Thinking of going from the 2 blade to the 3 blade prop. I have been told it work better in reverse than my 2 blade. Any input to what size I would need? Have one for sale?
Len
Len, I think my three blade is 17x12.But it will never back straight with the offset shaft.With the 3 blade you will have the power you need.Allen
It looks like I've got a three blade 17 x 10 on mine. Power is not a problem, but it's fairly random which way the stern will go when I start off in reverse. It helps to push the boat in the right direction first.
I checked with a local prop shop and they want $800 for 3 blade fixed prop! Any suggestion on where to find one at a reasonable price?
I have a maxprop 3-blade set at 10.4" of pitch, 17" diameter. Quite a few sailors on my dock have a "Campbell Sailor" prop, and a brand new custom machined prop will set you back 700$ on our sized boat. The blades look tiny compared to old-school screws but that's why they have such reduced sailing drag. They certainly have plenty of punch in forward and reverse, and after seeing them in action I believe their marketing. I've considered selling my maxprop to go to a campbell sailor but due to the shaft nut arrangement I would likely need a new shaft, so I'll just wait until I have a problem.
Mike
Boracay Star
Pearson 367 Cutter #26
Hi Mike,
Thanks for the tip, I may go that route but was hoping to find a good used one that needs a new home.
Len
I had 2 different 365's. The first one had a 2 blade prop, the second had a 17X10 3 blade. The difference in reverse was daylight and dark. The boat with the 2 blade you really had to be careful and start backing earlier. We were in a slip with a bulkhead in front. I never hit it, but a couple of times I thought we were gonna. When we got the second boat, I started backing at the same distance. I had to nudge it forward to get it in the slip. Abracadabra backed down MUCH better.
Quote from: swiftibis on April 23, 2013, 08:57:14 AM
I have a maxprop 3-blade set at 10.4" of pitch, 17" diameter. Quite a few sailors on my dock have a "Campbell Sailor" prop, and a brand new custom machined prop will set you back 700$ on our sized boat. The blades look tiny compared to old-school screws but that's why they have such reduced sailing drag. They certainly have plenty of punch in forward and reverse, and after seeing them in action I believe their marketing. I've considered selling my maxprop to go to a campbell sailor but due to the shaft nut arrangement I would likely need a new shaft, so I'll just wait until I have a problem.
Mike
Boracay Star
Pearson 367 Cutter #26
Mike (and group), I'm new to the forum having just bought Audrey (367 Hull #5) and am thinking about a Maxprop since I don't have a shaft lock. They are expensive (Maxprop), but what's a better alternative without the shaft lock and without sacrificing power when backing down?
Trip
Pog has an old post about the prop sizes and some comments on performance.
Sea Dragon, a 367 with a different underbody than the 365, came with a 2 blade (18Lx10). We sailed for one season with the 2 blade and during that time I was not happy with the handling in reverse or motoring efficiency. I replaced the 2 blade with a 3 blade 17L x 11 prop. I saw significant improvement in motoring as well as improved control in reverse (reduced prop walk and better stopping).
Garner
We will be replacing our original bronze shaft with a new 1-1/8" SS in the next few months. We currently have a two blade which seems to suit our needs. Is there a compelling reason to consider a three blade? I understand it backs down better than a two blade but is there a performance/economy advantage going forward? I have not had any issue with backing down to date and the pronounced starboard prop walk is something I have found to be an advantage (sometimes 😅). I thought I might pay the prop shop to recondition the 2 blade.
With all the other things we need to do to prepare for an extended cruise. I am not looking for additional expense unless there is a good reason.
Ritso,
For an extended cruise a spare prop is something I consider essential. (Along with spare prop nuts!)
Consider getting a new 3 bladed and throw the 2 blade into your spares locker.
We have a Kiwiprop. Excellent reverse, much better than the fixed pitch, and it was a noticeable increase in sailing speed with the feathering prop. Although, I gotta say, the spare prop was only used when the kiwi prop failed one time. Taught me the value of the yearly lubrication I read about in the manual.
Wayne
Ok, I got a price of $750 for a Campbell Sailer. They recommend 16x9.5.
Does anyone have experience with the CS? Size and pitch? Effectiveness?
I don't want to spring for a Max-prop so am looking for the best value for a three blade fixed. Local prop shaft that is making our new shaft quoted $600 for standard 17Lx11 3 blade.
Sailing performance is important but by the time we load up the boat with all the gear, my guess is that a half knot either way is not going to make a huge difference.
Risto,
You never clarified what motor (HP) you have in your boat ? Is it w40? ( HP vs rpm) I assumed you don't have a 4-108. Mine's been repowered with a larger motor and I found a very clean used 17"x 15" 3 blade ($150), which was close to what I wanted. I based that on the calculations from this tool. Of concern with larger motors is exceeding the tourque rating on your 2:1 RV-10. Its going to be close with a larger motor per Walter V drive specs. So you should check you v drive for backlash. That's the failure mode, its not bearings that wear out. (pinion shaft splines)
http://www.vicprop.com/displacement_size.php
Don't forget to specify the prop bore. FYI you can shim an 1 1/8" shaft taper up to 1 1/4" prop bore if need be. It will be hard to find reconditioned props in 1 1/8".
