C-Dory 25 prop decision

S

SENSEI

New member
I know this has been hashed over several times and I have gleened some info from this forum.

I have just purchased a Honda 150 fuel injected 25 in shaft motor for a repower from my Honda 90 which is on the 1996 25 Cruise ship.
I need to start somewhere with a prop for it and would like some sugestions from some of you 25 owners with 150 Hondas on them.
I figure I will start with aluminum and once I find the right one I will go with a Stainless and use the aluminum for a spare.

Thanks in advance.


P.S.
I have a 96 Honda 90 with 25 in shaft for sale if anyone is interested
 
My 150 on a 25 has a 14 1/2 x 15 SS. At ~5800 RPM we do ~27-28 kts - LOADED. I've just put on a 15x15 aluminum as I'm headed for the land of the "rockfish" this summer and wanted a sacrificial prop. We spend nearly all of our time at displacement speed, so I probably won't be able to tell the difference with the 1/2" larger prop - plus the aluminum will have more flex to it than the SS.
 
Roger,

My experience on my 25 is limited to one day on the water. I started with a 17P 3 blade stock Yamaha prop that would turn 5300 at 35 mph with a moderatly loaded boat (full fuel, no water, and not much in the galley). I dropped back to a 15p 4 blade Solas and got the same top end at 5700 rpm. At this point I am staying with the 15 pitch prop. I haven't installed my Permatrim yet but that is coming tonight. The 25 seems to be stern heavy (full fuel and no water in the tank under the V-berth). I got best fuel economy with nearly full down trim tabs. With the Permatrim I should be able to get a comparable attitude without full flaps. That should improve fuel economy.

I would say something in 15 pitch. I am even contemplating a 14 pitch stainless prop from Powertech but have a hard time with the $500 it will cost.
 
I agree 15 in SS for the 150, The Aluminum will have slightly more flex, thus act as a slightly lower pitch prop. For the 130, a smaller block, then the 13" pitch at sea level.
 
Here's my viewpoint. First, Journey On is the typical C-25 with a Honda 150. To make sense out of the propeller thing, I started looking at the propeller pitch as boat gearing and compared it to my bike. So there are several different propeller pitches that may be suitable; just as you would change gearing on the bike depending on the type of race you were running, one would select pitch based on how the boat is being used.

First question: how are you going to run the boat: loaded for long cruises, light for fishing,somewhere in between? And how fast are you going to drive the boat: hull speed ( don't laugh, we do that a lot of the time to enjoy where we are), up on plane at about 14 knts., or getting to the fishing spot as fast as you can at 25 knts?

Here's what propeller pitch did for journey On. Empty and in San Diego Bay on a smooth morning a 16' pitch got us to 25 knts @ 5500, right in the middle of the Honda HP range. Which I submit is fast enough for anybody. At that speed ripples get bigger and if anything is floating in the water, you aren't going to miss it. And fuel mileage is atrocious, <2.5 mpg. Loaded, if you want to go that fast, you're going to have to go to a 15" prop and buy more gas.

We travel well loaded and we cruise. So we settle for a 14.74" dia by 16" pitch prop. At hull speeds our gas mileage goes up to about 6 mpg and overall during the summer we average ~3.4 mpg. The 16" lets us comfortably cruise at 15 knts without straining the motor, and at that speed we can see the logs and weed in our path. There are times I put on a 15" pitch and yes it revs freer, but the mileage drops and the gas was $4/gal.

I tried a composite prop but the minimum pitch was 16 1/2 and that was a little too much for for the engine at our weight. Also composite props disintegrate when they hit anything.

An aluminum propeller is lighter and easier to shift than stainless ones. As Bob pointed out above, they do flex more than stainless, but at our speeds I don't worry. 3 blades give you more top end (so I've been told,) but 4 blades get you out of the hole faster. The latter is important to me.

One additional comment. Don't jam the gas open with a 150, it has enough torque to spin some propellers.

Boris
 
I'm running same set-up. 25' with 150 honda. I went from an aluminum Honda 15.25 x 15 to a 15 5/8 x 13 stainless solas prop. I could only turn the aluminum prop up to 5400 rpm's. The solas I can spin up to 5900 rpm's.
I burnt 10 gallons less on same trip running the solas vs the honda. Boat was loaded the same on both trips. Not having to work the motor as hard with the solas prop.
I would still like to try a 14 1/2 X 15 stainless. Gets expensive trying to find the right prop.
 
Nunya":17iqkd58 said:
I'm running same set-up. 25' with 150 honda. I went from an aluminum Honda 15.25 x 15 to a 15 5/8 x 13 stainless solas prop. I could only turn the aluminum prop up to 5400 rpm's. The solas I can spin up to 5900 rpm's.
I burnt 10 gallons less on same trip running the solas vs the honda. Boat was loaded the same on both trips. Not having to work the motor as hard with the solas prop.
I would still like to try a 14 1/2 X 15 stainless. Gets expensive trying to find the right prop.
Click to expand...


The "lower geared" but slightly larger Solas has more "adjustability", with it's lower pitch, so a greater "slip" allowance is encountered, giving you that adjustable range, and more overall efficiency.

Never discount the value of "slip", the difference between theoretical prop travel and the real deal in water, a fluid.
Joe. :teeth :thup
 
Roger, we have found the right prop for our CD25 / BF150 combo at sea level - a Quicksilver 15.5 x 15 aluminum prop. And we are loaded pretty heavy most of the time. It seems like a decent starting point for your Cruise Ship / BF150.

SENSEI":3kcbulb0 said:
I know this has been hashed over several times and I have gleened some info from this forum.

