£100 Reward.

[Tracy D'arth]

17 minutes ago, Mad Harold said:

On my boat the window film is stuck to the ally window frame with clear double sided tape which sticks like ----  to a blanket.It gives an air gap of about 3/4 of an inch.There is no problem with condensation.

Not trying to be clever with a boater of your experience but,are you sure that your hatch/windows havn't got a leak running behind the trim?

It does sound like rather a lot of moisture for condensation.

No leaks, the roof lights were new last year, well sealed in.

 

I could space and glaze the opening parts, the handles are a problem, but that still leaves the outer frames which are open to the interior inside the stainless steel aperture liners. These liners are insulated behind into the roof space insulation and do not suffer any condensation, even where they touch the ally frame. Its the huge thermal conductivity of aluminium causing the problem. 

Edited December 5, 2020 by Tracy D'arth
smelling

[Old Son]

I have fitted wooden boxes over the top of my hatches. They just sit on the roof with a vent each end. It does cut out the light but I don't get any condensation.

[magnetman]

What about wooden boxes with perspex on top for light. 

 

This was done on one of the grp boats I have previously owned. 

Edited December 5, 2020 by magnetman

[Tracy D'arth]

2 minutes ago, magnetman said:

This is why further up I suggested fixing a large sheet of perspex onto the top of the Houdini hatch. 

 

You can do this by running a bead of PU18 or sikaflex down each bar then dropping the perspex sheet on. 

 

4x4ft would probably be ok. 

 

That way you can open the hatch a bit and not get rain coming in. 

 

 

Good post above about possible leakage around the frame. 

You mean exterior insulation?  I got pilloried on here by an idiot this week for saying that a coat of paint outside would not work as insulation. Not going there again.

 

The idea would not work, the frame would still be exposed inside. I even tried complete exterior covers in timber with foam edges onto the roof, defeating the whole purpose of a Houdini, but it didn't make any significant difference.

 

Its obvious where the massive heat loss is when there is snow on the roof. The snow is on the glass and the safety bars, then a 4" melted gap where the ally frames are, then snow on the roof.

[magnetman]

3 minutes ago, Tracy D'arth said:

You mean exterior insulation?  I got pilloried on here by an idiot this week for saying that a coat of paint outside would not work as insulation. Not going there again.

 

The idea would not work, the frame would still be exposed inside. I even tried complete exterior covers in timber with foam edges onto the roof, defeating the whole purpose of a Houdini, but it didn't make any significant difference.

 

Its obvious where the massive heat loss is when there is snow on the roof. The snow is on the glass and the safety bars, then a 4" melted gap where the ally frames are, then snow on the roof.

 

It would work if you then opened the hatch a little bit. 

 

As for snow it would never make it to the glass and the bars on account of the 4 by 4 sheet of perspex you had stuck down, which would now be at a slight angle due to having opened the hatch "just a tiny amount". 

 

 

ETA and chuck shed loads more coal in the fire. if it's too hot open doors to get air in. 

 

 

 

Edited December 5, 2020 by magnetman

[Tracy D'arth]

2 minutes ago, magnetman said:

 

It would work if you then opened the hatch a little bit. 

 

As for snow it would never make it to the glass and the bars on account of the 4 by 4 sheet of perspex you had stuck down, which would now be at a slight angle due to having opened the hatch "just a tiny amount". 

 

 

ETA and chuck shed loads more coal in the fire. if it's too hot open doors to get air in. 

 

 

 

I do!   Its worse because there are 3 of them, none of them near the stove, one in the galley, one in the shower half  over the shower tray and one over the bed, daft place but I didn't build this boat. I normally have then slightly open but in the rain the prevailing wind blows in and the heat loss is massive, I've got a glowing Squirrel.

[blackrose]

1 hour ago, Loddon said:

I use clear acrylic cut to fit the roof held on with magnetic tape and two screws. I forgot to bring it up to the boat this time so am suffering from the drips. Not to much of a problem as I have a tiled floor

 

Couldn't you do the same thing but from the inside and mount the magnetic tape on the aluminium frame? Screw a couple of little handles or knobs through the perspex to easily remove it if you want to open the hatch.

[Mad Harold]

Sounds like a tricky problem.On a previous boat in winter I found that although it was warm within a few feet of the stove,move away and it was freezing.

The cause was a cheap and cheerful new fitout prior to me buying it.Removing trim to investigate a leak,I found hugh areas with no insulation.Might be worth looking.

Only other thing I can think of is to stick foam tape to the hatch frames.

Hope you get it sorted.

[matty40s]

I now have 2 houdinis, which I used to shut all winter....with relevant drips on kitchen and bed, now open throughout.

Tommorow, I will take a pic of my solution.

[Arthur Marshall]

When I had the last house but three, I was told that running a dehumidifier flat out full time made condensation worse because the dry atmosphere inside dragged more damp air in. I have no idea whether this was true, but mention it in case it is.

[GUMPY]

10 hours ago, blackrose said:

Couldn't you do the same thing but from the inside and mount the magnetic tape on the aluminium frame? Screw a couple of little handles or knobs through the perspex to easily remove it if you want to open the hatch.

Mine is on the inside on the outer wooden frame, the same as all the windows. I will be replacing it all next year as at 8 years old it's getting a bit scratched. No condensation on any of the windows or the metal frames provided I remember to bring it all back to the boat after painting.

[Tracy D'arth]

As my hatches are lined inside with vertical stainless steel I am considering clear polycarbonate with a rubber trim around the edge to make it a tight seal all around. This could give me an air gap of at least 3" but of course it would need to be removeable  to open the houdini.

