David Thatcher wrote: You could always fill the air gap with sheet polystyrene which is light weight and inexpensive. This would make the air gap more effective and reduce the likelihood of condensation which you could still get with just an air gap. On one of my boats which had just a 9mm ply deck I insulated the deck head and improved the interior appearance by covering one side and the edges of 20mm thick polystyrene with an off white vinyl and then glued the panels up between the deck stringers. I sometimes think about doing this on the deckhead of the aft cabin in Footprints which the only place in the boat where we get condensation. The main deck is 30mm thich so no condensation there.

There are two reasons I don't want to use polystyrene, David.  One is that it never degrades and is one of the worst of the materials that human beings inflict on an unhappy world.  The second is that I don't want the insulation to be too good, because I would need to light a fire to warm the boat up on spring and autumn mornings.

The deckhead has a 30mm air space.  On Fantail, the cabin sides were panelled in thin plywood: the cabin sides curved, the plywood didn't and therefore there was a gap between the two.  It was very little, but more than enough to stop condensation forming.  I'm a bit of a fresh-air freak, so I don't think it's going to be an issue - except alongside the bunk, in which I'm fitting insulating today.  I'm still not totally committed on the deckhead: Marcus acquired a heap of super-yacht insulation many moons ago, which would be perfect for the job ...

Very interesting that you never get condensation on your deckhead.  30mm thick!  Mr Tyler would have hysterics!!  Talk about solid - not surprising her big sister wrecked a house.

Annie Hill wrote:

I've thought quite a bit about insulation in the boat.  I've done my time in the Ant/Arctic, so don't need to get too fussed about it.  However, even at 36S we can get chilly nights which can cause condensation.  On the other hand, too much insulation means that it takes ages for the boat to warm up once the sun comes out.  My final decision is to have an air gap in the deckhead with no extra insulation and a panel with insulation behind it by my bunk.  Settee cushions will anyway have a gap behind them with the back rest at an angle for comfort.

You could always fill the air gap with sheet polystyrene which is light weight and inexpensive. This would make the air gap more effective and reduce the likelihood of condensation which you could still get with just an air gap. On one of my boats which had just a 9mm ply deck I insulated the deck head and improved the interior appearance by covering one side and the edges of 20mm thick polystyrene with an off white vinyl and then glued the panels up between the deck stringers. I sometimes think about doing this on the deckhead of the aft cabin in Footprints which the only place in the boat where we get condensation. The main deck is 30mm thich so no condensation there.

I haven't posted for a while, largely because while I have been beavering away (between going to the rig-raisings of Francis H and Shoestring), a lot of the work has been scraping, sanding, fairing, filleting and other equally unphotogenic jobs.  I've also fitted a number of pieces of wood to build up the sheer clamp, in order to get out a big plane and take most of it off again(!) and have been making a panel to go alongside the bunk. 

I've thought quite a bit about insulation in the boat.  I've done my time in the Ant/Arctic, so don't need to get too fussed about it.  However, even at 36S we can get chilly nights which can cause condensation.  On the other hand, too much insulation means that it takes ages for the boat to warm up once the sun comes out.  My final decision is to have an air gap in the deckhead with no extra insulation and a panel with insulation behind it by my bunk.  Settee cushions will anyway have a gap behind them with the back rest at an angle for comfort.

I have just started a new photo album and it would appear that this is my last one.  After this one, those of you who are interested in what I'm up to you just have to go to my blog to see what I've been doing.  If nothing else, it will mean that my blog gets kept up to date!

I take it you've considered and rejected lowering the cabin sole by the offending inch? Once again, I must intone my mantra - "higher, heavier deck - bad".

Like David Thatcher, I don't stand at full height when working at a bench or counter. I'd like to be sure that you're doing the right thing by setting a piece of MDF sheet above your kitchen in the boat shed, at exactly the height and angle of the deckhead, and then see whether or no you make frequent contact with it while actually cooking.

Well, I thought long and hard about it, but taking into account that I do sometimes have a back issue, and that, when I have time, I can often spend many a happy hour in the galley, I came to the conclusion that it was worth being able to stand up with a straight back.  It's only a matter of about an inch, but it's an inch that might make all the difference over the years. 

As to side decks, to be honest, I've never quite seen the point of them.  And I like the look for the flush deck and full-width cabin.