'73 E29 Propeller Specs

[Mariner's Honey]

Hello, I'm looking for advice on replacing the propeller on my '73 E29. It currently has a one cylinder Yanmar inboard. I believe it orginally came with a Atomic 4. The present propeller was installed by the previous owner, but was cut/shaved for some reason. Well as you can imagine the performance lacks. I have no idea what the orginal specs were when it had the Atomic 4. Any help on specs or suggested replacements would be great.
Mariners' Honey

 

[Loren Beach]

In general, try to focus on the present diesel engine /transmission / shaft/ strut / prop drive train. Whatever used to be there in its A4 days is not rellevant, IMHO.

The local Yanmar folks should be of some help.

Since this is relatively common conversion, a local prop shop should also have some idea of pitch and diameter.

Are you wanting a fixed two blade or three blade? A feathering prop would let you set and re-set the pitch as you need, but they start at around a thousand $.

Watch your tip clearance -- most prop books specify at least 10% of the Diameter for clearance and many say to have 15%.

A friend of mine swapped a new Yanmar one cylinder into his E-27 when the A4 died, almost two decades ago. I do not remember what he spec'd out for a new prop.

Someone here probably has a similar engine in the same hull... keep checking back...


Loren in PDX

 

[Jim Mobley]

Mine has a 12 x 9

My E29--and I believe most direct-drive Atomic 4 sailboats--has a two-blade 12 x 9 prop. This is over-propped and results in too little tip clearance. Better would be an 11 x 7 two-blade or one of the Indigo Atomic 4 replacement props which are 10 x 7 three-blade.

But Loren's right, what came with a direct-drive Atomic 4, correct or not, has little relevance to your Yanmar installation. I'd recommend a copy of Dave Gerr's book, The Nature of Boats, which has a chapter on propellers. Gerr also has a very complete book, The Propeller Handbook, which covers prop selection in great detail. The Propeller Handbook is not for the math shy. :nerd:

You can also get recommendations from propeller manufacturers, Michigan Wheel for instance:

http://www.michiganwheel.com/MIWheel/propit/main.htm

CDI also has a listing by boat or by engine which would at least get you into the ballpark:

http://www.sailcdi.com/ppmain.htm

As you can see, CDI recommends a 12 x 7 replacement, but according to Gerr, a 12" prop has marginal tip clearance on the E29. Michigan Wheel recommended an 11 x 7 when I filled our their form and .......... waited.

Good luck.

 

[maggie-k]

Yanmar diesel

Most likely you have a YS8 or YS12 yanmar diesel the props for atomic4's will not be of the same size as the Yanmar . Let me know which Yanmar you have the transmission could be a 2:1 or 3:1 depending on the transmission . I spent about a year and got on a Campbell 3 blade. As well check your rotation direction , Ys series yanmars used Left hand props.