Paani cat -OUT OF THE WEEDS

Discussion in 'Multihulls' started by paani cat, Apr 15, 2008.

  1. paani cat
    Joined: Apr 2008
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    paani cat paani cat

    Aloha to All

    So here is a good one for you. I aquired this cat a short while ago and thanks to some good reccommendations from F Russel found this site. This cat from what i am told is an 80's rudy choy csk 33 that has been substantially modified in the bow and stearn. the cat is now 35 loa with a beam of 19'2". When i got the cat i literally had to cut it out of the weeds. After clearing things out she seems to be a pretty kool Cat with some nice lines and all things considered the hulls are in great shape. No water damage, termites or dry rot. You can see that someone has taken care on laying the hulls up and the interiors actually look great. I have the mast, rudders, dagger boards cross beams etc and plannjng on getting her back in the water where she belongs. I have some questions that i am hoping that i can get some direction on.

    The hulls have pretty fine lines in the stearn and i am told that she hobby horses a bit, tacks fairly well and takes the seas in suprising order. one of the first reccommendations was to replace the mast because it is too big of a section (12"x5" approx) and weighs 5 lbs per ft Sparcraft. Idea being to reduce the weight aloft. I am looking at a section of approx 3.5 lbs a foot. (note the original mast was a shape 9"x4.5" approx) both being rotating 48 ft long and a boom lenght of 12'6". the cat weight 3500 + lbs

    1) is that enough of a change to make a difference? and worth the effort.

    The cat originally had a center pod that weighs approx 300 lbs with the engine box located forward and behind the mast step, but is damaged beyond repair so i am thinking on placing tramps over the entire boat similar to a huge hobie. to do this i would have to move the engine aft of the rear beam. Keeping in mind the fine stern is this a bad direction. My other thought was to fabricate an under slung pod with the engine mounted aft of the rear beam and but attaced to the fore and aft laterial supports to keep the wieght forward of the rear beam. note the under slunge pod and motor would be approximatly the same wieght as the original pod, less the weight of the motor.

    2) will the weight distribution be that critical on a cat of this size?

    It appears to me that the rig was designed as a high aspect rig, tall with a short beam.

    3) Should i consider increaseing the boom lenght with big roachy main and a fractional non over lapping headsail?

    note i was told the hulls are approx 1100 lbs each and when sailing the hulls will go lite but not too much on the flying side of things?

    any reccommemdations to get me started would be greatly appreciated, short of being nuts for taking on the project.

    jb

    :p
     

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  2. Gary Baigent
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    Gary Baigent Senior Member

    The CSK looks a very sweet design, what a find! Keep the high aspect sail rig and boom, get rid of that heavy spar but consider building a wing mast out of tensioned ply or strip planked paulonia or cedar or balsa planks or foam sandwich with glass/carbon laminations. You could actually increase the chord to a couple of feet - and that will give you a longer overall boom/mast length. And at 48 ft. height, that mast could be built light enough so that you could pick it up in the middle - a bit of a grunt but possible. I know because I have built a 51 foot version. With a decent chord and thickness you can get rid of spreaders and rely on the wing mast thickness and chord configuration to give you stiffness. You'll need a three quarter stayed rig with lowers as well, plus runners though.
    It is a good idea to dump the central pod - I would go even further and get rid of the motor as well. A 5 or 8 hp outboard will move your boat. You need to keep weight out of the ends of the platform. If you keep the boat light it will not hobby horse as CSK designs are prone to do.
     
  3. terhohalme
    Joined: Jun 2003
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    Location: Kotka, Finland

    terhohalme BEng Boat Technology

    At the first look, don't chance anything in parameters, just fix the catamaran. Happy working!
     
  4. garydierking
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    Location: New Zealand

    garydierking Senior Member

  5. garydierking
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    garydierking Senior Member

    He's alive as far as I know. His son Barry was involved in the business his whole life and has taken over.
    While I worked for him in the 80's, I don't remember seeing any designs like the one in the photo, but I could be wrong if it was done before my time.
     
