Ok here we go...PMF!

[dales133]

Yep I'm home!
Slept most of yesterday and shopped to fill the cupboards today.
Tomorrow my best mate from pukekohe is coming over for the day , havnt seen him for 7 years.
Then back to work and TD building

[pchast]

Glad you are home safe.

[dales133]

Thank you kindly!

[Atomic77]

Glad you're back. Hope you had a great trip

[dales133]

Thanks bud had a great trip.
I'll upload some pics of the switches ect I got once I sort my phone out.
It's freaked out and lost a bunch of pics and wierd errors on the others.
Thankful google backed them up by the look of things.
Think I need to reset my phone of had an issue with a few things

[dales133]

Ok my resizing app seems to have worked.....had to completly reformat my phone as i was having camera issues.
Heres a bit of a teaser of what i was up to this afternoon.
First hatch rib jigsawed and flush trimmed to my jig then bullnosed.
Mums visiting from NZ so i just snuck in an hour or sos work when we got home from the markets ect before i cooked dinner.
The timbers spotted gum and i routed a slot and fitted a fillet of the same timber to hopefully add some strength to the join.
Im thinking of going for the 2 rib hatch method to keep weight down,what are your thoghts

[KCStudly]

Looks beautiful!

Looks to be about 2-1/2 inches deep (60-65 mm)? I guess it depends on what you plan for the rest of your hatch construction and how big your hatch will be. Looking quickly back thru your build it looks like you are at least 5 ft wide and plan on doing your hatch from bulkhead to floor. I would be very leery about going with only two ribs at that size, although depending on how many spars you have it might work. I did not use any spars and did have some slight variation in the inner skin. It tended to wing up at the outside edges a hair.

Forgive me if this has been covered all before, but it looks like you are planning to have the ribs exposed inside the inner skin, similar to my build. Are you planning to have an inner and outer skin with foam sandwiched in between, or just a simple single skin? If the latter I recommend that you either use more cross pieces with a deeper hinge spar than mine, more ribs, or both. My hatch is still pretty flexible diagonally; in other words, if I lift from either bottom corner it will twist some. I'm not so concerned about that on my build because I think that it will stiffen up considerably once I get the outer skin on; and even if it doesn't because I will be using linear actuators it will always be lifted evenly from side to side (for now I just make sure to lift from the middle, but if I'm not careful it will rub on the side walls... should have left about 3/8 inch gap between ribs and wall).

If I had it to do over I would have made my hatch hinge spar extend down to header off the ribs, instead of under slinging them under the spar.

[dales133]

hey KC thanks for the comments and ideas.
yes they are around 60mm x 38mm or there abouts.
i am planning on leaving them exposed as i personally like the look plus its alot less work but primarily for looks.
i had planned on making the top and bottom spars out of similar dimension timber and the intermediate spars out of 19 x 70 spotted gum decking ripped down to suit.
ive run out of the spotted gum material ... well i have one more piece left but i might be able to track some down.
its actually warf decking planks i had and its very well seasoned so it should be very stable.
as for the hinge spar on the body im going to make it dimensionaly bigger than usual and same with the hatch hinge spar, i have no plans to insulate at this stage but im open to sugestions.
if i was to rebate the spars in 10mm or so into the two outter ribs i thought i might be ok with riggidity.. now youve got me thinking.

Heres a couple more pics




The rough sawn wood off the wood pile is the timber i used for my ribs.
Quite the transformation.

[dales133]

.

[noseoil]

Those planks look nice once they're planed down from the rough-weathered look. Should be a nice hatch to compliment the build & galley. Never worked with "gum" as we don't have it available, but it has a nice warm look to it.

About the twisting & racking, if you use some corner blocking it should be OK. Are you going to install lights, stereo speakers or some other types of inserts in the hatch? If so, putting in blocking to fasten to will probably give it a bit more strength and help with the twisting movement. I agree with KC, two ribs may not be enough to keep things from twisting when opening & closing. I still think of a hatch as being a big hollow-core door (skinned on both sides). The ones we buy here have cardboard inserts for fillers on the inside and solid blocking at the edges, but they're strong because they have skins on both sides. I wouldn't recommend cardboard for inner ribs, but even some 3mm ribs & a second skin would help things out quite a bit. Just sayin'....

[dales133]

Thanks noseoil...how do you think if i did two ribs in 19mm (3/4) thick that would work?
I can get this stuff in 140 x 19 otherwise i can also get some fijian mahogany in 38 x 140 witch is quite nice.
Might wait to see a few more opinions before i proceed.
Does the hendricks method use only 2 ribs?i had a feeling it did

[KCStudly]

My 4 hatch ribs are all 3/4 thk x 3 inches deep. I don't have any issues with spring back, but it has "sprung" open slightly, then pulled back closed with heat and humidity changes; still not done building yet.

[dales133]

More food for thought...gotta go to the timber yard tomorrow so ill have a look at whats avaliable

[dales133]

Well i found some spotted gum today with the same dimensions without having to thickness it (32mm) and im in the process of deciding on 2 extra ribs,i hoped to work on them tomorrow as ive got most of the day off.

Has anyone built with just the 2 outter ribs and what benifits/problems did they face further down the track with lock mouns ect.
What are the main advantages other than possible stability improvements with multiple ribs.
Apreciate any input.
Cheers Dale

[KCStudly]

Tony Latham posted pics of his Fredrick's method hatch over on the Oregon Teardrop build thread, but it uses a much beefier deeply webbed/gusseted style of rib with additional beef coming from the extra wood used to build up the sealing area, and it is a relatively short hatch with less curvature.