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[durhambargeman]

 Hello again, Is there anyone out there with experience enough of using glass fibre to cover a hull who can answer me a few questions? I am building a Thames sailing barge and have almost completed the hull. It is 42" long, made from 4mm ply frames covered in balsa, and I now intend to cover the exterior with glass fibre. What I would like to know is; Do I coat the inside of the hull  using the same resin mixed with catalyst, as for the exterior.? Is it possible to carry out the process indoors, albeit in a well-ventilated room, as I do not anticipate any long dry spells to do the job outside? Finally, how long approximately does it all take to be completely dry? I would really appreciate any advice on this subject.Cheeres. Ray

[John W E]

Hi there Halcyon

If you do a good search of this Forum, I am sure what you are after is discussed in some great detail - on certain threads.

I am not sure where they all are now, due to the Master re-shuffling the pack of threads and topics  around.  So you will have to do a good search.  If you dont find them, give a yell and we will all chip in and give our twopenneth.   Because, as with everything in life, there are many way of doing things.

Aye
John E
BLUEBIRD

[Colin Bishop]

Yoy can do it indoors but if you are married be prepared to change your own personal address! The styrene smell while the resin is curing is very pungent. However, if you use a marine epoxy resin with a fast hardener such as SP 106 it will cure in temperatures down to 5 degrees C although it's best if you start with the resin and hardener at room temperature by keeping it indoors for a few days before you use it.

As Bluebird says, do a search on the site using keywords such as GRP, resin, epoxy and sheathing. Ther's lots of info here.

[Bryan Young]

 Hello again, Is there anyone out there with experience enough of using glass fibre to cover a hull who can answer me a few questions? I am building a Thames sailing barge and have almost completed the hull. It is 42" long, made from 4mm ply frames covered in balsa, and I now intend to cover the exterior with glass fibre. What I would like to know is; Do I coat the inside of the hull  using the same resin mixed with catalyst, as for the exterior.? Is it possible to carry out the process indoors, albeit in a well-ventilated room, as I do not anticipate any long dry spells to do the job outside? Finally, how long approximately does it all take to be completely dry? I would really appreciate any advice on this subject.Cheeres. Ray

I have a copy (on disc) of a VERY old and out of print book that goes into minute detail of every aspect of the construction and
operation of Thames Sailing barges. Useful to you? Bryan Young.

[Tug-Kenny RIP]

I can vouch for Colins statement about the Wife.

They seem to have superior noses to us.  I did some glassfibre work may years ago on a 1/1 boat in the garage which is a lean-to against the house.  The smell and fumes came up the drain pipe into the bathroom and then throughout the house.  Mind you, it was awful.

Now I have started modelling, everytime I apply a little glue, she comes running out and insists the doors are flung open to the prevailing weather until the smell is gone.

 We have a caravan at Poole, which is the HQ of Sunseeker Yachts, and most days you can smell the stuff throughout the town, so what chance have we got !!


Cheers...Ken

[tonyH]

Hiya Ray,

I'd strongly suggest doing the inside first, simply because it will give the hull more rigidity when you come to skin the outside. If you've got the spare displacement, you could use coarse mat on the inside as well.
Also, the inside finish is, usually, a lot less critical.

Tony

[John W E]

halcyon hi there,

I am not sure if you have the answers you require from the Forum but, as I have previously stated, there are many ways of doing things.  I will explain my way and bear in mind, this is my way - some people may think its wrong or right - all I'll say is ITS RIGHT FOR ME 

First of all; there are several golden rules when working with fibre glass:

1.  The mixture ratio between your polyester resin and your hardener.  This is pretty critical.

2.  The ambient temperature of the area you are working in.  This should be anywhere between 18 degrees and 20-22 degrees.   Obviously the warmer it is, the quicker the resin will go off and the shorter the working time.

3.  Your resin to Mat ratio - e.g. for every 1lb of Mat in weight you must have (for the average laminator) 2 - 2.5 lbs of resin.

4.  Cleanliness of the working area and surrounding areas.

My Method:

I prefer to skin the outside of the hull and I tend to plank the hulls I make in either obichi or mahogany wood.  These are slightly harder timbers than balsa (which are working with).

Rub down the hull.   Make sure the hull is true and fair.   Any discrepancies/hollows/bumps either sanded smooth or filled with car bodge filler and sanded in.   When this is done, I give the hull one coat of just pure resin with hardener added.   I will not put percentages of hardeners I use to the resins as different resins vary in the amounts you mix.

