Friday, 20 December 2013

LV12 - Welcome to Radio Seagull

Lightship owners are a rare breed, up there with windmill owners I suspect.  I was recently contacted by Sieste Brouwer who is the owner of LV12.

It is great to see a ship which looks to be the same model as Gannet.  Photos of the ship in the Ship section and in their Gallery section of their website make me smile a lot.  It is great to see one of these ships being restored and looked after.  It is even better to see it out at sea again where they should be.

Makes me wish I still had anchors and chains!

I note that the ship is down to 8mm steel.  Gulp.  I know how thick that started out as.  That's half the steel gone.  I look forward to discussing this with Sieste.

I hope to meet Sieste over the holidays if I can arrange my complicated Christmas schedule.

Wednesday, 18 December 2013

Bang on

For nearly a year I have been disturbed by an incredible banging noise which sounds like someone hitting the hull with a steel hammer whenever it is windy.  I have been out at 3am in stormy winds in a dressing gown trying to determine what the noise is.

Everything is tied down. Everything.  In the end, I thought I had got the noise down to the gangway catching.  The issue is that no noise can be heard outside, only inside.

Tonight I solved it.  Mainly because the tide was out and that mean no gangway movement.  It turns out that two of the arms that hold the nets on the helipad move still.  And in the wind, now and again, they get push in and bang.

A few wedges in the gaps and hey presto.  No more banging!

Porthole and floor pics

The toilet floor.  All clear

The new portholes in the bathroom to be 

Wednesday, 11 December 2013

Time for reflection

Every now and again I try and look back at what has been achieved and what is left to do.  This is not always an easy job as there is always more to do than already done.

What has been achieved?

All original portholes were removed and restored and refitted.
This was an expensive (to say the least) exercise but one that will be worth it for years to come.  It was a now or never job.  Now seemed better than never.

All main ship strip out finished
Well not quite.  95% is done.  There are still old cables that need removing from the old radio room that went up through the ceiling into the tower.  This is a warm weather job and will not hold back other work.

Cabins habitable
This was the main achievement for two reasons.  The first was that I had somewhere to stay on board and live.  Not a palace, but comfortable if you ignore things like temperature.  The second benefit is the biggest though.  If you are going to convert a ship to live on, you need to live on it.  Otherwise your designs and ideas will be guesses and it is invaluable to get a feel for what is needed to ground your ideas and designs.

Mess woodwork done
The walls and ceiling of the old mess room were done.  This was a learning room and taught me a lot about what works and what does not work.  It was useful to get the nail gun and a few other tools to speed up the process.

Electrical and plumbing
Lots of planning and thinking here but none done because the rooms were not ready.  But the wiring in the cabins is sound and working fine and my ring mains worked well.  It did help highlight the challenges of earthing the kit so again some useful lessons learnt.  None of the water tanks were progressed sadly.  So the water pump and filter systems remain in their boxes.

So not as much progress as I would have liked lately but progress none the less.

I think the immediate focus will be to get the front locker cleared so that Dave can remove the metal lockers down there.  If I can source some portholes (I have some) then that will be the last major engineering job.  Apart from the other cabin portholes which I need 8 of and still have not managed to source.  But that is another £2k-£3k just for those to buy so they can wait until later next year.
One key lesson is that it is not worth progressing rooms too far before engineering work is done or the mess can be too damaging to the work done.

Finally, I have to get the woodwork done over winter if I am to have a chance of doing the insulation next year when the temperature is right.  Thats lots of work to do in a short time.  Gulp.

New portholes

The new portholes look amazing.  Great job again.  Fitted in 1 day, this must be a record.  Thanks Dave.  Refitted waste pipes and ariel lead.  I will take photos when I am next on board in daylight.


I was working in a company on Monday who make a very innovative set of products.  Based upon Nano technology.  They make a coating which is hydrophobic.  It will prevent corrosion on bare metal, can be pained over paint, a version for wood and a version for stone.  Amazing stuff.

