Reply
 
Thread Tools Display Modes
 
Old 08-15-2013, 12:54 PM   #1
Guru
 
Join Date: Aug 2011
Posts: 511
Raw water impeller question

I have a Jabsco that has eaten another impeller after only 20 or so hrs of use. I fear it was an OLD impeller (it came in a bag of spares with the boat). I didn't see any cracks when bending the blades and I did lube it during install. Anyway.....I'm going to put in a Globe impeller (I've ran them in all of my other boats and been happy). My question is 8 or 10 blades on the impeller? Which will move more water at same RPMs. Naturally the 10 blade unit has a larger diameter body and shorter blades than the 6. I have looked for about an hour and typed in every combination of words I could think of to pull up this info. I can't find any information regarding blade count effect on impeller performance. Any of ya'll have 1st hand knowledge about this one?

I think all the spare impellers and belts I got with the boat are going to be relegated to emergency use only and I'll buy new for routine change outs.
__________________
Advertisement

__________________
TIME well wasted
34' Mainship III
Cape Coral, FL
twiisted71 is offline   Reply With Quote
Old 08-15-2013, 01:04 PM   #2
Guru
 
skipperdude's Avatar
 
City: Whittier AK
Country: USA
Vessel Name: Apache II
Vessel Model: 1974 Donald Jones
Join Date: Oct 2007
Posts: 3,147
Sounds to me like it is just one manufacturer vs another. As long as it moves enough water. I don't really think it matters.

I have been wrong before.

SD
__________________

__________________
If you can't repair it maybe it shouldn't be on the boat
skipperdude is offline   Reply With Quote
Old 08-15-2013, 01:37 PM   #3
Guru
 
LaBomba's Avatar
 
City: Beaverton, Ontario
Country: Canada
Vessel Name: Airswift
Vessel Model: Ontario Yachts Great Lakes 33
Join Date: Nov 2012
Posts: 818
Quote:
Originally Posted by skipperdude View Post
Sounds to me like it is just one manufacturer vs another. As long as it moves enough water. I don't really think it matters.

I have been wrong before.

SD
I agree, you haven't changed the RPM of the pump so volume should not change significantly from one blade configuration to another. Be careful though that the width of the impellers are exactly the same for proper operation.
__________________
Allan & Ann
Airswift
LaBomba is offline   Reply With Quote
Old 08-15-2013, 01:44 PM   #4
Guru
 
Join Date: Aug 2011
Posts: 511
Globe makes an 8 and a 10 blade impeller that will fit my pump. I've got 6 and 8 rubber ones now. both Jabsco. So its not manufacturer vs manufacturer. There is a design demand difference-just can't find what it is.
__________________
TIME well wasted
34' Mainship III
Cape Coral, FL
twiisted71 is offline   Reply With Quote
Old 08-15-2013, 03:30 PM   #5
Guru
 
skipperdude's Avatar
 
City: Whittier AK
Country: USA
Vessel Name: Apache II
Vessel Model: 1974 Donald Jones
Join Date: Oct 2007
Posts: 3,147
Well get to work.

Let us know.

sd
__________________
If you can't repair it maybe it shouldn't be on the boat
skipperdude is offline   Reply With Quote
Old 08-15-2013, 04:40 PM   #6
Enigma
 
RT Firefly's Avatar
 
City: Slicker?
Country: Bumpkin?
Join Date: Oct 2007
Posts: 9,996
Greetings,
Contact Globe. http://www.globecomposite.com/pages/contact-form
__________________
RTF
RT Firefly is online now   Reply With Quote
Old 08-15-2013, 06:14 PM   #7
Guru
 
Join Date: Aug 2011
Posts: 511
LOL yeah that twas my next step, RT. I was hoping for a quicker response here. I'll post up whatever they say.
__________________
TIME well wasted
34' Mainship III
Cape Coral, FL
twiisted71 is offline   Reply With Quote
Old 08-15-2013, 06:35 PM   #8
Veteran Member
 
City: Wausau,WI
Country: USA
Join Date: Apr 2012
Posts: 54
Think of it as head vs volume. My guess would be that having more impellor vanes would allow a higher head pressure, with lower volume. More vanes take up the space that water should occupy. Also a factor is the center hub diameter. Larger diameter hub will allow less water volume but higher head.
theran5317 is offline   Reply With Quote
Old 08-16-2013, 01:28 PM   #9
Guru
 
Join Date: Aug 2011
Posts: 511
Well I just got a rather generic reply that they are recommending the 10 over the 8 in any application that there is an option to do so.

