| Re: DS12
[Re: Gato]
#135027 04/12/08 05:17 AM 04/12/08 05:17 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe | Still when I made the Blade it felt quite strange to drill a BIG hole trough the mainbeam and just put a tube in it. don't think that that is improving the strenght in any direction...
Currently the side walls of your beam are transfering the 1 to 1.5 tons of mast foot pressure from the underside of the beam to the top sit where the mastfoot fitting is. As you beam is rectangular this means the top and bottom planes will be pressed inwards and may develop micro cracks around the fittings. Whith a large hole in the bottom of the beam the pin can pass straight through and transmit the laods directly to the underside of the mast foot fitting. That is one the advantage of the regular setup that you don't have anymore. You may well be fine or you may not be with the current setup. Time will tell as I haven't done the math on your setup. Basically, keep an eye on it and if it is fine then you proven this setup to be a viable alternative. Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: DS12
[Re: Rolf_Nilsen]
#135029 04/12/08 06:44 AM 04/12/08 06:44 AM | Anonymous
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Unregistered | That's my experience also. No need to lose the text. | | | Re: DS12
[Re: Gato]
#135031 04/12/08 02:33 PM 04/12/08 02:33 PM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe |
If you are using a space tube inside the mast then everything will be fine, indeed.
Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: DS12
[Re: Wouter]
#135032 04/12/08 04:58 PM 04/12/08 04:58 PM | Anonymous
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| Anonymous
Unregistered | Good morning everybody (or evening/afternoon depending on where you are). This whole conversation reminds me of the old saying opinions are like a$$holes etc etc.
Time to answer some questions...
1. Do you design for strength or stiffness? 90% of the structure on a boat is actually designed for stiffness, where you are considering allowable deflection and using the Young's modulas to determine what you'll actually get. Checking that a part is "strong" enough if often secondary to the stiffness requirement.
2. Why use flat bar instead of wire. Using wire is fine, however, it requires some more difficult custom parts or the use of expensive tune buckles, neither of which I thought suited this project. The system shown on the drawings is basically the same as what is featured on the paper tiger and it has worked very well for a long time and is easy to build by the home handy man assuming you can find someone to perform 1 aluminium weld. My experiance is that the cost of this weld is usually about 1 case of beer.
Gato's system is even better (although a little heavier) in terms of its ability to be built at home, however, it also requires the use of a welder. With this in mind I'd recommend people make their decision based on what welding technology they have access to. My drawings suggested people buy an off the shelf mast step, however I'll now be recommending Gato's detail.
To be perfectly honest, the other reason I went for the flat bar approach was so the boat would look as much like mum/dads as possible. | | | Re: DS12
[Re: ]
#135035 04/13/08 04:06 AM 04/13/08 04:06 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe | Gato's system is even better (although a little heavier) in terms of its ability to be built at home,
Actually the most simple setup would be how several A-cat (home)builders do it. They make the receiver for the cone but the cone itself is nothing more then a threaded end. Basically they use a long piece of threaded rod with a tube (=pin) slid over it. They use 4 knots Two under the mainbeam; one to adjust the tension of the strap, the second to secure it. The two nuts above the mainbeam to secure the pin there. The mast foot itself it made from Stainless steel and there are several ways to make the cone receiver but drilling out the head of a large bolt like Gato has done seems to be the easiest. Both holes on top and bottom of mainbeam are now nothing more then 10 - 15 mm dependng on the threaded rod that is used. Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: DS12
[Re: Rolf_Nilsen]
#135043 04/13/08 05:29 PM 04/13/08 05:29 PM | Anonymous
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| Anonymous
Unregistered | Thanks Gato. Always interesting to see how others do things. 36gsm is not a lot! I heard that under 100gsm was not really worth the effort, looking forward to hear your opinions after some use. Rolf, because Gato has used 4mm ply rather than 3mm, the glass is not required as a structural element. so on his boat it is there only as a surface finisher/protector. The standard plans call for 3mm ply with a layer of more structural cloth (Two layers across the bottom). | | | Re: DS12
[Re: Rolf_Nilsen]
#135045 04/15/08 06:52 AM 04/15/08 06:52 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 9,582 North-West Europe | I haven't got pictures of that setup.
Sorry,
Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
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