The applications are of course extensive.  Marine usage would be huge as would painting of brick and blocks on housing.  If the water cannot soak in then it will not absorb heat as it evaporates and dries.

Clever stuff.

Portholes in

Txt just in.  Portholes fitted.  Can't wait to get home and see them.  But that means Dave is done at this end of the ship for now.  So cleaning duties here we come.  Fingers crossed its not a big job.

Next stop, front locker room door.

Freezing fog

I awoke for the second day running to freezing fog.  My gantry was less of a walk way and I would have been better equipped with a pair of skis and exited to the sound of clanking cow bells (Ski Sunday memories).

It was not a good morning.  It all went wrong last night.  'Can you remove the waste pipe running through the porthole cover please' says Dave in a text.  No problem says I.  Timing is everything.  I did not want to be without facilities this morning so everything just needed to be prepared so I could pull the pipe through this morning.  In the dark.  In the freezing fog.

I make few regrettable stupid mistakes but last night I realised I had made one.  When I went to prepare the pipe I realised there was also a black wire running through the hole.  WTF!  Oh crap.  I have wired the TV ariel from the front of the ship all the way down the shop cable tied and through the hole and then all the way through the ship to the TV room where the coax terminated.

Sigh.  45 mins later the cable had been threaded back from the TV to the hole and the job was done.

I can only think that once the ariel was up, the excitement of getting imminent TV was too much and  brain function shut down.

Note to self:  Don't do stupid things.

The second thing that did not go my way last night was the cold.  I ventured into the old TV room (one of the cabins on the sleeping side) to do the ariel lead.  There was a howling gale through one of the ceiling vents of freezing air.  I had to venture to the top deck to work out why when all the horns were covered.  Or should have been.  The one on that horn was a rubble sack taped on (did not have proper covers for all) and after the storm it had ripped.  But this time of night it was simply too cold, too foggy and too dark to do anything about.  That will be a job for tonight.

I have to say, on nights like that, having watched the film the fog, standing on a dark dimly lit ship alone was a little creepy.  But its an amazing place at night and the lights of the other boats through the fog, the moon on the pond still water and the silence was incredible to see.  But also creepy so I did not stay out long to watch it.

Monday, 9 December 2013


Now the floor is sorted I can turn my attention to putting up the woodwork.  I originally moved onto the ship to help speed the process up.  The theory being that a little bit every day will be a big step forward quite quickly.  It did not work out due to work levels.

But I do now have a small room to put woodwork up in.  So I am back to the sanatogen approach.  One a day.  Tonight I will clean up all the room from grinding dust and start to fit 1 piece of work a day (or maybe a few).  Getting into a routine - eat at lunchtime, home by 7, get changed, 1 hour's progress.

Let's see how that works out.  But it should mean I get the toilet done in 7 nights as its not that big.  Once that is done, Dave should have fitted the bathroom portholes (fingers crossed) and that is a much bigger room and needs some thinking about in terms of the layout.

I have been re studying techniques for sorting the walk in showers.  The walls are easy, the ceiling sort of ok but the issue is the height of the room and the depth of the floor required to do the drains.  I am rapidly coming to the conclusion that the shower will have to drain into the floor below.  Or I will need to lose another 10 cms in height to fit in.

Another attempt at the front locker ceiling last week saw progress.  The ceiling panel was inch thick marine ply.  Useful bit of wood.  That's half the ceiling down.  2 panels to go then just the walls!  Easy.  hmm.

As soon as Dave has finished the portholes then it will be time to cut the doorway between the chain room and the new master bedroom.  That will help as at the moment the only access is from deck.  That is a real pain for working as I have no light or power that far forward anymore.  Cutting the door will help access and will mean I can work over winter more easily at the front.  It is a great storage place too.