  6. paani cat
    Joined: Apr 2008
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    paani cat paani cat

    This is what i have found out about this cat so far thE vin no starts with HAZ and ends in 83 assuming 1983, i was told it was a CSK polynesian concepts, sundowner I think? the bow has been extended and shapened to improve the enrty ( original bow blunt radius) the transom has been extended and new rudders added, and the only other bit of info that rings true is "the hobie horsing aspect" that would lead me to believe it is "a CSK or rudy choy design" not really sure about any of this at this point but still, a pretty kool looking CAT.

    PAANI CAT.
     
  7. paani cat
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    paani cat paani cat

    what about Vince Bartalonies involvement in CSK in th mid 80's? any conection there, i read something on the hobie site, hence an HAZ # ?

    paani cat.
     
  8. Gary Baigent
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    Gary Baigent Senior Member

    CSK paani cat

    The CSK paani boat has only two not very large diameter beams (plus the two fore and aft mid beam supports for the cuddy) and the overall beam of the boat is near 20 feet – two beams may not be enough to stop this platform twisting and flexing. In an attempt to halt this perhaps the beams should be set into epoxied glass and carbon sleaves with uni directionals run over sleeves onto bulkheads or ring frames. Forget about demounting the boat. You want the boat to run straight and true and not with the leeward bow buried flush with the water surface and the windward one bent up in the sky.
    Which came first - the original mast noodling? - which forced a replacement of a larger and heavier sectioned spar? – or the platform twisting and jerking in a seaway because of the inadequate beams letting the stays flop about – so a new spar replacement was mistakenly introduced to halt this. Also I cannot see any dolphin striker support under the mast base – how did that heavy section mast not snap the beam like a dry biscuit? Nor can I see a mainsheet track on the after beam for that matter. Are those beams a recent replacement? They have a better paint job. One point: with the hulls lengthened that after beam has to do a lot of work – I would suggest another one set near the transom. Or somewhat more radically: consider building two larger sectioned faired box beam types to do a better job, epoxied integrally with the hulls of course. Did the former owner get depressed and give up placing the boat amongst weeds? Anyway, whatever, that bamboo bomber (as Rudy Choy used to describe lightweight open wing deck cats) can be set up to behave properly and sail very, very fast.
     
  9. paani cat
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    paani cat paani cat

    one paragraph says it all.

    Aloha Gary

    Ah, the bambo bomber, you could not have discribed it better. the photo of the hulls sitting on the trailer is pretty is enlightening. for the size of the vessel looks to me to be a fair amount of hull above/under water which lends to the power.

    The vessel has the tail tail signs of what you are describing. the forward beam is toast and looks to be layed up with bamboo (maybe mahagony). I currently have all the structurals removed, the center beam was cracked near the mast step. ( someone has made efforts to stiffen the center and aft beams by splitting them and installing a stiffiner the lenght of the beam) the mast beam is cracked and questional for repairs. The aft beam is in great shape. In both cases the beams are heavy then h__LL.

    I was going to post a queay on suggestions for the forward beam, since it is a layed up section and i need to rebuild it myself.

    as far as the center and aft beams are you taking bracing vertical or horizontal for support? if you look at the condition of the boat it looks like it was trying to pull its self apart?

    as far as parts, i have the traveller, dolphin striker, rudders, dagger boards and what appears to be some rod rigging cross bracing. misc sheves, blocks and some rigging. The chainpaltes (i have one of them) have been move the the outtermost hull lines aft of the cockpit (visable in the pics) and the runningbacks have been removed. I like runnig backs, they look pretty kool and dress a boat ready for a race.

    I really do not what to speak for the owner of the vessel and the conditions of purchase other than i bought a real project. Looking forward to the process and knowledge gained for this type of re-build.

    I wish i could get my hands of some of the missing pieces, but think i have enough of the original parts to have a go at it.

    first order is mods, to the strucaurals, cosmetic to the hulls so i can get it back togeather and splash the boat and rigging to follow. Since the center pod will be left out, mount the motor amid ships will be interesting. I was told that great effort should be made to keep the weight forward off the rear beam.