Anything closer to the frame is impossible due to the 2 handles that lock the houdini  closed.

 

I had a discourse with a farmer the other day who reckons that the air is damper when the wind blows after rain than it is when it is actually raining.

 His explanation for this is that the grass in the fields starts to dry in the wind, transferring the moisture into the air. Its logical and would seem to be the case, my condensation is worse when there is a breeze than in the rain, I thought it was just the chill factor but maybe he has a point.

[Onewheeler]

15 hours ago, magnetman said:

Have you got wet bilges ?

Is that a euphemism?

[pearley]

We have thin acrylic sheet held onto the hatch opening by magnetic tape on wooden battens. Plastic hook to enable them to be easily removed.

[Onewheeler]

Point a little muffin fan at it.

[noone]

15 hours ago, Tracy D'arth said:

1 hour ago, Onewheeler said:

Is that a euphemism?

I've got a glowing Squirrel.

Is this!??

[Tracy D'arth]

33 minutes ago, Leggers do it lying down said:

Is this!??

Better than a smoking beaver.

[Quattrodave]

If you don't mind blocking out the light, a cover on the outside works very well

[cuthound]

8 hours ago, Loddon said:

Mine is on the inside on the outer wooden frame, the same as all the windows. I will be replacing it all next year as at 8 years old it's getting a bit scratched. No condensation on any of the windows or the metal frames provided I remember to bring it all back to the boat after painting.

 

Mine has a similar solution, wooden window type surround with a removeable wooden centre bar. Two frosted perspex sheets (look like fluorescent light diffusers) rest on the frame a centre bar. No condensation and easily removeable in summer.

Edited December 6, 2020 by cuthound
Phat phingers

[peterboat]

21 hours ago, Tracy D'arth said:

I do!   Its worse because there are 3 of them, none of them near the stove, one in the galley, one in the shower half  over the shower tray and one over the bed, daft place but I didn't build this boat. I normally have then slightly open but in the rain the prevailing wind blows in and the heat loss is massive, I've got a glowing Squirrel.

This explains why my Houdini hatch is dry, it lives near my Rayburn and I suspect its double glazed, will have to take a look next time I am on the roof 

[blackrose]

Any horizonal deck or coachroof "window" on a boat should always be double glazed because unlike a vertical window it can only drain by dripping all over the place. Single glazed houdini hatches are a just a bad idea. You'd think any designer would have thought about it a bit more.

[noone]

If the reward is only £100...My solution is,gaffer tape "chunky" bubble wrap to the inside.?

[Keeping Up]

I have just used twinwall plastic (as used in greenhouse/conservatory roofs) which is easily cut to size with a sharp kniife. It is cut to the size of the frame of the opening part so that when shut it fits reasonably closely inside the fixed frame. Black sticky tape around the edges acts as trim which also sels the open ends, and it is glued to the inside of the lifting frame with Evo Stick, thus effectively.creating triple glazing. The receptacle for the prop that holds it open is just glued to the underside. There is no condensation at all, except from the exposed narrow steel of the inner of the fixed part of the frame - this could be covered but there is so little condensation from it that I never got round to doing so. Photos follow:

 

 

 

 

 

[Guest]

I've stared at my hatch long enough that I have a crick in my neck, not long enough that I have a solution.

 

It would be a many-pronged attack though...

 

First off, my hatch isn't the same as @Keeping Up's - it's like this:

 

 

For the hatch itself, I would do the same as @Keeping Up has done, only a little fancier because I'm fortunate enough to have access to just the machine for the job. I would laser cut a piece of 5 mm acrylic, something like the sketch below. Then remove the handles and the little stay nubbin, place the acrylic, remount the handles and nubbin (you would need longer screws at this point, not a problem but the screws in mine are self-tappers, rather than machine screws, which is disgusting but a minor snag).

 

 

You would have to seal it in place to prevent condensation forming behind. I think I'd just run a bead of Geocel clear marine sealant around it. Between the screws and this, I don't think you'd need any further means of attachment (although not fully considered this yet).

 

If all went well, you'd have another layer of glazing with very limited impact on light ingress and which covers up some of the metal frame...and provides a thermal break between the frame and the handles. And looks pretty decent. I think. There may be some fatal flaw though.

 

The first real problem I can see is that the the handles would now sit 5 mm lower and the closing 'rubbers' wouldn't be in the right place anymore [sigh]. So I would take them off and shim them. Or make a similar, but hollowed-out piece for the outer frame. Although I didn't get that far yet. Anyway, I think that's what I'd do for Phase 1.

 

For the groove around the inside (Phase 2), I think I would just buy some 10 mm x 10 mm foam rubber profile and run it round. Or just fill it with more of that lovely silicone. I didn't get that far either.

 

Anyway, yours for about £10 of acrylic. I don't get much condensation on mine (not trying to rub it in, just saying I couldn't give it a good test!), but I could run one off and do a test fit at least. Just let me know if you have any interest and the same style hatch and I'll give it a go. Or let me know if I've missed that fatal flaw somewhere ?

 

This isn't an attempt for the reward by the way ?

Edited December 27, 2020 by Guest

[matty40s]

On 05/12/2020 at 22:30, matty40s said:

I now have 2 houdinis, which I used to shut all winter....with relevant drips on kitchen and bed, now open throughout.

Tommorow, I will take a pic of my solution.

I forgot, it's dark now.