Filling in huge vent hole? - Fiberglass RV

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Old 11-14-2005, 06:19 AM   #1
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New Mexico
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Since I removed the inop and sloppily installed Dometic refrigerator from inside my winter project and will not be replacing with another, the huge (and ugly) fan vent and vent-vents cut into outside wall are not needed. I was originally content with simply cleaning these up, but now am wishing to remove entirely, and fill the holes. A serious fiberglass job, for sure!

Likely will try doing the bottom vent first, since if I cannot make it without leaving a visible scar it won't be so prominent. I was thinking I should (temporarily) screw down a 1/16 thick sheet of plywood on inside as a form. Then layer in the fiberglass, cloth, etc from outside. How to get the exterior hole to match up and disappear is something I'd be trying to figure out as I go along.

Anyone have expericence with such a project? Is it wiser to leave the plywood form permanently in place...ex-settera?
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Old 11-14-2005, 08:49 AM   #2
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Why not make slide-outs for your pets?
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Old 11-14-2005, 09:01 AM   #3
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I'm of absolutely no help here (not unusual, I might add) but I have to comment that I've NEVER seen a kitchen-style vent like that on one of these trailers! I know they used them in the '50s on trailers, but I've never seen one on a glasser. Most interesting!

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Old 11-14-2005, 09:14 AM   #4
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A good question for a real experienced fiberglass repair person. That size of a fill will need structural integrity as the flexing could cause cracks. They may suggest a fiberglass matting for the inner part of the glass job?

I am filling a heater vent hole, 4" diameter right now located on the side wall. But it will be noticeable for sure. I plan to paint the body as I have a number of places I am repairing to get the original look back. I am also extending the entrance door lip out with a short lip on it to make the water run sideways and not down into the door.

Let me know what you finally decide.

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Old 11-14-2005, 10:08 AM   #5
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>>serious fiberglass job

Hmmm. Several thoughts come to mind.

Have you stopped by a local boat repair (or autobody specializing in corvettes) place ... and picked the brain of their fiberglass man?

Might even pull the rig by and get a quote. (Not suggesting you have them do it ... but you might get some suggestions.) (an autobody shop once fixed a trailer boo-boo for me).

My fear (like Gary's) ... they are pretty large holes ... and without some sort of reinforcement will flex and crack any filler fiberglass

Also, wonder if the lower hole could become an "outside" access door ... to a storage compartment. And make the upper hole a window. Depending on the dimensions of available RV doors and windows.
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Old 11-14-2005, 10:20 AM   #6
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>lower hole could become an "outside" access door

Change its dimensions and make it suitable for bringing in the pizza!
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Old 11-14-2005, 10:29 AM   #7
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New Mexico
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Charles, Gary, Roger, Jack..............

It's evidently all the doing of the original kit buyer who bought it with a minimum of Burro options and then proceeded to install (inflict) his personal vision.

No go on the window idea. It opens under the sink (which is on the right side instead of left, contrary to Burro's kit instructions.) Agreed, wise move would be to attempt to pick brains at a boat repair shop. Will look for an oppy to do that for sure.

Bottom opening is 19 1/2 x 10". Have found no replacement vents that size. Anyway I think a huge vent down so low is a big invitation for road rain wash to slop into the coach while in transit.

Regarding needed reinforcemnt, right on, hence possibly leaving in the plywood.

My dog's too afraid of this Burro to enter it.
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Old 11-14-2005, 10:30 AM   #8
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Send a message via Yahoo to Kurt & Ann K.
I'm concerned about flex/strength also. On a boat I used to have, the deck at the bow was large enough to have had flex problems, but the manufacturer had split cardboard mailing tubes lengthwise and fiberglassed them in place on the underside of the deck using f'glass cloth and resin. I could actually jump on that deck without any give. I would probably use long enough tubes to completely straddle the opening. Checking with someone in the trade is a good idea. Isn't there a curve that should be duplicated?
Please keep us posted on your progress.
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Old 11-14-2005, 11:04 AM   #9
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Myron, we need to see inside picture of this "custom" Burro and your progress. May I inquire what model your taken out frig is and what are you going to do with it? I need some parts for my frig and if your's is just going to the dump?
1979 Boler B1300 | 1987 Bigfoot 5th Wheel | 1988 Bigfoot 5th Wheel | We officially have a collection!
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Old 11-14-2005, 11:23 AM   #10
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I am also wondering what you are going to do with your tear out refer. If it is going bye-bye, can I get in line behind Lizbeth?
I have a 'Dometic RM24 A' that needs a 110V/12V switch, flint wheel & flint. I like the idea of putting a door on the bottom hole for outside access. Wish that recent old thread was available, someone just did that and posted pictures. It turned out great.

