CD27 prop replacement source

[bevans]

I have a 1979 CD27 with the original 8HP yanmar, which after a valve job is running well. MY two blade prop, probably the original equipment, is pitted and cracked and needs replacement. I've read the pros and cons of 2 versus 3 blades. My questions are: where to obtain a replacement and how long it will take?
Blackwell

[Ken Cave]

You really need to go to a prop shop with your weight of the boat, dimensions, engine HP, etc
to get the right prop for your boat. Getting one "off the shelf" that will work is pretty difficult,as
all the above need to be considered, whether you choose a two or a three bladed prop.

If you know the dimensions of your existing prop it would also be helpful.

Hope this helps

Ken Cave CD 28
LaConner, WA

[moctrams]

These folks did a great job selecting the proper prop for me.

http://www.westbynorth.com/propeller-re ... tion-form/

[bevans]

Thanks for both replies. My self education continues. The CD27 prop is 12 inch diameter, pitch of ten, bore of one inch. Standard taper. Left hand screw. I found a variety of dealers online and locally for Michigan Wheel props. Other names to surface have been Campbell and Martec.

Various observations from local people:
If I go to three blade I should reduce the pitch by at least one.
Three blade probably won't significantly increase power or control in reverse on a full keel, especially with a prop in an aperture.
Vibration from my one cylinder diesel probably won't be significantly decreased with a three blade.

I asked the local prop shop guy about the Nibral alloy. He laughed and said it's so hard that if I hit something it might break the prop shaft or the transmission rather than bend the prop. Better to stick with bronze.

I saw a two blade prop from Michigan Wheel's M series that looked interesting because each blade had a bit more surface area than the usual two blade props.

I'm hearing delivery times of four to six weeks.

The local prop shop ground out the crack and welded it back together in two stages. I'll go back in the water with that for now. Assuming I don't hit anything he thought I'd be good for 'awhile'. I imagine this means that it will fly apart at the worst conceivable moment so I will be very prudent until I can make a permanent switch.

I'm thinking of sticking with two blades since I do a lot of light air sailing here. It made it 36 years with two so why change now.

Thanks again for the comments,
Blackwell

[godspeed]

i have a 1978 cd 27 with the original ysb8 and a three blade prop. is it original? your guess is as good as mine. i don't experience any vibration nor loss of power that i can attribute to the prop. the reversing issue is endemic to the full keel. there is an old post on this cape dory website offering some help in overcoming the problems in backing down. your search for prop info is helpful to the rest of us. thanks.

[bevans]

OK, new questions. When I look up recommended props from Yanmar or use a prop calculator I get twelve inches and pitch of 8 or 6 respectively for a two bladed prop. What I had was twelve inches and a pitch of 10. Nobody has been able to tell me what the original prop measurements were much less what is optimal. Any voices of wisdom out there?

My best speed was 4.6 to 4.8 knots before with clean hull, calm seas, fresh valve job, etc.

Blackwell

[bevans]

For anybody still following this thread, or those who find it in the future, here's the latest.

I sent Michigan wheel all my data and they responded very promptly with this recommendation:
Michigan Wheel Sailor Series
2 blade 12 inch 8 pitch or
3 blade 12 inch 7 pitch

This is in line with most of what I found elsewhere. The prop I have now, which I thought was the original, was 12 inch 10 pitch two blade.

Down the road, after replacement I might update this.

Many thanks to those who responded,

Blackwell

[tjr818]

Please do keep us updated Blackwell. I am sure that many are all interested, and I know that soon my our prop will need to be refurbished or replaced.

[bevans]

Another update:
I submitted my data to Campbell and got their recommendation. They were very prompt with their response, just as Michigan Wheel was.

They suggest a three bladed Left hand prop. Diameter 12 Pitch 6. They say that their cupped blades and leading edge foil technique 'produces greater thrust and reduces slip rate' hence the lower recommended pitch. They tout reduced drag under sail also.

They suggest 8-10 days manufacturing time and 4 days shipping currently.

Haven't made a decision yet. Currently still running with the old refurbished prop (diameter 12 pitch 10 two blades). Interestingly by GPS my top cruising speed is now 5.2 knots. Absolute max speed under power is 5.4-5.5 knots with a little smoke. The old paddlewheel used to read 4.8-4.9 knots max cruising speed and I never compared it to the GPS before. Currently the paddlewheel isn't working which I presume is due to paint.

This is probably the last update until I buy a new one. Anybody ever made a direct comparison between Michigan and Campbell?

Blackwell

[bevans]

One more bit of info:
Searching this site under "Michigan and Campbell" yields multiple threads that are pertinent. My previous searches tended to focus on CD27 or CD25 or YSM/YSB or 'props' and weren't as helpful. There is so much under "Michigan and Campbell" that I haven't had time to absorb it all, but much of what I learned in my research was already there and then some.
Blackwell

[Brian2]

I don't have anything good to say about Kelsey at West by North. When I installed a new Beta 14 on my CD28 I decided to give Campbell a try. The first time Kelsey sent me a prop it was over pitched, I couldn't get max RPMs and had black smoke. Not his fault, it can take some back and forth. I gave him the info he requested and sent the prop back, $100 round trip. He grossly under pitched it, and I got over max rpms and 3.6 knots in 10 knots of headwind. He said that was the best he could do. I sent it to Gabe at http://www.precision-props.com/ and he was able to pitch it so I could get 5.4 knots and max rpms. That cost $125. I was not at all pleased with west by North. As a side note, the Campbell sailor prop grabs seaweed (Maine) like crazy, and it won't unwind in reverse. I could always unwind seaweed with my Michigan prop, which sometimes got a big ball of weed on it, but nothing like the Campbell.

[karonoko]

Thought my travails with engine soot might interest this thread.... I have a CD 27 with original Yanmar YSM8R, and it works great. I moved from Lake Superior (boat, too) to coastal Maine. On Lake Superior - freshest of freshwater - I did not have much smoke - just a tad of a mustache. Prop pitch 12" x 8" and could get to 6+ knots. In salt water I have an objectionable amount of soot. My local engine monkey/genius figured out I was way over pitched and could not get the engine up to the proscribe 3400 rpms with the drag or whatever of the overpitch. He re-pitched it to 12" x 10" from the previous 12" x 8". I am assuming the density of water fresh vs salt has come in to play here. I will be curious how my sea trial goes this spring.

[mathiasben]

anyone considering a featherstream propeller?

[JD-MDR]

s.

[JD-MDR]

Thought my travails with engine soot might interest this thread.... I have a CD 27 with original Yanmar YSM8R, and it works great. I moved from Lake Superior (boat, too) to coastal Maine. On Lake Superior - freshest of freshwater - I did not have much smoke - just a tad of a mustache. Prop pitch 12" x 8" and could get to 6+ knots. In salt water I have an objectionable amount of soot. My local engine monkey/genius figured out I was way over pitched and could not get the engine up to the proscribe 3400 rpms with the drag or whatever of the overpitch. He re-pitched it to 12" x 10" from the previous 12" x 8". I am assuming the density of water fresh vs salt has come in to play here. I will be curious how my sea trial goes this spring.

I had problems getting Rpm's and smoke. I serviced the injectors and it solved the problems.