Any photos of water tight bulkhead access hatches?

[PeterSibley]

The Selway Fisher JIM that I am beginning does not have any drawings included for water tight hatches through the flotation bulkheads, something of an oversight in my opinion. However access seems desirable so at this stage, cutting out the bulkheads ( permanent) and moulds (temporary), I'd like to at least cut the openings and perhaps arrange stiffening timbers around those openings.

I've drawn up a couple of ideas but would like to see what more experienced builders and sailors have done.

Does anyone have photos of water tight hatches they have built that would suit ?

thanks,
Peter

[WX]

There's things like these, though they say, splash proof.
https://www.whitworths.com.au/main_i...AbsolutePage=1

[PeterSibley]

I've seen those Gary , as they are for a "watertight" flotation bulkhead I reckon better than splash proof is necessary !

[TerryLL]

Here's a shot of one of the Denman CYs.



If you spend some time on the Caledonia Yawl forum you'll find entire threads devoted to the issue of hatches.

Oughtred provides detailed drawings of bulkhead hatches for the CY. For my build I have opted for 8" Bomar plastic deck plates for the bulkheads and rectangular wood hatches on the decks.

Here's a look at the forward bulkhead where two Bomar deck plates will go. The aft bulkhead has just one deck plate.

[PeterSibley]

Thank you Terry , off the CY forum!

[TerryLL]

Peter ,

The permanent bulkheads can go in when you're setting up the molds, or later after the hull is fully planked and turned over. I've done it both ways and found on my current build that adding them after the hull is planked and turned was actually quite easy. But in either case, you certainly want to cut the hatch openings, the limbers, and holes for drain plugs BEFORE you install those bulkheads. Trying to cut all those openings after the bulkhead is glued in place will put your butt in the moaning chair for weeks on end.

[PeterSibley]

Now there's a good idea Terry ! I'm about to set up the moulds, 2 permanent and 2 temporary. I hadn't thought to use temporary moulds for all then install the permanent ones later... thank you very much ! I can now work out how to do these hatches to my satisfaction without slowing the whole process down to a crawl !

The plans for JIM are drawn for stitch and glue which appears to be quite a different process to glued lap ... in a very basic sort of way . Paul Fisher gives very specific drawings of plank shapes with the instructions to just wire the edges to draw the shapes together. However not so much information about the mould set up, in other words I'm having lots of "fun" setting up the moulds accurately on the base. I suspect I'm going to have to allow room for adjustment and run a few long battens to check the result.

Fun,fun, fun !

[WX]

I think you should start a build thread Peter. keep all the Q&As in one place. JMO.

[PeterSibley]

I'm going to , these are a bit pre build .

[Duncan Gibbs]

Yeah! Pictures or it ain't happening!

[PeterSibley]

I have 4 strangely shaped pieces of MDF to show ! Pictures later .

[Sayla]

If you get plastic ports , stick with the larger ones even though they're dearer. In my Mirror I have a couple of different sized plastic watertight ports, and the larger one is definitely more user friendly, for inspection, cleaning, stowage.......

[PeterSibley]

Where did you buy it Sayla ?

[Duncan Gibbs]

Andrew Denman has some really terrific ones he uses on the Swallow Boats he builds: Absolutely watertight. My round screw in ones on my Mirror will still leak if the boat goes over and then I have some serious free area action occurring in the side tank the boat was laying over on.

[PeterSibley]

I'll have a look on the Denman Marine site Duncan, but until then this is the kind of thing I have in mind. I found these somewhere on the forum but can't remember who the builder is ( apologies to you sir). I'd need two in the forward bulkhead as the mast obscures the middle section and one in the aft bulkhead. It should be possible to make them waterproof if they were made stiff enough, probably 2 layers of 9mm ply and some kind of compressible rubber gasket.

I've jotted down a few other designs too but would prefer to steal a proven design!

[Duncan Gibbs]

That's nearly the kind of thing that Andrew has, but in HD plastic and the outside screws in the bottom picture would be threaded bolts that would clamp the front piece in place from outside and the lip to the hole is both gasketed around it on the outside and lipped around the inside,... or something like that. I'm sure you could build such a system with timber, but his are pretty bullet proof.

[skuthorp]

It's waterproof you want, under pressure. I found it almost impossible to build wooden waterproof hatches even after routing a grove and a moulding to fit on a round hatch with a gasket. I think getting enough even pressure was part of it.

[PeterSibley]

Was that on your Rob Roy Jeff ? Where you constrained by trying to keep things very light?

