New Rig for Old Cruising cat...

Discussion in 'Multihulls' started by DirkP, Feb 16, 2010.

  1. DirkP
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    DirkP Junior Member

    We all know the old British cruising cats, some of them have made several circumnavigations, some amongst them rounded cape horn ( Oeanic 30), some followed Drake's route (Ocean Winds 33), ...

    Most of these have a rig that is way undersized, Pat Patterson wrote that his Ocean Winds 33 design could easily use a 3ft higher mast. (maybe more?) An Oceanic 30 owner told me he sails his boat singlehanded with full sails in F6 without even thinking of reefing...

    We all know these boats are slow to todays standards and windward performance is far from good...

    How would they benefit from a review of their sailplans? Would a good redesign allow to make them sail better? Improve light wind capability, improve windward sailing, etc... Obviously one would not be able to keep full sails up in F6 but if that's the price to pay to gain windward efficiency it might be worthwile...

    Obviously the underwatership is what it is and the boats will suffer leeway...

    Your thoughts ?
     
  2. djeeke
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    djeeke Junior Member

    Augmenting sailplan will improve speed and windward capability to some degree (I'm no rig expert so if others care to comment more, please do...) at the expense of the requirement to reef earlier as before, as you stated...

    Probably a bit off topic but if the aim is to improve windward sailing, don't forget that what you say here :
    is only valid to some point...
    Some owners do go through the expense of modifying their boats hulls to improve the sailing characteristics, see Practical Boat Owner #427 July 2002 on the modification of an Ocean winds 33, the bows are modified to extend the boat by one foot overall and the waterline by three !

    This extended waterline also certainly improves windward performance...
     
  3. Petros
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    Petros Senior Member

    A better sail plan will always improve performance. You can also redesign the sails and rigging to make handling easier as well.

    You can also improve the hull performance without having to rebuild the hull, but perhaps by adding high aspect ratio foil shaped dagger board(s). That with a new rudder, and the modern sail and rigging, it will behave like a new boat.
     
  4. djeeke
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    djeeke Junior Member

    Petros,

    Interesting point, you are correct, daggerboards will also improve a lot...

    Adding daggerboards requires some hull work too, this would need to be reinforced around the daggerboard box (in case of grounding the daggerboard)...
    Additionally, one would also even need to modify the interior to house the daggerboard boxes.

    How would one define where to install the daggerboards ?

    Alternatively, but I don't know if this has ever been done, some kind of 'swing down' board inside a slim box mounted on the inside of the hull, just above waterline could also do the trick...
    Invisible, easier to install. Obviously this may never lock in the down position, negative is that this probably could not really be trimmed and that there is no visual to confirm if it is in up or down position...
     
  5. DarthCluin
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    DarthCluin Senior Member

    Why put your board in a box? Richard Fisher uses external daggerboards on the inboard outer sides of his Cat25 hulls. If you prefer to swing, why not leeboards like a Bolger Black Skimmer?
     

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  6. djeeke
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    djeeke Junior Member

    First option, daggerboards mounted outside of the hulls so there would not be intrusion in the interior, might be a good idea but on the type of boats DirkP is talking about, these daggerboards would end up in the saloon area of the boat, not really ideal I would suspect...

    Swing boards on outer hulls might be a good solution although not very aesthetic. And as we're talking of 'classic' catamarans I think this should be taken into account... Since they're not in a museum but still in use I can understand why one would want to improve the sailing abilities and if it can be done discretely I can only approve...

    I mentioned mounting a kind of dagger board inside a slim box to house all the mechanics of the system, it would not need to house the whole board... But there is need for a very solid pivoting point and some control to stop the pivoting when the board is in position. A 'locked' in up position possibility and some mechanics to safe-guard system and boat upon grounding... (even using sacrificial parts)
     
    Last edited: Feb 16, 2010
  7. DarthCluin
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    DarthCluin Senior Member

    Sorry, I should have Googled the boats. When DirkP said old British cruising cats and mentioned circumnavigations I immediately thought of poly cats. With Polynesian style catamarans you can increase the beam of the boat, allowing it to carry more sail. For example, Wharram Designs offers upgrade packages for their Classic series designs.
    The beam on a bridge deck style catamaran is fixed, and can only be changed with major surgery. Are these early bridge deck catamarans wide enough to stand up to additional sail?
     
