Paani cat -OUT OF THE WEEDS

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

  1. paani cat
    Joined: Apr 2008
    Posts: 13
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: honolulu, hawaii

    paani cat paani cat

    paani cat - stuck on the beams

    Aloha Gary

    you are right, i am stuck on the beams. i like the idea of extending the bow sprint and dropping the need for the forward beam but at the same time i would like to keep the original lines if possible, so i am looking at a bow sprint extended past a smaller section on the forward beam and guying the bow sprint to the leading edge of the hulls.

    or a beam section with the bow sprint similar to the reynolds 33 guyed in a similar fashion? if it aint borke don't fix it. (or re-engineer it).

    The center beam is the biggie. it is usable, but i am stuck on what to use for connections ie. rod, strap or wire for the dolphin striker. everything seems to be breaking and the rod rigging is just down right costly.

    how can something that looks so simple be so complicated. the loads on the striker are huge? much bigger than my pocket book.

    hence the composite beam??? is looking better if i can lay up the section???
    i am trying to do as much as i can myself but not sure about building the beam. any ideas there would be greatly appreciated.

    I have had some good luck in that a may get a rig (mast & boom) off a r-33 which will lighten the mast loading a fair amount. on this boat the over all consesus is that it might not be a bad idea to shorten the mast to the 42 range anyway. if i use the formula 40 mast i was going to shorten it to drop the 40 or so lbs off the top since the head sail on this rig is much less than 3/4 fractional in size.

    When the provious owner got the formula 40 mast he just cut the bottom so it is more like a .65 fractional so i a steering torwards the new rig.

    may depower it a bit but considering the longer boom & square top main option???

    got to get he boat under it first so the bigger fish to fry is the structurals.

    no decisions yet,

    Paani Cat

    thanks for the pics

    aloha
     
  2. Gary Baigent
    Joined: Jul 2005
    Posts: 3,019
    Likes: 136, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    paani cat

    Kia ora team Paani
    You should not be having trouble with beam and connection breakages but apparently you are. So, the dolphin striker strap should be marine stainless steel (30mm x 4mm or thereabouts IMO) and drilled and bolted near the ends to the beam close to the inner hull sides, (4 stainless nuts and bolts each end and sealed with epoxy or silicone) then tensioned up with an adjustable nut at the bottom of the dolphin striker. Malcolm Tennant (internationally known local NZ designer) on most of his cat designs has the dolphin striker floating freely in the main beam under the mast so the vertical striker moves up and down under mast/wave loads - all compression loads being carried and spread and dissipated by the tensioned stainless strap - and not concentrating lads at a point under the mast.
    From what I can gather from your comments, that original mast has to be way too heavy if things are popping, maybe your fittings are too light and/or of incorrect material.
    Building, say, (guessing your overall beam) a 7.5 metrearched box main beam (like in the posted CSK beach cat image – but not necessarily so highly arched) should not be difficult nor expensive. It is just a slightly flattened D shaped box in cross section (say 400 x 250mm) and can be built out of a local lightweight wood in 8 to 10 mm strip planking. I don't know light Hawaiian timbers but there has to be some examples growing there. Otherwise cedar or paulownia or balsa - but the latter has to be very well sealed with coats of epoxy.
    If you don't want to arch the beam, build it straight but you will still need a dolphin striker setup. Laminate with box weave glass inside (built in two sections then glued together) and then wrap the outside with more box weave laid with a 45 degree bias plus uni directional glass and carbon in the high load areas, then epoxy them solidly into the hulls with the same materials.
    I don’t like the sound of the cut down F40 mast – the Reynolds 33 rig would be superior - and I wouldn’t cut the rig down to 42 feet either – you get light airs in Hawaii, you need at least 45, preferably 48 feet for your fast design. If you haven’t got speed in a multihull, then you haven’t got much. If you build the composite main beam (and your bow sprit of the same material) while retaining the original alloy after beam, it is not much of a step further to build a composite wing mast. Up to you team Paani ehores.
     
  3. fhrussell
    Joined: Dec 2004
    Posts: 156
    Likes: 2, Points: 18, Legacy Rep: 30
    Location: Long Island, NY

    fhrussell Boatbuilder

    James,

    The crossbeam layup was likely spruce and/or mahogany marine plywood, glassed on the outside if it is a CSK. The main beam and aft beam are aluminum, correct? The forward beam might be useful. It helps to keep the bows spread apart, therefore keeping your rig stiff. The "rod rigging" you found is the headstay bridle. It attaches from one bow to the other, and likely has a central stainless steel plate where the headstay attaches. When your rig loads up, the headstay pulls on this bridle wanting to pull your bows in toward each other. Without the forward beam, the headstay will really work on bending your hulls in....I'd rebuild and put it back on. Some boats don't have the forward beam, but I am sure the hulls were designed and built with that in mind on those boats. If this boat had one to begin with, I'd stick with the original design.

