Guys,
It's exactly the very slight flexing of an "H" type tilt bed that can damage the beams. When you support the hulls in snug fitting cradles where the cradles are connected by metal beams...any bending along the lateral tiltbed beams will tend to cause the cradles to pry the hulls apart in a direction that the hull/beam structure is not designed to handle. Even very slight bending can do damage and over many trips, this can(has) lead to boat failures.
Our hanging-from-the-mainbeam concept eliminates this risk entirely, since flex of the trailer cannot be applied between the two hulls. THe mainbeam is quite close to the balance point, so any windage or road bump loading on the ~80 lbs lifted hull should be easily handled by the structure. A structure designed to slam into waves and come to a rapid stop from 20+ kts speed (easily hundreds of lbs loading) is not going to be affected significantly by 60 mph winds from straight ahead while driving on the freeway. Many of these mainbeam support designs were built in the 70's for Tornados with no reports of problems.
Mike.
how about a rack that attaches not to the hulls, but rather the beams themselves... much like the scace design.
I'm not saying that your trailer is unsafe or dangerous, I'm just curious if there is a better mousetrap.
how about a rack that attaches not to the hulls, but rather the beams themselves... much like the scace design.
David Tilley, who has contributed to this thread, has designed a quite interesting tilting trailer. I have the second of the prototypes, and on the whole am VERY pleased. This trailer has easily several thousand miles on it with only two failures, and those due to the base (OLD conventional cat trailer - the leaf springs failed, and not catastrophically). That would be easily rectified by either fabricating a strong Aframe or using a powerboat trailer Aframe to start with.
Go have a look at Tilley's trailer:
http://tinyurl.com/nlva
sea ya
tami
Sorry, you have to log in to get the first reference. Here's another, and you can just go there:
sea ya
tami
tami:
I think I like that design the best. One question though. When "un-tilting" the boat, do you have to push it up to get it to come to vertical? I remember on the scace, Kevin and I had to push it a bit once it got vertical to make the winch to start working in the opposite direction.
Thanks! You wouldn't happen to have plans for this design would you?
Do have to push a bit. If you look at the pics at the TheBeachcats.com site (not the Yahoo Beachcats) and read the comments, they elaborate on its handling, and give contact info for Dave Tilley
Dave, hope you don't mind me plugging your work, I know you're monitoring this thread...
sea ya
tami
If you can handle a Cadkey or at least a dxf file, send me your US Postal address. I got a new print cartridge rearing to go, and it is all 8 1/2 x 11 cutsheets.
No charge and no liability.
(I have painted my trailer now, and may even post some pictures in action)
Carl, you really got me worried about Upper Hull Flutter now. Could you calc it if I tell you the torsional resistance of the crossbeam and the distance from hull to clamp? I guess if I stay under 120 I'll be OK? Don't give me that "I'm too busy 'cus Bush says we gotta go to the moon again" They did it with slide rules last time.