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  #136  
Old 12-12-2011, 04:09 PM
Boston Boston is offline
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ya thats a really nice rendition of Widgen one of my favorites.

another one I kinda like is this one


http://www.aeroyacht.com/power-catam...photo-gallery/

I'd carry the cabin house further back and although I hate the gigantic sunglasses look I suppose its light and easy. Wouldn't do it out of GRP tho, plywood again with a construction style kinda like that 30 footer I pictured earlier hanging in the slings.

I'd have to keep the era finish I'm after to the inside. Also do it out of cedar core material. or even balsa assuming I could get it at a descent price. Both soak up a lot of glue tho, also known as money. I wonder if I could manage to work a piece of cherry over foam core, IE cherry/foam laminate through the machinery. Might be worth a try. If the foam core ( any idea as to what form of marine foam coring is most accepting of glue ) will stick well enough to the wood and its reasonably stiff it should work. Not sure how well its going to go through a plainer tho. The self feed on that thing puts a lot of pressure on the work if your not really careful about it.


  #137  
Old 12-12-2011, 04:22 PM
Boston Boston is offline
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I think I might explore the option of a electric launch for the cat. Maybe vawt ( vertical axis wind turbine ) on the boat to charge the launch as well as it could be charged off the main gen set.
  #138  
Old 12-12-2011, 04:42 PM
groper groper is offline
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As soon as you goto a foam core sandwich construction, the cost of materials to get the shell complete goes WAY UP compared with timber construction... id reccommend you stick with wood as you know how to work with it and wooden boats in this size can be built almost as light as a full foam core composite boat, theres not much difference until the boat size gets larger say over 50ft..

However, i would look into your options of a timber cored, glass skinnned build as you can achive stronger structures for less weight this way and the timber is going to need a coating of epoxy anyway to ensure its waterproof, not much extra work to add the fibre with the resin... a friend of mine has a 3/4 built 46ft cat sitting on his front lawn... its built with 15mm thick ceder strip plank hulls, 750gsm glass/epoxy skin outside, 600gsm biax inside, the rest of the boat is mostly plywood with the outer surfaces laminated with the 750gsm triax, and the insides with no glass. Theres also alot of plain DAR timber used for making all sorts of stuff with no glass on it at all, just coated with epoxy... its a large volume cruising cat with fly bridge, ill try get round there and take some photos today...
  #139  
Old 12-12-2011, 04:56 PM
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sabahcat sabahcat is offline
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I think I might explore the option of a electric launch for the cat. Maybe vawt ( vertical axis wind turbine ) on the boat to charge the launch as well as it could be charged off the main gen set.
you're kidding right?
  #140  
Old 12-12-2011, 04:57 PM
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sabahcat sabahcat is offline
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I'd carry the cabin house further back
once again, it'd squat as it is not designed for it
  #141  
Old 12-12-2011, 05:04 PM
Boston Boston is offline
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true but it could be redesigned for it. You forget I've got this pencil in my hand and its got an eraser on it

and no a couple of batteries later and I'd have a nice quiet launch for getting back and forth. Wouldn't need to have any kind of tremendous range. The wind turbine is standard equipment on a lot of boats. Mine would just be a vertical axis rather than a horizontal one. wouldn't be huge though, maybe four feet tall and four around. Would keep the house bank topped off and provide a partial charge for the launch. I'm thinking a small launch that could fit on the back deck kinda thing.

I kinda like the helical ones

http://vimeo.com/7055716
  #142  
Old 12-12-2011, 05:10 PM
CatBuilder CatBuilder is offline
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Run the numbers on that wind generator. I suspect, being a power boat, you will find it's more economical to just charge up those batteries for the electric tender from your alternators or genset.
  #143  
Old 12-12-2011, 05:15 PM
Boston Boston is offline
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thanks for the coming pictures Groper. Looking forward to seeing what he built and how he built it. MR Wood has a link to his new power cat design that I'm starting to like as well but the cabin would have to extend all the way back. or at least the roof so I could put an insulated bimini type surround on it.
  #144  
Old 12-12-2011, 05:20 PM
Boston Boston is offline
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true to a degree but I'd have a wind gen of some type no mater an electric launch or not. I could if I really wanted to be a cheap bastad use some of the launch batteries as the house batteries as well. Say if I were going to have four bats as a house bank, two of them could be in the launch. That way I save the weight of an engine for the launch and don't add extra batteries to the overall weight of the boat.

