UK Boats in build

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Andy P
Posts: 97
Joined: Thu Sep 08, 2005 9:31 pm

Re: UK Boats in build

Post by Andy P » Sun Jan 02, 2011 10:16 pm

Ok here's a bit more detail on how I do it. ( maybe not the best or fastest way,
but it seems to work OK for me )

Mould surface :
Normally my boats are ply friendly, with limited double curvature. Alistair's boat
has a similar kind of bottom panel, so was easy to bend and fit the ply fair. The
Morrison boat required strip planking between the chines due to the high
curvature. ie many battens and filler for the gaps, and a lot of fairing.
Car body filler ( with glass bubbles mixed in to make it easier to sand ) if required
to fair it up. - 2 layers 200g/m² glass in epoxy, 2 coats of epoxy + glass bubbles
rollered on.
Roughly sanded with 40grit beltsander and long board.
For a nice mould that might get used more than a few times - Duratec mould
surfacer, quite easy to get a smooth shiny(ish) fair finish.
Otherwise parcel tape, is a lot faster and cheaper, but not so good long term, but
then it's easy to redo.
Lots of wax and polishing. I used to use Frekote which is easy and fast to apply,
but is expensive, has a short shelf-life, and a sudden separation. A bit of a worry
- " is it out of date and is it going to come off the mould...??". Wax + PVA gives
a more gradual separation, and you just know it will come off.

I cut templates from polythene ( old vac bags ), and precut all the
carbon/glass/peelply/release film/breather/vac bag, roll up the fabrics onto
cardboard tubes, and mark the mould with felt tip pen where the reinforcement
goes.

Everything has to be marked out and stacked up in order ready to go . Felt-tip
pen on the glass and peel ply, breather etc, tiny bits of pvc tape on the carbon,
so it can be rolled oout on the mould and get it right the first time. Practice from
my time many years ago working in a hospital laundry folding bed sheets also
comes in useful here for flipping and floating the fabrics if it goes wonky.

Laminating day - wet out the mould with resin, apply peel ply, reinforcements (
centrecase, rudderbox, forestay, around main bulkhead ), and then the main
carbon, then the peelply layer. Finally the perforated release film, breather and
bag.
Wetting out on the horizontal surfaces with a rubber squeegee, and a foam roller
to even it out, and for the sides.
This takes me several hours of nonstop stickiness, a late lunch and a sit down
afterwards is required!
It's a race getting it all on before the resin goes off, and having enough curing
time before say 7pm to turn the pump off.
It’s easier in the summer when the resin is more fluid, but I have to use slower
hardener.
I use P9 (?) release film/bread wrap with lots of holes, so even if the carbon is a
bit wet, the resin comes out. Two layers of the breather where there are double
layers of carbon.

Next job is the foam. Precut the sides, located on the mould with hotglued
patches of foam ‘above’ the gunwales.
Precut the bottom panels, with overlap, heating the curvy bits near the front to
prebend them if needed. ( the front 500mm mostly, or more than half for the
Morrison )

Alternatively use the grid-scored foam that just flops round the curves, but this is
heavier due to all the cracks that fill with resin.

Remove peelply from the topsides, wet out the carbon surface with resin. Apply
resin + glass bubbles to the foam with a toothed speader. Fit to the mould and
vac.

Next day, trim the chine foam, and fit the bottom panel foam.

Trim the overlappping bottom panels, and then do super-careful fairing of the
foam so it’s perfect !
Round the chines all the way to reduce the chances of carbon creases at the
chines ( which wil be filled to sharpen the corners anyway in the aft half of the
boat )

Skim the foam with resin and glass bubbles, with a flat spreader ( I have used
grouting and plastering floats to stop my hands/ fingers hurting with the pressure
required )
Sand with 40grit + long board to take off the shiny / rough surface.

Cut the fabrics etc.

Outer skin laminating day -
wet out the foam with resin, apply carbon + reinforcements, + a thin 86g/m² glass
layer, peelply, rel film, breather and vac bag.

It’s nice to have a new or freshly sharpened pair of scissors.

Music choice whilst doing it too is important - not too slow, but not too manic
either. recently this seems good for me with the right bpm - house/electronic stuff: http://radio.hbr1.com:19800/tronic.aac, and
this goes on forever so the hifi doesn't get sticky!

Wait a day or two... then pop the shell off the mould, using an assortment of
nylon and wood wedges. Waxy release tracks along with small creaky cracky
noises. Frekote - nothing happens apart from a bit of sweaty swearing and then
a big bang. and a bit of bent laminate at the biggest wedge.

Woohoo! it’s done.

SteveC
Posts: 551
Joined: Fri Dec 22, 2006 10:32 pm
Location: United Kingdom

Re: UK Boats in build

Post by SteveC » Mon Jan 03, 2011 2:20 pm

Andy and Steve - that's great thanks for the info - it helps considerably to hear from others with the experience on best practice. I have put your comments in a document and will post it on the website as an advice note
Steve Clarke (UK)
GBR338 "Money4Nuffin

Chris Maas
Posts: 110
Joined: Tue Oct 10, 2006 10:45 pm
Location: USA

Re: UK Boats in build

Post by Chris Maas » Mon Jan 03, 2011 5:44 pm

What Andy and Steve said.
One trick is after you sand the foam perfectly fair sand in some shallow indentations where your overlaps in the carbon go. It's much easier and lighter to fill a slight hollow than to fair out a high spot.

Andy P
Posts: 97
Joined: Thu Sep 08, 2005 9:31 pm

Re: UK Boats in build

Post by Andy P » Mon Jan 03, 2011 8:09 pm

Although my account is very long, there are still bits I have left out / can't remember when writing.

The carbon I use is ±45° stitched at 1.35m wide, so there are no overlaps, the width is just right from gunwale to gunwale.
The fine glass outer layer ( only 1m wide ) is overlapped at the centreline, but this is kind of a sacrificial / bulking / flattening layer that is easy to sand off.

My layup for a 'new rules' IC -
Hull
200g/m² stitched carbon at ±45° , 5mm 80kg/m³ foam, 200g/m² stitched carbon at ±45°, 86g/m² woven E glass 0°/90°.

Foredeck
200g/m² stitched carbon at ±45° , 5mm 80kg/m³ foam, 200g/m² stitched carbon at 0°/90°, 86g/m² woven E glass 0°/90°.

Crewdeck
200g/m² stitched carbon at ±45° , 5mm 80kg/m³ foam, 285g/m² woven carbon at ±45°, 86g/m² woven E glass 0°/90°.

With some 200g/m² UD carbon, in a strip along the centreline of the hull from the centrecase to near the bow, along the hull where the main bulkhead goes, and similar on the underside of the foredeck. And at 90° across the crewdeck from shroud to shroud.

With some patches of carbon at the centrecase, main bulkhead area, rudder box...

Bulkheads filleted on, with carbon strips over the fillets at the main bulkhead.

Joints between the hull and deck - simply bonded together, and then two strips of ±45° carbon over the joint.

You need to be careful and not add too much 'extra' to keep the weight down, so the boat comes out at or slightly under the 50Kg minimum when complete.

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