Ravenswing

Need ideas for a safer, better escape hatch

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Yesterday we had Farrier F36 Ravenswing tri romping across the SF Bay "slot", taking water over the leeward float deck, throwing spray everywhere through the nasty chop, etc. (should have reefed!). Went below once things calmed down behind Angel Island, and was SHOCKED to find the escape hatch wide open and about 18" of green water in the aft cabin. No wonder the helm felt wallow-y. We took on hundreds of pounds of water in a short time. Not good. On the ocean this could have been a swamping disaster.

At rest, the bottom of the hatch is about 8" above the water. At speed, to leeward, it's half submerged. The hull builder had installed a 2-dog Bomar deck ventilation hatch, and I (as finish builder) completely missed the fact that it is a skimpy deck model (major builder/owner mistake :(   The slapping waves yesterday pounded at the leading edge (top hinges, bottom dogs) enough to flex the plastic dogs away from the aluminum frame. I found handles had not been rotated. The dogs just don't reach in to the frame enough for this kind of duty. 

So, today, cleaned up the boat and my undies... why again do we want a damn window in such a dangerous place?   Questions for you all:

1) With our 18.5" square cutout, it looks like Vetus Magnus Heavy Duty MAG4747SL is the only offshore hull rated multi-dog escape hatch that fits. Anyone know of another? 

2) I have the hull cutout. (3/4" tongue and groove red cedar, glass uni skins) Thinking of bonding an outer flange, waterproofing the works, and through bolting it in place, with a wrench placed inside and out for backing out securing nuts. Who has a better execution idea?

3)  Do we really need to be able to get in from the outside???  If the boat flips and people are outside, aren't we going to swim in through the companionway anyway? I'd prefer a flush exterior, and nice big hand-turning wing/ring/knurled knob/etc. nuts inside...

4) I've read Lagoon is putting fixed safety glass windows, with car windshield breakers strapped nearby.  Could we really make a watertight window on a 20+kt tri hull near the waterline?  That sounds risky too. 

Please venture forth your clever ideas or actual experience. So glad this shit happened in the bay, close to our marina. 

Thx

-Greg

 

photos of the current hatch are in this blog post:

https://cartersboat.com/2017/11/

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In the Australia regs, escape hatches are only required for Cat 1, 2, 3 and 4 racing. This applies to all boats longer than 12m and less than 12m if built after July 2006.

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I mounted my [Moonlight] escape hatch with the hinges at the bottom. Not much use for feeding the ducks or peeing out of but easier to use when everything is the other way up.

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We've been using Goiot hatches ever since Lewmar discontinued making escape hatches. The Goiot are insultingly expensive, but they work. De-core and make a monolithic mounting flange on the inner skin. That leaves the hatch basically flush to the outer skin on a typical 25mm core thickness hull. 

A clever idea that I've seen is sticking on a clear mylar film outside the hull to fair the escape hatch. Presumably, a panicked man could break the adhesion of the mylar and bust his way out.

 

http://goiot-systems.com/en/escape-hatches/

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1) I had that Vetus hatch on the foredeck of our cat that would be regularly under a lot of deck spray / waves. It's a good one.

You do want a CE Category A hatch (designed for hull topsides and highest water pressure).

2) Mounting it recessed so waves don't hit the gasket directly is very important. i.e. recessed or small lip wave breaker on 3 sides. I really like the Mylar idea if it is never opened for ventilation. Could you just use Mylar tape over the seam though if the hatch is recessed?

3) Sure, the "break here" glass is fine. Research submarines have windows :).  It's a cheap approach but it does prevent leakage.

9 hours ago, Jethrow said:

In the Australia regs, escape hatches are only required for Cat 1, 2, 3 and 4 racing. This applies to all boats longer than 12m and less than 12m if built after July 2006.

Not that I think they should be required - but that is odd. i.e. only somebody racing will capsize.

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Take the Vetus Magnus, they are relative cheap for a class A hatch ,  I did want a round one and the only one I could find was the Goiot, I got three ones before I did get a good one. The first two had handels what just picked with a couple off mm the opening part, my shop had to press Goiot to deliver beter quality because they first did not want to change.

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Greg,

Will send the constructive drawing and pictures of the custom, flush fitting, 400 mm round hatch we built on Skateaway which still looks and works like new thirty years later.

Less compromising to the boats structure, lighter, safer when passing through (don’t need to gash your shoulder adding to your predicament after capsizing offshore), easy to open from inside or outside the boat - in the dark - no heavy plexiglass to degrade and fall out of the frame when the mastic fails and a tiny fraction of the cost - plus you get the satisfaction of creating and adding another piece of beautiful workmanship to the rest of your fine craft

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While boardhead's solution is likely to be rock solid, and Soma's mylar would do the job...since it only had an issue once on a big water day in the slot ... I'd just goop it up with RTV to keep the water out.  A sharp knife and it is operational again if (heaven forbid), you need it. Granted, I don't do ocean crossings, so maybe you want it perfect and instantly available.

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Yeah, perfect fit and as bulletproof as possible is the mission here. Gathering materials today and will report back to all on building this weekend and installing next week,  per "boardhead"'s ideas.  Stay tuned. 

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Sorry to hear this. You have put so much hard work into Ravenswing and had more than your share of new boat 'shakedown' issues. Sending you all the best!

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5 hours ago, boardhead said:

Greg,

Will send the constructive drawing and pictures of the custom, flush fitting, 400 mm round hatch we built on Skateaway which still looks and works like new thirty years later.

Less compromising to the boats structure, lighter, safer when passing through (don’t need to gash your shoulder adding to your predicament after capsizing offshore), easy to open from inside or outside the boat - in the dark - no heavy plexiglass to degrade and fall out of the frame when the mastic fails and a tiny fraction of the cost - plus you get the satisfaction of creating and adding another piece of beautiful workmanship to the rest of your fine craft

Boardhead,

     Does TRANSIENT still have the homemade minimalist escape hatch that we built just before leaving for the Two-STAR? You should have seen the looks on the faces of the Royal Western Yacht Club 'scrutineers' faces when they were doing their inspection of the boat when we arrived in Plymouth.

    Grab a photo of that simple hatch if you can, (if it is still there). 

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Quite a few years back - more than ten - Tim had Transient ashore in Lanoka and decided to open and service that “escape” hatch. After removing all (a lot of ‘em) the fasteners - maybe an hours work, shiny side up, dry, in daylight, with a big screwdriver and wrench - Tim gives the “hatch” a kick - no go - after many fierce kicks it’s like the fasteners had never been removed! He set about the perimeter with hammer and chisels - he got pretty hot so that part might have bee better immersed up to his shoulders in cold water, in the dark, but probably not!

Did you draw a circle, drill some holes and make a fake hatch Rasp? Just kidding but no way was the “hatch” or Tim coming out that hole! 

After weighing his options Tim ground out a faired ring around the bolt circle, inboard and out, epoxied some biaxial into that ring, dressed it off, primed and painted the area and the “hatch” disappeared.

I guess that “hatch” didn’t leak and the structural weakening was minimal but a hole cutter and saw would have been a lot faster escape from or better re- entry to Transient’s interior.

Good job the RWYC inspection crew didn’t ask you guy’s to “demonstrate the operation”  

Transient should have an escape hatch, especially given the offshore miles she has covered, but she doesn’t.

Only X-Rays would reveal it’s existence now.

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I always wondered about the goop holding that hatch in, especially on the race late at night as you had to look right at it across the hull from the head of the bunk. Most of the time it was covered up with foul weather gear though. I know we didn't use 5200 and it may have been Silicone. After your account here I would probably use cheap PolySeam Seal bathroom caulk. Did you say something about a lot of fastenings?

     I had a cabinet shop just across the street from the beachresort in our bay. I used the old (2 nails and a loop of string) method of making a slightly elliptical template which I cut out on my bandsaw and delivered to the owner/skipper who used the template to carefully cut around it with a sheet rock saw in about 5 minutes.

6673-Irwin-Protouch-Drywall-Jab-Saw-01-1k.jpg

    I took the inside cutout panel back to my shop to clean up the cut and using a router and guide made a doubler with about 2" overlap on the inside and 1" on the outside. When I got back to the boat the edge of the cut in the hull had been cleaned up and epoxy coated. I had pre-drilled all the holes on the drill press back and the shop and it was quick work to fit the ring to the hull and glue and recoat everything. The elliptical shape let you turn and pass the hatch piece through the hole and it was pretty quick and simple except for making those double headed wingnut/bolts. I wanted to fabricate an elaborate thing in my shop but TRANSIENT was always such a Simple Is Beautiful mindset that there was no need (or time) for that. 

    Are you aware that my reference to Simple is Beautiful above is how TRANSIENT was built on the plug/mold of a small trimaran project done in Dick Newick's backyard on the Vineyard. It was actually SIB (Small is Beautiful) but Simple was more of the philosophy rather than just merely Small.

Quoted from this excellent synopsis of Newick.

http://stephenlirakis.com/?p=6951

Dick Newick and Jim Brown, coupled with Phil weld’s bankroll and enthusiasm, focused on working sail, particularly for third world countries. they built SIB (for Small Is Beautiful, after e.F. Schumacher’s seminal book),

    I guess adding the shelf took up about half the space of where the original hatch was. 

Better link to the Newick article (with photos).

http://www.stevencallahan.net/images/proboat/newick-dec2010.pdf

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21 minutes ago, Rasputin22 said:

Quoted from this excellent synopsis of Newick.

http://stephenlirakis.com/?p=6951  [***AVOID THIS!***]

Dick Newick and Jim Brown, coupled with Phil weld’s bankroll and enthusiasm, focused on working sail, particularly for third world countries. they built SIB (for Small Is Beautiful, after e.F. Schumacher’s seminal book),

    I guess adding the shelf took up about half the space of where the original hatch was. 

Better link to the Newick article (with photos).

http://www.stevencallahan.net/images/proboat/newick-dec2010.pdf

The post you refer to at stephenlirakis.com is a rip off of Steve Callahan's article, and poorly done at that.  Avoid it!  Read the original at Steve's web site.: Intuitive Dynamics

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27 minutes ago, ProaSailor said:

The post you refer to at stephenlirakis.com is a rip off of Steve Callahan's article, and poorly done at that.  Avoid it!  Read the original at Steve's web site.: Intuitive Dynamics

Woah there! Didn't you see where I provided a link to the Callahan article in my post? The one I described as 'Better link'? 

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5 minutes ago, Rasputin22 said:

Woah there! Didn't you see where I provided a link to the Callahan article in my post? The one I described as 'Better link'? 

Yes, I did.  Just emphasizing the point and steering people away from the bad link you posted, which unfortunately will increase search engine traffic to his corrupt web site.

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8 minutes ago, Rasputin22 said:

So what makes Lirakis' website corrupt?

The specific page you linked to is a corrupted copy/paste of Steve Callahan's article.  That's not the way the web is supposed to work.  Posting the link to his page gives his whole web site a lot of traffic for no good reason.

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1 hour ago, Rasputin22 said:

So are you saying that Lirakis himself is corrupt or just his website?

Really Jody?  You need further clarification?  You posted a junk link, deal with it, as we all must in our own way.

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What makes that link a junk link? It showed up on a web search and I did notice that the photo links were not valid so I searched further down the list and came across the Callahan link via ProBoat and included that with a note that it was better and showed the photos. What else should I done beyond that point? You haven't really clarified anything since you can in with you sleeves rolled up calling people corrupt and ripoffs. Asking you to give your reasons for calling it a junk link is just my was of dealing with it. Have you looked at other pages on the  Lirakis website? Are they corrupt too? Lots of good articles there, should we beware of them? 

    That junk page does have at the very top attribution to Callahan and the same links that I posted and you later somehow hid the real link behind the Intuitive Dynamics underlined name (how do you do that?) so I don't think Lirakis may even be aware that his photo links are dead. How would one fix that? Just curious.

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8 hours ago, ProaSailor said:

The post you refer to at stephenlirakis.com is a rip off of Steve Callahan's article, and poorly done at that.  Avoid it!  Read the original at Steve's web site.: Intuitive Dynamics

 

8 hours ago, ProaSailor said:

Yes, I did.  Just emphasizing the point and steering people away from the bad link you posted, which unfortunately will increase search engine traffic to his corrupt web site.

Proa I have a hard time figuring out what you are going on about.

Perhaps you could clarify why you seem to have such a hate on for stephenlirakis.com. I’ll admit it’s a not particularly enthralling site.

He has on his site an article written by Steven Callahan that appeared in Professional Boatbuilder. He provides a link to Steve Callahan’s work. He clearly attributes the article and describes it as “Provided Courtesy of Professional Boatbuilder magazine & Steven Callahan”

That would imply he has the author and publisher’s permission. If so who are you to object? If not then plenty of reason to object. Do you know that it is reproduced without permission? If so have you contacted Callahan and Professional Boatbuilder to inform them?

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1 hour ago, KC375 said:

Do you know that it is reproduced without permission?

Yes.  I'd rather say no more and didn't mean to imply anything about the rest of that web site except that the Callahan article "mirrored" there is a corrupt copy of the original, which is available directly.  And the corrupted copy doesn't deserve the attention it gets from search engines and from posting a link to it here.

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I also very much subscribe to the KISS or Simple Is Beautiful rationale - complex is heavy - heavy is slow - I don’t like slow!

Closed cell neoprene sheet was probably not available in the time and place you hastily installed the hatch but that is the way to go.

Adhesive sealants like silicone and 5200 will never release with the kind of surface area you describe.

As I recall the wing nuts needed a wrench to apply sufficient torque to back them off and the build up of multiple coats of paint over the years jammed the threads up.

I will take some pictures of the hatch on Skateaway, open and closed, inside and out, next week  and post them here. That hatch opens in seconds and re- seals tight, without resorting to sealer and I will take a scale along to weigh the component. Also there are a couple of appropriate sized Lewmar Ocean series hatches in the loft, still in their original boxes that can be weighed for comparison, 

 

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12 hours ago, ProaSailor said:

Yes.  I'd rather say no more and didn't mean to imply anything about the rest of that web site except that the Callahan article "mirrored" there is a corrupt copy of the original, which is available directly.  And the corrupted copy doesn't deserve the attention it gets from search engines and from posting a link to it here.

Fair enough. If an article is copied in its entirety without permission from the author and publisher, that is offensive and should not be perpetuated. I can see how you could legitimately call the article corrupted as the quality of cut and paste is poor, mixing in photo captions with the body and losing some sections. Given your legitimate concern about this, and in particular about not perpetuating the google search engine ranking, have you informed the original author and publisher – Google gives some guidance on dealing with this here. The few people I know who raised like issues with Google were satisfied.

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On 6/13/2019 at 6:32 AM, soma said:

We've been using Goiot hatches ever since Lewmar discontinued making escape hatches. The Goiot are insultingly expensive, but they work. De-core and make a monolithic mounting flange on the inner skin. That leaves the hatch basically flush to the outer skin on a typical 25mm core thickness hull. 

The Goiot 49.42 hatch has a recall because of failures where the lens comes out of the frame with very bad results. They also are sending out reinforcing kits for the breaking glass style hatches as well (Lagoon escape hatch).

 

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So is the new hatch installed yet Ravenswing? You should lose a few pounds, mine weighs four compared to nineteen or more for a similar port sized deck hatch, which tends to leak in that application. 

Any time/cost numbers to share, or were you having too much fun creating your solution from offcuts to keep track!

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40 minutes ago, boardhead said:

So is the new hatch installed yet Ravenswing? You should lose a few pounds, mine weighs four compared to nineteen or more for a similar port sized deck hatch, which tends to leak in that application. 

Any time/cost numbers to share, or were you having too much fun creating your solution from offcuts to keep track!

https://cartersboat.com/2019/06/23/suction/

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Looks good, the only thing I'd say is carbon is anisotropic (or so I'm told) so fiber orientation around the gudgeons counts.

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What gudgeons?

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On 6/14/2019 at 12:24 PM, boardhead said:

Will send the constructive drawing and pictures of the custom, flush fitting, 400 mm round hatch we built on Skateaway which still looks and works like new thirty years later.

Less compromising to the boats structure, lighter, safer when passing through (don’t need to gash your shoulder adding to your predicament after capsizing offshore), easy to open from inside or outside the boat - in the dark - no heavy plexiglass to degrade and fall out of the frame when the mastic fails and a tiny fraction of the cost - plus you get the satisfaction of creating and adding another piece of beautiful workmanship to the rest of your fine craft

Hi @boardhead

could you share the design of your custom round hatch with me as well? I want to add some escape hatches to my new (to me) boat and think that a simple laminated hatch is a good solution to this problem, even if the videos you can shoot though a plexiglass escape hatch are pretty cool. :)

Paul

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Hey Paul, if you would like to PM me with a # I can call you on we can discuss and if my design makes sense on your boat (it did on Ravenswing) I can send you the drawing.

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Improved being more complex, heavy and expensive, should fit right in with the direction current multihulls are heading.

The acid proof stainless steel is really essential for those hardy individuals who frequently go for a spin in the calderas of active volcano's - don't forget your asbestos sailing suit!

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OK. but it's dark out now so will take some pictures in the morning.

Was working on the core of a new daggerboard for the Newick Native "Let's Go" all day, glorious day in New Jersey - too nice to check in on Anarchy!

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And man invented headlamp - there you go Russell

Outside view above, inside view here. This hatch adds only four pounds to the weight of the boat, does not leak, does not corrode, seize up with salt or take a piece out of you as you pass through. I made new hand nuts last year, the original seal is still good. Greg started this post and he built his new hatch just like this one to the drawing I gave him. Cost him a couple days work using offcuts left over from his F39 build.

1577579095424112003344.jpg

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Wow, Now I'm interested! I'm a long-time student of custom watertight hatches and have built many with varying success, but with more success recently. I have gone away from neoprene gaskets and am now using black Latex surgical tubing set in gasket notches that are almost as deep as the gasket itself. The surgical tubing has perfect memory, meaning it can be squashed flat for months and still pop back to its original profile. It's not perfect in other ways, but I'm learning about those areas too.

I sure would be interested to know how you are achieving gasket pressure with the above hatch.

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5/8" UNC stud with those plastic hand nuts. The outboard closure disc acts like a big poppet valve so no need for a lot of static seal pressure, over clamping closed cell neoprene destroys it. Waves smacking against the hatch drive it onto the seal to momentarily cinch the gasket.

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6 hours ago, boardhead said:

5/8" UNC stud with those plastic hand nuts. The outboard closure disc acts like a big poppet valve so no need for a lot of static seal pressure, over clamping closed cell neoprene destroys it. Waves smacking against the hatch drive it onto the seal to momentarily cinch the gasket.

I don't understand the mechanism?  Only one 5/8" UNC stud?  In the center?  Connected to that round white piece with finger holes?  Are there two disks, one inside and another outside?  Maybe inside and outside photos would help?

What about waves that don't smack the hull/hatch from abeam but come from straight ahead, possibly lifting an edge?

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15 hours ago, boardhead said:

And man invented headlamp - there you go Russell

Outside view above, inside view here. This hatch adds only four pounds to the weight of the boat, does not leak, does not corrode, seize up with salt or take a piece out of you as you pass through. I made new hand nuts last year, the original seal is still good. Greg started this post and he built his new hatch just like this one to the drawing I gave him. Cost him a couple days work using offcuts left over from his F39 build.

1577579095424112003344.jpg

It’s a simple and quite attractive piece that works easily. I was amazed at how simple it is just like the rest of Skateaway when I got the tour. Boardhead knows his stuff inside and out and there is not one ounce of wasted material on Skateaway. That would be slow to him!

Hell, he even stripped all the gelcoat and old heavy hatches from his Catamaran and rebuilt it to be a fast passage maker even with all the joinery and auxiliary power still aboard. He maximizes everything through minimization. 

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1 minute ago, Russell Brown said:

I don't get it either.

+1...

there has to be an external and an internal disk, separated by a flange. Maybe the plastic piece is just to tighten it all up, like a nut on a grinder arbor.

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17 hours ago, boardhead said:

Outside view above, inside view here. [...]

1577579095424112003344.jpg

Oh, you already posted inside and out!!  Missed that.

So it looks like two large disks, one inside and one out?  Connected in the center by a 5/8" threaded stud?  The white disks with finger holes act as large diameter "plastic hand nuts" on both ends.  The lanyard connects the two disks when the center stud is loosened completely and the disks become separated?

Can either disk fit through the hole?

Can it be locked to secure the boat when away from it?

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I guess it doesn't matter much if neither disk can fit through the hole. It's an escape hatch, not an every day use hatch. Seems pretty smart.

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Love it!  Keep going guy's - you ONLY need what you need - one piece doing two jobs - good, one piece doing three jobs - BETTER!

That hatch was designed and built 30 years ago - in all that time the external Awlgrip has been stripped and repainted three times, the inside paint, gasket face, gasket and stud are original, the hand wheels/nuts replaced once (the inside one was still good, I donated it to Ravenswing)

Waves hit from every which way, the  outside surface of the hull and the hatch are flush, the leak path is long and the resilient gasket is wide and not over compressed so it retains it's cushion and seals. 

The hand wheels have finger sized holes for grip and the lanyard is there to hold the opposite side nut when you - wet, cold and frightened, in the dark,seek to escape or gain shelter. This hatch is NEVER locked and if anybody wants to remove it and get in that way - go ahead - knock yourself out!

So I did the drawing in 06 for my buddy Charlie to install on his TRT 1200 which was in a yard in Wa. He was advised by the experts to install square deck hatches so he paid them to do just that - they leaked from day one - his yard bill for that winter was 43G - they still leak and look old now.

DIY boys!

1577679674024179148153.jpg

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Hey Rasp - Tim Ross, owner of Transient hanging out on Skateaway.

1577680302283275275870.jpg

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1 minute ago, boardhead said:

Hey Rasp - Tim Ross, owner of Transient hanging out on Skateaway.

1577680302283275275870.jpg

Thanks for that photo. I have to drop in on you guys the next time I'm up that way. Nice drawing for the hatch.

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11 hours ago, boardhead said:

Love it!  Keep going guy's - you ONLY need what you need - one piece doing two jobs - good, one piece doing three jobs - BETTER!

Not sure I get what you said. It is a two-piece hatch where neither piece can fit through the hole. It's simple, but probably not that easy to use for ventilation, etc. 

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The goals were always:-

     Easily opened - in the cold, wet and dark, from inside and out.

    Strong, light and watertight.

    Ventilation purposes.

Non important things included:-

       Watching the water go by.

       Quick bolt in.

       Being lockable

The hatch was designed and installed during the main hull build - two years before completion and launch - on this type of boat and for the intended use it was very important and yet, to date we never even came close to needing it.

Our previous trimaran had a more conventional, hinged, lockable hatch which leaked and was smashed open by wave impact.

We do use the hatch for ventilation, at anchor, on hot rainy days, using it makes all aboard familiar with it's operation.

What you quoted me on, Russell, was my general design philosophy, not specifically regarding this hatch but there are a helleva lot more parts in a commercially available hatch to up the cost, weight and go wrong.

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5 hours ago, Russell Brown said:

Not sure I get what you said. It is a two-piece hatch where neither piece can fit through the hole. It's simple, but probably not that easy to use for ventilation, etc. 

Couldn’t it be easily be made to fit through the hole by making it slightly oval? Not sure I know what you’re getting at.

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8 hours ago, boardhead said:

What you quoted me on, Russell, was my general design philosophy, not specifically regarding this hatch but there are a helleva lot more parts in a commercially available hatch to up the cost, weight and go wrong.

Agree. Thanks for sharing the details. I'm in hatch hell at the moment trying to complete four very complex curved watertight deck hatches, so thinking a lot about complexity and compromise.

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If you make it oval the gasket loading would be uneven but it might still seal OK.

I never really considered passing either the outboard (sealing) or inboard (clamping) disc through the 400 mm aperture as the closed hatch integrity is much more important.

The hand wheels/nuts and stud could be arranged with an inboard locking pin such that nether nut unscrews until that pin is withdrawn but, again, not a priority and I believe locks only keep honest folk out - maybe I have been lucky in that regard.

Anyway, it's a simple and different approach, certainly could be modified to better suit personal preferences.

Apparently food for thought - enjoy!

Good luck with your deck hatches, Russell - I spent a lot of time creating dead flat faces set into curved decks and utilized Lewmar Ocean series but replaced the plexi with foam cored panels in the amas - they seal adequately. Another trick there is to only dog them down tight when necessary - with green stuff washing the decks - thus preventing the sealing gasket taking a set.

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21 hours ago, he b gb said:

Couldn’t it be easily be made to fit through the hole by making it slightly oval?

Good idea.  Here's a Rhino/Grasshopper model for that:

hatch_ellipse_2019Dec31a.thumb.png.08a05252b3f4eaba2b4638a23d6ffeb7.png
hatch_ellipse_2019Dec31a.gh

Notice the difference between the max diameter of the opening (21" horizontally) vs. the minimum "size overall" (~19.5" vertically), leaving only 3/4" clearance either side (1.5" total) when the hatch is rotated to pull it through the hole.  Here is a front view; the inner red line is the edge of the opening, leaving a 3/4" rabbet all around plus 15 degree bevel.

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Happy New Year.

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When weight is not a factor...  Seriously love the "Hidden Hinge" though - can that be done in lightweight composite?

 

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That's great but the rule was/is 400mm minimum (OSTAR) so the circle represents the minimum compromise to the structure and going oval for the benefit of bringing the closures thru the aperture is just taking a hit weight/strength wise for an arbitrary purpose that I would not tolerate - maybe that's why my strong offshore capable 40 is in the Formula 40 weight bracket.

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FOUR pounds added to the NO hatch equipped spec.

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On 12/30/2019 at 3:23 PM, boardhead said:

Love it!  Keep going guy's - you ONLY need what you need - one piece doing two jobs - good, one piece doing three jobs - BETTER!

That hatch was designed and built 30 years ago - in all that time the external Awlgrip has been stripped and repainted three times, the inside paint, gasket face, gasket and stud are original, the hand wheels/nuts replaced once (the inside one was still good, I donated it to Ravenswing)

Waves hit from every which way, the  outside surface of the hull and the hatch are flush, the leak path is long and the resilient gasket is wide and not over compressed so it retains it's cushion and seals. 

The hand wheels have finger sized holes for grip and the lanyard is there to hold the opposite side nut when you - wet, cold and frightened, in the dark,seek to escape or gain shelter. This hatch is NEVER locked and if anybody wants to remove it and get in that way - go ahead - knock yourself out!

So I did the drawing in 06 for my buddy Charlie to install on his TRT 1200 which was in a yard in Wa. He was advised by the experts to install square deck hatches so he paid them to do just that - they leaked from day one - his yard bill for that winter was 43G - they still leak and look old now.

DIY boys!

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Thanks for sharing this Boardhead, was a bit tricky to interpret initially from the pics as the inside so neat, now get that the internal disc is a strongback & very helpful in loading the seal evenly. I love to learn new things & this year is looking great so far!!

Regards from Jeff.

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A mock-up sketch of a "hidden hinge", limited to 90 degrees rotation.  Needs detail work.  Instead of two "arms", it might be stronger to have just one long semi-cylinder arm...

hatch_ellipse_2019Dec31b.gif.8096aa3e2c16a234c3635f4e18206d96.gif

Maybe next year, Cheers.

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33 minutes ago, ProaSailor said:

A mock-up sketch of a "hidden hinge", limited to 90 degrees rotation.  Needs detail work.  Instead of two "arms", it might be stronger to have just one long semi-cylinder arm...

hatch_ellipse_2019Dec31b.gif.8096aa3e2c16a234c3635f4e18206d96.gif

Maybe next year, Cheers.

Yep - just managed to take a simple, successful device and turn it into complex flawed interpretation.

Love the disemboweling bracketry, the finger severing pinch points and the compromised gasket loading guaranteeing it leaks.

Can you even start to imagine that thing slamming open and shut in the kind of sea conditions it gets deployed?

Congratulations

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4 hours ago, ProaSailor said:

When weight is not a factor...  Seriously love the "Hidden Hinge" though - can that be done in lightweight composite?

 

Kidding - right?

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My buddy Brandon (Turn Point Design) has built a bunch of hatches and doors, some using the style of hinges that proa has shown. He runs a CNC shop and builds multiple molds and infuses the parts from carbon. They're incredibly complex and probably work really well, but well out of my price range (lots of them are for the military). I do think there's room for a custom composite shop to do nothing but hatches, but they will be very expensive, especially because so many of them would be custom shapes for specific uses. I'm working on a book about hatches. it will be for intended for home-builders, but could provide inspiration for hatch designers as well. I think that Boardhead's escape hatch is well conceived as a simple custom hatch that serves its purpose.

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10 hours ago, boardhead said:

Can you even start to imagine that thing slamming open and shut in the kind of sea conditions it gets deployed?

I can imagine many things.  I can imagine considerable difficulty dealing with your outer hatch thrashing around on a short tether because it can't be retrieved through the opening.  I can imagine leaving my boat on a mooring in Hawaii and finding that someone has boarded it through the unlocked escape hatch.

I can imagine refinements that allow 180 degrees of rotation instead of only ninety.  I can imagine the door being removable once opened.  I can imagine more secure variations (without the screw heads showing) of this flush two pin hinge idea for getting 180 degree rotation of the hatch:

664695540_71RAr152IL._AC_SL1400_.thumb.jpg.a0f3c74e274d4ebb5d9f0820f497e0c4.jpg

The animation was a quickie concept sketch, not a proposal.  The "compromised gasket loading" is only in your mind.  The full 3/4" rabbet for the gasket is shown only as a line in the animation but would be as before, as you have done,  allowing for the hinge.

Chill brah, read the thread title again, the key word being "ideas".  Simplicity and light weight are always preferred, of course.  Cheers.

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Single "hinge" with minimal intrusion.  Dark blue ring leaves 3/4" rabbet all around with 3/8" tubing (yellow) as gasket.  A second hinge (not shown) to allow 90 degrees more rotation (180 degrees total) could be located where the arm attaches to the hatch, pinned or latched somehow at either zero (as shown) or 90 more degrees.

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Still missing details like latching mechanism, pivot rod support and the finer points like clearances, fillets, materials, etc.  A concept, not a plan!

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4 hours ago, ProaSailor said:

I can imagine many things.  I can imagine considerable difficulty dealing with your outer hatch thrashing around on a short tether because it can't be retrieved through the opening.  I can imagine leaving my boat on a mooring in Hawaii and finding that someone has boarded it through the unlocked escape hatch.

I can imagine refinements that allow 180 degrees of rotation instead of only ninety.  I can imagine the door being removable once opened.  I can imagine more secure variations (without the screw heads showing) of this flush two pin hinge idea for getting 180 degree rotation of the hatch:

664695540_71RAr152IL._AC_SL1400_.thumb.jpg.a0f3c74e274d4ebb5d9f0820f497e0c4.jpg

The animation was a quickie concept sketch, not a proposal.  The "compromised gasket loading" is only in your mind.  The full 3/4" rabbet for the gasket is shown only as a line in the animation but would be as before, as you have done,  allowing for the hinge.

Chill brah, read the thread title again, the key word being "ideas".  Simplicity and light weight are always preferred, of course.  Cheers.

The title seeks to find a workable alternative to the disaster Ravenswing inherited with the 20 year, 3 owner build. His priorities matched mine. Ideas were pitched, he considered options and built to my suggestion.

I am ALWAYS interested in a better way to get the job done.

Give me something positive and I'm all ears but your refinements are all more costly complications adding the prospect of bodily injury and leakage.

I don't need to chill, the compromised gasket loading is real - you are engineering a problem - expensively!

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36 minutes ago, boardhead said:

the compromised gasket loading is real

What are you talking about?  I haven't mentioned any latching mechanism yet, only a way to move the flush hatch up out of the recess in the hull while keeping it attached to the boat.  I don't believe your inner disk contributes significantly to gasket clamping pressure though, if that's what you mean?  Pulling the outer disk at its center can be done without an inner disk.

But I hadn't said that yet, so what are you talking about?  I can appreciate the elegance of your proven design, I just have some issues with it, as stated.  To be clear, I wouldn't use it on my own boat.  Obviously(!), nobody wants "disemboweling bracketry [and] finger severing pinch points" or leakage.  But why get so bothered by me exploring a concept on this forum?

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44 minutes ago, ProaSailor said:
1 hour ago, boardhead said:

the compromised gasket loading is real

What are you talking about?  I haven't mentioned any latching mechanism yet, only a way to move the flush hatch up out of the recess in the hull while keeping it attached to the boat.  I

I suspect you might want to make sure the hinge doesn't constrain  the lid when in the closed position. Maybe like the slotted gudgeons on a lavac head seat assy?

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1 issue I could see with boardhead's design is it depends on panel stiffness (or flex depending on perspective) to seal. For some that might require tuning. The simplicity is hard to beat, the idea of being able to either pull it in or latch it open for at mooring access is nice, one could figure out some kind of internal lock that wouldn't need to be complex for at risk spots. I have a fixed plexi 10" port in my wingdeck that I'm thinking of upgrading to a 16" hatch but it's well above waterline, too far above I suspect in the event of inversion it might not stay dry. Under wingdeck hatch like boardhead's might work instead. One negative is a 16" escape hatch is about $600 +.

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Thanks weightless.

Bruno - panel stiffness and long term loading deflection is not an issue with this construction but good point.

It IS an escape hatch and l feel that making any concessions to it's long term water tightness and functional dependability as and when the time comes to use it is misplaced.

Obviously for placement on a single or compound curved surface this simple design would not be appropriate but horses for courses!

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This opening is 20 inches wide by 17.5 inches tall, the white pivot pin (1/2" diameter) in the red mounts is 18.3 inches long.
The elliptical hinge arm is 7.2 inches "tall" by 1.6 inches thick with 1/2 inch of clearance under it, so 2.1 inches of width is lost to it.

I have no idea how to build it, what materials and scantlings are appropriate, etc.

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hatch_ellipse_2020Jan1c2.gif.e494d398f3c736834b4617762ab7c246.gif

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OH BOY!!!!

I am just not gonna bother.

Hope you are having fun!

 

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All you need is a computer and a LOT of free time. 

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13 hours ago, ProaSailor said:

This opening is 20 inches wide by 17.5 inches tall, the white pivot pin (1/2" diameter) in the red mounts is 18.3 inches long.
The elliptical hinge arm is 7.2 inches "tall" by 1.6 inches thick with 1/2 inch of clearance under it, so 2.1 inches of width is lost to it.

I have no idea how to build it, what materials and scantlings are appropriate, etc.

hatch_ellipse_2020Jan1c.gif.165edc17e00af3e5fb9bf34894bcf0f1.gif

hatch_ellipse_2020Jan1c2.gif.e494d398f3c736834b4617762ab7c246.gif

That actually looks pretty good from a production and finger crunching standpoint. The hinge is a bit bulky, but everything is a compromise when it comes to hatches. Like I said, there's room for a composite hatch builder. It would take a lot to make it work, but with a CNC machine, infused parts and good design work...

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That hinge could maybe use a base plate.

There's a video making the rounds of a firefighter in full kit getting through between 2 ladder rungs, astonishing.

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Been spending way too much time staring at his front loading washing machine - they leak so we own a top loader!!

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Only engineers can turn a discussion about a hatch into a shitfight.

 

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Only engineers can turn a discussion about a hatch into a shitfight.