Needless to say I've replied with specific questions but not so specific as to require an engineer to answer. We'll see. I want to be able to put my old girl up on plane reliably! I ran it up to 12-13 kts a couple of times before the "new" impeller went. Its nice knowing I can do that if necessary.
__________________
TIME well wasted
34' Mainship III
Cape Coral, FL
twiisted71 is offline   Reply With Quote
Old 08-16-2013, 06:27 PM   #10
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 3,193
If your impellers are going that fast, I think there is more to the problem than just replacing with a more durable impeller. I'd guess that you have wear in the housing, end plates, or shaft. Or perhaps you have an intake or out-flow restriction that is allowing for cavitation or starvation of the impeller. I just think that if you have gone through 3 impellers in under 20 hrs each, the problem is probably not the impellers themselves.
twistedtree is online now   Reply With Quote
Old 08-16-2013, 07:02 PM   #11
Guru
 
Join Date: Aug 2011
Posts: 511
No it has only eaten 1 impeller. I can see how my first post would lead to thinking it was chewing them up everytime I took the boat out. The housing was pretty smooth as was the cam plate and removable cover plate. I further slicked everything up with some sandpaper. The PO owned her for about 15 yrs and I'm thinking a lot of the spares he passed along to me were bought by the orig owner back in '84! My boat came with the "cruising kit" offered by the manufacturer as an option. It has parts to rebuilt most of the engine accessories and even has a complete fuel injector! I think this impeller may be from that kit as it was loose in the bag. I have since read up on the deterioration rate of rubber impellers in storage improperly and all I can say is read up on it yourselves! You may want to go through your spares! I will be putting a lot of my things in a separate baggie marked "EMERGENCY USE ONLY", and replacing my true spares with new things over the next few months.

As far as Globe's response they closed at 2:30 EST today so I'll have to wait until Monday for the engineering dept to reply.
__________________
TIME well wasted
34' Mainship III
Cape Coral, FL
twiisted71 is offline   Reply With Quote
Old 08-16-2013, 07:29 PM   #12
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 3,193
I've personally never used a globe impeller before, but know a bunch of people who swear by them. I have also heard that when they do melt down, watch out! You end up with a blue glob of fused crap that is nearly impossible to clean out, so don't assume you can run them forever without water. Longer than a rubber impeller - yes. How much longer? You don't want to find out.
twistedtree is online now   Reply With Quote
Old 08-16-2013, 10:38 PM   #13
TF Site Team
 
FlyWright's Avatar
 
City: California Delta and SF Bay
Country: Sacramento, CA, USA (boat in Vallejo)
Vessel Name: FlyWright
Vessel Model: Marshall Californian 34 LRC
Join Date: Apr 2008
Posts: 10,179
I heard the Globes last longer when treated properly. Anyone have experience with that? I'm seriously considering going with Globes at my next impeller change out.
__________________
Al

Custom Google Trawler Forum Search
FlyWright is online now   Reply With Quote
Old 08-17-2013, 12:51 AM   #14
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 3,193
Quote:
Originally Posted by FlyWright View Post
I heard the Globes last longer when treated properly. Anyone have experience with that? I'm seriously considering going with Globes at my next impeller change out.
I've met a number of Nordhavn owners who swear by them. That said, in my own experience the hardest thing on an impeller is sitting idle for an extended time. So far my boats have all been winterized, and in the spring when I pull the impellers to change them, it's pretty clear why the manufacturers recommend annual replacement. I'm not sure I could get comfortable leaving a Globe impeller in my boat for multiple years where a long annual layup is involved. I hate changing them, but it still seems like cheap insurance for reliable operation. I'd probably run it for two years, then remove and inspect and take it from there. The part I'm sure of is that I don't want to change an impeller while broken down and drifting out in open water in a hot engine room with a boat rocking and rolling.
twistedtree is online now   Reply With Quote
Old 08-17-2013, 01:28 AM   #15
Senior Member
 
City: Pittsburg, CA
Country: USA
Vessel Name: NoMoBoat
Vessel Model: Trawlers
Join Date: Dec 2012
Posts: 278
Impeller Lube

Sorry folks,

Slightly off topic but, I am having trouble getting a good read on what I should use as an Impeller Lube.(Vaseline? KY gel?) I am probably overdue to change mine, though I check it regularly and looks fine, pumps great.