Toilet floor 0 Dave 1

It's done!  The floor toilet stands are gone.  Well done Dave for another fantastic job.  This is a great way to work.  I do all the jobs I can, Dave does all the jobs I can't.  Note, not won't.  I am not a big fan of outsourcing jobs because they are messy or hard.  I may as well just project manage then.

Dave will now be turning his attention to the remaining portholes and the anodes.  Its a useful job Gannet.  Most of his work is outdoors and I know he likes my work as when the weather is bad and he cannot work outside he can come be productive on Gannet.  It helps him up his utilisation and helps me spread the costs over a longer period.

It all works very nicely for both.  Dave is not the cheapest guy to do your work but he charges the going rate for someone of his experience and skill.  There are cheaper but needless to say a man with a welding machine does not maketh a welder.  Dave is the best and I firmly believe that you pay for what you get.  I know that I can trust Dave completely on my ship, that it will not burn down (he is very safety conscious), the work done will last the life of the ship and I will not (and never) have to have him back to redo anything.

Anyone who needs any form of metal work, fabrication etc done on their ship/home etc give Dave a ring.

Wednesday, 27 November 2013

Toilet Floor vs Grinder

Dave was on board yesterday attacking the toilet floor.  I think there should be a new entry in the Oxford English Dictionary.

To Dave:  Daving is the process by which solid steel is turned to dust.

He has done a fantastic job.  Half way there.  Go Dave!

Toilet floor is down but not out!  1 more session should do it.

Then I have to remove the dust.  An easy job compared to what I have left Dave to do.  Again.

Monday, 25 November 2013

Toilet floor vs jackhammer 2

The sequel!
Toilet floor number 2 came under the hammer this weekend.  This time I had recovered some strength from the previous attempt and got my technique back.  This floor cam up in about half the time.  With the floor now clear of tiles, concrete and bitumen I could now see that the wall was indeed connected to the floor.  My original thoughts re poor build were incorrect.  I should have known that this ship is engineered to last.

Dave has now been engaged to fit the portholes (remaining 6) and to do the cutting of the toilet pan stands and the wall base.  That should not take long.  With this done I can return to putting up the wall frames.

It had been wondering why the bitumen had been under the concrete.  It turns out its the only way to stop the steel sweating.  Dave informed me that the reason it is put down is that water will still be present between the concerete and steel floor if laid direct and it will slowly rot through.  So they put down bitumen to protect the steel.  Useful advice as I have several floors to lay.

Off to find some bitumen!

The second job of the weekend was another bash at the front locker (to be master bedroom).  The ceiling is (no joke) about an inch thick ply.  Why?  Probably to protect from blast as it was a storage locker no doubt for substances that might explode if it catches fire.  But as with all of the ship, the woodwork is fixed using 3 inch screws minimum which are screwed into the inch thick ply with the heads about 5 mm under the surface and then filled with filler and then painted.  Lots and Lots of them. So you have to look carefully for the slightly different texture under the paint to spot where the screws are and then dig.  45 mins to remove one ceiling panel.  2 more to do.  then all the walls.

Then Dave can come in and cut it all out.

At least he will have somewhere dry to work over winter.

Monday, 11 November 2013

Toilet floor vs jackhammer

The woodwork in the dinning room/mess was done so attention was turned to the bathrooms.  I am still awaiting the portholes to be fitted on the bathroom and a few other rooms but the old toilets could be started.  I cut the first piece of wood to place on the floor with a view to raising the floor over the existing toilet platforms and soon realised that the gap between the new floor and the ceiling would be too little even for me.  The old floor had to go.

As always, the ship engineering became a challenge.  The toilet floor had about a cm thick tile on top of about 3 cms of concrete over 2 cms of black tar type stuff.  

Although the toilet and wall was removed some time back the grey platform at the base was still in place for each toilet like some foundations for a throne on the black and white masonic temple floor it.  The flooring came up relatively easily in about 2 hours of jackhammer activity removing one room's worth.  What remained may require explosives.

