Thursday, 8 November 2012

Battening out the inside.

 There was one last thing  to do before painting the inside and yes I forgot and had to repaint some bits.  It has suffered rather badly when I was welding on the outside.  But hey, no-one's perfect.  Rubbing strakes, that's what I forgot.  Those bits of steel that take the knocks instead of your lovely hull paint.  Why didn't I get the builder to do this for me?  Well I wasn't sure where I wanted them and he didn't seem to know either.  I did try having them diagonally like the commercial vessels have them but this was rather fussy.  In the end I went for an extra two in-between the top and bottom ones already there.  Lengths of D section were welded together and dogged to the hull for continuous welding.  Dogged - scraps of shaped steel tacked to the hull for support and enable a metal wedge to be knocked in and keep the rubbing strake close to the hull for welding.

Of course the other things were the air intakes for the engine room, this is actually the air out, the intake is on the other side.

This is the inside and shows the hole into the engine room which will have a 24v Kenlowe fan. There is a baffle to allow water runoff and a top lid for access.

These are the permanent boarding steps as required.

There, that's better, now we can get on with undamaged paint inside!

So the inside was painted with zinc rich primer.  Actually a lot of it was sprayed with a HVLP spray system.  Cheap but very effective.  But I did use brush and roller too.  There was a holding primer on all the steelwork so after a clean it was on with the paint.  I alternated between red and grey so as I could make sure everything was covered properly.  In the middle of this battens were bolted to the frames of the vessel.  These frames are every 600mm and are used to attach the boat interior, walls, linnings etc.


I used 50mm x 50mm (2" x 2") for the floor and 50mm x 25mm (2" x 1") for the sides and ceiling.  I am using the word ceiling to mean the inside of the roof or cabin not in the true "boat"  sense.  I used douglas fir as I had loads of it.  It was treated with Cuprinol and luted and bolted to the frames.  For luting, I used Sikaflex 291, ok it's not a traditional luting but I reckon its fine.  What we are trying to do is make a barrier between the wood and the steel to avoid poltice corrosion and damp.


The insulation on this boat is sprayed foam.  They do say that the foam itself will protect the steel even unpainted.  This assumes the foam: a - covers all the steel and b - sticks to it properly.  This I could not be sure of and I wanted to try and make sure that I was not going to have to fix things later on.  Hence the, some would say, extreme paint system on the inside.  I is a well known fact that boats rust from the inside out.


You can see in the above photo that pre-painted battens are ready to be put up.

1 blast primer, 4 x zinc rich primer, 1 x undercoat (white), 2 x topcoat (white).  Traditional colours for bilges seems to be grey or red.  These are not good colours for picking up defects in a steel boat.  If there is any rust then I want it to stick out straight away.  White encourages you to keep it clean too.  It doesn't matter really what colour you use when it's going to be hidden behind the foam insulation.


I used galvanised countersunk bolts, nuts and penny washers for attaching the  battens.  I could have used stainless but they were all going to be oversprayed so I didn't think it would be worth it.  The cost difference in minimal really.


Spraying in a confined space is not to be recommended unless you have a decent mask and good ventilation.

 I had an axial flow fan mounted in a frame that would fit over the fore or aft hatch.  The air flow from that beasty would suck you had off.  

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