Preview: Going Fast with One Modest Engine, WHIO’s Propeller

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When it comes to speed and economy in powerboats, we usually think about hull shape and horsepower first. But what about the propeller? Is there fresh thinking here we ought to be considering?

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46 Responses So Far to “Going Fast with One Modest Engine, WHIO’s Propeller

  • Avatar

    Greg James says:

    Awesome video. I got a ton out of it. Thank you.
    I would love to learn more about the gear and engine in WHIO. Anyone know where there would be a little more info on these details?

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    Simon Houlder says:

    Will the kit design have a skeg (as per the profile view already released) that protects the propellor or follow the shaft line and show the lower half of the prop disc clean water, as per this example of WHIO?

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    Thomas Danick says:

    Hello everybody and happy holidays! A question to Peter: probably I missed it being mentioned, but what would be a typical prop speed in relation to boat speed? Would like to start thinking about the appropriate gear ratio.
    Thanks in advance and best regards

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      Richard (Dick) Trask says:

      A beautiful, beautiful boat. Is she essentially a day-boat or does she have cruising accommodations? Many thanks. Dick

      • Steve Stone

        Steve Stone says:

        You can check out the video we just released on the entire boat in “Related Videos” under the video above Dick.

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      Dave Monley says:

      Being short one torpedo designer, the obvious question will be;

      Will anyone produce this propeller and make it available for the boat/powerplant combination?

      This is such an attractive boat and such an attractive idea.


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    Paul Deaton says:

    Loved the boat and would buy one if available. Had a Hereschoff Meadowlark with twin 10 horse Sabbs and variable pitch props. This Toyota is much quieter.

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    Rick Clark says:

    Awesome Awesome Boat….A real Beauty…Thank You for your design!!!

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    Leif Knutsen says:

    One big disadvantage of a prop like that is that you must constantly remain aware of sufficient water depth and log drift, of which we have a lot of here in the PNW. Bend a fluke or two and you will be dead in the water and facing at tow home and an expensive pop repair that few yards are prepared to handle. Remember, every vessel is a compromise, so choose wisely.

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    Steve Zimmermann says:

    I’m a pilot, not a boat owner, and I’ve owned a number of very efficient gliders and airplanes over the years. I also drive an electric car. WHIO is exciting for all the right reasons: beautiful, lightweight, practical, and hugely efficient. At 7.5 knots she gets about the same gas mileage as my Pipistrel motorglider: unbelievable! I would think Peter’s hull and propeller design is a natural fit for an all-electric drive train.

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    Fred Mueller says:

    would be interesting to have some comments about prop walk … eagle eyes will notice asymmetric prop wash in the final few frames …

    amazing boat !

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    Paul Munafo says:

    Can and would this prop work on a Cape Dory 28 trawler with a 100hl Westerbeke diesel?
    If so how do you get one.

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    John Sims says:

    OMG, YES!!
    Please!! Plans, Kits, More videos about this boat, prop, design & coming availability!!

  • Tom Bryan

    Tom Bryan says:

    I can’t stop watching this video. The elegance at a goodly turn of speed is mesmerizing, seductive. If we give the prop some protection will the spell of efficiency the broken? Hurry with more.

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    Donald Jones says:

    Would this add any more speed to my sailboats displacement hull? I would also like to see this boat’s performance in heavy seas, not just the smooth as glass water we see here. Does she hobby horse through a swell like some race boats from the twenties and thirties??

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      Alan Johnson says:

      Donald as you know, a displacement hull has a theoretical hull speed calculated as follows:
      Hull speed can be calculated by the following formula:

      multiply 1.34 X Square root of waterline length. That will give you the “theoretical” hull speed of a displacement vessel.

      To exceed theoretical hull speed, depending on the shape of the hull, you would need to add 50 to 150% extra power to add only a few knots. In your case, calculate the theoretical hull speed and see if you have the necessary power to attain it. If you are, you would be wasting time and money buying one of these props for speed BUT it may be HUGELY more efficient at low revs which is what we all want. Hoped that helped.

