Kayak Rack on Top of a Traditional Teardrop

[markhusbands]

I am planning on doing something similar - mounting a rack and roof top tent - and am building walls out of 3/4 ply. I created two double spars with about a 5x5 block on each to take the screws through the roof, and notched the side wall so that the block sits in the notch (unlike the rest of the pars that are between the walls).

Now, my assumption is that I won't have a buckling problem in the side walls by distributing the load on two crossbars similar to a Yakima rack, with the four feet mounted over the 5x5 blocks near the edge of the roof. For one thing, when the tent is used for sleeping, the ladder DOES carry a good portion of the load. For another, I used this tent on a standard Yakima rack on a car last summer, and was surprised at how little flex I observed in the crossbars. And when you look at the Yakima feet, there isn't a whole lot of steel there.

So with two sleeping the weight is about 500lbs, with a portion being borne by the aluminum ladder. In motion the tent is 90lbs. I won't claim I'm not worried about it, however. So if anyone has any concerns or bracing ideas I'd like to hear them. For example, I may add an additional "sub-spar" under the ceiling ply just to help counter any spreading forces on the walls...

[Forrest747]

Pictures would help, but I get the idea of what you are doing. 3/4 walls i wouldnt think of too much buckling. If this is going to be a used a lot with a tent on top i would think of a thicker roof or closer spars to prevent sagging. The link is to a study i did to show how much weight our walls can take.

http://www.tnttt.com/viewtopic.php?f=21&t=47534

[Kharn]

I would carefully plan the roof rack locations to be on structural members, permanently mark the rack locations on the exterior skin, and use airline/L-track for the tie-down points.
Consider how the hatch opens with the kayaks on top, you might want to be able to stop for a quick snack or something without having to unload or adjust them.

[markhusbands]

That is encouraging. I'm not overly worried about roof sag, because the rack feet will be almost right over the sidewall on top of a 5 x 5 x 1.5 block that is sandwiched between two spars. That way the two spars will resist spreading forces and the block should deliver the load to the sidewall. I could add a little shelf-style bracket to the interior under the block to help a little more. But with 500lbs. spread on four feet (not counting the support ladder) on two walls at points about 3 feet apart on each wall I seem to be well within the 1600lbs it takes to buckle the 3/4 ply. And I am going to use plenty of spars just because I have a flat section of roof. I tried to add a quick sketch of one foot...

spar and block sketch.pdf

(97.13 KiB) Downloaded 87 times

[Forrest747]

Markshusband, the thing to take into account as well that is one side of the wall. since you are having two walls than load value it can take doubles. Your diagram helped clear your plan up. underneath your notch in the side wall I would have it be solid if you can to the floor. Good luck

[markhusbands]

Weeeellllll,
There are these things called "doors" that fall beneath the front rack bar by a few inches. Thought about it, but this is a small 4x4x8 trailer with minimal space in between wheel and front end. Couldn't see a way to put the front bar entirely in front of the door and retain an 18" front radius and a decent door width. Now, one option is to add another center bar just to spread the load among that many more feet (6 total) and therefore three points along each wall.

Worth it? Not sure. Might be just for peace of mind, I guess....

[markhusbands]

I decided to add a third crossbar just to spread the load across as many points on the wall as possible. I am planning on using 3/4 galvanized pipes (1" outside diameter) and elbows and screwing it together and screwing it down through the feet. Hopefully won't look too ghetto. I considered a variety of more professional looking options but have decided it is a place to cut some corners on cost. Grant did have some really nice looking bolt on hangers for the crossbar. Not cheap, though.

[rowerwet]

my sidewalls are 1/4" ply with 1X2s fully glued and then another 1/4" ply outer wall, the door frame is also the support for any roof loads (I was thinking of boats already) the laminated beam created by the sidewalls and 1X2 is probably stronger than a 1" sheet of plywood.

these tie down rings (stainless bow eye, boating hardware) through bolted at the top of each door frame post. they support my changing tents, and anchor any roof loads.
Inside there is a 1X3 spar (on edge) lined up with each door post to support the roof.
the canoe blocks worked just fine for our 1,000+ mile trip, I planned on making crossbars that are supported by the bow eyes, but don't think I'll need them. the painted canvas finish didn't even notice the canoe blocks for all that driving at highway speed.

clearing the hatch without removing the boat

the mouseboat is the same length as the TD, 8', longer kayaks are going to overhang, a lot. might be better on the TV.

[FastEddie2]

I've been thinking of this idea for a kayak rack. Getting the galvanized pipe and angles and supporting it from the sides. Possibly adding some backing on the inside for a stronger anchor point. Could also use the pipe to add a dressing curtain to support from. Just add a "t" and a threaded coupuler to attach a hoop to the side from post to post.

[markhusbands]

Wow. That's either a big woman or a small teardrop.

I'm planning to use the galvy but position the feet right near the edge on 6 (3 per side) 5"x5" blocks that sit in notches in the sidewall. I will probably add small brackets on the inside just to reduce any levering on the part of the block not supported by the wall.