The grey platform, if a lump of concrete would have been merciful.  Concrete I can handle.  What they had done is similar to the old galley cooker floor.  The had created a metal box welded to the metal floor (concreted in around) and the grey is a piece of very old, very very very hard seasoned hardwood.  The jackhammer just bounces off.  The chisels make no impact!

The only way to get this out will be drills and hole cutters.  When the wood is removed the metal box can be cut away and then and only then can the concrete at the back be removed.

Then the woodwork can progress.


Thursday, 5 September 2013

Resistance is Futile

The trouble with commuting is that you have two hours each day to fill on a train.  I tend to work most of the time but on quiet days I browse.  Ebay is a great place to explore and last week I realised that it is a good source of portholes.

On Saturday I will be collecting a pair from Gillingham and one from Deal.   Pairs are better.  It is less important that they all match (the odds of finding enough of the right size all the same are low) but as long as I get pairs I can place one each side of the ship opposite each other to at least keep uniformity.

The singles can be added into areas where rooms are on one side only (like the kitchen).

But while ebay is a good source I suspect I will still need to go to Trinity Marine in Exeter to get the bulk.  Sigh.  Its a long way and I will need a big van to both carry the cash needed and the portholes back.

Thursday, 29 August 2013

Portholes returned

I have to admit that progress has been slow lately.  But things have not stopped completely.  The portholes have returned.  A big thanks to Craig who sorted these out during difficult personal circumstances and family loss.  Enjoy your holiday Craig.

Friday, 19 July 2013


The summer winds, are blowing in across the sea... or so the song goes.  But not in Hoo.  The heat from hell is warming Gannet up into a 600 ton sweat box.  Ouch.  Luckily there is now enough air flow to keep it bearable.  But the heat has kept me off the main deck and doing the woodwork and I have moved down into the other 4 cabins to make them usable.

Necessity has meant that I will need to start to use those cabins while I complete all the upstairs work.  Simple common sense really.  The cabins would have been the last thing to do and the work upstairs is simply put, enough.  So rather than squeeze into the dark dark portholeless cabins I currently live in I will clean up the other 4 and expand until the upstairs is completed.  At least to a certain extent.

The 4 cabins with portholes were originally the captains side.  So the set of rooms is of higher quality.  They are also much lighter with natural light coming in.  At least my body clock will start to reset again.

The first room to be cleaned was the old captains mess.  It has come up a treat although it took nearly 8 hours of solid cleaning (walls scrubbed, the whole works).  The old seating cushions now gone, I fitted a makeshift seat cushion system for now.  Refitted the TV and phone etc and put down some carpet (thanks Ian and Sue for the off cut).

It really is quite pleasant down there now.  Just three more cabins to clean.

Some art, a few books, a couple of lamps and hey presto.  Could be comfortable.

Wednesday, 26 June 2013

Weather systems on Gannet

It has been some time since I posted.  I have been ill.  Chicken Pox eradicated the only spare time I had on board over the last few weeks.  It did give me the opportunity to sleep a lot on board.

One thing I realised was that while the winter months were cold the fight in terms of keeping warm revolved around the ari flow.  There was a constant draft from the upper deck, down the stairs and into the cabin section.  But now the weather has warmed up this air flow has stopped.  Not a bad thing in one respect but I soon realised that with the air horns sealed up on deck (to stop freezing air getting in) there was no fresh air coming into the rooms.  Gulp.  I nearly suffocated (ok over dramatised).

What of course is occurring is the simple fact that cold ari sinks and warm air rises.  So in winter the cool air on the upper deck sinks down the stairs giving a nice clean air flow into the cabins.  With the warmed up weather the air no longer sinks.  Its basically got its own weather patterns on Gannet.

This of obvious really but does lead to some rethinking.  The air flow will need to be more sophisticated.  The air horns on the deck simply allow too much cold air into the ship and to close them off leaves the ship basically air tight.  I will need to fit some basic warm air ventilation into each area to provide fresh air without full force direct exposure to the external cold air.

