Cruisers Forum

Join CruisersForum Today

  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
Thread Tools Search this Thread Rate Thread Display Modes
Old 28-09-2010, 18:54   #1
Registered User
timbenner's Avatar

Join Date: Jan 2007
Location: Ponte Vedra Beach, FL
Boat: Lagoon 380, 38', I Dream of Jeanne
Posts: 313
Images: 7
Propeller Advice

I have fixed, 2 blade stock props on a Lagoon 380 Catamaran. I've been researching a variety of prop upgrades, but haven't been able to justify the expense, based on my Cost/Benefit review. $1,425 X 2 = $2,850 for Kiwiprop, $2,700 X 2 = $5,400 for Gori (3 blade), etc. My questions / concerns follow:

1) Will a folding prop fail to open or unfold once aged with barnacles, growth and seaweed? Seems that the exposed rotating gears in folding props would create a new maintenance nightmare.

2) Will I only increase my sailing speed 1/2 knot? That speed increase doesn't seem worth it.

3) I've heard conflicting reports regarding whether my motoring speed will increase or decrease. I would hope that going from a 2 blade to a 3 blade would increase speed, particularly where there is a strong current?

4) I've heard that the Gori props would give me a more powerful reverse, when the Kiwiprop a less powerful reverse?

5) Are the folding props, like Gori, fixable locally or do you have to send them back to Gori if damaged or bent?

6) Fixed props only have the pressed in hub and pitch to worry about. With all of the moving parts on the feathering and folding props, is there a lot of maintenance?

7) If you have folding or feathering props, did they meet your expectations or would you gladly take your money back?

8) Does it make more sense to get 3 blade for the additional torque?

Since these after market props are a costly option, I would appreciate input from experience to justify or rationalize the cost, if it can be justified.


timbenner is offline   Reply With Quote
Old 28-09-2010, 19:15   #2
Moderator Emeritus
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Ohio
Boat: Now boatless :-(
Posts: 11,580
Images: 4
I think you would have to consider carefully going from fixed to feathering or folding.

We went from folding to feathering (MaxProp) and it was the best upgrade we did to the boat. The folding prop had marginal forward performance and poor reverse performance.

We went from 3 1/2 knots forward to 5 1/2 knots forward just with the prop change. Reverse performance for stopping was like night and day.

The prop has never failed to feather no matter how fouled. The maintenance is to remove it once every 14-16 months when we do the haulout. It needs to be removed to replace the saildrive anode and while it is open we clean the inside and repack it with grease.

I am not sure I would spend $3,000-$6,000 to improve sailing speed slightly if I had fixed props but I would definitely replace the stock folding prop again.

Here are some shots of our prop. This is typical condition after removal of residual grease, removal of external barnacles etc. and before polishing.

(edit - PS I moved this thread to the propeller area where it might get more traffic.)
Attached Thumbnails
Click image for larger version

Name:	P7060033.JPG
Views:	152
Size:	273.7 KB
ID:	19649   Click image for larger version

Name:	Open.jpg
Views:	183
Size:	110.9 KB
ID:	19650  

Click image for larger version

Name:	Exploded.jpg
Views:	158
Size:	131.3 KB
ID:	19651  

Relax Lah! is SOLD! <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 28-09-2010, 19:22   #3
Moderator Emeritus
David M's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: San Francisco Bay
Boat: research vessel
Posts: 10,393
That's a lot of money for a slight gain. I am also one who apprecites simplicity and the reliability that comes with simpler designs.

Life begins where land ends.
David M is offline   Reply With Quote
Old 28-09-2010, 19:30   #4
Registered User
Ziggy's Avatar

Join Date: Apr 2008
Location: U.S., Northeast
Boat: Contessa 32
Posts: 1,467
Images: 2
Originally Posted by timbenner View Post
3) [...] I would hope that going from a 2 blade to a 3 blade would increase speed, particularly where there is a strong current?

8) Does it make more sense to get 3 blade for the additional torque?
According to Dave Gerr, an optimally sized and pitched 2-bladed prop is more efficient than 3-bladed one. The reason to go to a 3 bladed prop is then you don't have sufficient clearance for an optimal diameter prop. So the choice between 2- or 3- bladed depends on your boat and engine.

