Folding Prop Desire

imiloa

Junior Member
Guys i need your help please.. i would like to change my prop. i have an old one with 3 baldes. rigid. and want to put a 2 folding blade!! i dont know wich one is the correct. i have a yanmar y3m30 engine. with kanzaki transmission. my shaft is 1 inch.

can you tell me wich one shoul i search?

thanks a lot!!!
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Welcome to the site, and squinting at your avatar you may have an Ericson 31C. Perhaps. Your bio needs to be fleshed out, and most important you need a 'sig line' that gives info to quickly help others help you... like the reply from Navman in reply #2.
:egrin:

Do you know the sizing for your present prop? Diameter and pitch? Great that you do know the engine and shaft size; that 's a very good start.

Our hull is different, but considering props, I do have experience with the stock two blade fixed, a two blade feathering, and currently a "sailor" design three blade fixed. All have plusses and minuses. You should mess around with the 'search' function here, with the word 'prop', along with modifiers. There are a herd of good threads. This is one boat bit that is often overdue for optimization, having caused slower motoring for years or decades, as prior owners chose to ignore it.

Gotta say, for max efficiency under sail a folder is always a good bet, but they do have downsides, both in basic fit (gotta have room in front of a rudder for the blades to fold in) and their reverse thrust can be -sometimes, and very design dependent - kind of iffy.
If you have a picture of your boat's underbody when out of the water, this can really accelerate the discussion.

Finally, since this is an inquiry about running gear, I will move it to a forum where it will be seen by more members.
 

frick

Member III
I have a two bladed Martec Eliptec 3. Picked it up used on Email years ago. Put in some new pins, and it has been working very well for years.
This is my 2nd Martec.. The first was on the Atomic 4, this one is on a Yanmar diesel
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
We have a Varifold 2 blade folding prop, geared so that both blades open simultaneously. It generally works well, folds nicely when under sail which I think increases speed by a half to one knot. In studies, it is apparently not as good in reverse as the Flexofold folding prop.
Frank
 

Navman

Member III
Martek will most likely already have you shaft size and other necessary spec's on file as they have outfitted many many Ericsons. Good Luck on whatever your choice!
 

supersailor

Sustaining Member
I have a folding prop on the SJ26's saildrive. I found the secret to backing with it is to give a little blast of power when engaging it to open the blades. After that it works fine. Too bad so many sailors are terrified of the thought of any use of power in a marina. The boat doesn't go squirting off unless you use a sustained burst. I think that's why so many complain about reverse with a folder. The blades are still shut.
 

imiloa

Junior Member
Welcome to the site, and squinting at your avatar you may have an Ericson 31C. Perhaps. Your bio needs to be fleshed out, and most important you need a 'sig line' that gives info to quickly help others help you... like the reply from Navman in reply #2.
:egrin:

Do you know the sizing for your present prop? Diameter and pitch? Great that you do know the engine and shaft size; that 's a very good start.

Our hull is different, but considering props, I do have experience with the stock two blade fixed, a two blade feathering, and currently a "sailor" design three blade fixed. All have plusses and minuses. You should mess around with the 'search' function here, with the word 'prop', along with modifiers. There are a herd of good threads. This is one boat bit that is often overdue for optimization, having caused slower motoring for years or decades, as prior owners chose to ignore it.

Gotta say, for max efficiency under sail a folder is always a good bet, but they do have downsides, both in basic fit (gotta have room in front of a rudder for the blades to fold in) and their reverse thrust can be -sometimes, and very design dependent - kind of iffy.
If you have a picture of your boat's underbody when out of the water, this can really accelerate the discussion.

Finally, since this is an inquiry about running gear, I will move it to a forum where it will be seen by more members.
thanks a lot Sr.
 

Attachments

fool

Member III
Martek will most likely already have you shaft size and other necessary spec's on file as they have outfitted many many Ericsons. Good Luck on whatever your choice!
https://www.martec-props.com/PropellerRecommendation.htm

I too have the Martec, an Eliptic MKIII on a 35-III. They no longer make the props, but still serviced them as of my last haulout two years ago. The size and pitch can be found stamped on the blades. There is also a nut to insert into the hub body that is checked by two monel cotter pins. If I recall correctly mine was sized RH (right hand) x 15 x 22, but don't quote me directly on that.

I've seen several of these props on shelves in used chandleries, usually missing the central nut and with tips touching. Touching tips can be refurbished by Martec but there is a limit (three times if memory serves) that this can be done. Gary Beck offered terrific service and advise, his email is gbeckprops@gmail.com.

Cheers,

Max
 

debonAir

Member III
If you are buying new, any of the manufactures will help you size your prop right. My research led me to want a flexofold first, a gori second. I like the folders better than feather-ers because they wont snag things while sailing, and I like the geared blades better than Martec-style because of more reliable reverse and avoiding the lazy-blade-dropping issue. You can get a rough idea of size/pitch you need with an online-prop-calculator. I am guessing a 1" shaft 31' boat you'll be around 14x10 to 15x12, depends a lot on your transmission gear ration and engine RPM so find those things first.
 

fool

Member III
If you are buying new, any of the manufactures will help you size your prop right. My research led me to want a flexofold first, a gori second. I like the folders better than feather-ers because they wont snag things while sailing, and I like the geared blades better than Martec-style because of more reliable reverse and avoiding the lazy-blade-dropping issue. You can get a rough idea of size/pitch you need with an online-prop-calculator. I am guessing a 1" shaft 31' boat you'll be around 14x10 to 15x12, depends a lot on your transmission gear ration and engine RPM so find those things first.

Good point, the Martec opens by centrifugal force and needs to be "centered" by either reaching over the engine, or climbing into the cockpit lazarette to get the blades to completely close. Otherwise gravity will cause one of the blades to droop. RH X 15 X 12 sounds a lot more accurate than my off the top of my head ability to recall. Never worried about reverse with the Martec, haven't hit the dock hard yet...
 

Captainken

Member I
I don't know what boat you have but I removed a good condition maxi prop 2 blade from my e32(prior owner was racing). I did extensive motoring on the intracoastal and decided on a 3blade fixed. The blades adjust parallel to the water flow when the engine is stopped in reverse gear. Reverse thrust is very aggressive! I would consider selling it if it works or your boat. Prop size: 15 in., 1in. standard taper shaft.
 
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