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-   -   MaxProp or Autoprop? (http://www.sailnet.com/forums/gear-maintenance/51249-maxprop-autoprop.html)

LJD 02-06-2009 02:52 PM

MaxProp or Autoprop?
 
We are going to buy a new prop for our 40' Island Packet and wonder if anyone can share their opinions on these two props. We have a Prowell feathering prop that is 15 years old and we think it's time to replace it. It seems that the Autoprop will be easier to install and has the advantage of having no pitch adjustments to make. However, it's priced a lot higher than the MaxProp which seems to be popular as well. Your opinons will be appreciated!
LJD

Capnblu 02-06-2009 03:42 PM

I just saw a KIWI prop at the Vancouver boat show. I looked the thing over real good, and it is a good looking unit as far as the machining goes. It was made totally out of stainless parts. To me I like the idea of SIMILAR metals in contact with the brine. It was adjustable, foreward and reverse like the MAX but quite a bit simpler design. I am sure the drag of the KIWI will be higher, due to the design of the foils, and the 3 stops for the blades. The KIWI could be had today in Canadian currency for $1200-1400 for a 18" feathering prop out of solid stainless, with some type of polycarbonate blade? Sorry if the material is wrong (some one is liable to know what it is.) The KIWI is priced good in my point of view, It would cost me only slightly less to make one, and be a PITA with the machines I currently have. I easily could have made a MAX for what they retail. As for the AUTO PROP it was a sleeker design, almost like a stainless MAX taking into consideration who will be putting these things on their boats. People with "X" # of $, willing to give it away to go "Y" faster, and feel "Z" cooler than you in the end! haha

padean 02-06-2009 03:54 PM

I actually just put in an order for a variprop 3-blade feathering prop. After looking as several options at Strictly Sail Chicago, I was impressed by the engineering and the new low-profile prop hub. I had planned on getting a Kiwi prop (which I still think might be a good prop), but the price of the Variprop was only a few hundred $ more. I am in fresh water, though, if that makes any difference to those worried about salt-water corrosion. Sorry I don't know much about the MAxi and Auto props other than seeing them in demonstrations.

christyleigh 02-06-2009 04:00 PM

As has been mentioned the Autoprop is expensive. I put one on my Catalina 320 after a couple years and used it for 4 years happily. My Nauticat came with one and besides the feathering and Great Reverse its Auto Pitching is great for Motor Sailing.

Maine Sail 02-06-2009 04:06 PM

If you read..
 
If you read the MIT prop study the Max Prop develops about 2 lbs of drag and the Autoprop about 9-10 lbs of drag. If the intent of buying a feathering or folding prop is to reduce drag then I think the Max Prop is the best choice..

Of course I chose a Campbell Sailer prop to have the lowest drag in a non mechanical prop..

padean 02-06-2009 04:17 PM

"If you read the MIT prop study the Max Prop develops about 2 lbs of drag and the Autoprop about 9-10 lbs of drag."

Do you know if the props currently made are the same as the props tested in the MIT study in 1994? Several props were not even made then, and at least some of the props have undergone significant changes in the last 15 years since the tests were done.

(Disregard if there is a newer MIT prop study.)

Of course, we are talking about a slight difference in efficiency and drag, and much of the choice will probably come down to ease of use, convenience, and local experience with a particular prop.

Rockter 02-06-2009 04:21 PM

$1400 to change a prop that works?

Maine Sail 02-06-2009 04:26 PM

Quote:

Originally Posted by padean (Post 444415)
"If you read the MIT prop study the Max Prop develops about 2 lbs of drag and the Autoprop about 9-10 lbs of drag."

Do you know if the props currently made are the same as the props tested in the MIT study in 1994? Several props were not even made then, and at least some of the props have undergone significant changes in the last 15 years since the tests were done.

(Disregard if there is a newer MIT prop study.)

Of course, we are talking about a slight difference in efficiency and drag, and much of the choice will probably come down to ease of use, convenience, and local experience with a particular prop.


Same 1994 study but the differences in these props externally from then until now is very slight. I just finished researching props for my own boat, and I would guess the Max still has one of the lowest drags for a three blade prop.

I looked at many including Autostream (HUGE HUB), Max, Gori, Kiwi Autopop and others. I also spoke at length with my local prop shop about repairs. They sell many different brands and for them the Max Prop has been the most reliable but still gets no cigar from Mike the manager. The had a total of four feathering/folding porps in house at the time for rebuilds/repair ranging from $500.00 to over 1k.

My reason for not choosing a floder/feather prop was reliability and the fact that they do not like to hit lobster pots which can literally sheer off blades (had one in house that had happend to). We have lots of lobster pots up here.. My own prop shop talked me into a prop they don't even sell..

padean 02-06-2009 04:48 PM

Feather vs fixed
 
The other question I would have is why buy a feathering or folding prop if not racing. The difference in drag can be made up by chucking a few of those extras off the boat that haven't been used in several years, and a fixed blade prop is essentially maintenance free (other than cutting loose the tangled lobster pots and fishing lines). As Maine Sail described, these props are not always the most sturdy. A nice 2 or 3 blade fixed prop will nearly always perform better under motor, and will certainly last longer.

Maine Sail 02-06-2009 05:00 PM

Quote:

Originally Posted by padean (Post 444435)
The other question I would have is why buy a feathering or folding prop if not racing. The difference in drag can be made up by chucking a few of those extras off the boat that haven't been used in several years, and a fixed blade prop is essentially maintenance free (other than cutting loose the tangled lobster pots and fishing lines). As Maine Sail described, these props are not always the most sturdy. A nice 2 or 3 blade fixed prop will nearly always perform better under motor, and will certainly last longer.

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.


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