Hatch Masters

[madjack]

Jim we used vertical ribs that were 3" wide at the bottom, tapering down to 2.25"(?) at the top, we only left an 1/8" gap between the ribs and side and will put a stop screw in the hurricane hinge to keep anything from sliding around...we fitted the hatch frame on the tear and wedged/shimed it in tight and then used Gorilla Glue and brads to apply the skin...it sure seem to have worked out fine by us
madjack

[Jim Marshall]

Thanks a bunch Jack. I appreciate the information. I may have goofed up though, I thought I had read that the ribs were 1 1/2 inches so I installed our countertop in our galley 2 inches back so the hatch would clear the top. Maybe I could put more than 6 ribs in to make up the differance. What do you think?

[madjack]

Jim, we used 4 ribs onna 4' wide hatch, so your six should be sufficient, one thing I think that helped, was that the hatch was wedged/locked in position on the tear when we skinned it...it couldn't move...after the glue up for the skin, we left it alone for 24 hrs before raising the hatch...a week now and no problems so far...as with everything we have done so far, all wood pieces were stained and finished before final assembly...another reason why we used Gorilla glue...we will take the hatch off and shoot another coat of polycrylic onit to tie everything together
madjack

[Gage]

1 1/2" will be ok. That's what I did. Now I have 1/8" birch skin, inside and outside. You'll have the same strength. You'll find that if you plan on skinning both the outside and inside, you can almost lay the hatch on the ground with the outside up and stand on it with no damage. Althought I don't recommend it. Even though the Madjack and I did it a little different than each other, we still end up with the same results. A nice strong hatch with no spring back.

Have a good day.

[Jim Marshall]

Thanks Jack and Gage, that is reassuring to know. I feel confident with building the hatch now. My next main hurdle will be figuring out how to make our doors seal but I will post that in another thread when I get real close to that.

I have done wood working for over 37 years and this is different and refreshing, I am learning so much from you guys and having a ball. Thanks again for the advice fellows.

[Guest]

Jim,
I'll be using 4-3/4" x 2 1/4" internal plywood ribs and 2-3/4" x 3" hardwood ribs on the sides of the hatch. I'm going to assemble the ribs and other framing members on the tear, then move the hatch over to a clamping form, which will contact against the interior 1/8" skin. (I also made a template for the exterior, but will probably only use that for a referencing template after the 2 layers of exterior skin are applied) I needed to nocth the master template back 3/4" at the hatch location and this is why I made all these templates first. The templates will be used as a guide to cut/trim the parts and sidewalls with a router.


Rib Templates


Clamping Form Template


Notched Master Template

[Jim Marshall]

Dean, I hadn't thought about two thicknesses of skin on the outside of the hatch but I like that idea a lot. I have been a little concerned about the 1/8 inch plywood being strong enough at the seal contact area. I plan to make a template also and cut our ribs with a router, I feel more confident that they will all turn out the same that way. I am a little confused as to why you are cutting back 3/4 of an inch though. Is that for your spar at the top? I thought about using solid oak for our ribs but I am afraid with the way the grain of the wood runs it would break so I am using the import Birch plywood. It is something like 12 ply, the best I remember. Thank you for taking the time to post the pictures, that is a big help my friend.

[Jim Marshall]

Dean, after reading your post again, I was thinking about a couple of the fellows that did have spring back. When I saw where you were talking about using your template, I had this thought. Maybe the guys that had spring back could make a template and check to see how much spring they had. They could cut short ribs, using their template as a guide,a hair short and screw them in between their horizontal ribs and pull their hatch back into shape and recheck with the template as they put the short ribs in. The could do a dry fit to see if the short ribs were short enough, then after the hatch is pulled back to the correct shape, they could go back and glue and screw them then. It is just a thought.

[Guest]

Jim,
My tear is going to have woody sides and will have a border trim around the profile. I'm going to carry that border trim on the hatch as well, except it will set out an 1/8" from the sidewall for clearance on the sidewall.
I didn't want to only have the two layers of 1/8" ply supporting the trim, so I'm going to laminate a couple of hardwood strips underneath the hatch right up against the outer ribs and they will extend out as far as the 1/8" ply. I'm also going to laminate a single strip of hardwood on the notchout on the sidewall to cover up the end grain on the wall. I'm figuring 1/2" for strips on the hatch, 1/8" stip on the sidewall and 1/8" for hatch seal... 3/4" total. That's why the sidewall will be notched at the hatch location.
Here's a side diagram...

Note: This diagram shows a dado on the external hatch rib, that's where I'm considering putting the reccessed snaps. I need to think this over a bit before decideing to comitt to it or not.

[Jim Marshall]

Dean, now that will work, I like your thinking and understand what you are doing now. I may have to rethink the way we were going to do ours. That does make a lot of sense. Thanks for explaining that to me and for the diagram.

[Guest]

Jim,
In case you're wondering... There will be two seals side by side. That dado in the sidewall is meant to be a gutter, in case wind driven water gets past the first seal on the outside of the wall. It's not really needed, it's just something I'm gonna try.

[Micro469]

Jim,
My tear is going to have woody sides and will have a border trim around the profile. I'm going to carry that border trim on the hatch as well, except it will set out an 1/8" from the sidewall for clearance on the sidewall.

Dean, did you think of planing your trim down by 1/8 to match your sidewall trim?

[Guest]

Micro,
Yes... The trim on the sidewall will be an 1/8" thicker, the trim on the side of the hatch will match the outer profile of the trim attached to the sidewall.
I know at highway speeds, it seems like that 1/8" gap will be a funnel for water to get in, but I think with the double seal, I won't have a problem of water getting into the galley while traveling down the highway. I didn't want a split in that trim, (Except at the hinge of course) which is really like a corner moulding...

[Jim Marshall]

Dean here is a sketch of how I plan to do our seals, I may have to include the gutter in between the two seals. I am just overly concerned about leaks.

[Guest]

Jim,
Are you attaching the seals to the sidewall or the hatch?
I considered attaching them to the sidewall and that would give me an automatic gutter, but I opted to attach them to the hatch, so that they are up and out of the way when the cook is in the kitchen!
No.. Huh-uh, my kids wouldn't poke at them if they were attached to the sidewalls... Not My Kids!!!