Pete
Risto, pretty sure your boat is a M50 Universal, 44 HP at 3000 rpm. So you have few extra HP over the 108.
The prop calculator says you need 17x10 for hull speed with those numbers. But if you back your motor off and ask the program to calculated hull speed using a lower RPM and HP it says to use a 17 x 13. The difference is being able to motor at hull speed at 2300 RPM vs. 3000 rpm. (3K rpm I think is too high for a diesel) This all supports 17x11 as the right choice for the 108. But I believe you have the margin to go up in pitch a little. I believe this allows you to cruise 7+ knots a lower RPM. Note: I enter the continuous duty HP and RPM from the graph for my engine not the max.
Interesting that this tool calculates HP put to the water for the Pearson 365 hull at 5, 7.5 and 8 knots as being 10, 33, and 48 HP respectively.
Since the fuel consumption for my Westerbeke is given in lbs per HP hour. (a railroad term) My fuel consumption goes from .6, 1.64, to 2.2 gallons per hour at 5 knots, 7.5 knots and running flat out at 8 knots. ( where it goes up by incredible amount)
Very interesting. Pete
Pete,
How do you get 17 x 10 on that prop calculator. I keep getting values that range from 15 x 9 to 15 x 8, depending on what I change, but never even close to what you are getting.
I have a 367 like Risto. The motor in mine is the M50, 44hp, 3100max rpm.
here are the values I'm inputting:
lwl: 30
beam @ wl: 9
hull draft: 3
weight: 20000 (I also put 17000 an still got round 15 x 9 or so prop)
# engines: 1
hp: 44
max rpm: 3100 (I even tried 2300, but still got prop recommendations of 15 x n
gear ration: 1.9:1 (hurth ZF15, Walter RV20)
shaft bearings: 2 (shaft log and strut)
Desired speed: 7
I changed the values , but still the 3 blade prop recommendation was always around 14.9 to 15 x 8 or 9.
Thanks
Risto, when you get the prop worked out, let me know. I have a sistership (#42) and am looking for a 3 blade prop.
I de-rated the M50 performance to 40HP at 2500 RPM (from the graph) and entered those as max HP and RPM. It spits out 17x13 with those numbers and specs 35HP to the water to achieve hull speed 7.3 Knots which shows that you have margin. And I assume the motor will be running slower at 2500 rpm. Which I think is preferable to flat out at 3000 rpm.
Gear ratio has to be 2:1 overall. 2:1 in the V-drive and 1:1 in gear box. A Hurth will not work in the Pearson 365 because you will be at 3.8:1 overall. 1.9x 2 = 3.8 With that gear ratio you need to swing a 27" x 21"inch prop which is impossible to do. Unless your RV26 has 1:1 gears in it meaning the repower was done right.
Pete
Thanks Pete,
I double-checked and you are correct the v drive is a RV26 with a gear ratio of 1.00:1 (maybe, hard to read, waiting for feedback from Walter).
The ID plate on the hurth shows ZF15M for the model with the following ratios: A=1.00 and B=1.95 (again, hard to read, but A value could be 1.88)
My mistake was that I was not reducing the rpm and hp correctly on the input table, giving me the odd prop values.
Walter Machine documentation does not recommend putting the gear reduction in front of the V-drive. It has to do with the max HP rating of the drive that is reduced by the gear reduction. (torque increases) I don't have a spec sheet on the RV26 but the RV-20 1:1 specs out at 59HP at 1315 RPM (2500 at the motor) . So you should Ok there.
Where you are not OK is in the Hurth ZF15 which has become your weak link. Bad news is that at 2500 RPM the ZF15 continuous duty rating is 38 Hp. You might be inclined to call that good margin but in this case I am not going to recommend gearing up by going to a higher pitched prop. Without an oil cooler on the Hurth it will overheat and burn out. So stick with the lower pitch prop (17x 11) and rev your motor to 3000 rpm for hull speed. At 3000 rpm the Hurth ZF15 is rated for 46 hp. I've seen too many Hurth gearboxes burn out in a very short period of time.
It's too late for this but I would have kept the 2:1 v-drive, got rid of the Hurth and put a Velvet Drive (direct drive) on the Universal motor. That's a 175 HP rated gearbox.
Meanwhile I'm very curious to see how you fitted an RV-26 into the Pearson 365.
Here you go Pete, pictures as you requested.
https://picasaweb.google.com/111274927949602013478/Vdrive#
Thanks for the info on which prop and the inadequacies of what I have. It's good to know what to watch out for.
I don't know when the V drive was put in or if its install was at the same time as the Hurth.
Wouldn't it be great of the many POs of boats had done stuff right, instead of half-assed? I guess that's one of the pitfalls of buying a used boat.
So , if /when my hurth bites the dust, which velvet drive should I use. I then have to 1)confirm that my RV26 is 1:1 and 2) find out how much Walter charges to regear it to a 2:1. Of course, this is low priority because it's working and I 've got a long list of otherthings I'm working on, but it's good to have the info in my hip pocket so I can get to it when the failure occurs.
Thanks again Pete. Let me know if you want more details of my RV26 install.