trailer rhs sizes

[garth44]

hey starting to store up gear for new build. can get a heap of 40x40 2.5 rhs for a really good price. is this too light for a trailer. just doing basic design with 3-4 cross sections and simple a frame up front.

is this too light?

[Paul]

Too light in my eyes.
My old trailer was 4" x 2" x 1/8" (100 x 50 x 3.2) and that fatigue cracked.
It was replaced with "100PFC channel" which is same exterior dimensions but far thicker web and flanges: http://www.steelweb.info/100pfc.htm

Trailer rebuild thread:
http://www.nzjetboating.com/yabbse/index.php?topic=23049.0

Stiffness is proportional to dimension-cubed, so comparing 40mm with 100mm, then there's a 2.5 ratio which is then cubed to 15.6, so the bigger rail is over 15 times as stiff due to exterior dimensions - even more so due to the flanges being thicker too.

[Paul]

You can get 100PFC section for about $20/m and you'll probably need about 8-9m.

http://www.steelcuts.co.nz/index.php?route=product/category&path=65