seems like its the cost of some extra wire to make it work. That and some descent batteries, which I'd be constrained to buy anyway given a jump start in the middle of nowhere is not an option

OH and I wouldn't buy a wind gen I'd make it. Windblue sells modified rotors for exactly this purpose at about $100 and the blades would be kinda fun to make. After that its a axis for it to spin on and some magnets to suspend the rotor. Pretty simple really, Use a alternator body with a self regulating system in it and your off. OK maybe off my rocker but off none the less. ;-)
  #145  
Old 12-12-2011, 09:57 PM
groper groper is offline
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Ok, heres the pics of my friends cat, built on his front lawn...





The boat is 46ft long x 24ft beam and he doesnt know what it weighs... its his own incarnation/modification of another design which he built previously, which was a simpson design -so he had the hull geometry from this... This one will not have a sail rig, its been adapted into a powercat and he plans to install 2 diesels around 80hp each hull and expects a cruising speed around 12kts...

The hulls are built from cedar strip plank with glass both sides - see my previous post... The rest of the boat including superstructure, decks, bridgedeck, bulkheads and beams etc is built almost entirely from plywood and meranti timber stringers to stiffen the undersides of decks etc. He uses 6mm ply layed over the inside surface of the stringers which makes a kind of sandwich structure for the decks and cabin and gets a flat surfcae on the inside for aesthetics...every exterior surface had glass over it, and only in structural areas on the inside... personally i would not build this way, i prefer glass composite panels with enough stiffness to skip the stringers, but each to thier own, it works either way and this is the 4th cat over 40ft he has built. So far his boats have had little trouble and covered many sea miles...

The main beam bulkheads are made from 4-5 layers of 12mm ply, so basically the beams are around 2 inches thick, and they essentially form the shear webs of a giant box beam with the bridgedeck underneath and top deck above taking some of the tension and compression loads. The backbeam is just a normal 'wavebreaker" as you liked to call it, made from ply but glassed all round.

He reckons if he puts the effort in, he can get the boat splashed in 1 year working full time from start to finish... he mentioned that strip planking the hulls was easy and with a helper he can have 1 x 46ft hull, planked in a day.

This is what the previous one looked like finished, its very similar to the one being built now but without the sail rig...

I know this isnt your style, but it shows that almost anything is possible using timber, it can be made to look like a modern plastic FRP boat, or it can be made to look old and classical...
  #146  
Old 12-12-2011, 10:18 PM
Boston Boston is offline
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Outstanding, I'm really impressed with his ability to pound out 4 huge cats. Great picts, lets see if the system allows me to hoist a pint in your honor
  #147  
Old 12-12-2011, 10:29 PM
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sabahcat sabahcat is offline
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Originally Posted by groper View Post

More here
http://mobile.tradingpost.com.au/ite...ch&page=1#pic2
  #148  
Old 12-13-2011, 01:50 AM
Boston Boston is offline
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this latest is drawn as a 40' but would scale down to 35 without any difficulties. At 40 its got 36" of tunnel clearance, tons. Probably more than I'd need. Its also got almost 8' of head room over the bridge deck. Crazy tall head room. So it would scale down to 35 really well without changing the profile view at all. I could also loose a bit off the hull height without to much difficulty

The width would remain the same, as per suggestion that most harbors have a lift of 20 wide. And I want to keep my haul out options as open as possible
  #149  
Old 12-13-2011, 03:46 AM
CatBuilder CatBuilder is offline
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Something sound off if you have 42" of bridgedeck clearance. It is rare to achieve that height with a boat this size, fully loaded. Are your weight and displacement calculations correct? Just visually, it looks like there isn't a lot of hull in the water in the drawing.


  #150  
Old 12-13-2011, 04:19 AM
Boston Boston is offline
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ya I accidently drew the water line 6" to low. The drawing also has a few flaws in it but all in all its close enough to get the idea.
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