prop question for a CD 28.

[rdmac]

I have a 28 ft. '78 CD with a 2 blade prop 13 X 13. Volvo Md7a diesel. Sure seems to take a long time
to get the boat moving. When docking, I need to put in reverse long before my bow crosses the end of my finger pier.
Has anyone switched out to a 3 blade? And did it help? I can't afford the feathering, but maybe a fixed 3 blade would help.
Thanks, Doug
Menominee, Mich.

[John Ring]

Mine was the same way - took forever to slow/stop with the old two blade, and it would walk the stern way out to starboard. I put a three blade on and it made a world of difference - much better stopping power. A fixed 3 blade will slow you down a bit under sail, but she'll maneuver better under power.

John
CD28 Tantalus

[rdmac]

thanks john. what dia. and pitch?
this is just the good news I was hoping for.
doug

[John Ring]

Doug,

My Volvo MD7a is long gone, and I'm running a Beta 14 now. The Beta turns much faster, and in the opposite direction from my old Volvo, so the prop I'm running wouldn't work at all for an MD7a. You'd need a left hand prop with more pitch than the 8" or 9" pitch RH that works for my Beta. Best bet is to use the guidance offered by the new prop maker, likely an inch less on the diameter, and of similar pitch to what you have now.

Best,
John Ring
CD28 Tantalus

[Neil Gordon]

How big a problem is this?

My MD7A + 2 blades push the boat at hull speed so that important test is passed.

As for taking a long time to get going... are you saying it's dangerous or are you trying to save about 10 seconds?

Without knowing, I suspect that if you slow your approach into your slip, it will take less time/effort in reverse to stop your boat.

Donate half of what you save by not buying a prop to your favorite charity.

[sharkbait]

I have always told my daughter to never approach the dock at a speed greater than what you want to strike the dock. Reverse is for backing and not for docking.

[rorik]

Mathilda has a 3 blade Campbell Sailor prop to go with the new engine. Reduced prop walk, better response in both directions.

[Neil Gordon]

I have always told my daughter to never approach the dock at a speed greater than what you want to strike the dock. Reverse is for backing and not for docking.

"Dead slow" is what I was taught.

[Paul Grecay]

Just typed a long response....and lost it....so here goes an abbreviated version. 2 blade prop: slow starting and stopping. Sometimes a bit of "speeed" is necessary for steerage. In a crowded marina full of expensive yachts, you need to be able to STOP the boat....a 3 blade prop does the job. Slower sailing? Yes...who cares...safety first. If we wanted speed would we own sailboats? if we wanted speedy sailboats would we own CDs?
I repowered with a Beta Marine (Kubota) and now my old 3 blade prop is sitting in my tool shed...it is a
Michigan Wheel bronze prop....one inch shaft, LH, 13" dia., pitch=6...always worked great with my Volvo Penta ... I also have another one (same dimensions but not made by Mich. Wheel) which I used as a spare...now both are not needed because my new diesel uses a RH prop. Let me know if would be of use to you....I will let it go cheap.
Love the three blade prop...it is a good feeling to be able to STOP the boat fast when I need to...like when there is boat or a dock dead ahead...saved my bowsprit, another sailors pride and joy, alot of cash, and my dignity on a couple of occaisions in the past 12 years. Like seat belts, they only have to work once in a lifetime to make it all worthwhile.

[Neil Gordon]

I'd be interested in seeing some comparative data... in particular, acceleration times and stopping distances.

[Steve_M]

Wolf's two-bladed prop moves her around just fine, and we sail out of the Merrimack River where the current can be a tad fast. A little faster is always nicer, I suppose, but the two-bladed prop gets her up to hull speed fairly quickly, and let's face it; Cape Dory's do NOT plane.

As for docking, I always sneak up slowly on the dock, as if I were trying not to scare it away. Normally, if I've done everything right, I usually throw the engine into neutral about a boat length away from the dock and coast up to it.

[Paul Grecay]

I didn't put a 3 blade prop on my boat to go faster ... (I'm not sure the three blade vs. two blade makes much difference for speed). I wanted the 3 blade prop so that I could STOP the boat when needed and 3 blades will definitely make a difference. Yes, as slowly as possible is the best way to approach a dock. But if the wind is blowing the bow off, sometimes a very slow approach is not possible. Three blades also helps when motoring into heavy seas. I learned about that during a June gale off Bartlett's reef in Long Island Sound in '76. The boat was a65' Alden schooner named TradeWind (I think Alberg was a student of Alden) The prop enabled us to keep the bow into the wind for seven hours...despite making no forward motion. It was memorable. I would also like to see comparative data...at this point I am only speaking from my own experience. I would imagine that this topic has been discussed before.

[rdmac]

Paul Grecay, thx for the response. I'm not looking to go faster as my 2 blade gets to hull sp just fine.
Like u I'm looking for more control when backing out of the dock and changing directions i.e. changing from fwd to reverse, and rev. to fwd. There have been times while backing out, that going from rev. to fwd and reving up, there will be a 10 second delay in getting the boat to stop going backwards, and start going fwd. And in the mean time the bow blows around 90 deg. so now i'm pointing somewhere I dont want to go. In a crowded marina this causes me lots of anxiety. Our CD 28's do very well out in open water, but in tight spaces with a cross breeze, they handle like a school bus on an icy hill. I will do some testing and learn more about props.
I possibly would be interested in buying your 13x6 3 blade. Think about a price.
keep me in mind.
R.Douglas MacArthur
rdmac@new.rr.com