Bathroom (head) floor construction materials

[UNCIVILIZED]

Originally Posted by UNCIVILIZED

Make it some sort of grate so that it drains. And it needs to be fully impervious to moisture. Meaning fully 200% non water absorbtive. As well as being super easy to clean. Plus, of course, it must be a nonskid surface. With sticky enough nonskid so that even when it's fully covered in shampoo, you can retain traction on it. Quite literally.

FRP plate would work, when drilled with an appropriate pattern of drain holes. Even the stuff you can make up on a bench at home. Or if you like wood, vacuum bag multiple layers of 3mm ply or veneers together with epoxy. So that the epoxy gets pulled all the way through the fibers of the wood. Thus making it essentially a composite.

I'm thinking that it's tough to seal regular wood well enough for such applications really. Since once the smell from liquids via the head get into the wood, you can't get them out again. And that's an unpleasant odor.

Also, Ann's correct about needing a sump. They're mandatory. And need to be super easy to clean.

Originally Posted by UNCIVILIZED

Marble, with flutes for drain channels. And skateboard tape for grip.

Originally Posted by GILow

Works for me. Just what a 17 ton boat needs.

AND, we've been up at the bow a bit too, that should fix it.

Come on now, I'd already previously suggested 2 much lighter options: FRP plate, & a homogenous wood/epoxy laminate. Or did your computer somehow translate those suggestions into French on your end?

Heck, if you like, get some thick acrylic. Drill drain holes in it until it looks like a cheese grater, & add some skateboard tape. Or even get some thin acrylic, do the same, but with a bolted on structural aluminum grid on it's underside.

You could even use aluminum plate painted with some industrial nonskid. Or get some aluminum diamond plate, & perf it similar to the above. So it'd be pretty much a no maintenance solution. Cheap & light too.

[SV Bacchus]

Originally Posted by UNCIVILIZED

Come on now, I'd already previously suggested 2 much lighter options: FRP plate, & a homogenous wood/epoxy laminate.

I noticed you had and started wondering why the OP was still typing and not out buying material!

[trifan]

Originally Posted by GILow

Hi Cruisers,
<snip>
So I started to think maybe I should use a piece of starboard, or something similar. Does anyone know if it would be suitable for this role, or can they recommend some other materials I should consider?

Matt

Maybe I'm missing something here but I would be tempted to use a sheet of 3/8 or 1/2 pvc cut to fit. No rot, strong, easy to shape, durable. I ordered some off ebay once for a project, Brown delivered it. No epoxy involved unless you use epoxy paint. YMMV.

[Dougtiff]

G 10 [epoxy laminate under pressure] works well, strong, won't rot, ect.

[Seabeau]

Some of you guys are trying to reinvent the wheel. Do as I did, purchase poly structural outdoor or industrial grating. Comes in several colors, various widths and lengths. Its in my head and throughout my vessel, including a 3X4 ft section directly beneath my companionway hatch. I can sail in the rain with the hatch open with no ill effects.

[Cadence]

Originally Posted by GILow

OK, sounds like I need to clarify.

Just to be clear, the whole drainage thing is sorted, the current setup has worked for 30 years, so I am happy to stick with it as it is. The bathroom on our boat has always smelled fine, despite the soggy old floor, so I guess we've been lucky. It is a pretty big space, so perhaps that has helped keep it dry and fresh.

The idea from Wotname has my interest, but the work involved might be out of my time budget.

I'm still keen to hear of any ideas on suitable substitutes for plywood.

Matt

I would be temped to just go with ply cut to shape -. West it top, bottom and sides and surface it with what ever you like. As long as the supporting structures a good glue it in. Don't penetrate the encapsulated ply with screws and leave a small clearance around the edge for hull flex. JMHO

[foufou]

if you are into fiberglass work, high density foam like Coosa board or similar with glass on both sides. this would be non absorbent of water and should last a long time if made sturdy

[Zach]

The way that I do them, is 3/4 occume marine grade plywood with a layer of 1708 biax over the top, sanded out and resin coated. The gist is that plywood rots if it doesn't have enough epoxy over the top to keep it water proof. Resin coating and even a 10 oz boat cloth isn't quite enough if the plywood gets wet from the other side, swells and splits its coating. 1708 is tough to split, and gives enough thickness that a hammer drop doesn't star craze and rot out the panel. Not much more weight or material, for that piece of mind. If you have a drain to fit, go ahead and router out the location and recess it in before you glass a bit oversized you can cast it in later, but it'll have glass under it too.

Once you have that, if you need to pull in any drainage I tack some thin strips down wrapped in packing tape around the outside edges and use screeds of different length to pull fairing compound to the angle it needs to be. If you have a drain to fit, go ahead and router out the location and recess it in.


Even if you have a trapezoid shape, you can pull from each side from something to nothing that comes pretty close to the drain location using different length sticks of 3/4 ply about 2 inches thick. Wait for it to tack up, then pull the thin wood strips and putty the channels left behind. Sand out with a DA... and take as far up the sanding cycles as you care to.

