Looking for suggested reading and info on high L/B powerboats

Discussion in 'Boat Design' started by mjozefo, Mar 6, 2022.

  1. mjozefo
    Joined: Mar 2022
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    Location: West Lafayette, IN

    mjozefo New Member

    Hi All,

    Firstly, this has been a great forum to comb for info. So thank you for the resource!

    My question:

    I'm interested in fairly high L/B ratio powerboats that are fuel efficient and seaworthy. At this point I am in the dreaming stage of a lightweight, modestly powered, reasonably quick, semi-displacement vessel.

    Something in the neighborhood of 30-35ft LOA, 7'-7'10" beam with roughly 15 knots cruising speed.

    So far I have read:
    Understanding Boat Design by Ted Brewer
    Elements of Boat Strength by David Gerr
    The Nature of Boats by David Gerr
    Devlin's Boat Building by Sam Devlin
    How to Design a Boat by John Teale
    Tolman Alaskan Skiffs by Renn Tolman
    Naval Architecture of Planing Hulls - Lindsay Lord
    Propellor Handbook - David Gerr
    The "Building Aroha" series at Off Center Harbor

    Peter Sewell's Whio was the boat that got me interested (gorgeous, but I'd like a more utilitarian aesthetic). I've seen many of the Pettersonn designs, which are beautiful as well.

    Where else should I be looking?

    Thanks!
     
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Welcome to the Forum MJ.

    Re a maximum beam of 7'10", that is a L/B ratio of 4.47, which is pretty skinny really.

    Did you find this thread about Whio on this forum?
    How does Whio do it? https://www.boatdesign.net/threads/how-does-whio-do-it.65157/

    Tad Roberts has some fairly slender designs, but they are all much tubbier than 4.47 re L/B.
    https://www.tadroberts.ca/services/new-design/power/

    Here is a fairly narrow design by Paul Gartside - she is 24' x 6'6".
    If we lengthen her to 35', and then use the same L/B ratio (3.7), her beam will now be 9'5".
    https://store.gartsideboats.com/collections/power-boats/products/24-ft-launch-wayward-design-119

    Jusat for reference, here is what a 36' x 6'10" boat looks like - ok, this is a narrow boat designed for canals.
    You could increase the beam by a foot, but it will still be fairly skinny, and you will have to be very careful re your stability and centre of gravity location.
    Motor Boats over 30' https://www.selway-fisher.com/Mcover30.htm#HAW
     
  3. jehardiman
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    jehardiman Senior Member

    Try High Speed Small Craft by Peter Du Cane and Performance by Design: Hydrodynamics for High-speed Vessels by Donald L Blount.
     
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  4. mjozefo
    Joined: Mar 2022
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    Location: West Lafayette, IN

    mjozefo New Member

    Thanks for the welcome Bajan. I did see the thread on Whio here, and I think I have googled everything there is to search on her.

    The B/L ratio of ~4.2 was just scaled from Whio. (29.5/7), I'm not necessarily stuck on it. There is a minor consideration of making this boat fit in a hi-cube container for storage and possibly transport, but I'm not sure yet. I don't want to whittle down options until I am better educated and able to do so.

    It seems like the majority of the research into these vessels was done prior to the 1960's?

    Re: COG and stabiltiy... that's a big part of the research I'm trying to find. I want to make sure the shiny side stays up!
     
  5. jehardiman
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    jehardiman Senior Member

    Actually for semi-displacement in the L/B ratio you are looking at most major early work was done in the 1880's and 1890's. You are basically looking at high speed steam launches and spar torpedo boats. A good portion of the Taylor Standard Series fit L/B ratios you are looking at. With the development of lightweight ICEs during WWI a lot of work was done in the late 1910's and 1920's for Gold Cup racers of similar L/B ratios. Inter-war development (and rum running) began dividing high speed small craft into planning and non-planning types. During the WWII the DKM invested considerable development into seakindly high L/B ratio small craft. After WWII, DTMB began work on systematic hull forms for high speed craft resulting in the Series 62, 63, 64, and 67 released in the early 1960's.
    State of the art 1970 and a very good bibliography can be found here: Guide to power boat design. https://apps.dtic.mil/sti/pdfs/AD0743966.pdf
    While there has been significant work on other types of HSVs since the early 1970's, with the exception of some work out of Delft in the 1980's, not a lot of additional design work needs to be done. It will be a lot of expensive work for little real gain.
     
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  6. Velsia
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    Velsia Floater

    You could do worse than to look at some of Steve Daschew's boats. They are a bit longer than what you are looking for, but he is also keen on the low l/b ratio for sea keeping and speed.
     
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  7. mjozefo
    Joined: Mar 2022
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    Location: West Lafayette, IN

    mjozefo New Member

    Thanks a lot everyone. I have ordered the books JE has recommended, and started down the rabbit hole of Taylor Standard hull shapes. There is quite an expanding list of things to read with that bibliography.

    Velsia, I agree that the Dashew designs are quite similar to the design ethos that interests me. They look purposeful as well, which I like.
     
  8. jehardiman
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    jehardiman Senior Member

    The Taylor series is more for ships than boats, so I'd go straight to Series 63 or 64. It is interesting to note that the Dashew designs are very similar to the last USN fast battleship designs, just scaled down. The long hollow bows, CB and maximum section well aft, and tucked sterns all show why they are so wet.
     
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  9. HJS
    Joined: Nov 2008
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    HJS Member

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