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    Ben Fuller says:

    The efficient human powered boats use blades like this as do some of the new electric outboards. I remember trying out a proa based pedal boat some years back. Didn’t take off because of the draft you needed to get afloat. Part of the secret is relatively low rpm.

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    Konrad Truempler says:

    What a good-looking and well balanced boat – congratulations!
    The whole installation reminds me very much of the stern gear of my 33ft steam launch VENUS with its slow-turning, narrow-bladed prop. As with WHIO, I designed the hull shape to match the displacement and available low power – balance is the magic word. As Pete mentions several times, it’s not just the prop or the shape of the stern but the harmony of the entire installation that makes for good efficiency. I would have loved to omit the skeg to leave the water in front of the prop undisturbed but did not dare… and rightly so, as it protected the screw several times during the last 20 years on my difficult home waters. VENUS has a 24 inch screw, displaces 1.2 tonnes and does 8 knots @ 360 RPM with an estimated 6 HP of its compound V-engine – but not for long, as I am running out of steam quickly at that pace ;). Bollard pull even at very low RPM is just unbelievable. I fully agree with Peter: Big wheels, low RPM…

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    Robert (Bob) Godfrey says:

    Terrific! Could we get more info in the future?

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    Daniel Hicks says:

    I think it is worth noting, that as is normally the case, this video could have been twice the length it is, as much has been missed out about these props. It is worth noting the relatively small blade area on these props, too much blade area just causes greater losses due to drag, and with minimal horsepower, this has a major impact. I have one of Peter’s props on my steam launch Zeltic, unfortunately it was buried in the back of the shed when this was filmed. The change of prop gave me an extra 1/2 knot from the previous one (which was more conventional, but still not huge blade area) for the same revs. With minimal horsepower and low revs, these props are the way to go. As is obvious in the video, this type of prop moves a lot of water, very efficiently, even from stationary.

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    George Conbeer says:

    Totally cool. Can’t wait to see/learn more.

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    Morgan says:

    Wow Wow Wow. My jaw is on the table and I am completely taken back. Like everyone commenting before me, my mind is whirling at high speed. Taking my 77 Sabre 34 from a 35 hp diesel, to an electric drive with that prop could be just wonderful. Thank you so very much.

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    David Walsh says:

    i’m impressed with the the amount of “bite” evident when he launched, both forward and in reverse.

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      Heinrich Meurer says:

      So was I. And the stern design certainly helped. I shall have a look tomorrow at the German midget submarine Biber on display here in Vlissingen Netherlands. It’s propeller and those of it’s two torpedoes. Dutch naval works are close by too…

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    william hunt says:

    I want one yesterday.
    Please respond your email
    Thanks wm

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    Reuben Smith says:

    This is brilliant. We work on early high speed launches from the 1900s and 19teens that are of the same design family, and run at similar speeds as WHIO. We have seen firsthand the efficiency possible with high torque and low RPM engines swinging big props slowly. Often, when these boats are repowered with modern engines there is not adequate reduction, and so the props get smaller. The end result is the boat with the modern engine uses more fuel to run the same speeds–sometimes a lot more fuel–than it did with the old, original engine. I see this as a key opportunity with electric power, since with them we have the possibility of very high torque and efficiency at low RPM. (We have a boat we’re trying this out on, this summer.) But of course someone has to supply these fabulous props that Mr. Sewell has built! Thank you Mr. Sewell, for bringing such a fully realized vessel into the world, and thanks to OCH for spreading the word. It has felt a little lonely proselytizing about low RPM shaft speeds, until now.

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    Brian McCoy says:

    Does it take a fifty horse engine to turn a prop that big on a boat that size, or could you do with a smaller engine?

