CNC Plans not Included

Discussion in 'Multihulls' started by jorgepease, Sep 19, 2016.

  1. waikikin
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    waikikin Senior Member


    At the forward end it's more typical to ramp and tangent into the curved section over more distance, what you have drawn is sudden & obtuse.
    The 45 may be for the alu construction and /or to assist the steps into the hulls- the crowther boats tend to narrow. Some of them had hulls canted at 8 degrees, this made the hull centerline stance wider and with the flare to inboard made somewhat of a champher panel that interfaced with the stepped area.

    Jeff.
     
  2. jorgepease
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    jorgepease Senior Member

    Thanks, Yes I know about tapering it into the side, hoping to avoid that if possible.

    I took the shelf all the way back to help transition the aft beam as you said.

    The deck is now same height as the ceiling over the shelf and at good sitting height. She is looking pretty sleek, way sleeker than I thought possible with all that bridgedeck clearance.

    Here is some progress shots

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  3. groper
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    groper Senior Member

    Imho its not worth it- why not just continue the level of the bunks right across!

    Make the hull a tad deeper to compensate and keep the bridgededk clearance at 40" all the way...
     
  4. jorgepease
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    jorgepease Senior Member

    Morrelli and Melvin say about 6 percent which would be 42 inches so I could probably do that. On the other hand, most of what I read says a lot of the slamming occurs in rough seas combined with the convergence of the bow waves. ... I think it's 1.3 meter right now so might be a nice feature.

    From a construction standpoint it's easy as long as I don't start getting into little taper pieces which would complicate infusing in one shot, for now I am going to leave it.

    The sheer is now low enough in relation to the cockpit that I can actually overhang counter space. Can't put anything under those counters but, depending on what I have on other side, that could win me an extra 4 foot in width up front. I have to study that, the roof structure a semi enclosing salon and placement of the helm.

    It's a good exercise for me anyway, otherwise I will go insane waiting.
     
  5. jorgepease
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    jorgepease Senior Member

    Making the top deck into counter space was a good idea. It gives me a massive galley as big as my home kitchen and barely any fit out. I did square and plumb the counters but it's very little material. Since I am all electric - Induction stovetop, toaster, blender, bindi robot, air fryer etc... I don't have any gas lines to mess with.

    Very little fit out below as well. The bunk shelf and bulkheads support the platform for the bed which is premade with all cabinetry pre installed to the shelf, it just slides onto the shelf and glues down. If fitout is 1/3 the game then cool!!

    Elec and plumbing don't intimidate me and they don't take a long time if you have everything worked out ahead of time. Rigging is where I am super behind starting with what does the mast attach too, I keep reading it sits on the main beam but I also thought I read it fits into a socket. I'm guessing it's a socket attached to the beam?

    cheers!!!

    [​IMG]
     
  6. groper
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    groper Senior Member

    What you are designing ia a full bridgedeck boat. You might aswell go ahead and design a nice looking cabin to go over it... i like the grainger style ones :)
     
  7. groper
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    groper Senior Member

    Or the sig 60 style :)

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  8. groper
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    groper Senior Member

    I hope the above gives some perspective to size... look at the size of that boom! Imagjne the rest of the rig! My wallet hurts just looking at the above pic....
     
  9. jorgepease
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    jorgepease Senior Member

    lol, I am pretty sure that is the 80, few million worth of hurt, but what a beauty.

    When I finish with mine, you will see, it will be nice. Honestly, I don't understand how you are going to cross oceans with only a Bimini. Why rough it? An open air cabin with a gourmet kitchen is the best of both worlds.
     
  10. groper
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    groper Senior Member

    Well for me , i was going to do a galley down in a hull. But like i said, my needs and wants difder greatly from the norm.

    If i was to do build again, it would be an extremely lean machine. Low cost to build, very minimalistic etc but it would sail like a race boat.... id put a full rotating rig on it with a wingmast also... not what you normally see on crusing boats and not as comfortable as a typical cruising boat.

    If i wanted a typical comfy cruising cat- i would not build one, theres plenty of them for sale on the used market for a fraction od what it wpuld cost to build one :D
     
  11. jorgepease
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    jorgepease Senior Member

    If you are going to those extremes, the SIG45 or Gunboat G4 sound right. I think though, that after a few thousand miles you are going to be worn out, if not you, then your woman )

    I want to see how light - for the luxury - I can build a boat. Minimal fit out and taking advantage of the structure to provide seating and counter space type of thing with the exception of a huge solar roof which has to look good and be as light as possible.

    Features like movable bar chairs, that can be plugged at the helm as well etc... are the type of ideas I want to implement.

    By doing this modeling I can see how efficiently I can build such a boat. All components have to be molded if I plan to ever build more than one and the molds should incorporate as much fitout as possible - A shelf for bunks and topside level ledge for galley means I only need to build a countertop and base for beds. The raised ceiling of cabins creates a perfect height for seats, I only have to provide cushions. The scallop for outboard bracket in hulls etc... etc ... most of the construction work is done popped out of the mold.

