interesting addition on the blade count - thanks!

generic comment.... I never heard of your explanations. Did you smoke a lot of funny tobacco when you were in college?

Comment is correct. Sail drives CAN have prop walk. Depending on the layout, they can have a lot of prop walk.

@Mission Gameliel Not when crossing oceans or night sailing or if you don't have enough room for the amount of panels needed for the amount of power required. Solar is good and very good, but it's not a solve all resource. If solar alone could do as you say then why solar is not fitting for all solar powered boats? More so the small day boats! (SOLAR HAS IT'S PLACE BUT IT'S NOT A SOLVE ALL)

Interesting your opinion on Kiwi Props. My experience, and the advice of the creator /manufacturer is lube on annual haul out! I've found that to be effective. I've not seen any erosion of the plastic blades, probably due to application of Prop Speed, so other than lube and prop speed I've had no maintenance issues in 6 years.

You are very welcome

🫨 18 foot!! Sailboat props must look like a handheld personal fan! Are you doing a button knot or the lovers knot? I like the lovers knot for a few reasons, but you can splice the tails of the knot into each other to make a single tail that is really handy for guiding the knot through the loop.

Thank you very much!

Thank you so much! I was wondering about the P-factor but you explained it perfectly later in the comment.

So glad we could help!

Thanks :)

Haha! It’s all good. Every bit counts, and there is a lot going out there!! Thankfully they are starting to clean up the massive amounts of fishing equipment that is floating out there to help the oceans. I do love these props and think they are the best design of feathering/folding props!

Glad it helped! Keep your life simple so you can focus on other parts of the boat 😎

Hunsted makes a really good vari-pitch prop.

The dominant vs weak arm comes into play once you go with the human propulsion, though. ;)

@@SkySailor75 🤣🤣

When I was in highschool in Puerto Rico, we referred to it as the “sinning arm”

@@RiggingDoctor LOL

prop-talk.

Some sailboats do have them and it’s very nice. The problem is they are complicated and expensive. Also, if the consumer doesn’t know how to work it, the boat builder will have to deal with all the complaints about how the boat doesn’t motor well. I’ve been on a few boats that had different styles and I loved them all! One was a high or low pitch, one for marina maneuvering and the other for cruising and range. Another had fully adjustable pitch instead of a gearbox. The prop was always spinning, but the blades could be rotated to be straight for neutral or pointing forward or back for the direction. By adjusting the pitch, you could make the boat have more torque or more speed without touching the revs. That was by far my favorite! The captain set the revs for docking and did everything by throwing the pitch one way or another. His only complaint was that the prop can’t free wheel while sailing and the blades don’t feather all the way. Also, if he ran over a line, he had to shut the motor down as neutral still had the prop spinning. Everything always has to be a compromise!

Thanks!

Thanks 😊

You obviously have lots of money and lots of time to install this system.

Thanks :)

Very welcome

They really are an awesome design!

I know what you mean, it’s practically a stern thruster! I tried to dock a boat that the prop was far from the rudder and it was a very ungrateful event.

That’s great to hear! Kiwi props are actually my favorite “non fixed” prop. They are the simplest design and have the fewest points of failure.

They were a pretty common sight in Portuguese boat yards. Very cool designs!

@@RiggingDoctor love my bilgey

That’s why we really like our fixed propeller. If it is present, it works ⛵️

😊

Good to know! I have friends in the Chesapeake Bay who have had to replace blades every 5 years or so. Makes me wonder what is in the Chesapeake! One friend barely moved his boat and the sun always hit one blade in particular. One blade disintegrated and it is assumed to have been the one that always had the sun hitting it while in the slip. Another friend (who first introduced me to kiwi props) told me about the polishing blades. He works at a boat yard in Baltimore and frequently would have to replace worn down blades on kiwi props. I really love them! Their simplicity, reliability, and adjustability make them the best non-fixed propeller in my opinion. I’m glad to know you didn’t have the blade polishing issue :) it might just be an issue in the bay.

Glad it was helpful :)

Interesting opinion on Kiwi Props. My experience, and the advice of the creator /manufacturer is lube on annual haul out is essential! I've found that to be effective. I've not seen any erosion of the plastic blades, probably due to application of Prop Speed, so other than lube and prop speed I've had no maintenance issues in 6 years.

Nice

Richard Mason , yes it was very nice

If you have any questions, let us know and we can make a video on the topic or point you in the right direction for that information.

@@RiggingDoctor well thanks! Appreciate that! Wind and/or wind direction, weather, and sails is still a huge topic I've been trying to learn about. So many differences of opinion!

Thanks! We are actually in Spain now

There was a 24 foot boat for sale for about €1000 that had just sailed to the canaries, Azores, and now back to Portugal! But it had a very “interesting” setup.