Once the resin has hardened, roughly about 30-40 minutes, I give a very light sand down with course paper knocking off any runs in the resin - I then use tissue Mat.   First of all, I work in small sections - obviously depending on the size of hull.   I will normally start at the bow to the half way mark and paint resin on their - just resin and hardener mix on first then lay the mating on the top of the wet resin and stapple the resin through the mating.  This removes any air bubbles or creases.   I have used a fluted roller on a larger hull, which does aid the procedure.   Then, whilst that is starting to set - I move over to the opposite side of the hull and the opposite corner at the stern working up from the half way mark to the centre again.   Same procedure resin on first, mating on top and stapple the resin through removing all air bubbles.

I then go opposite on the hull - from the stern to the middle meeting where I put the first piece of resin.   Once that is done, I do the last piece.   

I leave this to go off for another 40 mins - this is where the smell comes in - as the resin starts to cure.  What you can do, which I have heard of, but never actually done.   I place the hull in a large polythene bag whilst curing - Ive never personally done this (scared in case the bag blows up  ).

When its cured (resin gone off) I search for air bubbles and defects where the resin hasnt wetted through properly and mark so when I put the top coat of resin on , I know just to stapple in harder at that point.   

Before I put the final coat on - I put black felt tip mark pens on the tissue Mat - then I cover over the top  these are guide lines for when I rub down with coarse wet and dry working through to fine wet and dry - smoothing the hull off and finishing.    If I rub any of these black felt tip pen marks off I know Ive gone too far.   If I did rub too far down - I would put another coat of resin on top and allow it to cure.

So, in theory, there is two coats of pure resin and one with tissue Mat.

BEFORE I DO ANY RUBBING DOWN - I ALLOW THE HULL TO CURE FOR AT LEAST 48 HOURS.

All I do now, is to coat the inside of the hull with just pure resin with hardener mixed.   Work that into every nook and cranny.

Well, hope this helps and gives you some insight.

As I say, its just one method - plenty more out there - there is also an epoxy method.   These all have the good and bad points.

its up to you to make your decision.

aye
John E
BLUEBIRD

[boatmadman]

Hi,

In answer to the drying question, it depends on the temperature of where the hull is kept during the drying process. As an example, the last one I did was in a boiler room at work at about 25deg c. It was dry and hard in 8 hours. At the other end of the scale, I have known it take 2 days to harden in cold garage at home.

The other great advantage of doing it warm (warm epoxy, hull, and surroundings) is that the mix is less viscous and flows better for a better finish. The lower viscosity also means you get a thinner coat on, which means the chance of runs and sags is minimised.

This was using a marine epoxy laminating system, odourless as well!

As for multiple coats, if you want to put more than one coat on a surface, depending on the epoxy being used, the time between coats governs whether the bond between the two coats in chemical or mechanical.

The supplier of the epoxy I use (http://www.fyneboatkits.co.uk/) advised me that their epoxy gets a chemical bond if re coated within 12 hours, after which it relies upon a mechanical bond.

Hth

Ian

[Colin Bishop]

For coating the inside of a hull it's worth checking out E4 Pond Sealer which is a polyurethane sealer. It looks a bit like resin but is one part, moisture cured and can be used down to 0 degrees C!

[Bryan Young]

As I say, its just one method - plenty more out there - there is also an epoxy method.   These all have the good and bad points.
its up to you to make your decision.
aye
John E
BLUEBIRD

And there talks a professional...so listenup. B.Y.

[Bryan Young]

As a cadet, if the "super" was going to visit we had to paint over ice. Barking mad. B.Y.

[kayem]

Mostly good stuff Bluebird, only a few very minor quibbles.

A roller is an essential for consolidating mat & resin, but after trying everything available over many years, I've found that the best by far for our kind of work is a small washer roller, alternate large and small washers. I use one about 50mm by 12mm diameter, and this is the best for everything to do with model hulls, a fluted roller is OK with larger stuff but not model sized work, it tends to be messy, they flick resin everywhere, and you can't do inside corners with them. Also,they tend to drag the glass mat fibres. You want a roller with loose washers on a spindle, some I've tried with aluminium bar turned to look a bit like washers in one solid piece of metal are nothing like as effective as the built-up ones

The polythene bag thing, I do this a lot with moulds, which I always leave to mature for at least 48 hours before releasing. I only put the boat in a bag after it's no longer sticky though, then leave it by a radiator in the house for a while, you can tape the bag up, so there's no smell.



PS, I had a couple of goes at getting my earlier post right, but gave up in the end. Now, Bluebird will end up getting the credit for all of it, but that couldn't happen to a more lovable modeller.

