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Author Topic: HATCH SEALING  (Read 8015 times)

kiwimodeller

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HATCH SEALING
« on: September 27, 2008, 11:36:47 AM »

Hi there, can anybody offer any tips on a nice easy way to seal a hatch when it is flush with the deck? Usually I would make the opening in the deck the same size as the cabin, put a coaming around it and then sit the cabin down over the cabin however my latest project, a J class yacht has only a very small cabin and I need a hatch that is larger than the cabin by a fair amount. I therefore will need to cut a section out of the deck and then seal it keep the wet stuff out. I thought of building a U shaped channel with a neoprene ring in the bottom of the U but that seems like a lot of work and I am worried that the deck will not sit flush unless I put several screws in to keep it down. Anyone have any better ideas? Thanks, Ian.
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DickyD

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Re: HATCH SEALING
« Reply #1 on: September 27, 2008, 11:52:11 AM »

You could try a thin smear of clear silicone around the opening, place shrinkwrap over the silicone, position hatch cover and let silicone dry.

Remove hatch cover and remove shrinkwrap, then replace hatch cover making sure it is the same way round.

Job done. O0
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JayDee

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Re: HATCH SEALING
« Reply #2 on: September 27, 2008, 11:55:19 AM »


Hello Ian,

I am building a J Class too, got the same problem as you you have.
A J Class needs a large hatch cutting into the deck, to enable winches, radio and nicads to be easily fitted.
My boat will need a hatch about 14 inches long, by 5 inches wide, to give good access to all the gear.

I have been thinking along the lines of a Silicon Sealer layer for the hatch to sit on, held down with
small, strong magnets, using the Cabins as "handles" to lift the hatch on and off !!.
A layer of plastic tape on the underside of the hatch, with some wax applied to it, will act as a release agent
 and stop the Silicon sealer from gluing the hatch in place, been there, done that !.

John,  O0
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kiwimodeller

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Re: HATCH SEALING
« Reply #3 on: September 28, 2008, 09:18:11 PM »

Thanks for the ideas guys, it seems I always end up with the difficult bits to do. John some great photos in your galleries. It seems your J is quite a bit bigger than mine which is 48" o/all. I was going to try and get away with a hatch a bit smaller than yours but it is not as if I have small delicate hands so might have to rethink. I have the winch and pulley mount under the deck ala an article on scale sailing in an old Marine Modelling mag of the early 90's. Rather than have the running rigging loop above deck I am trying to just have each sheet coming out of a fairlead directly below each boom for neatness. So far it looks promising. How have you done yours? Thanks, Ian.
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JayDee

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Re: HATCH SEALING
« Reply #4 on: September 28, 2008, 09:51:34 PM »

Ian,
You have a PM.
John.
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Mickymike

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Re: HATCH SEALING
« Reply #5 on: October 12, 2008, 09:38:27 PM »

Hi there
I find with my yachts with a flush deckhatch to seal them I use Sellotape Diamond tape it is transparent, waterproof and leaves no residue on the deck
Hope this helps

Mickymike
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kiwimodeller

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Re: HATCH SEALING
« Reply #6 on: October 13, 2008, 02:21:04 AM »

Thanks for that, I had seen the tape in use on racing yachts but as this is going to be a scale boat in appearance I was trying to find a way of sealing it that will not be visible. Cheers, Ian.
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Greggy1964

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Re: HATCH SEALING
« Reply #7 on: September 08, 2009, 08:32:19 PM »

A good way, provided you have some deck fittings

- like a convenient scale bucket and the odd dog sat around or even a scale crew member.

The trick is to have a threaded bolt underneath them that passes through the hatch cover and engages in a nut below deck fixed to a frame attached to the boats below deck structure. These figures are place strategically on deck to provide an even downward force on the hatch via means of the threaded bolts.

Your deck house / removable deck area has the be built rigid, the reason is that these bolts are intended to provide an even clamping down force all round the opening.

What I would do is provide a shelf below deck level running around the circumference of your opening in the deck with a shallow lip on its inner edge. The inner lip is to provide a keeping force for the tubing in the next step.

Depending on room and scale, take some fine bore silicone tubing and make a ring to fit around the shelf so that it is trapped between the inner lip and the side wall of the opening in the deck forming a sort of channel.

Because silicone tubing is springy it will compress slightly when your hatch is clamped down by the force provided by your dummy dogwith the screw up its bum and the one under the bucket as the opening hatch is screwed down.