Duncan, I looked on the Denman site but couldn't see a mention. Did you just email a request?

[Canoez]

I'll have a look on the Denman Marine site Duncan, but until then this is the kind of thing I have in mind. I found these somewhere on the forum but can't remember who the builder is ( apologies to you sir). I'd need two in the forward bulkhead as the mast obscures the middle section and one in the aft bulkhead. It should be possible to make them waterproof if they were made stiff enough, probably 2 layers of 9mm ply and some kind of compressible rubber gasket.

I've jotted down a few other designs too but would prefer to steal a proven design!

Looks like the hatch design on Harry Bryan's Thistle, no?

[keyhavenpotterer]

http://www.armstrongnautical.com/dckplates.htm

[Duncan Gibbs]

Duncan, I looked on the Denman site but couldn't see a mention. Did you just email a request?

Andrew showed a bunch of us at his stand at the last Hobart WBF. The pressure is applied in the corners IIRC. Jeff is correct in that pressure is the key.

[RFNK]

Plenty there to choose from.

Rick

[bloggs68]

Armstrong Nautical deck plates. Work well, no fasteing holes and a range of sizes.

Been using them for a few years now and no complaints. If anything the seal can be too good when trying to remove a hatch on a locker that has cooled.

regards,

AD

[PeterSibley]

They look good Andrew, where can I buy them ? Do you stock them ?

[chuckt]

My favorite movie Rick. I don't remember some bits of that clip. Time to find my DVD and watch the whole thing again.

[Bruce Hooke]

For what it's worth, I had good success making waterproof boxes using the following technique:

1. Make the box and lid and mill the mating surface between lid and box smooth so there is a nice tight fit. The mating surface between box and lid needs to be at least 1/2" wide. I used hardwood sealed in epoxy. I expect the face surface of plywood would also work fine. I'd be more suspect about plywood edge grain.
2. On one side use a 1/4" core-box router bit to cut a 1/8" deep grove, with rounded corners. A template of some sort will likely be needed to guide the router.
3. Use rubber adhesive (e.g., "Pliobond") to make an o-ring to fit the grove out of 1/4" diameter natural rubber cord (available from McMaster).
3. Carefully glue (with epoxy) the rubber cord into the grove. Keep the epoxy off the exposed surface of the cord.
4. Now, install hinges on the box and draw latches to pull the lid tight.
5. Finally, carefully cover the rubber cord with one layer of Saran wrap.
6. Spread a little thickened epoxy on the mating surface that the rubber cord closes against.
7. Close the box and latch it shut while the epoxy cures. This makes a nice smooth mating surface for the rubber. After the epoxy cures, if there are sharp edges you may want to knock them off with some sandpaper, just be careful not to sand so much that you damage the surface that the rubber seals against.
8. TEST! For my box I did the simple bathtub test and as I recall I left the box weighted down in the tub for a while and did not see any bubbles and did not find any water inside the box when I opened it. A box made this way has survived whitewater rafting trips and kept my camera dry, but I have tried to be careful not to leave the box where it would get totally slammed with water or left floating in standing water. It probably would do fine in either situation but I do not feel like pushing my luck!

This, of course, was for a box. For a hatch a modified approach would be called for. Among other things, on a hatch I might go for larger rubber cord to provide for more ability to adjust to flexing in the bulkhead without resulting in leaks. Still, it will be important to make sure the hatch and bulkhead are pretty rigid.

Of course it should go without saying that if you have $10,000 worth of gear that absolutely has to stay dry then spend the money for a Pelican case, and if your life might depend on the absolute integrity of a waterproof hatch then spend the big bucks on an appropriate metal hatch that can be dogged down against storm seas and be expected to stay watertight for weeks while you wait to be rescued!

[PeterSibley]

Thanks Bruce, I think that it might be a little easier to get a waterproof seal on a box as the deeper structure offers the possibility of considerable stiffness . This hatch is on a bulkhead on a small boat and while it will be quite stiff it probably not be as stiff as a box.The obvious solution of course is a shallow box structure on the inside of the bulkhead. I'll try something very similar to your instructions and try very hard to get the whole structure stiff enough.

[Sailor]

Don't use the one at the end of that video clip. In our boats, they "burp" when you dive. A little pressure difference and they burp water down the conning tower hatch on whoever is there making sure the hatch is shut.

[TerryLL]

Peter ,

You don't need a zero deflection bulkhead and hatch system to get a watertight seal. A plastic deck plate like a Bomar or Armstrong will bend as the bulkhead bends. They both have big fat gaskets and a flexible frame and can be mounted very simply in a 9mm bulkhead with no additional stiffening.

