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DIY Cockpit extensions?

Discussion in 'General Yachting Discussion' started by rcrapps, Dec 23, 2017.

  1. rcrapps

    rcrapps Senior Member

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    Anybody ever complete a Do It Yourself cockpit extension?
    I have looked over many 58' MY Berts like ours and always dreamed of a cockpit glued on.

    Been looking for years for an old Bert SF to salvage it's cockpit but never found one.
    Nobody ever had a kit.

    Not moving the keel or running gear further back, just a lower deck to get closer to the water.

    My oversized back porch is fine but not a real fishing & diving station.

    I'm still dreaming but that itch is getting more attention.
  2. Capt J

    Capt J Senior Member

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    I've never done one but yards do it all of the time. It will extend hull speed and possibly planning speed on a boat like yours as there's more flat running surface to create stern lift. I've run lots with extensions. But I really think you want a naval architect to design one and then just make a mold and do it, not slap another hull onto it. That will create more work as you'll have all kinds of things to fix on it like the rudder posts. Usually you also add a fuel tank or fuel and water tank to counteract the positive buoyancy......The 65' Hatteras I ran that became a 75' had a 650 gallon fuel tank added and a 300 gallon water tank that gravity fed to the original water tank. You need to keep weight back there, but trimming the boat has to be done also......valving fuel out of whatever tank you need to to keep the trim right.
  3. rcrapps

    rcrapps Senior Member

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    My faverate is a job that Cable finished years ago. The nicest extension of all and made a Bert 70 YF.
    The largest Bert was in Alabama years ago. Extra cabins and the cockpit to 80'.
    Original engines and no relocating of the running gear, ships performance always improved.

    Were also working on one of those Hatteras of Lauderdale conversions. A 65 MY converted to a 74 YF. Big gen-set and fuel tanks back there.

    A few years ago I was on a Burger with an extension. To reduce the added buoyancy, the added hull bottom tapered up to the new transom.
    This is where I got the salvaged SF cockpit idea from. To help reduce some of the added buoyancy issues, the new hull bottom would not be as deep as the original hull but the fairing, decks, hatches and cap would already be made.

    Yea, yards do it all the time. That Cable job was near $90K when delivered over 10 years ago.
    Huckins will probably top $100k.

    Money I do not have and looking at the market (Yellow Ribbon), The boat will never reflects it's new value.
  4. Capt J

    Capt J Senior Member

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    Call Cable and see if they have the mold and if you can buy the mold or rent it......THAT would be the easiest remedy would be to find a mold and just pop it out yourself. The extra fuel and water is very nice to have.
  5. 30West

    30West Member

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    How about a bigger swim platform, on a lift? Mine is 4' deep and a couple feet off the water, wife uses it to lay out, sets a couple chairs out there when the kids are swimming or just to sit. Kind of a nice extra place to hang out close to the water but dry, for a few people.

    It doesn't give extra waterline length or storage, but if it was hydraulic it sure would be versatile and extra space.
  6. rcrapps

    rcrapps Senior Member

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    I have already improved the swim platform into a back porch. added 2.5 feet. Now near 5 feet. It really helps.
    But, it's just not the same as a working cockpit.
  7. Ken Bracewell

    Ken Bracewell Senior Member

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    We had one done on a Hatt I ran a number of years ago, and I was there every day. It went something like this (in simple terms)...
    ~Haul the boat
    ~Build a mould, out of plywood, directly behind the boat
    ~Applied formica inside the mould (this makes releasing the mould easier)
    ~Mould Release
    ~Gel Coat
    ~Fiberglass mat
    ~Core Material
    ~Fiberglass mat
    ~Stringers
    ~Tabbed it to the hull.
    ~Built the deck inside the cockpit (we used an existing mould to get the camber)
    ~Enlarged the rudders to accomodate

    Check the lay-up schedule of your boat
    Make sure to grind back several feet for attachment adhesion and strength
  8. rcrapps

    rcrapps Senior Member

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    Hi Ken
    Thank you for your thoughts.
    That is the usual procedure. Nobody has a standard mold. It's all one-offs.

    Thru the years I had this planned out;
    I was thinking to ease up the finish surfaces to purchase pre-(cored?) finished panels.
    Punch thru the transom and attach the stringer extensions and inside chines inner gussets with pre-made glass angle or channel.
    Build supporting frames to act as baffles below decks and pre-made glass angle or box tube to stiffen the sides and cap/gunnel.

    We want the new deck low to walk out our aft master to the cockpit. This would leave a tapering 10" of new bilge. Not much for anything but fuel.
    New cockpit deck, as our aft state room deck, rite at water line. Using a nice water tight door.
    The old Bert has plenty of glass to skin in the outside skins for the side joints to the new panels and heavy attaching tabs on the inside from the old transom to the new hull sides should keep things glued on.

    Pre-made glass angle, box, channel and bars are cheap, straight and strong. Been using them for years under decks and gen-set stands.

    Rudders were enlarged a few years ago already.

    Just looking for any new input before I really start planning next fall.

    Plan #2 was salvage a Bertram cockpit from a fire or totaled sinking. That's not panning out.

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