PPS, managed to get that post right at the third attempt. Bluebird is still lovable though, all the same.

[John W E]

hi Halcyon

Just talking of hull finishes, and using fibre glass.  A gentleman on this forum who wears many different jackets did an article one time about finishing a hull model - I think the model was a Huntsman.  The model was built of balsa wood, he didnt fibre glass the outside instead he used, I believe, a doped/tissue method.  The finish on the hull was exceptionally good, it was more like a polished fibre glass hull.  He sent me details of the method he used of doing this, and, if I get time I will try and email this to you - I know its around in my dreaded filing system somewhere!!!!.   Unless of course the said gentleman (with the jackets) pops up on this thread and explains how he did it.

Still doing my 100 lines 

aye
john e
BLUEBIRD

[durhambargeman]

Hello again, Thankyou once again chaps for coming to my rescue. Lots of wonderful helpful advice as always. It may take me a little longer to get round to this part of the job than I at first thought as I have decided to replace the balsa wood that I already have on the hull with a stronger balsa, as I am finding that every time I do any rubbing down, even with fine sandpaper, it wears a hole in the surface. So. stronger balsa or even a hard wood would be better. I will have to give it a bit more thought. Thanks again. Ray

[John W E]

Hi there Ray

Just as a thought, you are going to replace your balsa wood - there is an option here.  If the hull will permit and sizes will permit.  You could plank over the top of the balsa wood with obechi strips.  Billings do packs of these strips 1.8 x 7 x 8 MM long. Obechi Is a fairly simple timber to work with, characteristically like balsa wood, but its harder.  But not too hard - so you can bend it, sand it etc. without the fear of sanding through - unless you go aggressively at it  .   

There are plenty of companies that supply various timbers Jokita being one of them, and I have dealt with them - if you do a search though on the forum there are other members who have dealt with other companies - with the same satisfying response.

You could just plank straight over the top of the balsa as above, and then rub it down and glass over the top or, like you intended you could remove the older balsa wood planking and start afresh.  The option is yours as long as when you have finished with it you are happy with your model.

aye
john e
bluebird

[Shipmate60]

Or Epoxy the whole hull, the resin will soak into the balsa and give a more stable base.

Bob

[CrashRescue]

has anyone tried using envirotex? would it be advisable?
its does say its water proof
:) just a thought. i was thinkin on using it on my hull. i have a Aerokits  vosper R.A.F Crashe Rescue Tender 46"

[andrewh]

If i can add a couple of thoughts without confusing matters:

Most of the discussion and advice has been related to Polyester resin - car body resin.  It works well, hardens in about 30min (VERY temperaure dependent), and Smells very pungently!
(If you use this please get hold of liquid catalyst rather than paste as sold at Halfords, etc since it is extremely difficult to evenly mix the paste into the mix)

Less smelly and slower hardening is Epoxy - this is what I use for large hulls.  Remains workable for an hour, "green" in 4 to 5 hours, hard overnight.  More expensive.  Protect skin from the stuff.

I am assuming that you are doing this for finish and a little local hardening/toughening of the balsa skin
As somebody said - don't forget dope and tissue - it works for Glyn Guest. who am I to quibble?
Again there is the issue of smell, as many Social Advisors (Wives) dont much go for eau-de-dope either (except in their hairsprays!)  The tissue/dope method is ALWAYS reversible - you can backtrack all or any part of it at any stage by brushing on more dope or better still thinners.

tissue can also be applied with diluted white glue or any acrlyic paint (well diluted) or any of the water-based quick-drying varnishes - add some microbaloons for sandability and you have a useful goop.  If you use a water-based adhesive, you need to use a model aircraft tissue (with wet strength)  Florists tissue will disintegrate!

Instead of paper tissue you can also use a synthetic tissue - there are some made to replace aircraft tissue, or nappy liner (polyester felt) or horticultural fleece.

Sorry to ramble on - it may be an idea to try your chosen method on a dummy panel to build confidence first

andrew
an experienced dope

[787Eng]

Use West Systems EPOXY No Smell, it nice and thin and you get a great finish.
I have used vast qtys, in side the house with NO complaints from the rest of the family. Sanding is a bit dusty but you would get that with polyester resin. The picture shows my attempt at glassing, wings are made of balsa and then glassed.
 
There are dealers in the UK, but here is a link to west systems web site http://www.westsystem.com/

[craftysod]

Imagine putting one of those engines in a boat,it will fly

[787Eng]

its been done