  8. DirkP
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    DirkP Junior Member

    I mentioned these two boats as I do have some info on them...

    Pat Patterson is the designer of the Ocean winds, He said the ocean winds would take it... I even think some of the boats did recieve (or upgraded) to the 3ft taller mast but I can't get any feedback on to the actual improvements.
    The Oceanic30, if someone sails singlehanded with full sails in F6 without even thinking of reefing, I would say the boat can take it, some of the later models were actually wider but kept the original conservative sailplan...

    As or the others, I can't say, any Catalac (or other brands/models) fans that care to comment?

    Prout did not seem to be doing too bad, they used their own concept of mast far-aft and huge foresails, (but I read somewhere some did use a taller mast).
    Mc Alpine Downie had his sailplan issues on the other end of the spectrum and used centerboards, some of his boats flipped over.

    Although not the original question, I do like the concealed board idea : half-a-daggerboard, on a swing arm, no intrusion in hull or bridgedeck. This could give some non-board cat owners another way of improving their sailing...
     
  9. DirkP
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    DirkP Junior Member

    Rig modifications

    Another possible rig update would be to move the Genoa's attachment point forward onto a bowsprit ...

    I appreciate this only increases the size of the foretriangle, but what are the effects (and side-effects) when one does this ?

    Combining this with a taller mast will give a lot of extra sail and power to the boat...

    My question remains, would performing these rig upgrades have an effect on the windward abilities ?
     
  10. oldsailor7
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    oldsailor7 Senior Member

    They certainly would. :eek:
    The rig has to be balanced otherwise you are relying on the rudder(s) to correct the turning moment of the sail area. (Lee or Windward helm). Both bad, although a small amount of windward helm is benificial.

    Lock Crowthers Kraken 40 (Ringo), had a pivotting centreboard which had the planform of a segment of a circle. This enabled moving the board up or down to increase or decrease the area without altering the centre of pressure.
    A vertical sliding daggerboard does the same thing. Fine with the standard rig.

    But if you add a big foresail on a prodder to an existing balanced rig you are going to experience Lee Helm. Offsetting this by rudder is going to increase drag and if your steering is by tiller, it is just plain uncomfortable.

    This can be cured by tilting a pivotting centreboard back some to regain balance.

    I had a Buccaneer 24 Tri and I fitted it with a daggerboard which had an area of 2% of the projected sail area. It had the standard set of sails as designed, and was the best windward sailing boat of any I have owned.

    I subsequently had a Buccaneer 28 and this Tri had a pivotting centreboard which was controlled by two lines leading to the cockpit over the cabin roof.
    This board could be adjusted to any point of sail so that the helm was always balanced. It was even capable of tilting Forward beyond the balance point, which enabled the boat to be hove to under full sail, a very conveniant trait when just a few meters behind the start line in a race. :D

    My very first Tri, a Piver Frolic had a fixed fin on the inside of the skin on the outer side of each float. Worked well for that small boat.

    I tried the same thing on my Piver Nugget. Two surface piercing boards which pivotted from slim boxes at the hinge points of the wing deck. They were a pain and didn't work very well as they entrained air badly under load.
    I subsequently scrapped them and fitted a Norm Cross type low aspect ratio fin keel. Armoured with a half round section metal strip along it's length, it transformed this fine little early generation Tri to a real joy to sail.

    So you can see. For your particular multihull you have a lot of choices.

    For MOHO on a big cruising Cat the Low Aspect Ratio Fin Keel is the best way to go, (with the extra advantage that the boat can be safely beached on the keels.)

    For racing the choice is yours. Go for it. :D
     

  11. bill broome
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    bill broome Senior Member

    os7 is right about lar keels. they perform will enough for a cruising boat. better, they are very comforting when you are probing for new rocks and reefs on an unfamiliar shore. plus, you can dry out and clean/paint the bottom.

    if you just want to sail faster, a case grafted to the bottom of the deckhouse deep enough to stay below the waterline may be best. add a cavitation plate at bottom, with a garden variety pivoting centerboard within.

    it might be worthwhile to use 2 lines to control its position, with a shock cord in the 'hold-down' line. but maybe a weighted board is good enough, these boats are never going to go very fast.
     
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