Having said that, you will certainly give up some sailing speed in light air with a 3 bladed prop.
... He knows the chart is not the sea.
-- Philip Booth, Chart 1203
Ziggy is offline   Reply With Quote
Old 28-09-2010, 20:17   #5
Registered User
Marksman's Avatar

Join Date: Apr 2009
Location: Kingston, Wa.
Boat: 1966 Buchan 37
Posts: 302
I had a Martec

Maelstrom came to me with a Martec 2 blade folding prop. It was marginal in fwd an near usless in reverse, would simply fold back up. Occasionaly only one blade would deploy in fwd resulting in much vibration. I only had to pop it into neutral then reverse and back to fwd to fix the issue but was still annoying. I replaced it with a 3 blade fixed and feel much better about docking. If my boat made longer voyages on the ocean I may have kept the martec but where I live motoring often becomes important and that little 12 inch egg beater simply wasn't up to the task. I'm a little slower for it under sail but I don't loose any sleep over it. If I were rich I would have a feathering screw but that will be in another life I'm afraid.

Fred Guy
Marksman is offline   Reply With Quote
Old 29-09-2010, 05:18   #6
Registered User
colemj's Avatar

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,097
Images: 12
We have 3 blade volvo folding props. No problem with growth folding/unfolding. A folding prop will increase your sailing speed 1/2kt per prop - that will be a full knot for your boat. I know we are a knot faster when they are folded vs. unfolded. They reverse well, but I don't know their motoring performance vs fixed.


You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 29-09-2010, 07:18   #7
Marine Service Provider

Join Date: Aug 2008
Location: North Carolina
Posts: 283
Here at Beta Marine we have good reports from our customers on both of the prop types that have asked about.

I wont go into the Kiwi vs Gori debate but you have also raised the question of 2 vs 3 blade. In theory your max motoring speed should be the same with a 2 blade or a 3 blade propeller but how you get to your cruise speed will be very different. The 2 blade propeller will have a lot of slip and thus you will slowely gather momentum. The 3 blade propeller will seem to bite into the water and thus you will have good acceleration. This will help if you have to motor off a lee shore.

I suspect that you are correct with the about 1/2 knot speed gain under sail for the 2 fixed blade 2 blade propellers as opposed to a folding or feathering propeller.

NCboatrx is offline   Reply With Quote
Old 29-09-2010, 07:48   #8
Registered User

Join Date: Dec 2008
Location: Oriental, NC
Boat: Mainship Pilot 34
Posts: 1,461
Also consider that feathering props produce double the thrust of fixed props in reverse. Several times I was able to get off from a soft grounding by reversing the engine where I am not sure that a fixed prop would have worked. To me that is as much an advantage as improved sailing performance.

djmarchand is offline   Reply With Quote
Old 29-09-2010, 08:03   #9
Registered User

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 19,047
Folding props are cheap and good. They do not grow barnacles if you use them. Make sure you have space for them.

barnakiel is offline   Reply With Quote
Old 29-09-2010, 08:20   #10
Eternal Member
capt_douglas's Avatar

Join Date: May 2003
Location: Ft. Lauderdale, FL
Boat: Vancouver 36 cutter????
Posts: 620
Send a message via Skype™ to capt_douglas
There have been considerable advancements in folding props over the last few years. To me, there are four reasons to consider them:
1. you gain a bit of speed - 0.5kt isn't much going a few miles, but if you're crossing an ocean it can be considerable
2. less chance to snag on submerged items - more hydrodynamic and less chance of snagging lines or gunk
3. no need to lock off the propeller shaft or worry about the transmission
4. better performance in reverse - since the prop can be designed to provide a better bite in reverse, you can get a bit more control (if your harbor or marina is more difficult to navigate under power, you might gain better control)

Maintenance is generally minimal and not difficult. Some folks will grease the gears during haulouts, check and clean the prop when cleaning the hull, or occasionally run the prop forward and astern to keep the operation smooth and controllable.

Are they worth the money? Can't answer that because I don't know your requirements. IMO, I'm looking at them as my prop, courtesy of the PO, isn't what I'd call in serviceable condition. If I could find a well respected one for about the cost of a fixed 3-blade, I'd probably go for it. My cruising plans call for crossing oceans.

Capt. Douglas Abbott
USCG/MCA IV/M.I./C.I. 500-ton Oceans
capt_douglas is offline   Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Propeller BEAUSEJOUR Propellers & Drive Systems 1 18-07-2010 05:08
I Need a Propeller valentingrosu Engines and Propulsion Systems 2 01-07-2010 16:24
New Propeller Advice Alex128 Propellers & Drive Systems 3 27-11-2009 20:07
Which Propeller? nhschneider Propellers & Drive Systems 15 13-07-2009 17:08
new propeller keller Propellers & Drive Systems 2 22-06-2007 13:14

Advertise Here

All times are GMT -7. The time now is 11:51.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.