Mini J Class

Discussion in 'Sailboats' started by Tim Judge, May 28, 2010.

  1. rcnesneg
    Joined: Sep 2013
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    rcnesneg Senior Member

    I don't see anything wrong with it. The Presto 30 (13 inch draft, 4000 lbs, unstayed wishbone ketch) has a kick-up rudder, among many other similar boats. The biggest problem for you will be putting the kick-up rudder underneath the boat, with that long overhang over the back. The other problem with kick-up rudders is the steering is insanely heavy when they are raised.
    [​IMG]
     
  2. ahg
    Joined: Jul 2015
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    ahg Junior Member

    I have found this picture which seems to be the retractable rudder plate solution from the scandinavian cruiser 20. It seems quite clever, although probably not that easy to make the rotating parts fit in a wooden boat

    My preference goes clearly towards a shoal hull with a fin keel and a ballast, like the F class Firefly Rcnesneg was showing, and a quite large beam for the overall length of the boat (6 feet bam for 20 feet LOA)
    However, after reading a few things, I have the impression that those two elements are source of bad windward capabilities, which could be an issue, as I will be sailing in an area where I have a narrow access with strong tides, and under some circumstances it is difficult to go out or in the bay if you can not sail towards the wind.
    Any thoughts on this how to get windward capability while keeping these two design options?
     

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  3. CT249
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    CT249 Senior Member

    Fin keel and ballast are excellent for upwind capability; how good wide beam is depends on what you call "wide".
     
  4. CT249
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    CT249 Senior Member

    The Flying 15, which is 20' overall, initially 15' on the waterline* and 5' in beam, has a hull weight of 136kg. They can be built in wood at that weight.

    I take it you know the Flying 15, since it's so popular around England. With only 2'6" draft it can sail in very shallow water, and you don't even need a car to pull it out of the water if you have a shallow launching ramp.

    With its classic looks and lots of second-hand boats (or second hand gear if you want to build your own wooden hull) it could be worth a look. The Loch Long class is another possibility for a little shoal-draft classic, but I assume you also know of it.

    * the current boats are "optimised" around the rule so they are really about 16'6" on the waterline

    [​IMG]

    [​IMG]

    Loch Long;

    [​IMG]
     
  5. Tim Judge
    Joined: May 2010
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    Location: Hudson River

    Tim Judge Tim J

    Kay Fore is back sailing

    After three long years out of water Kay Fore's restoration is now complete. The deck and structural deck of this Endeavour J (mini J) have been replaced and strengthened. All of the foam in the fore and aft chambers has been replaced. Many new fittings, re-gel coated the cockpits, new steering and helm.

    My thanks to Matt Tulleson of Tulleson Boat Works who taught me many things about boat building as he helped with the restoration and the teak deck. Hiring Matt was the best thing I did and I could not have done this without him. The folks at Annapolis Performance Sailing, Samalot Marine in Haverstraw, NY, Doyle Sails on City Island all gave me practical advice. Harry Judge (my brother) and Peter Relyea, cabinet makers extraordinaire, milled the helm, toe rails and trim. I learned to varnish. A big thanks to Peter Wormwood at Teakdecking Systems of Sarasota, FL who worked on Endeavours decks and did the one on Kay Fore too. All of you have my thanks.
     

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  6. rcnesneg
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    rcnesneg Senior Member

    Absolutely beautiful! Can we get some video footage?
     
  7. ahg
    Joined: Jul 2015
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    ahg Junior Member

    Very nice boat. Good to see that the projects come to an end!


    My ideas of what I am looking for progress. The deck and rig of the Watch Hill 15 with the beam, LOA and LWL of the Safe Harbour 12 (6', 20', 12'), with a fin keel and bulb, retractable.


    Now, reading on construction techniques, I see that all have their supporters. I hesitate between carvel and strip planking.


    I thought I would have time to decide this, but it seems that the design is affected by this decision, and it seems that the former is considerable heavier, so here are my questions:

    Can I do the basic design (fixing dimensions and fairing all lines) regardless of the construction choice?
    Can I fix a displacement, and then play with the ballast weight to adjust the difference in weight of the hull, depending on what construction method I have chosen? (I was targeting about 1000Kg, which seems to give me a draft of around 1 foot)
    What is your personal recommendation between carvel and strip planking for this boat design, round bilge and retractable fin keel, knowing as well that it will spend (at least until I retire) 11 months a year out of the water?

    Thanks in advance
     

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  8. WhiteDwarf
    Joined: Jun 2011
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    WhiteDwarf White Dwarf

    Another design to consider - The Sandhopper

    This is the shoal draft version of the National (UK) Squib.

    http://sandhopper.org.uk
     
  9. The Q
    Joined: Feb 2014
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    Location: Norfolk, UK

    The Q Senior Member

    And also from the UK the Yeoman and Kinsman classes
    The Kinsman being the lift keel Version,
    There is quite a lot of information on this site.

    http://www.yeomankinsman.org.uk/

    I'm helming the boat (210) on the right of the picture as you look at it.!
    Our nationals a couple of years ago were in winds hitting 40 knots!