The corners of the opening are dealt with by allowing the shelf and inner lip to curve around the opening while the hatch corners above are left square to make a tidy ish joint along deck plank edges on deck. It's a bit fiddly but worth the bother. This is to allow the silicone tubing sealing ring to take a nice curve without kinking as it goes around the corners of the deck opening.

If this is all drawn out and planned properly before construction begins the underneath framing of the opening hatch will engage with the top of the inner lip so that the silicone tubing is boxed in on four sides and compressed providing a seal on all four faces it comes into contact with.

The net result, if it's done properly is a very good seal, water can get down the gap between the deck edge and the hatch edge but no farther because it's blocked by the silicone tubing seal all round.

I have used this successfully in the past with the clear acrylic access lid on a 4" PVC drain pipe submarine to seal the radio hatch, so for decks mostly above water it will work fine. The mating surfaces with the tubing must be smooth for it to work efficiently but if not a liberal daub of vaseline helps.

When I find my camera or get my scanner running I'll put up some sketches soon.
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Greggy1964

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Re: HATCH SEALING
« Reply #8 on: September 10, 2009, 11:34:48 PM »

Sketch of my hatch seal ideas
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roycv

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Re: HATCH SEALING
« Reply #9 on: September 16, 2009, 03:06:12 PM »

Hi all, I like the drawing Greggy, I used a similar but deeper hatch sides system on my smaller J class (Amati kit). This was I wanted to stiffen up the hatch.  In my case I modified the big brass winches to have a screwed on brass strips underneath,  which located each corner of the hatch.

Mine are angled so that as the winch is turned they tighten up.  I used bicycle type valve tubing with vaseline for sealing and it works well.  No water in yet!

Something else I did was having taken the hatch on and off a few times for battery charging I soldered  the charging points of the battery to the underneath of the two winches and just clip charging wires on.  The red is to port of course!

I have attached a photo taken at pond side and I think you can just make out the hatch.  (Look for the lines across the deck starting just aft the mast and the other end of the hatch just forward of the aft set of winches).

It is quite big and the 4 brass winches are the fasteners for the hatch.  This photo is about 6 years old and the hatch has not deformed in that time. If I remember right there are about 80 deck plank widths each of 2mm. at the widest part of the hull, took rather a long time!

regards Roy
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Boomer

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Re: HATCH SEALING
« Reply #10 on: March 16, 2010, 04:51:05 PM »

The guys on the forum have already provided you with some good ideas on this but, I thought I'd add one more. It is in the same thought process. The hatch described was made for a 1M Seawind RC Sailboat. There are at least two of these being made professionally and sold here in the states for this boat, as it is famous for having a leaky hatch. This idea can be adapted for your applicaton and would work for your boat as well. This was made at home for a lot less.

The hatch in the picture is made from clear acrylic 3/32", some nylon "thumb turns", nylon nuts and washers and epdm door gasket material, all from Home Depot. Cut the cover to fit, carefully, (plastic can be brittle) drilled 4 holes in the hatch, installed the epdm gasket material on the boat deck (it is adhesive backed), marked on the gasket material where the holes in the hatch were, melted holes in the gasket with a soldering iron, drilled the holes in the deck where the melted holes were, superglued the nylon nuts under the deck, painted the thumb turns black to sort of look like winches and then bolted the thing down. It is totally waterproof, easy to put on and off, and clear so you can see inside the boat to see if everything is OK. In addition I suggest mounting an exterior switch water proof switch, so once the batterys are in, You won't have to open up again until the day is over. The hatch cost less than 20$ into the whole thing and that gave me enough to do two hatches! Tip: add some vaseline to the nuts threads before gluing to prevent the super glue from messing up the threads.

If you draw the hatch lay out (draw on the plastic) on a sheet of plastic, use two of the factory edges for 2 your edges, and you eliminate a couple cuts. This one was cut with a small saw like a hack saw and then use a dremel tool to finish off the edges. To get a nicer finish you can use a hand sanding block with varying grit of sandpapers, then finish up to 2000. It does almost polish it but it certainly gives it a finished enough edge for me. Another hint is to put vaseline on your threads of your “thumbturns” when you superglue the nuts to the underside of the deck. That way it any superglue does get on the threads it wont stick.

I must give credit Mr. John Ebell, a contributor on the RCGroups.com the credit for this information. He and I were sharing information on a new version of this idea that was seen on E-bay. This is his fix for the problem. I attached a picture of the factory hatch, which looks like it won't leak, but it does.
Good luck
Windchaser











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