Some say it is bad for the transmission, but apparently it depends on the type of transmission that the boat has. We have an electric motor with direct drive so the spinning prop in neutral acts as a hydrogenerator to charge our batteries.

@@RiggingDoctor Right, but I meant for diesel engines.

Awesome! I will get you detailed info shortly. Brief info is: 4 years on our first batteries, 0.5 years on our new batteries. Charger is Delta Q IC1200 I keep the regen set to “5” as this gives the least drag with regen still on. I also set the motor limiter to 30-50% when we are not in a marina so that we have more fine control of the throttle setting. In a marina, I raise the limiter to 70% of maximum power. In really tight places I take off the limiter so we can use all the power available.

@@RiggingDoctor wow! That's great to know. And makes great sense. Thank you. I'll keep you up to date we have a 1973 formosa ketch, she also has full keel. I think we will share similar results. Thank you for your time 🤙

While the various methods for explaining prop walk exist, I still do not know for certain which reason it is, or if it is wholly one reason and not a combination of reasons acting in synchrony. Our outboard motor has no cavitation plate and is a 13 inch propeller. When I have the motor trimmed perfectly, I get very little prop walk (which makes docking hard for me). I tilt the motor up a notch or two and suddenly I have plenty of prop walk to make docking easier for me (as it behaves more like our sailboat which has a level shaft in an aperture).

@@RiggingDoctor Another explanation is that the hull impedes the water at the top of the prop's path, which allows the water at the bottom of its path to move more freely. Agree it's a bit confusing.

It’s going to be dependent on the pitch of the prop. If you decrease the pitch, you will increase your torque but cut your top speed. I’m not sure if the pitch is adjustable on Kiwi props. If it is, you are golden!

Thanks! I appreciate it :)

Good idea!

I’ve met a few cruisers with variable pitch props and it’s amazing! They set the RPM and then play with the pitch to set their speed. It gives them incredible range and efficiency while taking it easy on the motor.

I have only had a 3 blade on Wisdom but Windpuff has a 2 blade that I would rotate (I marked the shaft so that I could tell where the blades were) so that they would be blind behind the keel. Windpuff sailed better than Wisdom in light air! This is however a very unfair comparison as Windpuff weighs 9,000 pounds and Wisdom 34,000 pounds. I don’t know if it is a full knot of lost speed, and you can get thinner blade props. Wisdom has massive blades that are a lot of drag but I’m certain a thinner blade would not be as horrendous. The issue with maneuvering a 2 blade over a 3 blade is the constant fluctuation in the number of functioning blades. On a 2 blade, the oscillation will be 2 - 0 - 2 - 0 and so on. This is because you will have 2 blades out to the sides of the keel then both blades behind the keel and blind to it, then the two blades come out again, then they hide, then they come out again. This results in a fluctuation in thrust and lost efficiency. When you are moving, you want a constant thrust but a 2 blade will give you thrust “most of the time”. A 3 blade however will always have 2 blades working as the top or bottom blade will go behind the keel but the other two will be out to the sides. The fluctuations of a 3 blade will be 2-3-2-3-2-3 and so on. This will give you a constant thrust when you are motoring which also makes them more efficient. Less time on a passage makes it safer, and electric let’s you set the prop to barely spin so that it isn’t giving thrust but it also isn’t causing drag, or you can turn off regen and let it free spin which is less drag than having it stopped. On Windpuff, the prop is too small of a diameter to produce power from regen, but I am still going to put a 3 blade on. I will be looking for a very thin fixed blade prop though as I don’t want the complexity of a feathering prop or the drag of a wide blade. I would suggest looking into the Sharrow props, they are a torus blade and offer very little drag with incredible performance. If they have finally come to market when I’m at that stage, that is the exact propeller I plan on using.

@@RiggingDoctor that makes sense about being behind the keel and the 2,0,2,0,2,0 etc.... Is there still benefit of using this 3 blade Sharrow on a diesel engine as I don't have plans to go electric as far as motor. Sounds like they have much less drag?

Skeg hung rudder

In fact I challenge you!!

I have thought about doing that, using the plastic bits as the mold too. The only hiccup is the blades are supposed to be buoyant so that they feather better, but that drag seems rather trivial compared to a fixed prop.

It’s not great. They will always put wear on the driveline in some way. If you have an electric motor though, the spinning actually charges your batteries while you sail!

Thanks 😊

In a single prop boat, yes you would still have some prop walk (think of it as a paddle wheel) but it wouldn’t be as noticeable. Most high powered twin engine boats have counter rotating props, even if the shafts are horizontal (saildrive & outboards)to cancel it out. I once owned a trawler with a massive four blade prop which was horizontally aligned with the keel, in an aperture, and it would only go one way in reverse.

