"Steve B" wrote

"Stephen B." wrote

Based on Carl's previous numbers I would tend to agree that it
should be sufficient.

My gut says it's good to go, but approaches strain at 350# on center
beam, and redlines at 500#. I have a 497# atv that will be a test
lift, and deflection noted. Perhaps even put in vertical temporary
stiffener whenever lifting more than 350#.

I would personally move the angles out until they are
over the edges of the containers (opening up the 140 deg apex and
leaving the height about the same).

It's all 3 x 3. The reason I brought them in is that is the point
of attachment to lift the boat, the biggest thing I'll lift.

I understand your resoning, but you are actualy not helping yourself
much. You are proposing to attatch the stress load of the boat on the
cross bar at the point that the beam stifness changes. The load would
be slightly higer where you are not stifening (added weight of the
stifening). If you look at
http://www.classictruss.com/roof_truss_facts.asp their is a reson all
the trusses shown have both the uper and lower span coming to the
bearing point . For ease of manufacturing, you may want to consider a
Modified "2x4 roof truss". make to laders with only a couple of short
cross brases (at load locations). or if you have some small stell,
make thboth trusses like one side of
http://www.garrettsbridges.com/wp-co...ss-bridge5.jpg
heavy outer beams and thin stock stringers between them.

This will deliver the load from
the center I beam to the containers directly instead of just
stiffening the middle of the cross bars. Leaving the "boat hooks"
mid span on your cross bars should not be a problem. I am sure you
would think of it, but I would also weld 4 stops to the cross bars
so they can not slide across the roofs of the containers.

Better than that, four base plate structures will be welded to the
tops of the containers to receive the ends. NO CHANCE OF MOVEMENT
ONCE IT IS WELDED OUT.


Are you basically welding everything so the two containers are
indirectly welded together or are you trapping the ends so they can
not move much? If the containers are not on good foundations, I would
lean towards the later.



--
Stephen B.

Thank you for your comments.

Steve

Your welcome. I am sure you will be fine whatever way you do it.

--
Stephen B.