    As for the central pod, of course, keeping things light is of utmost importance, but 300 pounds on a 33' boat is not too bad, given all the added stiffness you'll get from the structure. Also, if you mount the motor forward of your aft beam within the pod, the prop will not cavitate as often and it is better to put that weight closer to the center than hanging on your stern. I'd seriously consider the central pod...it seems to be a designed feature to stiffen the boat....that is a serious consideration.

    And the modification of building box beams is a good one. Aikane X5 was built with four aluminum tubes as cross members and cracked, then replaced with box beams to obvious success. On the other hand, Machete had box beams and was converted to aluminum tubes eventually. Gary Baigent's post of the b&w photo looks like a Joe Quigg cat.... I took a photo of the same boat I think in 2004.

    97fc.jpg

    Again about the central pod, you could make a simple tray with a motorbox and add a large canvas dodger to create a convertible cabin. ..very light and I just did the same on my boat.

    Aloha!
    Frank
     
  4. fhrussell
    Joined: Dec 2004
    Posts: 156
    Likes: 2, Points: 18, Legacy Rep: 30
    Location: Long Island, NY

    fhrussell Boatbuilder

    PolyCon

    Also, a thought on the mention that the boat is a PolyCon Sundowner. It is a little short for a Sundowner and the deckline was straight on the Sundowner. But, the hull may have been laid up in the molds (which are for sale in California, by the way). If the boat was built in California in '83, it might be a possibility that these hulls were pulled from those molds. And, since there is a hull number, it has me thinking that this might be the case. Vince Bartolone was always in touch with the other builders and cat guys in SoCal at that time.

    Are the hulls symmetrical?
     
  5. fhrussell
    Joined: Dec 2004
    Posts: 156
    Likes: 2, Points: 18, Legacy Rep: 30
    Location: Long Island, NY

    fhrussell Boatbuilder

    Another thought on the forward bow crossbeam...

    You could construct a flying crossbeam. Basically, the headstay comes down to the central plate, then the bridle attaches to a light weight beam that is the exact beam at the bows, and then from the crossbeam are two more short sections of wire that attach to the bows. This lightens things a little and also raises the crossbeam up above the bows and lessens the probabilities of a pitch-pole.
     
  6. Gary Baigent
    Joined: Jul 2005
    Posts: 3,019
    Likes: 136, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    paani cat

    Great information fhrussell on CSK designs - your suggestion of replacement of fore beam makes obvious sense.
    When I removed the fore beam on Supplejack I ran two forestays to the bows instead of one to the seagull striker on the alloy forebeam - and I forgot to mention to the Paani guys that I increased the wing mast rig and went to a large una version of an A Class cat, no headsails; a reacher could be set off the leeward bow. They will probably not be interested in such a rig approach. However they could still set up like a modern Tornado or F18 with a box sectioned bowsprit and bridles and still carry headsails/reachers.
    I know a little about but like the look of Joe Quigg cats but Supplejack was Kiwi, a modified 32 foot Malcom Tennant Bamboo Bomber design: increased beam to 20 feet, taller 45 foot wing mast rig, no blister cabins or central cockpits (crew sat on tramps), lifted main and after beams to sleeve in above gunwhales, removed fore beam and secondary main beam and replaced fixed, sloping, skegged rudders to fit lifting, balanced, vertical rudders. You can see I am slightly minimalist. There was one true Bamboo Bomber built in Auckland named Superbird.
     
  7. paani cat
    Joined: Apr 2008
    Posts: 13
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: honolulu, hawaii

    paani cat paani cat

    paani cat is back......

    Aloha Frank and Gary

    And many Mahalo's for your imput. i am likeing he idea of the flying corss beam. The good news is that i have not done anything yet until i get several issues resolved. What i have been doing is looking for cross beam material (an aluminum section of the right size and length) but it sounds like i might be able to build my own. Frank you are right the old beam was mahagony built up with 1x8s and 1x2 vertical and then fiberglassed over. It had serious water problem. I have been trying to find a light aluminum section that i can have crowned to match the old??? if i am understanding you correctly the it sound like the flying beam set up puts the cross beam in compression with the split head stay. it looks like this boat did have tangs just forward of the cross beam (6" or so) for a split head stay. if iwere to consider this option seems like i can use a smaller lighter section.

    interestingly enough i have been to the Ali Wai and had a look at the blue cat.

    I have another issue with the mast section that i have... The mast came off of a formula 40 (sparcraft) that weights about 5.6 lbs per ft and i am told i need to change it. The mast height is 47'6" with a boom of 13'6". do you have any idea what would be considered a light section for this size vessel. I am looking at an f31 section and a reynolds 33 setion at about 3.6 lbs/ft but the weight gain is 2lbs. is that worht the effort???? the main difference is that the sections are 42'6" in length so i loose the height. I was thinking of going with the shorter section and increasig the boom lenght. hopefully lowering the cg but do not konw how that would effect the cf fore and aft or balance of the boat?

    the guy that changed th mast just cut the base of the formula 40 mast off and i do not think the goemtry is correct, just guessing though, the main on the f31 is about 430 sf and the r33 rig is 540ft or so. me being out here in hawaii i am trying to work with what is availabe with out going the new route with shipping..... any thoughts there would help.

    followup on the CSK issue, i was told the boat is a polycon design/rudy chow but the hulls where changed and actually pulled out and rebuilt so the they are fuller in the mid section, the photos show a much fuller mid section. in effort to take out some of the rocking...