Friday, 3 May 2013

Tray bon

Yesterday saw me clearing the stove pieces to the back of the ship.  Good weight of scrap.  It will never go back together as it was a complex jigsaw of interdependent pieces.  Shame but there you go.  When the room was clear and cleaned attention turned to the tray that the stove sat on.  The condition of this was just awful.  It was rusted beyond a point of recovery to a standard that would make it look ok in a renovated room.  So it had to go too.

Of course it did not go without a fight.  The hammer I was using to free some of the rust from the bolts broke.  Maybe I was a little over enthusiastic beating the rust to death.   The tray has 4 legs.  Each leg welded to the metal floor.  But the metal floor is under an inch or so of concrete.  Out with the reciprocating saw.  Solution to all problems lately.  With the feet cut the tray came away easily (but as usual weighed a ton).

The last job was to put up the walls.  This was done in a few hours and I am happy to say (apart from where the chimney goes through the ceiling) that room is now done.  Next job is to fix the conduit and wiring.  I will do this as an experiment as if there are wiring issues caused by the wood now is the time to learn before starting the wood elsewhere (next room is the new toilet).

Finally, it looks like I may have found a source of new portholes!  cheap too.  Watch this space.

Wednesday, 1 May 2013

Chim Chim-in-ey

Chim chim-in-ey, chim chim-in-ey 
Chim chim cher-ee!
A sweep is as lucky, as lucky can be
Chim chim-in-ey, chim chim-in-ey 
Chim chim cher-oo!
Good luck will rub off when I shakes 'ands with you

Well, not quite.  But dismantling the stove left me looking like one of the sweeps out of the movie Mary Poppins. 

It will be no surprise that the job was not easy.  The stove is basically screwed and bolted together large sheets of very very heavy steel and filled with bricks.  It took several hours.  But in the end Simon 1 - Stove nil.

First job was to remove the chimney.  It was covered in heat protection.  Nasty fibreglass type stuff so protective gear on and breath kit in place.

Next job, remove the chimney flue connection to the stove.  Relatively easy job.  This was the first time I noted that most of the stove is a kit bolted together.  Obviously at this age the screws and bolts are well rusted.

Next job was to remove the stove top.  Held down by 4 rusted screws meant that I had to drill them out to get the top off.

With the top off it was rather like a chinese wooden cube puzzle as each piece is interlinked and it has to be dismantled in order or it would not come apart.  Also, heat retaining bricks needed to be removed to get to other parts.

Eventually I realise that many of the screws and bolts needed to complete the job were underneath.  So I had to remove it from the plinth upon which it was bolted.  30 mins later and a lot of working upside down in the dark with rusty bolts and nuts I managed to separate the system from the plinth and move it to the floor.  It weighed a ton.  I then realised that the weight of this was such that it could not be moved as a whole but needed to be taken to its smallest parts.

3 hours later, the parts.

What was interesting about this stove was how inefficient it must have been.  There were 4 heat retaining bricks in the whole stove.  It really was not designed to retain large amounts of the heat produced from the small fire and I cannot see how anything could be cooked effectively.  But the job is now done and work can progress on the wood around the remaining walls.

Friday, 26 April 2013


Frustrating delays on the porthole front.  The guy who does the sandblasting has gone on a long hol apparently.  So no progress.  The good news is that the new bout of warm weather has made a pleasant change on board.  Temperatures are at comfortable levels.

Tonights plan (now there is no need for the fire) is to dismantle the stove.  It should just be bolted together.  If so, getting it into parts should be straight forward.  Then stick it on ebay.  It needs restoration but is doable.  Just beyond my capabilities on the ship and my interest.  Even if it could be restored it is not the right fire for that location.  The fire box itself is too small and fiddly and does not produce enough heat to be useful.

Anyone interested in the stove is welcome to it.  Any of my followers can have it for free if they pick it up as a reward for loyalty to my blog.

