How To Build A Steel Hatch From Scratch?

[xymotic]

Does anyone have any links to diagrams or guides on how to build a nice waterproof hatch (metal) from scratch?

I'm particularly interested in flush mounting it if possible, but everything I can think of for 'how' to seal it leaves a ring of water around it making the deck itself vulnerable to corrosion.

The "easiest" way I have thought of is 3/4 stainless angle with the lip out, weatherstripping on top, and a lid that overlaps the angle. But it seems like a trip hazard.

And I've completely failed to find anything online that has useful diagrams or profiles showing a good way to do it.

[Lepke]

I think it's cheaper to buy a ready made one than build one. Years ago I built boats and couldn't build one for what they could be bought.
Attached is the drawing for a hatch I installed on my current boat. I paid about $450 on sale. But the time you buy the metal, cut and weld, fabricate clamping system, and so on, you have 20 or more hours. Not even minimium wage.
And it won't look as good.

[Schooner Chandlery]

How big does it need to be?


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[Snowpetrel]

Originally Posted by xymotic

The "easiest" way I have thought of is 3/4 stainless angle with the lip out, weatherstripping on top, and a lid that overlaps the angle. But it seems like a trip hazard.

I did exactly this on Snowpetrel1. The angle was more like 40x20mm as I cut up some stainless RHS to make the coamings.

The hatches were mostly folded aluminium with a nice angled 60 deg flange rather than 90 degrees. But I alao made one with angle stainless and perspex. For the main skylight.

They never leaked, and were welded to the deck.

Bit of a job getting them all square and flat, without too much warping.

[Briarpatch]

Xymotic,
I built two steel hatches with frames for my Roberts 36 Cutter (using Bruce's sketches as a guide) awhile back. Boy was I proud of them!
But after they were finished (several months later), I realized that they were heavy, did not pass any light and the sealing relied on neoprene seals and I still had to address the dogs.
I ended up removing the entire hatch assemblies with my blue wrench and purchased two Bomar aluminum framed hatches. I built the frames to match the hatches.
I agree with Lepke, buy off the shelf hatches. They are engineered (and not over engineered with a SF of 10 or higher).

[xymotic]

Originally Posted by Schooner Chandlery

How big does it need to be?


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The ones that are there now are about 24x11 and they suck because they were not square, the PO had them welded closed and they were corroding pretty bad which is why I cut it out.

I want to make them bigger, and these are in the rear, I'd like to make them so that they can open with one mechanism like a butterfly and ventilate the rear compartment. Don't really care about light because it's not over a living space.

And I have oodles of time, but no money
They are in the bottom of this old pic.


http://www.ontheboat.net/gallery3/va...g?m=1329406474

[xymotic]

Originally Posted by Snowpetrel

I did exactly this on Snowpetrel1. The angle was more like 40x20mm as I cut up some stainless RHS to make the coamings.

The hatches were mostly folded aluminium with a nice angled 60 deg flange rather than 90 degrees. But I alao made one with angle stainless and perspex. For the main skylight.

They never leaked, and were welded to the deck.

Bit of a job getting them all square and flat, without too much warping.

What thickness Aluminium did you have to use to avoid flex when standing on it? I think 1/8 would actually be "ok" but I'm leaning towards 1/4 but then I think that might make bending the edges problematic.

[xymotic]

Originally Posted by Briarpatch

Xymotic,
I built two steel hatches with frames for my Roberts 36 Cutter (using Bruce's sketches as a guide) awhile back. Boy was I proud of them!
But after they were finished (several months later), I realized that they were heavy, did not pass any light and the sealing relied on neoprene seals and I still had to address the dogs.
I ended up removing the entire hatch assemblies with my blue wrench and purchased two Bomar aluminum framed hatches. I built the frames to match the hatches.
I agree with Lepke, buy off the shelf hatches. They are engineered (and not over engineered with a SF of 10 or higher).

Don't the Bomars also "rely on neoprene" to not leak?

Some of their cast Aluminium ones sure are pretty though. That's what I wanna make for something less than a grand though...

[xymotic]

Originally Posted by Snowpetrel

I did exactly this on Snowpetrel1. The angle was more like 40x20mm as I cut up some stainless RHS to make the coamings.

The hatches were mostly folded aluminium with a nice angled 60 deg flange rather than 90 degrees. But I alao made one with angle stainless and perspex. For the main skylight.

They never leaked, and were welded to the deck.

Bit of a job getting them all square and flat, without too much warping.

Did you make the hinges or use a pre manufactured one of some sort? Any pictures?

[xymotic]

Originally Posted by Lepke

I think it's cheaper to buy a ready made one than build one. Years ago I built boats and couldn't build one for what they could be bought.
Attached is the drawing for a hatch I installed on my current boat. I paid about $450 on sale. But the time you buy the metal, cut and weld, fabricate clamping system, and so on, you have 20 or more hours. Not even minimium wage.
And it won't look as good.

Thanks for the reply, I have a few problems, # 1 I just "don't wanna" spend the money.

#2 I actually plan on fabricating some sort of power mechanism to open these. and I'd hate to mess up a 'nice' hatch.

#3 if you look at the PDF you attached, honestly part #4 is the only thing that's freaking me out because it seems like that design still holds water to the left of the gasket. Seems like you could make it out of U channel and put a drain in.

But you are right about the dogs etc. I've got no clue how to do that bit other than buying something.

[Snowpetrel]

Originally Posted by xymotic

What thickness Aluminium did you have to use to avoid flex when standing on it? I think 1/8 would actually be "ok" but I'm leaning towards 1/4 but then I think that might make bending the edges problematic.

I used 1/8 plate, but I welded some 50x6 flatbar stiffners in an X pattern underneath to strengthen them. They felt rock solid. As I said I only had them folded about 60 degrees down, giving a nice water and rope shedding edge.

Interesting looking boat. Any more pictures?

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[scherzoja]

xymotic,

I didn't make a hatch, so can't help you there, but I did make the riser arms for my two 20" bomar hatches. The crappy aluminum raisers broke, but used them as a model and made a pair out of stainless. I stuck a stuff spring in the tube to catch some of the momentum when the hatch closed.

Good luck.

https://picasaweb.google.com/1112749...HatchRebuild02