Box-beam or I-beam question

[o2batsea]

OK amend that to read "Vegamite consistency", and you won't need any steel inside.

You probably don't want to hear that I am picking up a CLC 16.5' tandem kayak that has two outriggers and a sail that was built a few years ago by a "loyal" CLC customer. Clearly not his first project as it was done very nicely and needs pretty much nothing done to it, maybe new paint.
I offered Ed at CLC Annapolis 350 for it and he took my offer.
Go to http://www.clcboats.com/shop/boats/...creek-16-5-tandem-recreational-kayak-kit.html

That's the boat and it has the sail kit and the outriggers. Need some nice Werner paddles now!

 

[MichiganIron]

The one design issue that I don't think was mentioned is the laterally unsupported length of the beam. If you look at the thumbnail of the Uniform Load table from the AISC Manual, one of the most imporatant design considerations is the lateral support of the compression flange (zone) of a section. Most beams will fail from Lateral-Torsional Buckling before they fail in bending. You can have all the section modulus you need, but exceed the allowable stress based on the unsupported length of the compression flange, and have a failure.

A box section will have more resistance to Lateral Buckling than an I-Beam. Wide Flange sections were developed to increase the allowable un-supported length of a section by increasing the weak access section modulus over the older I-Beam shapes.

Use steel. From the description of your trolley set up, your total span will be laterally unsupported. By the time you have enough lumber in the section to handle your load properly, you may as well use a steel section. Be careful of using the uniform load loable from AISC unless you are faniliar with how to use it. A concetrated load at the ceter of a span develops considerably more bending moment than a uniform load. In addition to that, you should also add a 25% impact factor for all lifted loads.

Hope this helps.

 

[o2batsea]

Sail kit thing:
http://www.clcboats.com/shop/boats/...ries/clc-sailrig-kayak-canoe-sailing-rig.html

I didn't get the sail, but there is an old Sunfish sail with it, which should work. Not a bad deal, eh?

 

[o2batsea]

He's just trying to flip a 22 foot boat hull. I don't think it would weigh more than several hundred pounds. It's a narrow center hull from a trimaran. It won't be lifting off the ground, just rolling over. His beam will be way more than plenty.

 

[tungularafishcamp]

For a 2x time deal is it worth it to build a beam, what about get a few extra hands and roll it over?:2cents:
Rick

 

[Shield Arc]

The one design issue that I don't think was mentioned is the laterally unsupported length of the beam. If you look at the thumbnail of the Uniform Load table from the AISC Manual, one of the most imporatant design considerations is the lateral support of the compression flange (zone) of a section. Most beams will fail from Lateral-Torsional Buckling before they fail in bending. You can have all the section modulus you need, but exceed the allowable stress based on the unsupported length of the compression flange, and have a failure.

A box section will have more resistance to Lateral Buckling than an I-Beam. Wide Flange sections were developed to increase the allowable un-supported length of a section by increasing the weak access section modulus over the older I-Beam shapes.

Use steel. From the description of your trolley set up, your total span will be laterally unsupported. By the time you have enough lumber in the section to handle your load properly, you may as well use a steel section. Be careful of using the uniform load loable from AISC unless you are faniliar with how to use it. A concetrated load at the ceter of a span develops considerably more bending moment than a uniform load. In addition to that, you should also add a 25% impact factor for all lifted loads.

Hope this helps.

MichiganIron nailed it!
That is why I went with a HP-section with a ripped S-shape welded to the bottom for the trolley to run on for my bridge crane.

 

[Aussiebushman]

Thanks again to all who contributed suggestions. Working alone (no near neighbours) on a remote property accessed by dirt roads imposes some serious restrictions. I enjoy working in steel but in this case, timber was more practical. (Ever tried welding from a ladder 12' off the ground inside a shed full of timber)? This way, a relatively light frame could be constructed and lifted into place and the ply faces added later

Getting the beam into place by myself was not easy, even with a temporary tackle from the ridge. Even without the ply cladding, it was fairly heavy and housing above the cross beams on the vertical posts took some doing.

The job is nearly finished - just 4 hours work and FREE using bits of timber and steel lying around the shed. Needs just some epoxy, the plywood facias and a light steel rubbing strip on the top to finish the beam. The chainblock will be shackled to a rolling car sitting on the top steel strip.

 

[Aussiebushman]

OK amend that to read "Vegamite consistency", and you won't need any steel inside.!

Bloody Yanks! It is VegEmite- now owned by the fine Kraft Comany of the USA

Good luck with the tandem kayak - sounds like a great buy

Alan