Better Hinge Seal?

[RKH]

Hi folks. Been a while since I've been here but hope one of you can give me some help.

Background: I've got a 2005 Little Guy 4 wide Deluxe which means it has the cabinets and the shelf for a galley at the rear. Over the years, its been parked outside, sometimes covered and sometimes not (probably covered less than half the time). It sets in a storage lot when I'm not using it so its hard to keep covers on (sticky fingers?) and I also don't see it often so I don't know when it blows off.

Anyway, turns out that there was a leak around a screw that went through the top filon piece which finally did enough damage that I saw it so I'm trying to repair the dry and make sure that I don't have new leaks. I'll be replacing the rotted wood and reattaching the hatch and would like to ensure the best seal.

THe LIttle Guy of this era's top is made with a 2x4 frame with a layer of what we used to call Masonite (pressed fiber board) and then a layer of Filon on top. The hinge (as shown in the pictures) is the black aluminum hinge and mounting flange. From outside in, there is the hinge flange (black in the picture), a layer of butyl tape, a piece of aluminum bar stock (silver in the picture) and then another layer of butyl tape. Next in this sandwich is the filon, the masonite, another layer of butyl and the frame piece.

In reinstalling this, I'm wondering whether I would get a better seal if changed the order to this--> From outside in the hinge flange, a layer of butyl tape, the filon, butyl, the piece of aluminum bar stock, butyl tape. masonite, another layer of butyl and the frame piece.

Your guidance including better ideas would be greatly appreciated.

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[RKH]

One more picture that may help visualize

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[aggie79]

I was very concerned - probably overly concerned - about moisture intrusion in the build of my teardrop.

Many successfully use butyl tape, but I don't like the thickness of the tape and I have concerns on how well over time it works with expansion and contraction. So, my weapon of choice to seal out water was 3M 4200 marine adhesive/sealant. The 3M 4200 is rated for continous immersion in water and is approved for use on many surfaces - metals, wood/plywood, fiberglass, etc.



Between the outer 1/8" plywood of my teardrop shell and the exterior aluminum, I applied a continuous bead of the sealant around the perimeter of the aluminum sheets and around all openings (vent fan, electrical inlet, door latch, etc.) I also used the same sealant underneath trim (between the trim and and aluminum sheets) including the hatch hurricane hinge. For the trim fasteners, I pre-drilled holes, injected the holes with 3M 4200, and then installed the fasteners.

In this picture you can see the hinge fastener holes being filled. After I filled the holes, I ran a continous bead where the hatch hinge overlapped the aluminum sheeting.



In this picture you can see the squeeze out from the sealant around the hinges edges and fasteners.



This isn't the only way to seal the hinge; however, I hope this gives you some ideas to think about.

[Mike46]

aggie79, thanks for the tip on the 3M product. Filling the screw holes was a concern for me In my new all plywood build, as we all know water will find its way in.

Mike

[RKH]

Thanks for the tip on the sealant. Does anybody have any input on the location of that flat aluminum piece in the "sandwich"?

[aggie79]

Keith,

Regarding the aluminum bar stock, here's a SWAG as to why it is there.

Hurricane hinges are available with no offset - the two flanges are in the same plane - or with an offset. The hinge with no offset allows a continuous profile along the roofline of the teardrop and the teardrop hatch. This picture is a chicken scratch of a hinge with no offset:



On the hinge with the offset, the flange on the galley bulkhead side of the hinge is higher (closer to the hinge point) than the flange on the hatch side of the hinge. I believe the offset is 1/4". (The hinge I used on my teardrop did not have an offset, and my memory these days is fuzzy, so I can't confirm the offset distance.) The offset hinge does not allow a continous roofline profile. The hatch roofline sits 1/4" below the teardrop profile roofline.

It appears that you have the offset hinge. My SWAG is that the aluminum bar thickness plus the compressed thicknesses of the butyl tapes are a spacer to "offset the offset" so that a continuous roofline profile is maintained even though an offset hinge is used. If this is true, you could save some complexity (and reduce places for moisture to infiltrate) by switching to a hurricane hinge with no offset.

Take care,
Tom

[RKH]

You may have the reason correctly, Tom.
The Little Guy of that era had the rear hatch setting above the roof line, not inset into a notch like most of the custom/homebuilts. (I've got the hatch off right now so can't get a picture.)
The hinge then may have set on top of the barstock and on top of the Filon roof to help make up some of the thickness of the hatch panel itself.
The actual leak developed where a piece of trim was added in front of the hinge at a 45* angle, rather than flat across the roof, probably to help even out that joint. By not being installed flat, the butyl on the back of the trim didn't seal but created a pocket where water could pool and eventually leak down through the screw hole.

With all that said, I believe I will just leave the barstock off completely if I can make the transition from roofline to hatch fit without it.