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    Stephen McClure says:

    Very impressive, and well in synch with the world’s urgent need to increase efficiency as we consume fossil fuels. And such a pretty hull. I wish I had seen this 30 years ago!

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    dave lathrop says:

    as inspired as I’ve been by a design in quite awhile… I would actually BUY this boat…

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    Kelly Brown says:

    Just when I think mankind has really mucked it up, something like this restores my hope.
    You’ve mad my day and add me to the list awaiting more info.
    Like Conbert, I fell in love with the 10 hp SAAB variable pitch. Ran on in a 22′ fishing boat a 1,000 miles up the inside passage to Alaska on 60 gallons of diesel.

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    David Badion says:

    Put me on the list for plans. I have been looking for a boat to build to do the Great Loop, for several years. WHIO looks like she fits all the criteria. Fairly shallow draft, trailerable, low fuel burn, seaworthy and quite beautiful. Perfect for river cruising…davey

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      Tony Verga says:

      I as thinking this would make a fine looper…

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    Dave Dickmeyer says:

    If I only had the time and $…..
    Simply beautiful, beautifully simple!
    Thanks for showcasing this one.

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    Roger Mellem says:

    Fascinating design but nothing was said about backing down. I’ve got a heavy, single diesel, boat and propwalk is a major handling concern. Just curious.

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      Rod Johnson says:

      switch your prop to a Max-Prop. I did on my Gulf 32. literally no propwalk in reverse and you can stop it on a dime.

  • David Tew

    David Tew says:

    That’s intriguing regarding how the skew of the blades decreases vibration due to the ‘shadow’ of the skeg.

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    Rod McKenzie says:

    Very intriguing
    My 36 ft Lobster round chine hull Designed by Spencer Lincoln displaces 15,000 lbs takes a 420 hp Cummins running at 1900 rpm to push it to 15 knots

    Has the developer created specifications to use as a comparison to similar designed hulls.

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    Conbert Benneck says:

    When I lived in Paris, I bought a Norwegian double-ender with a Norwegian 10 HP SABB single cylinder diesel engine that had a variable pitch propeller. We took delivery in Rotterdam and then went to Paris via inland waterways with 140 locks..
    After using the variable pitch propeller you are ruined for life. If I had to wait for a lock to open, you just pull the throttle back to idle RPMs; put the prop in flat pitch, and then just play with prop pitch if you want to go ahead a bit or go backwards if the current or wind is pushing you in the wrong direction. It wouldn’t do 20 knots, but it was very efficient too. From Rotterdam to Paris the amount of tax-free diesel I used cost about $6.50.

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      Mark Johnson says:

      Sounds very nice. How long ago (what year?) was this trip?

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    Kevin Russell says:

    Absolutely beautiful boat and great to see some contrary thinking that really works. Thanks for sharing!

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    Robert Bond says:

    Blade shape resembles US nuc sub prop design. Low rpm = less noise and cavitation = more speed submerged. Translates nicely into surface craft propulsion.

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    Jeff Hickman says:

    I am giddy with excitement as I wait for a set of plans to be created!

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      Mark Ritter says:

      OK, I’m sold. We’ve been looking for a comfortable day boat that’ll cruise efficiently at 20 knots, look good and handle the local chop.
      Now where can I buy one?!

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    Paul Gilbert says:

    As a footnote, that 50hp is a marinised Toyota 2c diesel and even at 20knts is just ticking over. She is a very capable seaboat looking dainty but when on board she handles the roughest weather far better than most. In spite of being described as a classic she is a new build using time tested notions for efficiency and works as an integrated overall design concept, to change any one thing would invoke the reaction worthy of Hereshoff.

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    Brad Babcock says:

    Pretty lines and she really scoots. The prop looks a bit vulnerable, but if the boat is mostly used in well-known and clear areas that should not be an issue.

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    Charles Jahn says:

    Wow! It’s like a miniature and modern 1880s NGH torpedo boat.


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