    The molds will take a lot of thought and care but they aren't complicated and with CNC I can establish the framing through stations. Thankful now for my extensive experience as a carpenter I feel comfortable in my ability to execute such shapes without a hitch.

    If I keep it light enough, then I can ease off on the size of the rig. I don't need a mast that would normally be used to push a 60 footer if it only weighs as much as a 45 footer and I don't need the speed of a SIG or Gunboat.

    Other things I don't need - extensive electronics. I like the trend toward multifunction displays, give me the very least possible. For sure I don't want to see multiple monitors at a helm or chart table. Looks good but do you really need it? No! It's like all the fancy fishing boats down here in the keys, radar, two fish finders, and gps, heck my neighbor with the rattiest boat of all wins most fishing tournaments he enters and all he has is a handheld gps.

    Of course none of this makes good business sense. A good business person would go out and buy a couple of used cats for a 100K each and renovate them and start making a profit from the get go, I can't argue with that logic but in the end you also have to consider what it is you want to accomplish in life, building for me is part of that journey.

    I will probably end up penniless or dead but neither of those are worse than being unhappy.
     
  12. rob denney
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    rob denney Senior Member

    I agree with your attitude and reckon the easiest (probably the only, but you will find that out as you get to the costing and weight part of the cat design) way to achieve it is a harryproa.

    But given that you are fixed on a cat, maybe look at flat bottomed hulls which are also the cabin floor. Saves the weight, cost and work of fitting floors, frames, stringers and hatches (which is the worst job in boat building apart from hand glassing large overhead areas and fairing), lowers the topsides by 2'6" in the middle, makes for much easier infusion as the core does not need to be shaped for the compound curve of the hull and makes the bulkheads easier to install. Probably has a higher top speed as well. You lose the storage space which will mostly be filled with junk, the hassle of water and fuel tanks that cannot be cleaned, and a false floor which will almost certainly be damaged in a collision serious enough to justify it.

    If you are worried about the sailing exhausting your lady friends and are not interested in constantly trimming the sails to get an extra couple of degrees upwind, then unstayed masts are the way to go. Far less work, very little to go wrong and virtually stress free. And on a boat of this size, cheaper than a stayed rig; way cheaper if you build it yourself.
     
  13. jorgepease
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    jorgepease Senior Member


    Hi Rob, how is testing going on your new race boat?

    I really like the idea of an unstayed mast. Less lines, less work, safety, less maintenance and less expense, I wonder what are the compromises?

    How badly will it affect performance? Will I go 1 knot slower or 10 knots slower, or is it better into the wind or going with the wind etc...

    I like the infusion idea Groper posted earlier in this thread and most likely I would build it that way.


    Found this, a good read. http://www.ericwsponberg.com/wp-content/uploads/state-of-the-art-on-free-standing-masts.pdf
     
  14. rob denney
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    rob denney Senior Member

    Slowly. Telescoping trackless mast works well. Had a couple of sails, broke the rudder mounts, which I am currently rebuilding. Info and video at http://harryproa.com/?cat=2

    On an average day of set and forget, it will be better than a stayed rig. Not so good upwind, better reaching and running. Extras, especially those with tight luffs are not as easy to use, but the main(s) can be made bigger to compensate. No wires to hang onto (bump into) as you move about the boat.

    Unless you know what you are doing with sail trim, and do it each time the wind changes, I doubt you will notice any performance difference. You will notice that it is far less effort.

    Had a quick look, but couldn't find it. What post #?


    Very good, but a little dated, particularly on the price and the build methods. Eric has now retired and sends all his mast information requests to us.
     

  15. jorgepease
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    jorgepease Senior Member

    Checked out video 2, can't wait to see how it does once the fixes are in place and you can turn her loose. Hard to see much in this vid but looks like she slices the water very cleanly.

    Upwind is where I need it most I am afraid as I am using electric propulsion and no genset.

    Gropers idea basically is to infuse in as a U shape in a non rigid form (metal) within a rigid jig which can, after resin has flowed, be closed to the finished shape via a second jig. The mast is finished off by gluing an insert, on the inside, the two ends together. It sounds like it would work and simple.

    I also have an idea but using prepreg on a thin foamcore mandrel that becomes part of the part.

    An autoclave doesn't have to be expensive… I mean we are talking pretty low temperatures here and it's much easier to control than people think, just turn on or off bulbs as needed or vent the cover. A fan on one end would help even heat though lamps would be all the way down the length.

    It wouldn't cost much but it is more labor intensive since you have to first build the mandrel. Sponbergs methods for doing that would work fine but if I was thinking to build more than one i think I would make a simple half mold.

    When baking, I would bag the inside of the mandrel to the outside so the vacuum doesn't deform the mandrel.

    [​IMG]
     
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