Boson's Mate 23 by Bowdidge Marine Designs

Discussion in 'Boat Design' started by Green65, Nov 1, 2021.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    That boat would need at least 25hp I would think to get any sort of speed out of it. Possibly more. I am a little puzzled by the drawings, the sections appear straight forward, which doesn't fit with ply construction.
     
  2. Green65
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    Green65 Junior Member

    I am guessing that it is lightly built and not intended to go too fast as it calls for only 10 - 15 hp. My question is: would 15 or even 20 hp be enough to push it to 15 kts or semi-planing speeds, being over 700 lbs empty.? It recommends up to 30...that is why I would like some real word performance numbers, to see what power is required to actually get this hull moving at a good trot. I'm not looking for a speed boat anyway.

    Could you elaborate on "section appear straight forward"? Not sure what that means. Minimal twist perhaps?
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    You might as well power it toward the higher end, that way you will have a margin for extra loads and adverse conditions. If you look at the Atkins Ninigret design which would be similar in power requirements, there are some speed details quoted. What I was referring to was the straight sections throughout in the bottom, shown on the drawing, that would not be obtainable with ply, that I can see, there certainly is twist in the bottom.
     
  4. Green65
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    Green65 Junior Member

    OK, shoot for around 30 hp. It will probably be more efficient that way when throttled back to a slower cruising speed as opposed to a smaller engine running near full speed.

    Contacted Duckworks and they contacted 2 previous purchasers to see i they would be willing to sell their plans, but nothing back yet. The emails were 10 years old anyway, so maybe not good anymore. Emailed the original designers again and have heard nothing back.

    Anyone know if it is acceptable to create plans for a similar hull using the existing, online public information? Have any idea what that would cost to have that done?

    Sure, there are similar designs around, but this one has hooked on to me and I just can't shake it.
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

  6. Green65
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    Green65 Junior Member

    In order to have access to their forum, it seems one must first be invited in order to register...and they do not answer emails and the contact page does not work for me. So, that is a good idea, but so far, no go.

    How much is a lot of money? There are many pictures online and a complete (but small) line drawing of bulkheads and frames...as long as doing so is acceptable.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    Just looking at that build blog of "Ron's" boat, you can see curvature in the forward bottom sections, the drawings don't show it. I can see you have fallen in love with this boat, but what is the duty you intend the boat to do ?
     
  8. bajansailor
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    bajansailor Marine Surveyor

    I don't see why you should not be able to do something like this - especially as most boat designs are based on an existing (type of) boat which is then tweaked and modified a bit. You would effectively be creating your own design, using the Bosun's Mate 23 as a reference.
    You would need a lines plan - @TANSL could be your man for this, he is very good at CAD systems.
    And it should be possible to build up a construction plan even based on the limited amount of info shown on the Duckworks page.

    The Bosun's Mate reminds me a bit of Bolger's Diablo Grande, although the Diablo is 'only' 18' vs 23.
    Diablo Grande – 18′-0″ x 6′-3″ – H.H. Payson & Company https://www.instantboats.com/product/diablo-grande-18-0-x-6-3/

    Here is an old thread on here discussing the Diablo Grande and a couple of oher boats -
    Bolger diablo vs. Tolman skiff vs. Panga https://www.boatdesign.net/threads/bolger-diablo-vs-tolman-skiff-vs-panga.45716/

    Re other plans, one of Geoff Spira's vee bottom dories might be suitable? They appear to be similar in some ways to the Bosun's Mate.
    Here is a link to the 24' Chesapeake -
    Spira International Inc - Chesapeke V-Bottom Carolina Dory https://spirainternational.com/hp_ches.php

    And have you had a look through Sam Devlin's design catalogue?
    Devlin Design Catalog | Devlin Designing Boat Builders https://devlinboat.com/about-devlin-design-tech/devlin-design-catalog/
    The Candlefish 18, Curlew 20 and the Pelicano 23 appear to be similar in some ways to what you have in mind.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    There's a degree of rocker to that hull that suggests to me that 15 knots would be beyond its best, maybe 10-12 knots it would be happier
     
  10. Green65
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    Green65 Junior Member

    Found this on another forum. It is from Mark Bowdridge, the designer of Bosun's Mate 23. :


    G’day Sailing dreams,
    Great to hear your considering the Bosun’s Mate 23.
    Regards to previous comments, there are around 15 BM23’s under construction around the world, but as of yet I’ve only seen photo’s of one under construction. There is another about to commence construction down in South Australia which will be participating in a voyage as part of a Murray River 1000 mile expedition flotilla next year. The owner is already expecting the Bosun’s Mate will end up becoming the “mother ship” with its ability to carry stores/ spare parts etc for all the other boats.