    I have cut the bows back to the original line since it was only scabbed on with some cheap insulation and glassed over. basically a 8" sectin was stuck on the bow to make it a shaper entry for spray.

    again Mucho Garcia for the help....
     
  8. paani cat
    Joined: Apr 2008
    Posts: 13
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: honolulu, hawaii

    paani cat paani cat

    additional followup on the flying forward beam - I was possibley thinking of something similar... just thinking????. does this type beam connection delete the pelican - my original thought was to build a new beam and install the pelican, add a bow sprint for a schreecher and spinnaker tack and guy the beam and the tack points for the schreecher, spinnaker down to the bow
    below the beam line mid to near the water line for support???

    at this point i am looking at a hanked on #1 or heavy air sail since the mast to boom is 12'4" for the foot dimension. and a schreecher furler for light airs and the spin point just for fun (if possible) .

    I am not sure if i the bow sprint will add forces to the beam so i will need to add a mid span support for (compression strut?) the mast to the forward beam at the center line of the boat??

    does any of that make since or am i just killing myself here????


    on the mast height, short of ordering a new section and shipping,i am trying to work with what is here if possible. the question i have is with the new sail designs , sqaure tops etc... will the loss of 6 feet on the top make the difference or can build a sail plan that meets or exceeds what what i currently have?? i am trying to keep in mind that the hull design is and will allways be a mid 80's cat so how far can i take it..

    keep it coming guys, i need all the help i can get.

    paani cat
     
  9. paani cat
    Joined: Apr 2008
    Posts: 13
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: honolulu, hawaii

    paani cat paani cat

    Assym hulls i think so Frank. It is my understanding that the hull were pretty much split at the water line pulled apart and added onto so they would get more flotation. it was done some fifteen/twenty years ago and appears to be in fine shape (the hulls actually look to be in great shape from inside?) i can see where the hull line was split so the foam core starts a ways up on the hulls. I think that is one of the reasons that it looks less like a polycon CSk, but i am told it is one.....still? i think i have traced it back to rudy choy and the Sea Scouts with some four different owners ,maybe five.... any of that make since?

    paani cat

    on the aluminum beams, i am having the center beam repair at this time. AT some point the beam was split and a stiffner was added full lenght and welded back in place so it appears to be a pretty beefy section. it had a crack in it near the center span when the dolphin strke broke but was repaired. the continuious stiffner appears to have held it in place????

    with out failing. do you know if any of the other tube boat have been stiffened in this fashion??
     
  10. Gary Baigent
    Joined: Jul 2005
    Posts: 3,019
    Likes: 136, Points: 63, Legacy Rep: 509
    Location: auckland nz

    Gary Baigent Senior Member

    paani cat

    hey Paani crew
    Okay, if you decide on the lighter R33 section at 42,5 feet (obviously the earlier monster was too heavy) then don't lengthen the foot of the main but, and to compensate for the loss of mast height, get a square top new main (and I mean square so your leech stands almost near vertical) - that will give you a far better high aspect ratio main and better performance and probably be close to the same sail area as before.- but keep your original boom length. That is only my humble opinion of course. I like high aspect ratios, doesn't matter if the mainsail top falls away in gusts, that is what you want and your light air performance will be up. To be honest I am no expert on alloy rigs since I've always built wing masts, but if the new spar is too flexible, you can always stiffen the softer sections with layers of uni directional carbon fibre (make sure you roughen the surface first and lay glass/epoxy for the first layer (to stop the carbon/alloy fizzing). This is anathema to many spar builders but I did this to a soft section alloy mast for a Crowther 24 stretched to 28 trimaran and it has lasted 15 years with no problems (we also changed from mast head to three quarter rig and made it rotating - among many other changes to the boat). Actually re reading your letter I realize/guess, since you have to make do with what is local in Hawaii, that you are talking about F31 or R33 mains Well if you have to make do, then make do it is. Actually the Randy Reynold's rigs look excellent to me but maybe a little light for your heavier craft.
    That is a some story about that bloke crudely hacking down the F40 mast.
     

  11. Gybes On Time
    Joined: May 2009
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: CA

    Gybes On Time New Member

    Contact from Tom Trento

    Hey Jeff...

    Tom Trento is trying to contact you. His cell is 808.286.3849

    This message is from Steve Cullen - 1bodysurfer@gmail.com

    Thanks,

    Steve
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.