Galley walls and hatch

[Hubert]

I am wondering if there are some weight savings to be had by modifying the galley walls and hatch from what is described in Tony Latham's book. The sketch below shows a cross section of the galley wall and hatch as described in the book on the left. The construction process is to skin the wall of the galley on the inside and out just like the rest of the wall and then cut off the hatch side pieces. Then, an 1/8" spacer is glued to the inside of the wall, followed by the 1/4" galley wall that protrudes and seals against a gasket in a recess in the hatch.

On the right of the drawing is a design that removes 1/4" of plywood from the thickness of the galley wall. I would construct this by omitting the interior wall skin aft of the bulkhead and instead attach the 1/4" galley wall directly to the 3/4" skeleton. In Tony's design, there are about 7 square feet of galley wall area on each side. The modification would save approximately 12 pounds if Baltic birch is used for the plywood.

Is there any reason why the modified design might cause problems?

[tony.latham]

Is there any reason why...

It looks like you are considering removing the hatch wall cut-offs from the skeleton before the exterior/interior plywood is applied? Is that correct?

How are you finishing the cabin? Monstaliner? Aluminum? I'm trying to think through how this may cascade.

Tony

[Hubert]

Thank you for looking at this. I have been thinking about it for a while and can't see a problem with it, but I thought I'd ask here before I shoot myself in the foot.

I plan to use bed liner for the finish. The hatch wall cut-offs would have to be removed before skinning the walls if hand tools are used. I plan to use a CNC machine, so the hatch end pieces would be cut out separately anyway. The CNC would make it easy to cut the interior galley wall panel out of 1/4" right up to the bulkhead dado. The one downside to doing this I can see is that the wall would not lay flat on a table with the inside facing down. That means I would either have to glass the outside before skinning the inside or put a piece of 1/8" under the cabin area to prop it up. A benefit of building the wall this way would be that you can pre-finish the entire wall, including the galley area. The weight savings are not huge, but every little bit adds up and this modification does not seem to be more difficult to build.

[tony.latham]

A benefit of building the wall this way would be that you can pre-finish the entire wall, including the galley area.

You can pre-finish the walls, including the galley area, either way.



You're right about every bit adds up. When I built my sis's little 4 x 8' several years ago, I tried saving weight by cutting the lip so it didn't cover the entire galley wall. I think they were 3" wide. It was a mistake that cost additional work and didn't save much weight since I had to add material for the drawer slides.



CNC? Are you using my files or drawing your own? https://www.tonylatham.net/teardrop-cnc-files.html


Tony

[Hubert]

I must have misremembered about the finishing process, it's been a few weeks since I read the book.

I have downloaded your CNC files and have spent a good bit of time with them, they are really helpful. There are some modifications I want to make in the galley and maybe to the doors (I might go with prefab). I have only done a couple of small projects that were cut on a CNC, so I have a lot to learn before I start on the teardrop.

I have another question about the galley hatch. As I understand, the gusset is mainly there to prevent spring back when attaching the plywood skins to the hatch, and also to offset the strut attachment point. Would it be possible to eliminate the gusset aside from a small bump-out for the strut by using skins that do not stress the hatch?

[tony.latham]

Would it be possible to eliminate the gusset aside from a small bump-out for the strut by using skins that do not stress the hatch?

What are you planning on skinning with? I'd be extra leary of omitting them. When the hatch is closed, the struts are pushing with 180 pounds of pressure.

Tony

[Hubert]

That's a lot of force. I was thinking about 1/8" bendable plywood that has the grain running in one direction only for the skins. That should not put any stress on the hatch, or at least not enough to cause spring back. My other thought was to omit the plywood altogether and just use foam and fiber glass. That would help with the weight, but probably add a lot of work to make it look good.

Maybe I was not clear earlier. I don't mean to completely eliminate the gusset, just reduce the width of it so it does not take up so much room. Basically, make it the same width as the outside piece except for a bump out to mount the strut to. I don't plan to put a Propex heater behind the cooler where you have it and would really like to turn the cooler ninety degrees and get the counter top closer to the rear edge. There seems to be plenty of room (over 30" IIRC) behind the bulkhead, but the counter top is inset about 5" or so because of the gusset and the way the hatch slopes back at counter height. I can create a bit more room there by lowering the counter height and slightly changing the profile, but if I add the extra couple of inches for the gusset, I can't seem to draw a profile that I'm happy with. That's why I'm trying to reduce the size of the gusset.

[tony.latham]

but the counter top is inset about 5" or so because of the gusset ...

Go stand by your kitchen countertop. You'll find yourself about 5" from the edge.

My other thought was to omit the plywood altogether and just use foam and fiber glass.

I think you'd regret that. It would take a lot of epoxy, glass, and labor to make it work.

I was thinking about 1/8" bendable plywood...

You may make it work with a narrower gusset. I can say that if you use 1/8" Baltic and apply it with the grain and with my suggested gusset, your hatch will work fine.

Tony

[Hubert]

Go stand by your kitchen countertop. You'll find yourself about 5" from the edge.

It's not about how far away from the edge I stand, but about what the counter top covers and how long a drawer slide I can use for the cooler. I'd like to use 28" slides for the cooler if I can. With a smaller gusset I think I can make it fit and have the front of the cooler under the counter top.

I think you'd regret that. It would take a lot of epoxy, glass, and labor to make it work.

I would not attempt it the way shown in the picture. I think it might be feasible to cut cross sections out of 2" foam with the CNC and glue them together with wooden spars top and bottom. Would probably still involve a lot of work fairing, but I think it might be doable. Might save a good bit of weight, too.

You may make it work with a narrower gusset. I can say that if you use 1/8" Baltic and apply it with the grain and with my suggested gusset, your hatch will work fine.

As I understand, the original implementation of this hatch style was a lot beefier than what's described in your book. I'll try to take it a small step further and report back if it worked or not. The poplar plywood I have in mind is much weaker than Baltic birch and should not cause spring back. The only problem is that right now, I cannot get any 1/8" plywood aside from 2.7mm luan. I checked a couple of weeks ago and there was lots of stock (150+ sheets), today there's nothing. I don't plan to start before the Christmas holiday anyway, so I hope the situation improves before then.