    In regards to you wants and needs, I noted that you mentioned that the boat had a dock to dock journey of around 7 miles. As you also stated: “Although protected, the tides are big and run fast, which causes nasty wind over tide waves, steep and powerful maybe a couple of feet in height and frequent. The biggest hazard is motorboat wash, it's not uncommon for a 50 foot plus motorboat to come tearing past at 40 knots, often far too close.”

    Having been in situations like this in the past from when we lived aboard our yacht, in reality, you really need a boat that is comfortable to drive, good freeboard and the ability to take sea’s as you describe. Seven miles doesn’t sound far, but doing 5-6 kts and it means your sitting for over an hour and if the boat has low freeboard, it means also that you’re going to be shipping water from time to time. Add for sloppy conditions and stability/ freeboard and comfort now becomes paramount.

    This is the type of conditions that the Bosun’s mate 23 was designed for, passage making between islands, in sloppy/ choppy and tidal conditions in a comfortable and safely manner.

    In regards to powering the Bosun’s mate 23, a 20HP Yamaha (6000 rpm) with its 2.08 gearbox ratio and swinging a 9.25” x 11” prop (standard) will provide an approx max speed of 17 kts (31 kph or 19.5 mph ) and an approx cruising speed of 10 kts (18.5 kph or 11.5 mph) at 3500 RPM (pending sea conditions of course) This power configuration is an almost perfect match in regards to the transferance of Hp to the prop for this design and speed

    Overall the decision is yours as in reality; you’re the only one who knows what type of conditions and weather you’re going to be operating in. Also, you’re the only one who knows what loads you intend to carry, whether it is people, stores or both. Another consideration you may want to think about in regards to the carrying of passengers, is the European RCD compliance. In this regard, all our designs comply with this standard.

    As I said, I hope this helps in regards to whatever design you finally chose.
    All the best

    Best regards
    Mark Bowdidge (MRINA )
    Bowdidge Marine Designs
    www.bowdidgemarinedesigns.com
    Last edited by Mark Bowdidge; 12-07-2012 at 07:48 PM.
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    For starters, talking about top speed is more academic than practical, you don't sensibly run outboards at full throttle for reasons of fuel economy and engine longevity. My concern is the boat would be porpoising at any sort of lively speed in chop, with that rocker. If you are happy with a cruising speed of 8-12 knots it is probably going to do OK, in ruffled water. Probably explains why the required hp figure is quite low
     
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  12. Green65
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    Green65 Junior Member

    I would use this boat around Michigan, on rivers, on the Great lakes and maybe even over to the Mississippi river. The Great Lakes can brew up some pretty big waves, and while I would not intentionally be out in bad weather.....this boat should be able to handle some weather. It would be a marine camper / fishing boat. I am retired now and this is something I would love to do.

    I also like that it is a semi-planing design and can move at a pretty good clip (mid teens mph) using minimal fuel. For some reason that is important to me. Displacement designs are way too slow and I do not need to go faster at planing speeds, especially if slogging through waves for most of the day.

    I like that it is an open drawing board able to carry lots of extra weight. I have an aviation background, so keeping the weight down comes naturally to me, but still weight adds up over time. The plan would be to divide the boat in half, forward and aft. Aft would be an open cockpit, Bimini, fishing / lounge area. Forward would be essentially a pop up camper. When stowed, there would be a slightly curved deck at sheer height. The deck will become the tent roof when the pop-up tent is raised, providing a stowable cabin that is very light weight (with fabric walls), and when you are done sleeping in the morning, simply lower the pop-up to deck height, walk on the roof like on a bass boat and go about your day without a cabin in the way.
     
    Last edited: Nov 12, 2021
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    Uncanny the way you have been stymied with this, the seller of plans not wanting to sell their plans (unusual !), you can't get in touch with others who have used the plans, private forums and what-not, it is almost as if it isn't meant to be. I notice there is no provision for spray damping, which could be a problem, being an open boat in a cooler climate, and I don't see any provision for a skeg to keep it running straight. I think I saw a thread on the Wooden Boat forum about this boat, and someone listed some alternative designs they thought might suit.
     
  14. Green65
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    Green65 Junior Member

    I believe that is probably correct. I would be happy with this.
     

  15. Green65
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    Green65 Junior Member



    Thanks for all of that. I will try contacting @TANSL and see what he thinks. It would be great to find someone that can re-invent this design!

    As far as these other designs, I prefer a semi-planing / displacement boat for their relative speed and efficiency, even in rough water. If I am correct, these designs on your list are planing hulls. I am hoping to get away with using a smaller engine and using / carrying less fuel / going further between fill ups. Going diesel if possible.
     
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