Thanks for the pictures and explaination. I live in New Mexico which is simi arid and we don't have those beatutiful green lawns for rigging. I've always rigged my H16 on the trailer and i think that is common practice. but, maybe a beam supported boat can be rigged while on the trailer?.....Will Lints
Will_Lints one-up, Blade 706, epoxy bottoms
--Advertisement--
Re: Blade Trailer Layout
[Re: WillLints]
#76271 06/08/0607:33 AM06/08/0607:33 AM
This is probably a dumb question, but I'll ask it anyway....
Doesn't "hanging" the boat by its beams put undo pressure on the the 8 bolts/nuts/connection points that hold the beam to the hulls? Are the hulls so light that this pressure is negligible? Seems like, over time, the threading for the beam bolts would weaken.......
Personally, I'd rather sit in a chair - rather than hang from a chin up bar <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
My boat lives on the trailer and I try to reposition it a little after each use. It makes me feel better about "wearing" out the areas where the cradles are.
Just curious to see if others have this same concern about "hanging" boats for storage....
Tom
Re: Blade Trailer Layout
[Re: tshan]
#76272 06/08/0608:09 AM06/08/0608:09 AM
Tom, In my book there is no such thing as a dumb question. Just dumb answer. Hopefully this isn't a dumb answer.
This is just the way I see it.
One hull weighs between 20 and 25kg. It is supported by 4 bolts.
If the load was even between front and back it would be between 5 to 6.25kg per bolt.
I would expect each bolt would be capable of taking over 100 times that weight.
Compare this to the tension load applied to the hulls at the rear beam when fully powered up upwind and double trapped. This load can be so high that I know of boats that have snapped inner rear beam bolts that were 8mm in dia. If really concerned look up the tensile breaking strain of an 8mm bolt just to see the type of loads involved when sailing and then compare it to trailering. I personally don't see a problem with trailering by the beams. Regards, Phill
I know that the voices in my head aint real, but they have some pretty good ideas. There is no such thing as a quick fix and I've never had free lunch!
Re: Blade Trailer Layout
[Re: phill]
#76273 06/08/0609:04 AM06/08/0609:04 AM
If you look up the shear (side load) strength of bolts you'll find it is incredible, so as Phill says hulls simply "hanging" by bolts is no problem.
The uni-strut product is used for mechanical and electrical support in construction, and is available at the next step up from the Home Depots of building supplies. I also found that a trolley/car is available (P2570) for the 1 5/8" stuff. It's rated for 100 pounds but meant to be used in the inverted mode and for it's limited use (movement) in this application should last for years.
Had planned on using this Aussie beam support on my old Hobie trailers (patiently waiting for used/affordable T4.9/F16/?) and may have some concern with hull weights in 30 to 35 kg range, but seriously doubt it, and/or I'm going to find out.
John H16, H14
Re: Blade Trailer Layout
[Re: tshan]
#76274 06/08/0609:57 AM06/08/0609:57 AM
Just curious to see if others have this same concern about "hanging" boats for storage....
Following Phil's reasoning: my cradle's are apporimately 144 sq. inches in area, x 4 is 576 sq. inches. Divide that by the 240 lb. boat weight= 2.4 lbs/ sq. inch.
If the experts say "hang" the boat I would consider that "best Practice", but it isn't high on my priority list. One day though! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
My 2 cents.
Re: Blade Trailer Layout
[Re: fin.]
#76275 06/08/0610:27 AM06/08/0610:27 AM
Yes Pete, but are the cradles 144 sq.in. equally supporting the load? Or is the boat sitting on the bottom of the cradle and the sides just limit sideways slip.
Ok. You convinced me on the bolts. What about the glass/kevlar/carbon joints where the bolts attach to the bolts? Completley different scenario, but I've seen where people had to reseat beam landings on old old old old Nacras because the bolts pulled out/got stripped out.
Yes Pete, but are the cradles 144 sq.in. equally supporting the load? Or is the boat sitting on the bottom of the cradle and the sides just limit sideways slip.
dunno', but I'm still not all that worried. If I were less cautious when driving, maybe.
Tshan,
I too am more concerened about the glass than the steel. Either way the bigger factor may be the bumps and pot holes in the road, the rail road tracks, the cattle guards, the graveled roads. It isn't the smooth road that wears out a car's suspention. I went out and bounced on one side of the TheMightyHobie18 trailer with my 150 pounds (56 KG) and i don't think it moved up and down an inch (2.5 cm). Of course it depends on how much weight one carries around in the cat box, but it just seems like it's too stiff for something that is designed to float in water.
wondering, Will Lints
I'm with you, Will. If the boat is suspended from its beams, the road vibration alone, not to mention the bumps, is going to cause the connection between beams and hulls to always be "working."
Using Phill's photos as a starting point, I came up with my trailer setup--easy to load/unload solo, very secure over thousands of miles so far, low friction Trex for the beam rails, and a clever way of integrading the dolley. See photos attached.
Eric Poulsen A-class USA 203 Ultimate 20 Central California
If the boat is suspended from its beams, the road vibration alone, not to mention the bumps, is going to cause the connection between beams and hulls to always be "working."
But...if the beam support is approximately 4 to 6 inches from the hull, how much flection can there be? I can't see how there would be any significant movement.
Need the physics boys again.
Eric, very nice work!
Will, were you born in Missouri, the "Show Me" state? <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />