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Need ideas for a safer, better escape hatch


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Post 100 is just another example of why most wouldn’t contribute here.
 

Plus, just like Proa, I have never designed an escape hatch

2 hours ago, ProaSailor said:

Following your lead, it has degenerated into another SA pissing contest for skunks.  So typical.

And for Keith to be treated in this manner is unnecessary. 

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Looking at Boardhead's drawing, I don't think a full internal disk is required, Its only function is to provide a fixed point for the center bolt to draw tension, it could be any shape strong-back, like an I-beam and therefore lighter. Also an oval section shouldn't lead to unequal gasket loading as long as it is symmetrical.

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1 hour ago, Mizzmo said:

Looking at Boardhead's drawing, I don't think a full internal disk is required, Its only function is to provide a fixed point for the center bolt to draw tension, it could be any shape strong-back, like an I-beam and therefore lighter. Also an oval section shouldn't lead to unequal gasket loading as long as it is symmetrical.

100% agreement on both points!  @he b gb suggested the oval solution that allows bringing the detached hatch aboard in post #59 and I modeled it in post #63.

hatch_ellipse_2019Dec31a.png

That single, simple, minor change satisfies 90% of my concerns with the design @boardhead presented.  It has a bonus of increasing diameter of the opening by ~2.5 to ~3.5 inches in one direction.  Might add a pair of keyway notches to help rotational alignment of the elliptical hatch.

I would choose "I-beam" over inner disk to mount the inside handle that pulls on the center of the hatch.

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Yet as usual, Proasailor is wrong. Handy with Grasshopper (a plug in for Rhino 3d modelling software) but sadly lacking in real world design ability.

Boardhead offers us all drawing of a proven, reliable, simple and lightweight escape hatch that has worked for years (thanks), and you want him to provide a video? 

If you want to retain the inner or outer hatch, a piece of string with a fishing line swivel will do. An offset hinge like the one modelled will always compress the gasket closest to the hinge and make sealing harder.

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It has everything to do with engineering and if you can’t recognize the advantage of the inner disc vs your bar scheme I sure as hell am not going to walk you through it, step away from the computer and open your mind.

Still talking FOUR pounds added weight, low tech materials, no tooling, no computer time, utilizing offcuts at build time and DIY (read inexpensive - but only if you get on with the job and stay away from the computer). 

Bit cold around here at the moment to make a video of a four year old or a granny escaping out or entering from outside but sounds like fun and I have volunteers in mind - watch this space.

BTW this really isn’t an upsmanship contest, a question was asked, options suggested and decisions made, go make yours any way you wish, I really don’t care.

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It has everything to do with engineering and if you can’t recognize the advantage of the inner disc vs your bar scheme I sure as hell am not going to walk you through it, step away from the computer and open your mind.

Still talking FOUR pounds added weight, low tech materials, no tooling, no computer time, utilizing offcuts at build time and DIY (read inexpensive - but only if you get on with the job and stay away from the computer). 

Bit cold around here at the moment to make a video of a four year old or a granny escaping out or entering from outside but sounds like fun and I have volunteers in mind - watch this space.

BTW this really isn’t an upsmanship contest, a question was asked, options suggested and decisions made, go make yours any way you wish, I really don’t care.

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15 minutes ago, boardhead said:

It has everything to do with engineering and if you can’t recognize the advantage of the inner disc vs your bar scheme I sure as hell am not going to walk you through it, step away from the computer and open your mind.

Still talking FOUR pounds added weight, low tech materials, no tooling, no computer time, utilizing offcuts at build time and DIY (read inexpensive - but only if you get on with the job and stay away from the computer). 

Bit cold around here at the moment to make a video of a four year old or a granny escaping out or entering from outside but sounds like fun and I have volunteers in mind - watch this space.

BTW this really isn’t an upsmanship contest, a question was asked, options suggested and decisions made, go make yours any way you wish, I really don’t care.

How did more time go into this discussion about the oval escape hatch on a trimaran? The owner of TRANSIENT probably spent less time BUILDING his hatch than this thread has generated... 

    Of course he and I might have been surprised if we couldn't have broken the caulk line mid-Atlantic as I think Boardhead has hinted... 

    That simple hatch would have worked with the central knob idea I think. Those simple hatches to close those offshore WC's on tris such as Virgin Fire are pretty effective with just a simple crossbar and a Spanish Windlass to clamp them down and I think that their horizontal orientation to the water surface probably makes them subject to higher water slamming and pressure loads. 

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All true Rasp and the hinged, lockable hatch on my previous trimaran that was smashed by wave action was indeed horizontal.

It’s just amazing how much you learn when you build a boat then race and cruise to the limits of your expectations whilst being honest to yourself about it’s shortcomings.

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8 hours ago, Max Rockatansky said:

FWIW, @boardhead‘s idea has given me inspiration to replace the rectangular (stock) hatch in my Catana’s bridge with something similar. Only in the case of my rectangle, I’ll have to use two latch mechs to even up the pressure distribution. Nevertheless, simple is elegant, and thanks for the idea @boardhead

Ravenswing who opened this discussion filled in the corners and made his round, making the rectangle seal really is a PITA.

The “outside disc that’s bigger than the hole” is particularly relevant to your under bridgedeck location as the intensity of the wave action is greater and the inner disc offers added stiffness and a secondary seal - with gravity aiding drainage along the way for free.

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Round is nice, I kind of like the idea of elliptical but round works with lathes, trammels, dividers etc for easy machining/building on the bench.

Retaining the pieces could be very handy- as Zonker points out some string could retain the hatch & hatch boards often retained with lanyards- some webbing maybe 2 pieces could be bonded with some slack allowing the hatch to shiggle into its correct position- or a connective lanyard between inner & outer given the pieces don't fit through the hole. Zonkers point on the hinge restraint very valid.

Wondering how thickish acrylic sheet or polycarbonate might go- would definitely be heavier(even sink!) but see through & might be relatively easy to machine a nice cove for Russel B's surgical rubber/O ring arrangement- kind of like the sound of it.

If tooling developed for the hatches having the inner & outer the same could be advantageous(& similar for any install) but moves away from using the "cutout" piece which is good to use too.  In contact/female molded hulls the hatch could be set into the mold with the landing molded in situ- would be nice to experiment that along with a standard molding for retrofit. Some small amount of "crown" in the hatch could be nice also.

The full disc on the inside is magic, on materials subject to creep a much deeper return within the hull would be nice/necessary to use if a single strongback used- maybe a spider arrangement with 4 or more legs could look groovy but at what level of complication- with strategic uni fibre to the inner disc some cutouts would be possible but at the cost of having two hatches sealing with inherent sealing redundancy..

Having the handwheels set flush could be more streamlined/neat but would require that more material be used in the hatch skins to compensate- Boardhead's drawing really illustrates the inner skin meeting the outer and supporting very strategically the bearing area of the nut & hard to argue against that.

All as above just thinking out loud on the concept & obviously complications can be the enemy of good..

Regards from Jeff

 

 

 

 

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Good logical thinking - each time you come up with heavier, costlier, shorter lived, less resilient, more complex look for an alternative or a justification.

That way regular guys can afford these wonderful craft.

Thanks for the downvote Proa - real constructive

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11 hours ago, Sail4beer said:

Post 100 is just another example of why most wouldn’t contribute here.
 

Plus, just like Proa, I have never designed an escape hatch

And for Keith to be treated in this manner is unnecessary. 

Pretty sure Proa Owned Moxie.

So  why don't you FUCK OFF and leave this thread to the adults.

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7 hours ago, Russell Brown said:

Well, as much as I agree with Octopus, this thread has gone south. I'm out.

Plus one. 

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Owning 1/3 Moxie has given Joe waaayyy too much street cred. Sure he had a great run in the 80’s - location is everything. All I ever get from him now is google search results and insults to everyone. Then he’ll claim ad homonim attacks as he always does. Thin skin and thick skull. 
 

Keith designed every aspect of Skateaway and offered a real world tangible solution for the OP which was accepted and adapted for use.
 

The fact that you important guys never tell Joe to cool his heels a little drive people away from this thread who would otherwise offer their opinions and design ideas for the crowd to consider. Zonker seems to understand the situation here. 
 

And I don’t think that many of you act like adults on this thread. The multihull threads are the most toxic of all the forums, which as usual, marginalizes the entire multihull community as zealots and dogma guardians.

Have at it...

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Heading offshore on a weeks cruise and no service so won't be able to respond but for now:-

Recessed round is the best approach for sealing and minimal compromise to surrounding structure.

Because of the higher burst potential with underwing slamming I would increase the hatch perimeter angle from 15 to 30 to improve that and reduce the likelihood of jamming.

I would also increase the size of the inboard perimeter flange and improve the filament orientation, still simple to build but a little different.

You might also want to consider the capsized location of the hatch - maybe need to stand on the table underside and reinforce it's fastening accordingly.

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  • 2 weeks later...

Well that thread went well. Jesus. Proa part-owned MOXIE as a used boat for a while, huh? ....

...who the hell cares?

boardhead, you have some really cool stuff going on. Will take a closer look later at the whole shebang. Thanks for putting it all up here!

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I was in awe of Moxie until we raced against her in a Buzzards Bay Regatta twenty five years ago, quite sobering!

She was perfect for the time, place and job in hand - the 1980 OSTAR. I recall talking to Nye Williams in Blagdons yard, Plymouth in May and him telling me how Phil Weld had dumbed down his 50’ rocket ship with a 50’ stick and all roller furling sail plan - the geriatric rig - man, did Phil teach everybody a lesson about percentage performance yield - the ‘ol man won!

Nye had the fore decks off Starpoint, a Greene 53’ tri that he was beefing up in way of the foreword beam attachment, the following year she made it to the TWOSTAR finish while her sister ship came undone with Mike Birch asking his co-skipper, Walter about the warranty situation!

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As the originator of this thread, I took Boardhead's drawing, built the new 2-rounds hatch and went sailing. Had no idea the thread got 100+ posts until I logged back in tonight to the forum for the first time this year. The comments back and forth make me want to share a little more... Working in a rush during the unanticipated haul out, too far from home tools, I wasn't able to cut perfect circles for (1) the hull hole, (2) the outer disk, (3) the inner disk. Result is the alignment can get off just a bit, and then the seal isn't perfect. Also, my first version of the hand-nut was made by me threading in not-strong-enough plastic. It was departure day from San Francisco, aiming for Los Angeles. Crossing the bay, the hatch weeped just a little bit so I went to crank down on the inner nut one more time. And of course I stripped the threads, compromising the whole works. An emergency stop in Sausalito and call to the wife to ask for a hardware store run and "bring the big drill" resulted in a beefier through bolt and big metal wing nuts. In refitting the outer disk lying on the paddle board in the afternoon chop, the imperfect cuts revealed the importance of the inner disk for holding the outer disk in its correct position. That wouldn't happen with a straight board or other less-than-hole filling solution inside. Again, just making the two disks is a straightforward ask and very elegant solution. In my case the execution wasn't perfect but using thick enough "wetsuit" rubber has kept that hatch watertight in Ravenswing's first 1700 miles offshore. The outer disk has a lanyard permanently connecting it do the net, so we don't lose it during an emergency. And thanks to Boardhead, Skateaway's "old" interior hand-nut is now Ravenswing's outer nut. I posted pictures of all this last fall up on Ravenswing's site, cartersboat.com   Search on Escape hatch and it should come up for anyone wanting to see the DIY version. 

Now looking forward to sailing her LaPaz to Puerto Vallarta in early Feb. Gotta stop at Isla Isabel to see the Boobies!

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@Bruno Why did you downvote Ravenswing's helpful update.

I assume that was just an error in clicking. If so easy enough to fix. If not can you elaborate on your concern?

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1 hour ago, KC375 said:

@Bruno Why did you downvote Ravenswing's helpful update.

I assume that was just an error in clicking. If so easy enough to fix. If not can you elaborate on your concern?

Fat finger failure, was trying to give upvote, still can't get it to work.

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I never made the connection of this thread to Ravenswing and his boat.  Sort of justifies the lengths and excesses this thread has grown to. That guy will try anything and if it breaks, leaks or just doesn't satisfy him he will just try it all over again. His rebuild thread is amazing.

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30 minutes ago, Rasputin22 said:

I never made the connection of this thread to Ravenswing and his boat.  Sort of justifies the lengths and excesses this thread has grown to. That guy will try anything and if it breaks, leaks or just doesn't satisfy him he will just try it all over again. His rebuild thread is amazing.

That’s Greg!

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I love the elegant simplicity of Boardhead's hatch design - it seems relatively straightforward to implement in larger multis with suitable nearly-flat hull surfaces that remain above the waterline whether inverted or not.

Any thoughts on how to implement this, or any other hatch design on smaller multis (e.g. Farrier designs) with more aggressively curved surfaces?

Or is "cut here" the only realistic option for smaller multis?

 

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on Mollymawk (45ft Tri) i had a solid hatch with single s/s to hinge and it was locked closed against a neoprene seal with cheap home bathroom sealant to ensure watertightness.. i used 2 lewmar style  hatch lever handles to secure it closed with a pull string thorough a bathroom sealant sealed hole to a large s/s ring on the outside which when pulled operated the handles 

never leaked and worked fine.. inc when i "tested" it during the 2006 Route du Rumb 

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13 hours ago, gspot said:

I love the elegant simplicity of Boardhead's hatch design - it seems relatively straightforward to implement in larger multis with suitable nearly-flat hull surfaces that remain above the waterline whether inverted or not.

Any thoughts on how to implement this, or any other hatch design on smaller multis (e.g. Farrier designs) with more aggressively curved surfaces?

Or is "cut here" the only realistic option for smaller multis?

 

Escape hatches are required as part of the safety equipment on longer and more hazardous offshore races where 30’ would, in most cases, represent the minimum eligible. At some point the hull becomes too small to provide a safe haven when capsized and your “cut here” strategy might be more realistic - BUT - there is a greater probability of capsize so for more adventurous usage (RAK)  it’s something to be taken very seriously.

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