Another point. In spite of your best efforts to keep water out, there will be considerable condensation in those enclosed spaces, so plan for a plugged drain hole at the base of the bulkhead, which is also handy if you need to wash out the compartment after your jar of Vegemite explodes.

[PeterSibley]

Peter ,

You don't need a zero deflection bulkhead and hatch system to get a watertight seal. A plastic deck plate like a Bomar or Armstrong will bend as the bulkhead bends. They both have big fat gaskets and a flexible frame and can be mounted very simply in a 9mm bulkhead with no additional stiffening.

Another point. In spite of your best efforts to keep water out, there will be considerable condensation in those enclosed spaces, so plan for a plugged drain hole at the base of the bulkhead, which is also handy if you need to wash out the compartment after your jar of Vegemite explodes.

Agreed , I'm visualising a few inches of copper 3/4" ID epoxied in at the lowest point, one on each side of the keelson with corks in both ends , what do you do?

[Duncan Gibbs]

If you're going to use copper plumbing fittings why not have a threaded flange with a bolt tapped in to cap it? Corks or their rubber equivalents can get lost. DAMHIK.

You can get a just about totally watertight seal if the gasket is shielded from wave action/direct wash by a lip either side of it: One on the bulkhead opening and one on the hatch rim and the gasket in between the two.

Terry, Vegemite is a non-volatile substance at any age. It just "is."

[Duncan Gibbs]

Whitworths sell these, amongst others:

https://www.whitworths.com.au/main_i...AbsolutePage=1

[PeterSibley]

2 good suggestions Duncan , thank you !

[TerryLL]

I've used these in the past. They have such a small lip that the tubes can be installed at the very bottom of the bulkhead.

[Russell Brown]

I have made water tight hatches for my boats for many years. I also use Beckson screw out deck plates and found them to be very reliable. They make them in 4, 6 & 8" opening sizes. We produce a water tight hatch kit for our PT 11 nesting dinghy that has proven to be reliably water tight and even air tight. We use thin walled surgical tubing glued into a notch as a gasket. The hatch lid does need to be stiff and we use multiple turn dogs. I will see if I can attach a photo of our PT 11 hatch kit. ...could not seem to load the pictures so I am inserting a link to pictures on our web page. (the top 3) Please let me know if you would like more photos of other water tight hatches.http://www.ptwatercraft.com/ptwaterc...1_Options.html ,
Russell

[PeterSibley]

Thanks for hose photos Russell , that looks like a great way of doing it. It must be great to own a CNC router !

[Russell Brown]

Hello Peter, I don't have a CNC machine. I don't even do my own CAD work. We have to pay for both of those things, but that's okay.
I do have a fondness for custom watertight hatches. I'll try to get some photo's of other hatches I have made and post them here.
Regards,
Russell

[Bruce Hooke]

Thanks Bruce, I think that it might be a little easier to get a waterproof seal on a box as the deeper structure offers the possibility of considerable stiffness . This hatch is on a bulkhead on a small boat and while it will be quite stiff it probably not be as stiff as a box.The obvious solution of course is a shallow box structure on the inside of the bulkhead. I'll try something very similar to your instructions and try very hard to get the whole structure stiff enough.

Yes, that is definitely a concern. A bigger o-ring should help. Another approach to take is to try to figure out a workable dogging down system that will pull the hatch tight at multiple points around the edges. Then everything can flex together.

The easy solution is, of course, a screw out deck plate. These are reliable, cheap and time tested. They are, unfortunately, not very pretty. My approach is for someone who wants something that looks pretty and is willing to do some experimenting to come up with a solution that works!

[Canoez]

Yes, that is definitely a concern. A bigger o-ring should help. Another approach to take is to try to figure out a workable dogging down system that will pull the hatch tight at multiple points around the edges. Then everything can flex together.

The easy solution is, of course, a screw out deck plate. These are reliable, cheap and time tested. They are, unfortunately, not very pretty. My approach is for someone who wants something that looks pretty and is willing to do some experimenting to come up with a solution that works!

The solution that one of my students had was to take a standard plastic deck plate and bond a wooden cap on that covered the hatch with thickened epoxy. He put recesses into the wooden cap to turn it and it looked nice.

[donald branscom]

Here is a nice one.

[keyhavenpotterer]

The home made hatches in the Wharram Amatasi were very simple but looked very effective. They work on the same principal as the plastic hatches recommended by Denman Marine.