Feedback on hull design please

Discussion in 'Boat Design' started by Andrewski, Feb 2, 2023.

  1. Andrewski
    Joined: Mar 2020
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    Location: Sydney

    Andrewski Junior Member

    I am thinking of purchasing this hull, to convert to a junk rig, or cat-ketch,
    I think I’d be happy with either, as a bilge keeler, does anyone have any criticisms of this hull design. I, thinking of going northern climates. Many thanks
     

    Attached Files:

  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Re how you are in Australia, will 'northern climates' be the tropics, or much further north in high latitudes?

    The hull looks like it has a nice shape with fairly well balanced waterlines.
    I do not think that she will beat to windward terribly well though unless you have the engine helping you.

    How much are they asking for this hull 'as is'?
    And how old is she?
    If she is 'old', like 20+ years, and the owners cannot produce any evidence of any previous surveys where ultrasound thickness testing was carried out, be very careful.
    Inspect the bilges carefully - you could perhaps take some photos and post them on here.
    Do you know what the hull shell plating thickness 'should' be in all the different areas?
     
    Last edited: Feb 2, 2023
  3. Andrewski
    Joined: Mar 2020
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    Location: Sydney

    Andrewski Junior Member

    Thanks bajan, I hope to be mostly trade winds, but I’ll attach an article on some seemingly proper testing of keep design.
    It’s build in 82 of Corten steel in Brisbane au. It has been on the hard for many years as top deck is rusty and will need patching.price $10k aud or 7.7usd
    Not bad. I’ll make masts and sails myself. Here is a good link for twin keel research. There seems to be assumptions and opinions abound
    Bray Yacht Design and Research Ltd. - The Advantages of Twin Keels http://www.brayyachtdesign.bc.ca/article_twinkeels.html?fbclid=IwAR1pw-ZwP1HZYNWHTLb2vIKv0BE8EklrvZRkRe7LjPeZs4I6sNFe7FWaeTE
     
  4. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Ok, so she is 40 years old, and some areas on deck will need to be cropped out and new plates welded in - you mention 'patching', but welding a patch on to a steel plate over a hole or thin area of plate is not good practice.
    Are you certain that she was built of Corten steel?
    If the deck is in this condition, what are the bilges like? Have any recent thickness tests been carried out?
    Do you have any interior photos?
    That is an interesting article by Bray Yacht Design. I agree with you re the merits of twin keels - we had a steel boat with bilge keels for a while in the 80's - one major advantage is no need for props when hauled out.
    One disadvantage is the often tight space when cleaning / painting the hull area between the keels.
     
  5. Andrewski
    Joined: Mar 2020
    Posts: 9
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    Location: Sydney

    Andrewski Junior Member

    Custom Steel Craft Bildge Keeler Add Value Cheap: Sailing Boats | Boats Online for Sale | Steel See Out Of Water No Lifting Costs For Survey? | New South Wales (NSW) - Port Macquarie https://www.boatsonline.com.au/boats-for-sale/used/sailing-boats/custom-steel-craft-bildge-keeler-add-value-cheap/279251

    here is link to all photos and survey. It says corten on survey. Ozzy built, we have good steel. A holverson Freya built here in late 70’s was corten. Merops, is her name. Same design won Sydney to Hobart 3 times. Deep keel design. im thinking shallow keel better for most places. Deep maybe better in ocean but that report seems to say twin keel is same as deep for tracking and stability. So plus plus. If I do twin masted junk rig, I’ll get under bridges and into shallows. As well as repair sails myself.
    I was looking at this one, but 100k aud is no longer an option. But amazing vessel , has 3 rudders, and build in ladder. Interns; steering etc, I worked hard for a year to buy but a client went bankrupt and I lost a lot. My risk.
    Halvorsen Freya https://www.halvorsenfreya.com/
     
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  6. Andrewski
    Joined: Mar 2020
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    Location: Sydney

    Andrewski Junior Member

    I meant to say cut and weld, not patch over.
     
  7. Rumars
    Joined: Mar 2013
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    Location: Germany

    Rumars Senior Member

    It's a double ender, pretty symmetrical, you can read all about the advantages and disadvantages of this hull form. Bilge keels are advantageous in high tidal areas but this boat has a pretty "normal" draft at 1.65m, she's not especially suited for shallow water work.

    Converting to junk or cat ketch is certainly possible but why? Repairing the sails yourself is a question of you learning to sew, the shape is irrelevant. The conversion will be expensive and involves a lot of work. Every penny you imagine saving by sewing the sails yourself from cheaper material (the perceived advantage of a junk) will be spent on hiring a NA to work out the sailplan and hull reinforcement. Then you need to rip out half of the interior to add the new mast support structure, the welding will distort hull fairness and you end up having to use a ton of filler.
    There are better ways to save money on the rig, the boat already comes with a mast and boom, you just have to add rigging and sails.

    Looking at the add pictures I can say for certain that the engine has problems. The good news is that you can still buy spares, the bad is that you need a specialized mechanic, and those are getting thin on the ground. The buyer can safely budget a minimum of 10 000$ for engine work, and without that she will not return to the water and you are stuck paying for storage.
    We don't know what type of insulation she has, that will determine how complicated welding on the hull will be. The keels look pretty thin, she probably also has some inside ballast, that can also get interesting.

    Realistically, presuming there are no major surprises, this boat needs a minimum of 50k over the asking price, and that's for the local diy owner.
     
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  8. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    If you want a versatile rig for balance, a cutter is a good type. It also does not require any major modification. In fact, if there is a spinnaker pole topping lift, it can be used as a jib halyard. Also, a short mast aft for a yawl setup will not require much in terms of structural reinforcement.
     
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