    The forward beam was such a noddle that it could not have provided any support other than keep the head stay in place. (any advice on fabricating a new one would be greatly apprecaited).

    paani cat

    aloha from hawaii
     
  10. Gary Baigent
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    Gary Baigent Senior Member

    CSK bamboo bomber

    hey paahi cat
    Absolutely right, keep the weight out of the ends BUT you are going to have to stiffen that platform and contrary to what many people think, the after beam stiffness is very important as it provides the bracing complement to the main beam - the further apart the better. The forward beam you could chuck - and set up one into two forestay system like a Tornado. And you don't need a trampoline there if you have furling head and reaching sails. But what you do need is a modern, faired and deep box beam for the main beam (plus a dolphin striker) and a slightly lesser one for the after one. Build them out of strip planked whatever with glass and carbon in high load areas. Best would be all carbon - but who can afford that? The lower tech materials will still produce a strong, stiff and light beam - certainly lighter than the old fashioned and heavy alloy ones.
    You are going to get a lot of timorous and conservative advice from many armchair experts - who like to name drop designers (which of course reveals their own expertise) - but you and your friends can do the work yourselves - after all lightweight catamaran construction is known by many after all these years; the knowledge has been refined and the work quite basic and straightforward - but the armchair brigade will not mention the latter of course - it is supposed to be a dark art known only to the initiated. Having said that it would be advisable to have a practical sailing/boatbuilding friend who knows his stuff help you on your way. Go for it mate.
     
  11. Gary Baigent
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    Gary Baigent Senior Member

    CSK paani cat

    hey Chris
    Relaxez vous mate, I was commenting generally - absolutely no intention of targeting you, calm the paranoia.
    regards Gary
     
  12. paani cat
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    paani cat paani cat

    Good Furtune, I like that!

    Hey Guys its all Good

    If the end result is that that i come out with a better built cat then it will all be worth it. And believe it or not this is where most of the changes will take place. I can not really afford to get an NA involved for more than probably an overview our ideas.

    The center pod will not be replaced so i can see the requirement for addition bracing. The cl from the mast step is approx 12-4 in each direction to the fore and aft beams. if i eliminate the forward beam and go to a bow sprint w/guys seems like i have to do something. If i consider some type of x bracing, does it need to be a solid member for tension and compression or can i look at wire and turnbuckles. And if the dolphin strikers are taking the beam loads do i need to look at some additional support like struts from the beam to the hull walls. The beam ends are supported with stainless steel brackets, thru bolted with compression pads. (typicla at all connections).

    The existing center and aft beams are preped for dolphin strikers, the forward one is a pretty beefy striker w/3" stainless strap support to the beam ends connection.

    I am going to try and keep the topsides as clean as possible w/miles of nets.
    for the after you are done sailing comfort? My guess is that the center pod provided some of the braceframe reqiurements?

    Many mahalo's

    paani cat.
     
  13. paani cat
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    paani cat paani cat

    Opps! Good Fortune, I like that
     
  14. Gary Baigent
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    Gary Baigent Senior Member

    paani cat

    hey paani team
    This is just my opinion and some will disagree but my thoughts on the two beams is again what I mentioned before - they need to be set solidly into the hulls, uni-dirctionals (and not metal clamps) taking the loads over and down into ring frames. If the beams are stiff enough (and from what you say they are heavy so I presume they are) then if embedded with epoxy and laminates so there is NO movement in the beam sleeve hull connections, then the platform will not flex very much (there will be some twist) but you can live with that. The cuddy fore and aft beams are not going to contribute much to platform rigidity - but leave them there, they will good for mounting sail control blocks, barber haulers and other gear to, plus your drop down outboard. If set up this way you won't need diagonal bracing wires to stiffen the platform. I reiterate, it would still be better to make larger, faired box beams to do the job but if you are determined to retain the alloy ones, then fixed solid into hulls will be a reasonable compromise.
    Here is an old shot of my 32 foot bamboo bomber Supplejack - you can just see there are two main beams (later I got rid of the foreward beam- no trampoline forward after that) the after beam was close to the transom and had a semi circular main sheet track attached to it. All beams went into sleaves and I had no trouble with cracked beams or breakages.
     

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  15. Gary Baigent
    Joined: Jul 2005
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    Location: auckland nz

    Gary Baigent Senior Member

    paani cat

    hey Paani team
    Found this old image of a CSK Hawaiian cat, check out the beams.
     

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