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Old 11-14-2005, 02:38 PM   #11
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I didn't have that strange upper vent with fan on mine but a regular vent. No door on top but my bottom vent door is the same. I elected to use those vents as intake and exhaust for a Walmart air conditioner. Works just fine, very comfy.
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Old 11-14-2005, 03:25 PM   #12
fudgie s.
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i am a sailor and frequently make fiberglass repairs on my boat, though thank goodness none so large as what you describe. i use west expoxy which is very simple and reliable. i would prep the area by sanding with 150 or so grit sandpaper and roughing up the edges of the opening and all sides of the opening a couple of inches inside and out and then clean with acetone. i would tape a piece of hard plastic to the inside of the hull of your trailer, ie, cut the bottom out of a large tupperware container or some such. prep would include using wide longlife blue tape in a square two or three inches outside the cutout. then from the outside, i would wet the edges of the area out using a small throwaway brush, (one of the metal handle ones that doesnt lose bristles), with activated resin. i would then fill the area and a couple of inches around it with a peanut butter thick mix of resin and proper catalyst ratio, (its easy 2/1), and a microfiller made by west. if it is too runny just thicken up a bit. but it must be smooth and wet. if you want a stiffer finished patch you could put in a bit of the coconut gap filler, but if you put that in then build in the gap, (doing two separate applications) but do not let the coconut exceed the width of the hull as it takes some grinding to make it disappear. i can't imagine that you would need that strength anyway, you just want to watertight it, not take it to sea. anyway, after you have filled the gap with the peanut butter, use a squeegee to smooth it out as close to the curve you desire as possible. then continue so that it bulges a bit more. the excess microfiller will sand off smooth easily with 150-220 grit. sometimes i wet sand. on a curve like this you would want to hand sand and go slowly. if you are in a cold climate use the quick kick catalyst. i use plastic cups to mix the stuff and plastic picnic knives to smear it in. mix only a cup at a time and if it starts getting dry, or heating up mix fresh.
wait 24 hours or until you can sand without clogging the paper. the epoxy does not stick to plastic and you should be able to free the tupperware piece. it might free a bit easier if you wrapped it first in saran wrap. if you wanted at this point to put a couple of layers of cloth on the inside, simply sand it down, wet it out with resin and then add wetted out cloth. after the outside is faired, (you can sand and add another batch of peanut butter if it isn't faired to your liking and sand again), sand with 180 or 220 and you can prime and paint the hull. it should be invisible.
a quick tip. the epoxy can be removed from your hands, (though i neglected to mention that you should wear surgeons gloves), with white vinegar, actetone is not good for you. you may tidy up any splatters or drips while in progress with acetone. this patch should be so much simpler than this long explanation sounds.
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Old 11-14-2005, 05:45 PM   #13
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I see three approaches to the cosmetic challenge of matching the patch to the existing shell:
  • give up and make panels that look like nicely fitted doors (even if they are fixed in place)
  • blend the patch in and paint the whole thing - but that means the whole trailer shell if the shell is currently in gelcoat
  • use matching gelcoat for the repair
I have near zero fiberglass experience, so I can't help much, but I'm interested to see what the more useful people think is the best approach. Personally, I would probably be making doors for outside-accessible storage, so it wouldn't be a big issue. I wouldn't want paint on the whole trailer just because of this one mod - I'm just thankful that my current Boler has decent gelcoat (in the original blah beige) so I don't have to paint or re-gelcoat.
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Old 11-14-2005, 06:46 PM   #14
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Trailer: Escape
New Mexico
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Have made no plans yet on the fate of the removed refrig. Don't know if it works and finding out is a zero priority right now. Hell, it might even work! Just too much else on my plate, but it's being kept warm and dry. Your interest in parts is duly noted and will be remembered.

