Offshore safety boat

Discussion in 'Boat Design' started by George T, Jan 28, 2020.

  1. George T
    Joined: Nov 2019
    Posts: 6
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    Location: Portsmouth

    George T Junior Member

    Hi,
    I am thinking of a design for a coastal centre console (not a RIB)along the lines of a Core Sound 21,
    It needs to be powerful enough to tow a boat that is SB20 or J70 sized and carry 4-6 people with enough seating and storage for 8-10 hours on the water. It will be operating in the solent and needs to cruise at 15-20 knots and max out at 25-30 knots It will need to handle waves and high winds as well as flat water and need to be as dry and as safe as possible in all conditions. Any ideas regarding shape, design, design parameters or current boats to have a look at would be greatly appreciated.
    Many thanks,
    George T
     
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    For reference, here are a couple of links re the Core Sound 21 .
    Core Sound 21 https://www.woodenboat.com/boat-plans-kits/core-sound-21-0

    Build a Boat - Core Sound 21 Boat Design - Salt Boatworks https://www.saltboatworks.com/product/core-sound-21-boat-jig-kit/

    George, are you specifically looking for a new boat 'off the shelf', or do you want to build your own boat - or would a second hand boat that fits your criteria above be suitable?

    Re a secondhand boat, try having a look on www.yachtworld.co.uk - I just did a search for small centre console boats in the UK and found a few that might (?) fit your requirement.
    Here is one -
    A White Shark 245 for GBP 40,000?
    2006 White Shark 245 Power New and Used Boats for Sale - https://www.yachtworld.co.uk/boats/2006/White-Shark-245-3232885/United-Kingdom

    Or a Jeanneau Cap Camarat for GBP 54,000?
    2020 Jeanneau Cap Camarat 7.5 CC SÉRIE 2 Power New and Used https://www.yachtworld.co.uk/boats/2020/jeanneau-cap-camarat-7-5-cc-s-rie-2-3600192/

    Although you note that it should be able to carry 4 - 6 people for up to 8 - 10 hours on the water.
    And in the Solent, where the weather can be quite unpleasant at times (I used to go sailing there many years ago).
    A centre console will usually give reasonable protection for the helmsman and one other behind the console, but anybody else will be rather exposed.
    A boat with a wheelhouse would offer better protection from the elements - maybe something like a Targa 23?
    23.1 | Targa https://www.targa.fi/boats/23-1

    Or a Jeanneau Merry Fisher?
    Merry Fisher 795 Marlin | Jeanneau Boats https://www.jeanneau.com/en/boats/powerboat/13-merry-fisher-marlin/95-merry-fisher-795-marlin/

    Or a Beneteau Barracuda? Like the Targas and the Merry Fishers, they come in different sizes.
    Motorboat Barracuda 7 - Powerboat Beneteau https://www.beneteau.com/en/barracuda/barracuda-7
     
  3. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    Look at the designs by B&B yachts, in particular the Ocracoke and Outer Banks series. ://bandbyachtdesigns.com/
     
  4. George T
    Joined: Nov 2019
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    Location: Portsmouth

    George T Junior Member

    Thanks bajansailor,
    I am looking for either secondhand (maybe) or own built as I have engines waiting and I can procure aluminium or plywood (like the core sound), I only need the driver and "co-driver" to be covered permanently, it also has to be fast and manoeuvrable with the ability to go around all sides thus eliminating a cuddy cabin or similar.
     
  5. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Boston Whaler Montauk or any of their boats above 21.
     
  6. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    Ss
    These are primary requirements which will set up a minimum beam amidships (assuming a center console type arrangement). Do you want the drive and co-drive to be side-by-side? If so either look at an anthropometric reference for the width of two people side by side, or find two people of the appropriate size and them standing/sitting side-by-side. Include clearance for the driver's elbows when steering. That gives the width for the occupants. Next is width besides the occupants. Do you need only sufficient room to move past the console area, or does a person need to stand alongside the console facing outboard. Consider both the space needed at the rail height and the space needed for feet. Also feet need to under the torso to stand or move comfortably. If a person needs to stand facing outboard then there needs to sufficient space for their feet to be turned with the toes facing outboard and the feet far enough outboard to be able to provide support when the boat rolls. Also the thickness of structure needs to be accounted for. Put everything together, possibly in a simple sketch/drawing and a minimum midships section is created.

    Are there other requirements on mid-ships beam such as maximum width for trailering, or maximum width of a berth/storage space? If so these need to checked against the midships section created above. If requirements or their implications conflict then trade-offs/compromises will be needed.

    A list of requirements/needs/desires can be very useful in assessing alternatives. Write down everything you can think of ranging from the absolute requirements to the nice-to-have but not necessary. It may be helpful to rank the items on the list as:
    1 - Absolute essential. Typically legal requirements and fixed infrastructure requirements. The boat will be unacceptable if these requirements are not met.
    2 - Essential but may be modified the minimum amount necessary for the boat to be feasible.
    3 - Very desirable but not as important as the items above.
    4 - Desirable but not critical to the success of the boat.
    5 - Nice to have but not if any of the items above would need to be compromised.
    Some types of requirements may have different values at different levels. For instance the level 2 requirement for top speed with 4 occupants may be 20 knots while a level 3 or 4 requirement for top speed may be 25 or 30 knots.

    Outboards? What power?
     
  7. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    I'm slow on the uptake, but what's this towing business all about ? I am not clear on what the duty of your intended boat is.
     
  8. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    I think he probably wants a boat to function as a support / rescue boat for sailing regattas involving boats like the SB20 (formerly the Laser SB 3) -
    SB20: the original easy, affordable 6.15m racing keelboat https://sportsboatworld.com/boats/sb20/

    and the J 80 (which seems to be a bit bigger than the SB 20) -
    J/80 https://jboats.com/j80

    And that the support boat will need enough power to tow these boats (maybe even a few simultaneously) in the event that they have to be rescued (?)
    I would have thought that pretty much any centre console speedboat over about about 22' would be suitable for doing this?
    Diesel is easier than petrol to get in marinas and waterfronts in England, so it might be a bonus to have an inboard diesel instead?
     
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  9. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Thinking that it will be a new design, to start talking and that others are giving concrete opinions about what you ask, I would say that the boat should have a high bow, freeboard greater than normal, very full stern and a relationship L / B close to 3.5. There is one clear thing, if the boat must have a lot of towing power, I could not have a maximum speed of 30 knots. Just for opinions to begin.
     
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  10. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    I guess you'd have to be on site to get a feel for what the typical duty is, obviously towing a string of sailing boats would be best accomplished with a displacement boat. The most comfortable ride in bad conditions would be either a deep vee or cat, but the former is tippy, when off plane for hours, not ideal. If he is committing to twin engines, I would think a power cat best.
     
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  11. Ad Hoc
    Joined: Oct 2008
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    Location: Japan

    Ad Hoc Naval Architect

    Then look no further than the tried and hugely successful Nelson Boats by Arthur Murssel, based in Seaview on the IoW.
     
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