I am looking for a name brand Lube type, not just something that someone picks up from the local h/w for $3.95.

Can I get good recommendation from some knowledgeable, experienced folk with quite a number of these under their belt?

Appreciate it.

Thanks.
__________________
JimS on the Delta
Delta_JimS is offline   Reply With Quote
Old 08-17-2013, 01:55 AM   #16
TF Site Team
 
FlyWright's Avatar
 
City: California Delta and SF Bay
Country: Sacramento, CA, USA (boat in Vallejo)
Vessel Name: FlyWright
Vessel Model: Marshall Californian 34 LRC
Join Date: Apr 2008
Posts: 10,179
Not sure how about the pumps on your Volvos Jim, but I use lube that comes with the Jabsco impellers or just plain dish washing liquid. Mine fit in and come out pretty easily. Sometimes I do it without any lube...just a twist and a push.

Some folks who have issues find it helps to use a tie wrap to hold the impeller in a compressed position. As the impeller slides into the pump, the cable tie slides off the impeller blades. It might help to try a practice run on the impeller you remove if you need to verify your technique.
__________________
Al

Custom Google Trawler Forum Search
FlyWright is online now   Reply With Quote
Old 08-17-2013, 04:11 AM   #17
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 3,193
Quote:
Originally Posted by FlyWright View Post
Some folks who have issues find it helps to use a tie wrap to hold the impeller in a compressed position. As the impeller slides into the pump, the cable tie slides off the impeller blades. It might help to try a practice run on the impeller you remove if you need to verify your technique.
I did this for a while with modest success. It was better than nothing, but far from satisfactory. Then I finally realized that an automotive piston ring compressor was just what I needed. I picked one up at Napa for $12 and wow, what a difference for installing large impellers. The little ones are easy, but the big ones can be a real bear. The ring compressor made a huge difference.
twistedtree is online now   Reply With Quote
Old 08-17-2013, 07:13 AM   #18
Senior Member
 
captrigney's Avatar
 
City: Port Huron, MI
Country: USA
Vessel Name: Meander
Vessel Model: 1983 Grand Banks 36 Classic
Join Date: Sep 2012
Posts: 176
My previous boat had a pump that used to eat impellers for breakfast. I rebuilt the pump with a new cam and still could only get 20 or 30 hours on an impeller. My marine supplier suggested switching from the black Jabsco impellers to a Globe. It lasted a couple hundred hours and counting. I just bought 2 for my Lehmans. 40 bucks each but worth it IMHO.
captrigney is offline   Reply With Quote
Old 08-17-2013, 07:20 AM   #19
Senior Member
 
captrigney's Avatar
 
City: Port Huron, MI
Country: USA
Vessel Name: Meander
Vessel Model: 1983 Grand Banks 36 Classic
Join Date: Sep 2012
Posts: 176
Quote:
Originally Posted by Delta_JimS View Post
Sorry folks,

Slightly off topic but, I am having trouble getting a good read on what I should use as an Impeller Lube.(Vaseline? KY gel?) I am probably overdue to change mine, though I check it regularly and looks fine, pumps great.

.
Another plug for the Globe impeller. They come pre lubed and seem to be more flexible so they are easier to install. I have used the dish soap and zip tie method to install impellers. I've found the biggest problem is getting the old ones out. I have used impellers (not Globes) with a threaded end that uses a bolt that forces the impeller out nicely. I haven't seen this feature on the smaller impellers.
captrigney is offline   Reply With Quote
Old 08-17-2013, 08:39 AM   #20
Senior Member
 
dach side's Avatar
 
City: N. Kingstown, R.I.
Country: USA
Vessel Name: Harmony
Vessel Model: 36' sabreline fast trawler
Join Date: Nov 2010
Posts: 103
Twistedtree: I'd gone to a diesel class and the instructor recommended taking out the impellers in the fall and leave them in a container full of olive oil or mineral oil.
__________________

dach side is offline   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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 07:47 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012