To Fudgie the Sailor---- You sound like my guy. I have copied your instructions and will keep them close. Thanks. Question: wouldn't leaving the plastic in place, I mean securing it in place, acting as sort of a "splint," insure a stronger patch/fill? I mean without that its only the 1/16th or whatever thickness of the shell edge that's keeping a foot from driving through the filled opening. I would substitute a plastic or other thin material that the filler would adhere to and overlap the opening a couple inches. Oh, and the vinegar trick---how I wish I knew about that a few weeks ago! Yeah, I got the gloves now.

Lizbeth---- here's a shot from the inside. Those are fallen leaves on the ground outside. And that's my new sub-floor, skim coated with fiberglass, and the cabinet doors I made. There'll be more in good time.

Brian --- I'm considering making the nicely fitting door idea and in fact I did make one but just don't like what I did. It's a good idea for me because I just finished bringing the entire gel coat back up and the results have cancelled earlier plans to paint the exterior. May try again.
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Old 11-14-2005, 07:02 PM   #15
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The exterior paint-matching problem is a big one for me. I know without a full paint job no way this patch will come out invisible.

Hey, here's an idea that just came to me: What if I follow through with Fudgie's directions but on the outside I build up a phony frame relief, say 3/16" thick, that looks like its door trim. Then I just paint the new fiberglass "door" and if it's a different shade of white it won't matter. A template would shape the doors' edge.
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Old 11-15-2005, 11:56 AM   #16
fudgie s.
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attaching an inner piece of wood is a great idea for two reasons, it is hard to get the epoxy to fill in on such a vertical surface without falling out, (don't know if you could somehow jack the trailer to create a downhill to the hole area), i don't know alot about the construction of these trailers, (though i am shopping for one and learning alot), but it seems to me they are so flimsy that drilling holes in them is a bad idea. the backing plate will create a 'hard spot' in the hull and i am also a bit inclined to think that given the thinness of the walls, (and what seems to me to be a brittleness), you might want to keep the flex of the unit...i also had mistakenly thought you were planning to paint the whole trailer anyway. the great thing about this epoxy with filler is that it is like playing with clay and as i can not measure..(i have to use pieces of string for some reason), and i know nothing about woodwork, you can mold it however you like. as far as strength goes, if the epoxy kicks nicely in place, you could hit it with one of those door busters the cops use and it would not give.
ps: i am a lady! i singlehand my little boat with my best friend lola, another middleaged girl, my chihuhuahua.
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Old 11-15-2005, 06:06 PM   #17
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Just came in from spending the afternoon covering the lower vent opening with 1/16" plywood base. Made it lap over on inside, nearly 2 inches.

Prep wood with a dry-fit and drill holes all round that will take sheet metal screws to make a fit tight to the wall. Then slathered much Bondo gel all round the inside where wood will lap wall. Moving fast, now, I put the wood back in place, braced from behind so wouldn't move, then ran around to the outside to screw it all in tight. When resin hardened I removed the screws. It worked! Oh, yes, Fudgie s., this will be strong patch.

Then added 2 layers of fiber cloth into more Bondo. Tomorrow will add more layers to build up exterior the new wall.

(Tell Lola I think this Burro can go to sea.)
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Old 11-30-2005, 07:03 PM   #18
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New Mexico
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UPDATE: Today's weather got back to the 60's so I removed the kitchen fan previous owner had installed behind the fridge. There goes another 30+ pounds of ugliness. Same routine applied: screwed in 1/16th ply set in fiberglass filler - remove screws when set. Will build up the outside wall as a circle this time.
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Old 12-04-2005, 11:26 PM   #19
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British Columbia
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Hi, Just a thought, a trick I have used and seen other people use is to sandwich a piece corrugated cardboard that fits the opening and then do about 3 layups of choped strand fiberglass matte on each side. You will have to Bondo, sand, prime and paint the outside no matter how you procede. When you get cardboard soaked down with resin you would be amazed how strong it is. Helicopter blades are made with a fiber type beehive honeycomb core in side and the covered with a plastic layer, I can't remember what type though.
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Old 12-05-2005, 07:22 AM   #20
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Looking like you're moving right along Myron

FYI: The ONE thing that trashes moisture. I'm certain we've all seen bondo that's falling out of a repair on motor matter how well the surface is prepared. It's typically caused by moisture coming in from the backside. My point, is make certain the repair is completely sealed from the inside of the trailer. None of us like to think about water, etc. coming into the inside, but you never know. Unsealed wood can absorb moisture like a sponge. Sure would hate to see all this hard work look bad after a year or two.

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