When you go to bond it in, you can lay the whole panel down on tropical hardener on another sheet of plywood with a few weighs on it. I have a few bags of reclaimed lead shot for the purpose. That gives you enough beef to get a good bond to the substrate under it. When that is bonded in, pull a fillet around the edge to seal it to the rest of the shower pan. The fillet gives you a little bit of play, if the walls taper from tight at the top to wide at the bottom you can still fit the panel in... Sometimes there isn't any winning if you have to have a tiny fillet, if the walls aren't plumb. You can be slack 3/16ths all sides and let the slow hardener goop out to fill the difference and then pull a 1 inch or 1 1/2 radius fillet over the top so it is very easy to sand out.

I do the same thing with ceilings in showers, as sanding overhead in a small box is a pain... Instead of lead weight, sticks and another piece of plywood to jam it up into place. You can put in 320 grit primed panels in 545, and scuff up just where the fillets need to go, only sand the fillets and respray the 545. No screw holes...

Imagine now pulling the trigger on the spray gun inside the shower. That is the definition of a white out. There isn't a real easy way to get a perfect Awlgrip job in a shower. My two cents is to stop the color of the shower pan 4 inches or so up so you can DA the walls and get a tape line in that is easy to maintain.

Cheers,

Zach

[GILow]

Hi all,


First, my apologies to those of you feeling like I am ignoring your advice, I realise now we are probably talking at cross purposes.


There are some excellent suggestions around a floor structure that drains through, I suppose into the bilge. But I am trying to avoid this, for much the reasons raised by Ann. Currently the floor has worked very well with a conventional single shower style drain fitting, which leads, via a nice long hose, to a dedicated pump. Meanwhile any "normal" incidental water destined for the bilge, say from rain coming through an open hatch in the forward locker, or a big wave coming over the front and getting past the same hatch, will drain BELOW the bathroom floor to the main bilge pump, just forward of the engine bay.


I like this arrangement. I have read enough cautionary stuff about shower water in the bilge to make me very happy with the current setup.


So really I was just looking for a material that is like plywood but maybe more suited to the task, and there have been some good suggestions for this here. I just got a bit confused by the whole drilling drain holes thing. So we've got FRP, PVC, Coosa board and G10, just to name a few. I will look into price and availability of each of the suggestions and any others that I have missed in the thread.


And there were also some excellent suggestions on how to better handle doing the job in plywood again, which, considering the last floor lasted 30 years, is still a strong contender.


So thank you all again, your advice was sought, has been heeded, valued and not ignored.


Matt

[jhulmer]

You could use a fiberglass panel as the sub-floor and add teak strips to the surface as non-skid and appeal.

something like this structural FRP:
https://www.mcmaster.com/#8537k37/=17jg7yz

teak strips available on eBay.


PS: it is also easy to layup your on fiberglass panel on a sheet of plastic for the smooth side. this is a less expensive option.

[HoneyRyder]

I have two ideas for you:

1. Get a piece of marine ply, 20mm thick (minimum) cut to size and shape, route your edges to smooth the edges. Then sand it using some 80 grade paper. Then West epoxy both sides and all edges. Let it dry. Do it again two more times. Then paint it with a decent polyurethane paint. It will last for years.

2. Or, get some Brazilian hardwood decking planks. Use the old board to give you the shape and mark it out. Make a frame with some of the planks and then screw the top planks to the frame. If you screw from the frame into the planks from below then you can fill and cover the screw heads with a decent waterproof glue. Alternatively it will be easier to screw the planks onto the frame from above, but you will have to fill the sunken screw heads with a very decent caulk if you want it to last. I filled mine with Sikaflex 290DC (deck caulk). Then sand it all down (Sikaflex can be sanded easily). The black caulking offsets the redwood nicely, and it looks very "boaty". I'd mark out the screws carefully so they are all aligned nicely. Make sure you countersink the screws deep enough so the there is enough of a recess to take enough caulk so it can bond nicely to the screwhead and surrounding wood.

Leave a small gap between each slat and the water will be able to drain through, and as air can get to the bilge it will dry easily.

It will look very nice, and it will last for years.

[JPA Cate]

Original plywood lasted 30 yrs,? Why not go again with marine grade ply, two coats of expoxy, paint of your choice? How long do you think you'll have this boat? More than 30 yrs.? Might have to do the job over? ooookay, how about a layer of fiberglass over the whole deal, with epoxy, and then paint. Maybe do you 50 yrs. Will that be enough?

Oh, yeah, for the part that drains, lose squares, keep circles, way easier to clean. This from the girl who scrubs the grate with a toothbrush to try and get the corners clean.

Really, since you wrote your time for this is limited, go for the fastest palatable solution.

Ann

[UNCIVILIZED]

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