73 posts in this topic

Fair dinkum it didn't look like that when I had it, as a temporary fix you can do what I said above once you have dried out the timber, for a proper fix I would sand of the tape along all the bottom edge back to timber, do the Everdure treatment then glass on some very thin tape, the very diluted Everdure will fill all voids so keep putting more half strength on until it won't accept any more, it keeps soaking in and basically turns the timber to glass. I wouldn't use edged tape as the edge leaves a ridge to sand down just buy a sheet and cut into ribbons.

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Totally different, everdure is used to waterproof timber and give you a sound surface to bond to, the Arafura I restored had seams like your pics so I stripped it to timber, Everdured it with as much as it would absorb then painted it, once Everdured correctly even if your paint scrapes off, water can't soak into the wood. Resins only grip to the surface or a bit down whereas when you do the full Everdure treatment you start with it runny as water so it soaks in as far as water will go and seals that deep

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Sorry if this is a silly question ...

How do I calculate the weight of finished fibreglass? For example, if I have one square metre of 400GSM cloth, I assume it weighs 400 grams before it is used. How much should it weigh when resin has been added and it has hardened?

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400gsm cloth .....holy mother of god.... what are you making ??? a heavy duty sail box or patches for the Titanic  !!!!

 

Yes the cloth weight is the weight of the cloth only and doesn't include the added weight of resins

 

As for the weight of the cured resin and cloth ...... depends on the saturation and 'thickness' of the resin you use when you apply it

 

A very basic rule of thumb I use is to simply multiply the cloth weight by 3.

 

basically -> 1 layer of resin + 1 layer of cloth + 1 layer of resin

 

 

so your 400billion gsm cloth will come in roughly at a heavy 12,000 billion gsm's cured

 

 

:D

 

the only really accurate way is to measure the weight of the resin mixed / pre laying.....

bathroom scales wont cut it unless it is the Titanic your fixing up

;)

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Haha Kingy ... well you will have to wait and see I guess ... :)

So - the cured resin weighs the same as uncured?

Your rule of thumb was what I was looking for. Many thanks!

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yup.... cured resin doesn't alter its weight from un-cured

 

its a chemical reaction between the resin and hardener and there's no 'product' loss

 

 

 

About the only way you'd get a "weight reduction" is to mix a super hot load...

The chemical reaction will emit a "steam" looking vapour for a short period but you wont have time to lay

it let along hang onto the pot, it will get that hot !!! 

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Matt,

 

when laying up cloth (as against Mat) by hand boat builders aim for about 50:50 ratio by weight.  Infusion or pre-preg can get it even lower.  However, to consistently achieve that you'll have to use a vacuum bag.

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You don't need very heavy cloth to do the edges, use really light cloth because it does the job but more importantly it goes around the corner and stay in shape when you apply the resin, you run the risk of the cloth lifting before it cures if you use heavy cloth, I would use thin layers of resin applied when the last coat is tacky so you limit your sanding

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I thought I should post an update on my AC project.

Unfortunately there has been no progress! I started a new job in February and with more time on the road now life has got in the way. I have not done any more work on the boat apart from starting to sand back the hulls to repair the damaged areas.

Last year I focussed on getting the trailer and the Cobra ready and was pleased with the results. There was no time to work on the AC.

I have made a few decisions about the AC though. I have purchased some parts. I have some questions too.

Some decisions:

- I will get new 'square top' sails.

- I will strip and repaint the hulls. I have decided to do that because I have to re glass the edges anyway. I am comfortable with sanding and painting. They are small hulls so I will just paint them by hand.

- I will replace beams and centreboard case.

Questions:

- Does the AC still need a boom vang with the square top sail?

- Are there any problems with using paint stripper to remove the paint?

- What is the procedure for fitting the new beams?

When the weather starts to get better I hope to start working on the AC again. Hopefully we will get it on the water this summer.

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G'day Matthew probably doesn't need a boom vang if you have exactly the right amount of main sheet but I found it did need it with the original sail. I stripped an Arrow with paint stripper and it was a pretty messy job, I did my other Arafura with a heat gun and that was much better. Whichever you do the most important thing I found was to use good scrapers with curved corners as the square corners can dig into the wood, you will have a lot of sanding to do afterwards to fair it

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Thanks Geoff

My question about the vang relates to the new square top sail I imagine it will work quite differently to the original sail.

I will give the head gun a go on the paint. It seems to only work on some paint types. It did nothing when I tried it on the old mozzy.

Thanks for the tip.

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I had a go with the heat gun today. It didn't get much of the paint off, but it lifted a bunch of the glass.

It seems to lift some of the glass and not others.

The paint isn't really lifting the way it has when I have used the paint gun in the past.

Photos below.

http://www.dawson.id.au/ArafuraCadet/Photos/ac20.JPG

http://www.dawson.id.au/ArafuraCadet/Photos/ac21.JPG

http://www.dawson.id.au/ArafuraCadet/Photos/ac22.JPG

http://www.dawson.id.au/ArafuraCadet/Photos/ac23.JPG

http://www.dawson.id.au/ArafuraCadet/Photos/ac24.JPG

http://www.dawson.id.au/ArafuraCadet/Photos/ac25.JPG

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Great weather today so got to have some time out in the sun stripping the hulls.

I purchased a better heat gun and that made a difference.

I tried paint stripper too which worked well but I preferred the heat gun.

It's slow work ... but I am getting there.

I have some pictures for those interested.

http://www.dawson.id.au/ArafuraCadet/Photos/ac29.JPG

http://www.dawson.id.au/ArafuraCadet/Photos/ac27.JPG

http://www.dawson.id.au/ArafuraCadet/Photos/ac28.JPG

I also have some video!

http://youtu.be/NCFIKz6YvLA

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I have stripped back the port hull. I weighed it after I removed the beams and hardware and it weighed 16.2kg.

After stripping off all the paint and glass from the hull it now weighs 14.4kg.

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Can anyone suggest a good online/mail order supplier of stainless fasteners? I need beam bolts for the AC.

I dont tend to have much time for traditional shopping so online works best for me.

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New square top main and jib arrived today.

 

:)

 

I think it may be the first AC square top in VIC?

 

AC square top 1

 

AC square top 2

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Enjoyed reading this thread - please keep up the updates.  I'm hoping my boy will get in to Arafura's when he's old enough (and if I can find someone to build me/him one). 

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I thought it was time for an update.

The beams are all cut, drilled and anodised.

I have worked out just about all of the hardware I will use - mostly stuff I have already lying around. 

I am slowly making my way through the sand-fill-sand-undercoat-sand-fill-sand-undercoat-sand etc stage.  It is taking a long time but has been enjoyable. I am confident that I will achieve a good undercoat finish.

I am using two pack undercoat. A bit of an error there really (expensive and toxic) but at least I know it is 'high quality'. I am applying with a roller. 

I have some time on my hands at the moment so I should have it ready for topcoat in a week or so.

I am considering getting a professional top coat. What experience have others had with this? I have plenty of panel beaters around here. How much should I expect to pay for two AC hulls?  They won't need any prep - just the top coat. I haven't had any car spraying work done for about 25 years, so I wouldn't have a clue!

 

 

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