Progress with the wood work has been slow.  Been busy for last few weeks.  With only one wall left to do in the mess the end is in sight for that room.  After that, bathroom I think.

So much to do, so little time.

Still, leaving the marina yesterday morning in bright warm morning sunshine and no noise other than the sounds from the various birds inhabiting the river reminded me why I am doing this.

Thursday, 11 April 2013

You've been framed

Good progress yesterday with the ceiling of the mess woodwork put up (some of it).  Hard to make even, parallel etc etc etc.  Moan moan moan.  But its up and it should be enough to hold up the ceiling.

The tricky bit was the frame to box in the air vent.  It took most of the day fiddling around with the saw and nail gun.  But its up and it should do the job.

Thursday, 28 March 2013

Level - I wish

The first all day session on the boat for some time.  I had the BT engineer coming to fit a telephone line so I had to take it off anyway.  Two things were on the agenda yesterday.  The BT engineer was due to fit a telephone line to the ship (which should have been easy) and a delivery of 100 pieces of 1 by 2 from the timber yard.  Timber in the morning.  BT in the afternoon.

The morning was spent using up the remaining 1 by 2 on the mess walls.  I ran out about 10.00 am.  So I started to grind off the old rusty around the rivets on the inside of the ship.  The surface needs to be clean and rust free (ish) to give the insulation a better chance of sticking.  Messy but necessary.

Cut a long story short, despite telling BT it was a ship and with all the other ships having lines the BT engineer took that deep intake of breath followed by ' specialist job this'.  But after lots of huffing and puffing off he went and fitted a line with me working as engineer's mate.  He of course turned up an hour early which was great.

Sadly the wood due in the morning was late.  By an hour beyond the latest delivery time ensuring both BT and wood guy were present at the same time.  Sigh.

But with wood on board and new line fitted I could progress on.

The speed of progress as I get used to the handling of the nail gun, the cutting of the wood and the fitting of the battens meant I completed another wall in an hour or so.  

Ceilings next, but there lies a whole story of woe.  Nothing in the boat is level, parallel or straight.  Nothing.  The problem with using a spirit level is that while it enables you to make a piece of wood level in relation to the planet earth, if the boat itself is not sitting level then it will look like the set of a 1970s batman episode.

But luckily the boat was relatively level yesterday (I use the door ways as the baseline.  But the ceilings are a different story.  It turns out that not only does the ceiling slope (to make the roof angle towards the edge to make water run off, very sensible) the beams that hold the ceiling up are arched (as is the roof) so that if you put wood along the edge of the beam there is a big gap in the middle.  On top of that the beams are not parallel, even spaced and two are actually bent along their length.

Needless to say, after a long day, the ceiling can wait.

Tuesday, 26 March 2013

Nail Gun

The day arrived, the batteries charged, the gas in place and the nails loaded.    First battens clamped to the uprights and time to nail that sucker!

Eye glasses on.  Push nail gun onto wood, fans kick in, whirrrrrrrr, pull trigger.


Oh my god who invented this!  Nothing prepared me for that! lol

But there was a nail nicely embedded in the wood and they were well secured.  But lordy, what a bang.

The next few nails made me wince.  You try and pull the trigger and wince before it goes off.  The next few nails went ok and then it started to go wrong.  I'd push the nose of the gun onto wood, the fans would start, I'd pull the trigger and nothing would happen.   Try again.  Nothing.  Push in harder this time (yes this is starting to sound like a Carry On script) and wince, pull the trigger


Holy crap!

Then nothing on the next two.  Hmmm.  This is less like nail gunning and more like Russian Roulette of the building world.  My heart cannot take the uncertainty.  Surely this cannot be right.  I referred to the instruction manual (which I had read thank you very much) and it is just pictures.  But one set shows the whirrr and no bang.  It says a nail is stuck.  So I dismantle it as per diagram but there is no nail in it.


What I noticed is that there were only 4 nails in the nail strip left.  So I put in a new strip.


