MaxProp or Autoprop? - Page 2 - SailNet Community
LinkBack Thread Tools
post #11 of 58 Old 02-06-2009
Senior Member
blt2ski's Avatar
Join Date: May 2005
Posts: 7,162
Thanks: 1
Thanked 43 Times in 41 Posts
Rep Power: 14
Then again, folks that want to sail in area's with lower wind speeds, where it is harder to hit hull speed, will find that a folder/feathering prop will net you upwards of .5-1knot of boat speed in those lower wind ranges, ie less than 10 knots. Obviously if in a 20+ knot wind, the prop is not the worst thing for slowing the boat down!

With that in mind, my boat came with a max prop, and the previous owner did report .5-1 knot gains in lighter winds! In Puget Sound where I am, in the summer we do get quite a few days with winds under 10 knots during the day. So if you want to sail more, faster etc, it really will not matter if you race or not, a folder WILL allow you to motor less!

Another prop option, is a Kiwi. An identical boat to mine north of me that races heavily, he mentioned he gained a bit more speed with a kiwi over having a max prop on the boat. ALong with a bit more motor speed at the top too!

overall, I am happy with the max prop that came with my boat!


She drives me boat,
I drives me dinghy!
blt2ski is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
post #12 of 58 Old 02-06-2009
Unpaid Intern
josrulz's Avatar
Join Date: Oct 2006
Location: Maryland
Posts: 992
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 11
I'm kind of in a similar position about where to go... My boat came with an old-style Martec 2-blade folding prop (no gears). It's in good shape, but once we splash the boat, I have a feeling I'll be unimpressed by it's performance in reverse, while being happy with the sailing performance. I'm also not thrilled about the potential reliability factor.

From my perspective, I'd hate to buy a replacement prop that would noticably slow me down sailing (I'm not racing, but like moving in lighter air on the Bay), but I'd like to be able to reliably back up when needed.

The Kiwi prop interests me due to the price point when compared to other feathering props, and I'd never spend the bucks for the others.

My problem is that I don't really have a clear picture of the actual performance implications of my current Martec, versus a Kiwi, versus a 3-blade Campbell sailor. I know the pluses and minuses of each, but how noticable those differences are is something I can't really quantify. That makes the choice more difficult.

1984 Sabre 34 Mk I

Last edited by josrulz; 02-06-2009 at 05:53 PM.
josrulz is offline  
Quote Quick Reply Share with Facebook
post #13 of 58 Old 02-06-2009
Senior Member
Join Date: Dec 2008
Posts: 716
Thanks: 1
Thanked 7 Times in 7 Posts
Rep Power: 9
I bought my boat new in 1985 (Tayana 37) and installed a 3 blade max prop. After some adjustment to the pitch after a year or so it is doing fine to this day. Everytime I haul out I repack the prop with grease which is somewhat of a hassle requireing another set of hands to get the blades properly lined up. I think the newer ones have a grease fitting. The nice thing about the pitch adjustment is that you can play with it to get the proper rpm on your engine. It is excellent in reverse and there is a slight ineffenciency in forward since the blades are flat and not curved as a fixed prop, but the difference is very hard to quantify.
lancelot9898 is offline  
Quote Quick Reply Share with Facebook
post #14 of 58 Old 02-06-2009
j34035's Avatar
Join Date: Nov 2006
Location: Jackson, Missouri
Posts: 343
Thanks: 1
Thanked 1 Time in 1 Post
Rep Power: 11
Originally Posted by Maine Sail View Post
That is why I went with a Campbell Sailer... I don't currently race and prefer the reliability over the .1 knot..

The funny thing is that a Campbell Sailer three blade at 4 knots has the same drag as a 2 blade Michigan Wheel Sailer prop and only about 1.5 lbs more drag than Martec 2 blade folder. In higher winds 12+ the hull speed is slowoing me not my prop.

I don't hear folks talk about this much but folders/featehring props only really help in lower wind speeds. Once you hit hull speed.... In 13-15 knots I can tow my dinghy with the motor on and still hit hull speed so at that point I could have a 2X4 as a prop and still hit hull speed.
You are correct that once you reach hull speed, a folding/feathering prop will no longer help your boat speed. Dont forget though, windward ability is a function of the lift/drag ratio. If you decrease drag or increase lift, you can point higher for the same boat speed. A folding/feathering prop will give you a few points toward the wind with no reduction in boatspeed. My 2 cents......