I have just purchased a Honda 150 fuel injected 25 in shaft motor for a repower from my Honda 90 which is on the 1996 25 Cruise ship.
I need to start somewhere with a prop for it and would like some sugestions from some of you 25 owners with 150 Hondas on them.
I figure I will start with aluminum and once I find the right one I will go with a Stainless and use the aluminum for a spare.

Thanks in advance.


P.S.
I have a 96 Honda 90 with 25 in shaft for sale if anyone is interested
Click to expand...
 
Glad to see you got your motor Roger Man!!!

Now, if Papa Glenn/Slow Ride will let you off the farm a few days.... it should be sweet!!! :thup :smiled
 
Hi
sorry, I know the prop debate never goes away...
I am once again trying to figure out the best prop to use on my cd-25...Most of the post have been from owners with 150hp honda's. I have a 135 and wonder if having a 135 would make much difference overall regarding my prop choice. I run my boat heavy ( normally 6 to 7 persons on board).
I started with a factory stainless prop 14 1/2 x 15 stainless and felt I was over propped. My max rpm was 5000. I now have an aluminum 15.5x13 and my max rpm is 5200. It's all rather voodoo magic to me, but because I am a business I spent a lot on fuel and I would love to get this prop fine tuned to my boat..any input would be appreciated

thanks
carli whale watching tours
 
bcarli":13iwykd8 said:
Hi
sorry, I know the prop debate never goes away...
I am once again trying to figure out the best prop to use on my cd-25...Most of the post have been from owners with 150hp honda's. I have a 135 and wonder if having a 135 would make much difference overall regarding my prop choice. I run my boat heavy ( normally 6 to 7 persons on board).
I started with a factory stainless prop 14 1/2 x 15 stainless and felt I was over propped. My max rpm was 5000. I now have an aluminum 15.5x13 and my max rpm is 5200. It's all rather voodoo magic to me, but because I am a business I spent a lot on fuel and I would love to get this prop fine tuned to my boat..any input would be appreciated

thanks
carli whale watching tours
Click to expand...

Hi Bill,

We run that same stainless prop on Wild Blue and get 5500-5600 at sea level. When we're cruising, we generally loaded (generator, dinghy, dinghy motor, food, extra water, etc), but I'm guessing your load is still more. Sorry I don't have experience with another prop (other than the composite 4 blade adjustable that was less than satisfactory and is now just our back up).

I do have a question, though: where do you put 6 to 7 people on the 25?

TIA.

Best wishes,
Jim B.
 
Hi Jim
good question...
When we had our boat built we had the factory recess the sink and the stove enabling us to put a cushion in that space. So with me driving I can seat 6 people inside plus I have a few folding chairs for outside seating so I can seat six outside as well. It's tight but it works. Wish I could find the right prop and get better fuel economy... I'm lucky to get 2 miles a gallon.
 
bcarli":1012ntpi said:
Hi Jim
good question...
When we had our boat built we had the factory recess the sink and the stove enabling us to put a cushion in that space. So with me driving I can seat 6 people inside plus I have a few folding chairs for outside seating so I can seat six outside as well. It's tight but it works. Wish I could find the right prop and get better fuel economy... I'm lucky to get 2 miles a gallon.
Click to expand...

Hi Bill,

With that load, 2 miles per gallon sounds about right... assuming you can get the boat up on plane. I've gotten as low as 2.2 mpg on a tank, running in the upper teens with a full cruising load. I've since learned to ease back a bit on the throttle, settle in between 15 - 17 and will usually get 2.5+. Or, pull back to displacement speed and get 5+ mpg.

I would enjoy seeing a photo of your interior if you have the time and inclination.

Best wishes,
Jim B.
 
What is your cruising speed and RPM--you may actually be better off going down to 11" and keeping a 15 5/8" prop in SS. (That was what was advised for my 130 by Prop Gods--and ended up being down by the new owner (on Powell)--and dramatically increased the speed there--I suspect it would also increase the economy if you are lugging the engine--which is quite possible, since you are not turning up full RPM at WOT. You want to keep as much blade surface area because of the load--and even going to 4 blades might be a consideration--giving more lift to get on a plane faster.
 
Instead of creating a new thread I jump in here.

Our new to us 25CD has a Mercury 150 Verado; Max RPM at WOT should be 5800 to 6400. The boat came with a Mercury 3 blade 19 pitch stainless prop; I was only able to get 5500 rpm. I called my local prop shop and settled on trying a 14.25in 17 pitch 4 blade stainless Solas, could only make 5250 rpm. Although I didn’t get the RPM I was hoping for the 4 blade picked the stern up and fuel economy improved. Next prop we tried was a 14.5in 15 pitch 4 blade stainless Solas, max RPM about 5500, even better fuel economy.

So now I’m thinking of just going to a 13 pitch 4 blade, I don’t think dropping one pitch is going to get me into the RPM Range I’d like.

Is anyone else running a 150hp Merc Verado?
 
My c-dory 25 with a 135 honda came with a three bladed stainless 141/2 x 15 prop. I used that prop for a few years putting about 600 hours on it before trying a 151/2 by 13 aluminum three blade prop. I have put about 1400 hours on the new prop. Last week I hit a dead head and had to put the older stainless prop on and boy what a difference. The 151/2by 13 drives my boat SO much better. I get much better fuel economy, get much better boat speed at lower rpm's and get up on a plane easier and quicker with the aluminum prop. The difference between the two props was amazing. I carry a heavy load on board ( average 6 to 7 people) and that may influence my prop size. I'm wondering about going to a 16 by 13 as there is about a 1/16 of an inch clearance using the 16 x 13 prop....
Just my experience
Bill.
 
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