I can’t remember the brand, but there is a company that makes a propeller that works the same forward and reverse. The prop doesn’t look too fancy as the blades are plain and symmetrical. In a test comparing it to other fixed props, it had pretty low drag but it’s thrust in forward was the lowest of the bunch; but, it’s thrust in reverse was the highest of the lot and equivalent to its forward thrust. The main issue with it was that it would end up consuming more fuel to motor a long distance compared to the other props that are biased in their thrust. That said, low drag means that you can sail there and not use any fuel! I apologize for not remembering the name, or where I read about it. All I can remember is that it was in a magazine article where they compared a bunch of props which leads me to believe that it was Practical Sailor or Sail Magazine since they do tests like that. Good luck with your new prop! Reverse is the most important aspect in my opinion. When you want the boat to stop, you need it to stop in a hurry!

@@RiggingDoctor Thanks for a long answer :) I will look myself if I find some who mention that problem

My info is from other cruisers who had the blades polish down over the years. It was all word of mouth but from first hand experience on their part. I do not know what material or age their blades were, or if they still have the problem. I contacted Kiwi Prop to see if they would send me a prop to test out on our return voyage. I offered to weigh the blades before and after the crossing to find out conclusively what happens over thousands of miles of sailing but they were not interested in my proposal. Of all non-fixed propellers, Kiwi is my favorite design; it has simplicity which I find elegant. I just wish that I knew definitively if the blades polishing off is an issue or not.

Gori claim that theirs are, due to their ability to pivot over centre effectively reducing the diameter which has a gear/change like effect.

Pretty much, but you won’t get Regen with a 2 blade, so you need to weigh out your options.

1st: I’ve tried casting bronze and it is not as easy in practice as it is in theory. 2nd: I wonder if the plastic blades are needed for weight reasons where s bronze one might flop from weight. I imagine they would need to cast it hollow, not easy to do.

To free wheel or not to free wheel, that is the question. Weather 'tis nobler to suffer the thrums and degredation or, by selecting, end them? Personally, I would arrive slower but without the noise.

When we get back, I do plan on teaching on the side. Part time faculty at the dental school and give talks at sailing classes.

@@RiggingDoctor you should! You will be fantastic! And all you have to do for your resume is show them these videos! Resume, check, check!

At about 3-4 knots, we could run for about an hour or so. But this would completely discharge the batteries and wreck them. Safely, we can only use about half of the power in them and therefore around 1 hour at that speed. We find that we can usually be out of the marina and inlet in under 30 min and that lets us have time to get away and sails up safely.

Good idea! They will be coming out soon ;)

This was all with a Hero5 on a selfie stick. We just bought an 8 and the stabilization on it is unreal!

Ah cool. You're right, it looks like it's done with a gimbal. Wish they had a screen on the front! Thanks for the reply. N

Thanks! It’s a lot of practice to hold the thing straight regardless of what you are doing :-P I do wish they had a screen but after a while you get to know what is in frame with your arm stretched out. Honestly, we film most of the “selfie” shots on Medium. The new GoPro doesn’t have a “medium” setting, and on “wide” we are plenty in frame!

I assume that as well, but if you are unlucky, it could be both snagged or pinched in the blades

sounds like you need a new prop shop! plenty of metric bore props on the market. adapter is bad advice.

Cool setup! What kind of powerboat? We want to get a trawler and make it electric when we get a little older :) At 5 knots, we get about 2amps, at 6-7 knots we see about 6 amps, and once at 8 knots we had 12 amps (all in 48v)

@@RiggingDoctor Sorry, it is not a powerboat, it's a sailboat... a Pearson 35. Max hull speed is about 6.5 knots. I'm in the Chesapeake with light winds in late summer, so regen won't be a huge factor. Thanks for the info, I was just curious what you experience.

Also shaft angle will make a feathering prop be more in the way than a folding prop.

We have a 16 x 14 three blade. The keel does a good job of pushing crab pots out of the way but we have snagged a few in the Chesapeake Bay over the years (thankfully they always slip free).

All these comments got trapped in the spam filter, I’m just seeing them now (and cleared them as not spam, not sure what youtube thought was spammy about them). Encasing them in something would be a good idea and shouldn’t alter their performance if it’s light. I think I’ll be going with something like this in the future :)

@@RiggingDoctor you make me proud Herb, thanks for your feedback it means a lot to me coming from someone of your experience. Fiberglass is really hard and the area is small enough that expense should be low if it had to be resurfaced and it's light enough that it shouldn't affect proformance. I've never hard of that type of prop before can you give me a company name or a starting place to begin my research on that type of prop? It seams to be perfect for my future build or modifications. Happy sailing and I hope the wind is always at your back, cheers.