    They are about 20ft long with an all up weight of 1480 to 1545 pounds. 700Kg -6 Metre
    The kinsman lift keel which is locked down for sailing, lifts at an angle so that when up the majority is forward of the mast, and when down the majority is aft of the mast. there is a stub ballast bulb which sits outside the hull, http://www.ykboats.co.uk/300skeelk.htm
    The framing for the keel box forming part of the supports for the cuddy stepped mast.
    The original hull was a strip wood construction from which the moulds were taken for all boats.
     
  10. rcnesneg
    Joined: Sep 2013
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    rcnesneg Senior Member

    Started working on some plans. What do you guys think?


    LOA: 20'
    Empty boat weight(no ballast) 300 lbs
    Ballast: 300 lbs (max RM @ 90 degrees is around 600 ft-lbs)
    Beam: 3.49 ft
    Mast height: 25 ft
    Sail area(main and jib) 150 sq. ft.
    SA/D(nominal weight): 27.95
    Bruce number: 1.34
    Ballast ratio: 0.39

    Empty (boat only, no people on board, 600 lbs total)
    LWL empty: 10.5 ft
    Draft empty: 2.38 ft

    Nominal weight(Empty boat plus 175 lbs(skipper only),775 lbs total)
    LWL: 11.4 ft
    Draft: 2.51 ft
    Freeboard: 9.6 inches
    Drag at 2 kts: 2.149 lbs
    Drag at 3 kts: 4.539 lbs
    Drag at 4.5 kts: 17.211 lbs
    Wetted surface: 45.9 sq. ft

    Fully loaded(empty boat plus 525 lbs(skipper plus two crew), 1125 lbs total)
    LWL loaded: 13.7 ft
    Draft loaded: 2.73 ft
    Freeboard: 6.9 inches
    Drag at 2 kts: 2.459 lbs
    Drag at 3 kts: 5.162 lbs
    Drag at 4.5 kts: 16.910 lbs Interestingly, this value is lower with more weight.
    Wetted surface: 55.07 sq. ft

    What do you guys think? I'm mostly worried about the lack of freeboard, and steering control with a keel hung rudder. I think I will have just a large foot-well(minimal cockpit), so water over the side is not a big deal.
     
  11. WhiteDwarf
    Joined: Jun 2011
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    WhiteDwarf White Dwarf

    You're right about the freeboard, in my opinion, it is far to low. A keelboat of this length should be capable of going into coastal waters and caring for her crew. Not exposing them to hypothermia.

    With so little freeboard you will have the lee deck under much of the time to windward and the bow buried in every wave off the wind. Both will increase drag. The foredeck will be unworkable - I was a foredeck hand in keelboats!

    The Dragon has more freeboard than, say a Yingling, but is a very wet way to travel because the freeboard is proportionately less.

    It is great that you are exploring these ideas. May I respectfully suggest that you look at the similarly sized day boats racing at Cowes and try to shape your ideas a little with them. Classes like the X-Boat have endured because of their excellence.
     
    Last edited: Aug 7, 2015
  12. Jammer Six

    Jammer Six Previous Member

    The X-boat is not beautiful.

    The Dragon is beautiful. The boat rcnesneg is drawing certainly looks like it will be beautiful.

    That matters, in spite of everything that says it shouldn't.
     
  13. WhiteDwarf
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    Location: Sydney

    WhiteDwarf White Dwarf

  14. Jammer Six

    Jammer Six Previous Member

    Nope, I'll give you that they're prettier than I first thought, and that they're very close to beautiful in wood.

    I'm a Dragon guy, I guess. :)

    But yes, they look much nicer than the first photos I found of them.

    Are they as versatile (meaning range of adjustment, for want of a better term) as a Dragon?
     

  15. WhiteDwarf
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    WhiteDwarf White Dwarf

    Jammer, Thank you for that.

    I raced the X's clinker built sisters - The Victory Class as well as Dragons and Yinglings. Alfred Westmacott's designs, the Xs and Victories, are superb in the short chop which the Solent's 6 kt tides can kick-up. Their success can be measured in the fact that these relatively local classes are continuing to be built, after more than 100 years. (The original Victories were bought in 1934 from Bembridge SC for which they were built in about 1908 by Woodnuts, for whom Westmacott was designer.)

    To be successful, every design has to suit the environment in which it is operated, beauty follows from functionality in that environment. They used to race Dragons at Cowes (I don't know if they still do) but in those waters, or Sydney Harbour where I raced them, the spoon bow makes them a desperately wet way to travel.

    An elegant sheer, balanced profile and long ends do look beautiful - I love McGruer's designs, but each must be used in the right situation. McGruer built Dragons, but also Loch Longs etc, again, shorter ends for tough conditions on the Clyde...
     
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