Worked fine.  Then, after a while the same thing happened.  Strip it down again, nothing!  Again, last 4 nails in strip.  Put in a new strip and

BANG  off it goes again no problem.

The damn thing won't work when there are not many nails in the gun.  You have to put a new strip in as the spring is not strong enough it seems.

The paslode im350 is quite expensive but certainly does the job if you can stand the noise.  It speeds up the process.  You have to be careful as with 1 by 2 the nails can split the wood.  But mainly you get used to it.  Its not very heavy (which surprised me) and once you start to handle it right (do not be too gentle with it, it is not  craft tool, its a nail gun and you have to be quite rough when loading each nail when you push down on the nose).

But I did the remainder of the wall in about 10 mins which would have taken a good hour.

Its performance on the 2 by 4 was especially impressive.  Having tried to put a screw through the 2 by 4 and ruined 2 screw driver heads in the attempt, the nail gun put through the nails as if it was butter.  So for delicate work its over the top but it does what its designed to do well.  A few more walls to do now and then its time to tackle the ceiling.  Anyone got anti gravity MDF?

Thursday, 21 March 2013

All in all its just a nother stick in the wall

Ok, I accept that is a poor rip off of Pink Floyd's Brick in the the Wall.  Sorry.  Its hard to be funny at 8.22 in the morning.

The walls are closing in.  But only slightly.  The wall build is starting and it is going both quite well and quite fast.  The photo below shows the first bit of 1 by 2 that went in.

This is a landmark really.  It is the first 'rebuild' piece on the ship.  The wooden frame is going to be built out of 1 * 2 and 2 * 4.  All treated wood to help it last longer.   The uprights are easy to fit as they are replacing existing ones in this space.  The trick though was what to do about the cross pieces.  I could have cut out lots of individual pieces and tried to nail gun them in (hmmm, nail gun, droool) but I thought that this would be time consuming.  

What I have done (further photos to follow) is build the cross beams on top of these which extends the wall thickness outside of the existing metal beams.  The reasons I have done this are simple.

1) The build is far quicker and makes no cosmetic difference as it will all be behind the wood anyway.
2) The speed of build is much much faster and more importantly easier.
3) There is no worry about structural strength.  Unlike stud walls these ones get their strength from the underlying metalwork.  There is no worry about rigidity.  When this baby is built, it isn't going anywhere.
4) The porthole boxes will be easier to build.

the 5th and final reason (which is actually the main reason) is that this extra inch thickness to the wall makes no difference to the size of the room but will enable me to put in more insulation.

The spray insulation is expensive and the reason for using it is that it will insulate and seal the metal from the warm air and stop damp and condensation.  But once sprayed on I can then put in conventional insulation (if I wish) in the outside walls.  I could just keep spraying to the required depth but the foam spray is expensive.

The insulation could then be

Layer 1 metal
Layer 2 foam insulation
Layer 3 rock wool (or similar)
Layer 4 Plastic insulation sheet (its like cling-film and seals everything below)
Layer 5 MDF
Layer 6 Plasterboard

Heat loss should then be minimal and in summer, the place should not heat up.

I preach all the time to people that when rebuilding boats, its worth doing well as redoing it later is hard and expensive.  The layers here may be well over the top.  But if that is the case I will simply have been inefficient £ wise on the build but the result will be extra warmth and lower £ running costs later.  

If I have learnt one important lesson this winter and in visiting other boats on the marina its this.  They are wonderful places to be when warm.  They are frustrating and uncomfortable when you have to fiddle around with lots of wires and fires and heaters and stuff.

Even without the nail gun in action (that is tonights joy) I managed about 2 walls in a day.  This should mean I can get a room done a week in evenings.   The trick will be getting the wood delivered.

Medway builders merchant is a great place to buy wood.  £1.28 plus vat per 3m length of 1 by 2 and they are much cheaper than all other places and they deliver all orders over £50 free.  Thanks to Chris for the great deal on the wood.  Lots more to purchase!