Access "port" for Alde yellow flappers, T@B 400 . Done !

B0atguy · December 2025

Been putting off this mod for a while now . Warning , this project is not for the faint of heart ! lol
I am getting tired of pulling the rear bed apart every-time the Alde needs the "air cushion" burped, or every-time we need to winterize our T@B 400 . Seems kind of silly to have to completely take apart the rear bed just to have access to the little "yellow flappers" for the Alde and Alde Flow for various reasons . Has to be a better way (ahem , NuCamp !) !
Have a trip down south (Florida Gulf coast) shortly , and will need to winterize the 400 fairly quickly before we head back north to PA into freezing temps . Decided to install an "access" port to easily gain access to the yellow flappers without taking apart the rear bed .
Purchased a 4" marine access deck plate , (overall is approx 6") and CAREFULLY drilled a small hole (ok, its a LARGE hole !) , in the side of our 400 !
Measure 10 times , cut once is the motto here ! I used a 4 1/4" hole saw , but had to trim it slightly larger so the port would fit snug. I think a 4 1/2" hole saw would work better actually . Placement was perfect in a 2024 400 , but the tolerances are very tight and leave NO room for error .
Installed the new access deck plate , sealed it up with silicone and it works perfect . I can easily reach my hand/ arm in and access both yellow flaps within seconds . Just unscrew the access port cover and reach in to find the yellow flaps. Easy peasy . No more tearing the rear bed apart !

Warning - attempt at your own risk ! Measure , measure, measure - then measure again . Then drill / cut .

If you get it wrong , there is no going back !

Here are some pictures .

BandB · December 2025

@B0atguy great work! We did that to access our 2022 320 Alde fluid reservoir. Great idea to install one for the yellow flapper, too, but I'm not sure we dare cut through the outer wall like that. Bravo!

B0atguy · December 2025

BandB said:

@B0atguy great work! We did that to access our 2022 320 Alde fluid reservoir. Great idea to install one for the yellow flapper, too, but I'm not sure we dare cut through the outer wall like that. Bravo!

Thanks ! Yes, it was a bit of a nerves of steel kind of thing , lol . Was fairly confident in my measurements , and also had a trick up my sleeves with a little help from mother nature .
On one particular cold but damp morning , all the internal framework and structure of our 400 revealed itself . At least I knew I was not going to be drilling through an inner support structure member ! Just had to make sure I did not drill through the edge of the internal box that holds the Nautilus component's .

Image: https://us.v-cdn.net/5021717/uploads/editor/sb/0xgc6osruhv1.jpg

HedCount · December 2025

This is a great idea. I didnt have the guts to cut the skin of the trailer so I took a different route. I cut an access hole in the deck below the mattress and above the valves. Unfortunately, that means we still have to tear apart the bed, but at least I no longer have to lift the whole plywood panel out to do a simple job.

Image: https://us.v-cdn.net/5021717/uploads/editor/j1/rav7j2jpi324.jpg

B0atguy · December 2025

@HedCount , that is a great alternative to "major surgery" .
Nice work !

We also use a mattress topper on the rear bed , so 1 more thing to get in the way and remove to access the yellow flaps. I don't love the placement of the access port I had to drill through the sidewall (because I have OCD, lol) . It just looks a little awkward , but it was literally , the only possible location to drill/install it to reach both yellow flappers .

Binghi · December 2025

That’s the problem with placing essential equipment and storage compartments under the bed - hard to access with all that bedding on top. But then, in trailers (especially small ones), you don’t want to waste that space. I partially alleviated the problem in my 2021 400 BD by installing hinges above the Alde compartment along the outboard edge of the platform at the head of the bed and re-hinging (if that’s a word) the platform above the storage compartment in the middle of the bed. Not perfect, but it helps.

I notice the trend continues in NuCamp’s new trailer the Haven. Looks like entire bed platform is hinged at the head of the bed and you access a bunch of storage by lifting the foot end of the bed up, aided by a couple of struts. That must be fun with the mattress in place and the bed all made up.

The joys of trailer life!

Maxcamp · December 2025

Another creative alternative was posted last year:

https://tab-rv.vanillacommunity.com/discussion/18238/modification-to-access-yellow-flappers-from-nautilus

jimcenname · January 6

The nice thing about the 2019 400, a cargo door for access to the Alde area, no Nautilus.

Image: https://us.v-cdn.net/5021717/uploads/editor/j0/yf88xe4o7h7r.png

B0atguy · January 7

@jimcenname Lucky !
Cant say I love the Nautilus system . It makes things pretty convenient , until something doesn't "flow" right . Then its a maze of hoses and valves to trace . So far , my Nautilus has been pretty ok.

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Access "port" for Alde yellow flappers, T@B 400 . Done !

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