Jboat J/37c (new to me Jan 2011); J/22 #1003

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
j34035 is offline  
Quote Quick Reply Share with Facebook
post #15 of 58 Old 02-06-2009
I don't discuss my member
Fstbttms's Avatar
Join Date: Feb 2003
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 2,420
Thanks: 13
Thanked 44 Times in 41 Posts
Rep Power: 15
The Max Prop is a robust, well-engineered piece of gear that does its job very well. The Autoprop has a nasty tendency to throw blades. Read all about it:

Autoprop?? - Cruisers & Sailing Forums
Fstbttms is offline  
Quote Quick Reply Share with Facebook
post #16 of 58 Old 02-06-2009
Courtney the Dancer
jrd22's Avatar
Join Date: Nov 2000
Location: San Juan Islands., WA, USA
Posts: 3,968
Thanks: 5
Thanked 30 Times in 29 Posts
Rep Power: 17
We put an Autoprop on the last boat which replaced a three blade fixed. This was on a 34' sloop, 13000 disp. We noticed a large increase in light wind speed -app. .5+ knot. This allowed us to sail instead of motor more often in the light winds of summer here in the PNW. There was a huge difference in motoring efficiency and reverse power was amazing. There is also no prop walk, none. It made docking easy, and backing out even easier. We gained about 1 knot at the same rpm which allowed us to run just under hull speed without the noise of the engine at higher rpm. We put over 1000 hours on it over 12 years and never had a problem although I have read the thread provided above and wonder if something has changed. Seems like Autoprop would be out of business pretty soon if it was a widespread problem. The current boat has a fixed three blade sail prop, not sure if I'm going to spend the 4K for the Autoprop or not, I sure miss the ability to reverse in a straight line.

SV Laurie Anne

1988 Brewer 40 Pilothouse

jrd22 is offline  
Quote Quick Reply Share with Facebook
post #17 of 58 Old 02-06-2009
tomhuntdmd's Avatar
Join Date: Apr 2008
Location: Florence, Oregon
Posts: 33
Thanks: 1
Thanked 0 Times in 0 Posts
Rep Power: 0
The Catalina 470 we bought two years ago came with an Autoprop and has served us very well. As stated, there is no propwalk. I couldn't tell you if it is port or starboard. Also, when the blades swing around, they give full thrust in reverse.

But to me the biggest advantage to the Autoprop is its ability to self pitch. This was discussed at some length on our C470 forum. This can result in fuel savings, especially when motorsailing. As the sails add speed to the boat, the blades dig in deeper, keeping the engine under a more proper load and RPMs lower.

For reference, we usually cruise at 2200 RPM at 7.2 kts in flat water, burning 1.08 GPH with a 28,000 lb boat (Yanmar 75 horsepower).

So far, we have had no maintenance issues, just grease and change zincs.
tomhuntdmd is online now  
Quote Quick Reply Share with Facebook
post #18 of 58 Old 02-07-2009
Senior Member
Valiente's Avatar
Join Date: Jun 2006
Location: Toronto
Posts: 5,491
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 13
I am (finally) installing my VariProp this year. Long story, but I expect great things from it. As for "why", my steel full keeler will benefit from it under sail probably more than my fin keeler did with a Gori folder (and that impressed me), and the ability to have separate forward and reverse pitch settings that I can adjust with an allen key and a snorkel (in the water) makes it worth my while. Basically, I want to stop the boat and maneuver better than I can with a fixed blade, and I have seen most feathering props perform very well in this regard.

Can't sleep? Read my countdown to voyaging blog @
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Valiente is offline  
Quote Quick Reply Share with Facebook
post #19 of 58 Old 02-07-2009
Senior Member
Shortman's Avatar
Join Date: Feb 2006
Location: Western MA & Maine
Posts: 177
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 12

I've had it two seasons & like a lot. Less drag, way better reverse & forward than my previous two blade fixed. Lots less $$.
Shortman is offline  
Quote Quick Reply Share with Facebook
post #20 of 58 Old 02-08-2009
Senior Member
Join Date: Sep 2006
Location: Scotland
Posts: 2,365
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 11
Buy a long-keeled double-ender, mark the prop shaft so that you know when the prop blades are vertical, and turn the prop so that the blades are in line with the keel.

On the point about "hull speed", drag always slows the boat. At higher speeds the fractional contribution of the drag from the prop drops off as there is so much drag from the hull shape, but the drag from the prop is steadily rising.

With a lot of wind around, you won't notice it much, but it will be there.

At very low speeds I reckon you won't notice it much either, as the vast majority of the drag will be from surface drag, and the prop, though an obstruction, does not wet much area. It obstructs (from form drag), but do you not need a decent bit of speed to see that one? There should be a good graph to plot in there somewhere?

Next time I am out in light airs I will try to turn the prop in line with the keel, and then perp to the keel, and see if it gets noticed. It should be a good experiment.

Last edited by Rockter; 02-08-2009 at 07:53 AM.
Rockter is offline  
Quote Quick Reply Share with Facebook

Quick Reply

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Similar Threads
Thread Thread Starter Forum Replies Last Post
AUTOPROP rleslie Gear & Maintenance 5 11-10-2011 11:27 PM
Flex-o-fold v. MaxProp? danielgoldberg Gear & Maintenance 2 08-06-2008 09:56 PM
Autoprop - Exceptional customer service jreidvt Gear & Maintenance 1 06-13-2006 03:59 PM
Volvo Folding vs Maxprop feathering uri General Discussion (sailing related) 1 06-27-2002 07:06 PM
First Look: AVP Autoprop Mark Matthews Gear and Maintenance Articles 0 04-19-2000 08:00 PM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome