
Alex
1976 Catalina 30
Perth Amboy, NJ
Reply With Quote
  #2   IP: 70.185.132.167
Old 11-03-2019, 11:34 PM
JOHN COOKSON JOHN COOKSON is offline
Afourian MVP, Professor Emeritus
 
Join Date: Nov 2008
Posts: 3,500
Thanks: 54
Thanked 855 Times in 629 Posts
Let's Start With The Easy Stuff

Could be a spark plug not firing or firing intermittently. Maybe the advance is sticky. Or maybe a combination of a sticky advance, a weak spark plug, and a fouled prop.
Sticky valve? Try a compression test.

Did you tune the engine when it started to lose power?

TRUE GRIT
Reply With Quote
  #3   IP: 98.153.27.101
Old 11-04-2019, 01:25 AM
tenders tenders is offline
Afourian MVP
 
Join Date: May 2007
Location: Harlem YC, City Island, NY
Posts: 1,439
Thanks: 46
Thanked 259 Times in 170 Posts
If left uncleaned since launch, barnacles on the Indigo prop in the Northeast will absolutely affect boatspeed and vibration exactly as you've described by the time September (never mind October) rolls around.

Tachometer...not so much, but it seems like you're on the track with a poor connection someplace.
Reply With Quote
The Following User Says Thank You to tenders For This Useful Post:
sastanley (11-06-2019)
  #4   IP: 47.16.178.29
Old 11-04-2019, 08:23 AM
Wisakedjack's Avatar
Wisakedjack Wisakedjack is offline
Senior Member
 
Join Date: May 2015
Location: New Jersey
Posts: 118
Thanks: 19
Thanked 29 Times in 16 Posts
Thank you for the comments.

I did not clean the bottom/prop since launch (I don't race) and there is anecdotal evidence that things went down after I was not using boat for about 3 weeks in August due to vacation. I had similar issue last season, but it continue to question whether so little barnacle growth can have such an impact.

John, I have EI, so it can't be a sticky advance. I pulled plugs one by one and there was notable change in engine speed/sound. I did compression test in spring after I changed head gasket and the numbers were really good. I did not tune the engine before I started to loose power. But I am debating whether to look into timing. Pros: should I be getting to 2300 rpm as Indigo states? Cons: don't fix if it ain't broken. Engine started well all season and runs smooth at idle.
__________________
Alex
1976 Catalina 30
Perth Amboy, NJ
Reply With Quote
  #5   IP: 24.152.132.140
Old 11-04-2019, 08:51 AM
ndutton's Avatar
ndutton ndutton is offline
Afourian MVP
 
Join Date: May 2009
Location: Torrance, CA
Posts: 9,619
Thanks: 198
Thanked 2,208 Times in 1,425 Posts
Quote:
Originally Posted by Wisakedjack View Post
I have EI, so it can't be a sticky advance
Oh yes it can. The advance mechanism is completely independent from electronic ignition. Per John's advice, it should be checked and lubed as long as you're there.

I don't have an Indigo prop but mine is roughly the same diameter and pitch - and with a monthly diving service, clean. Following a careful timing adjustment I can reach 2600 RPM (direct drive just like yours) although in use I'm usually around 2100~2300.

My recommendations therefore:
  1. Inspect and lube the centrifugal advance system
  2. Get the timing set as accurately as you possibly can
  3. Clean the bottom, shaft and prop
__________________
Neil
1977 Catalina 30
San Pedro, California
prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
Reply With Quote
The Following User Says Thank You to ndutton For This Useful Post:
Wisakedjack (11-04-2019)
  #6   IP: 100.36.65.17
Old 11-04-2019, 01:00 PM
edwardc's Avatar
edwardc edwardc is offline
Afourian MVP
 
Join Date: Aug 2009
Location: Laurel, MD
Posts: 2,509
Thanks: 153
Thanked 595 Times in 388 Posts
Just a few barnacles on the outer portion of the blade can completely disrupt the lamanar flow of water over the prop, killing most of the thrust from that blade.
__________________
@(^.^)@ Ed
1977 Pearson P-323 "Dolce Vita"
with rebuilt Atomic-4

Reply With Quote
The Following 3 Users Say Thank You to edwardc For This Useful Post:
sastanley (11-06-2019), tenders (11-07-2019), Wisakedjack (11-06-2019)
  #7   IP: 74.107.30.7
Old 11-06-2019, 01:51 PM
sastanley's Avatar
sastanley sastanley is online now
Afourian MVP
 
Join Date: Sep 2008
Location: Solomons, MD
Posts: 7,016
Thanks: 1,134
Thanked 600 Times in 442 Posts
Quote:
Originally Posted by ndutton View Post
Oh yes it can. The advance mechanism is completely independent from electronic ignition. Per John's advice, it should be checked and lubed as long as you're there.
+1 - my experience is with stuck weights the engine will either want to run WOT or won't throttle up. If they are stuck advanced, the engine will stumble at low RPM, but run great at WOT..if stuck at rest, they won't swing open on throttle up and engine timing is affected.

Vibration leads me to believe primarily dirty prop. I have found the Indigo to be especially sensitive to growth..I think it is because we are getting pretty low on working blade surface, so things go south quicker with just a little growth. I try to clean mine 2 or 3 times per year.
__________________
-Shawn
"Holiday" - '89 Alura 35 #109
"Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
http://www.moyermarine.com/forums/signaturepics/sigpic3231_6.gif
Reply With Quote
The Following 2 Users Say Thank You to sastanley For This Useful Post:
Administrator (11-06-2019), Wisakedjack (11-06-2019)
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
Winterizing A4 and General Boat Preparation Mo General Maintenance 85 11-05-2021 06:26 AM
old boat..new owner..needs tlc..might as well start a thread about it and its A4 sastanley General Interest 136 12-16-2019 12:04 PM
Systems Troubleshooting Don Moyer Troubleshooting 0 02-28-2007 08:48 AM
Troubleshooting Exercise Don Moyer Troubleshooting 0 10-12-2004 01:42 PM


All times are GMT -4. The time now is 05:27 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2024 Moyer Marine Inc.

All Rights Reserved