HULL GLASSING AND FAIRING

[Manos Amanakis]

I have finally started glassing the starboard hull of the Tiki 31 I have been building for some time now. While filling the wire stitch holes and the keel, stem, stern gaps and sanding to prepare the hull for glassing I realized that it will be impossible to accomplice a perfectly fair surface unless I used some kind of fairing compound.I am using West System products and thinking of using Low Density Filler to fair the ups and downs of the plywood but I don't know at which stage of the glassing process should I do it. I am giving the hull a coat of epoxy, applying the glass cloth and then two more epoxy coats. Should I then wait for the last coat to cure, sand the surface and apply the filler? There are also some larger hollow areas that need to be filled. How thick the coat of the filler can be without the risk of cracking ? Should I mix it with colloidal silica if I want to make a thicker coat ( up to 5-6 mm)? My epoxy and paint supplier suggests I should use an Awlgrip epoxy fairing putty for this job but this material is very expensive and I already have large amounts of Low Density Filler. 

I would be grateful for any ideas or advice on this matter. 

Best regards

Manos Amanakis

[Hector de Ezcurra]

Hi Manos:

I´m in the process of filling and sanding too. I'm using ceramic microspheres with epoxi-resin. A filler made this way costs less than a prepared epoxy filler and you can prepare it with the consistency you need. You can sand it easily. We don't use silica because it makes it too hard to sand. Before applying the glass, we only filled holes or gaps that would leave an air bubble under the glass. I wouldn't do 6 mm coats at once, because it would be very difficult too sand. Try to apply the second glass coat 1 - 2 hours after the other, so you don't have to sand that much. Glassing is quite fun. Sanding.... agh! Good luck. 

[Adrian Hall]

Hi Manos,
I was at your stage about 18 months ago in my Tiki 38 build. I can relay what I did; I'm not sure if it is regarded as accepted practice but I am really pleased with the results.
I did a basic fairing of the hull before applying the cloth, filling all holes and hollows with epoxy and colloidal silica followed with a basic sanding fair. I applied the cloth in one go, starting in the middle and working to the ends. I did it solo, with a broom handle on a frame holding the cloth, but it would be so much easier if you have help. I applied the cloth DRY, as I experimented using the wet technique and had trouble with air bubbles. The big discovery for me was Peel Ply. It is frowned upon in some circles but I found it to be a great help. it is not that cheap but a good investment in terms of saving you a lot of hassle. You apply the peel ply to the wetted out cloth and soak epoxy through the weave and leave to cure. Once cured you peel off the peel ply and you are left with the cloth with a generous epoxy coating, a beautiful stippled surface and NO AMINE BLUSH!
No sanding is required before the skim coat. I used West epoxy with micobaloons applied with a plaster's float. The result was pretty good for saying I am useless at this sort of thing. It took about a couple of hours to sand the whole hull fair. I didn't get on with a longboard and just used an orbital sander.
If you go to my web site/ blog buildingkira.com and go to archive around Spring last year you will see all the pictures.
Best of luck!
Adrian Hall in the UK
Adrian Hall.

[Marty Peters]

Argggh fairing, don't talk to me about fairing....
I have been fairing the hulls of my tiki 46 renovation for 4 months and am finally happy with the results. I am going for the "pro" finish and trying to get it as good as I can.
What we did was first sand all of the old paint off back to the glass. Then a light coat of jotun high bold Pengard HB primer. Then longboard with 80 grip paper. I can highly recommen abranet sandpaper ( actually a cloth) for this as it doesn't clog. Then we filled the big low spots with epoxy thickened with microballoons. Then another good coat of high build. Keep sanding with 80 grit until fair. Then another Coat of high build preferably in another lighter colour and sand with 150 grit long boards. Repeat until happy with the result. Once you are happy all the wobbles are gone we then longboard with 220 grit to remove the orange peel and the scratches. Then machine polish with 400 grit in prep for the top coats.
If I was going to do this again I would do it slightly differently.
1. Full HB coat in a dark colour.
2. Light coat of white hb primer. and longboard with 1 m boards
2. Fill the low spots with balloons. ( the places where the White primer is still visible)
3. 2 or 3 full coats of dark HB primer, allowing the paint to flash off and then re-coat.
4 light mist coat of White HB. Longboard with 150 until all uniform colour.
5. If any White still showing touch up these spots with more dark HB.
6. Sand with 220 longboards until you are happy and all orange peel and scratches are gone.

I wouldnt bother with doing the 400 polish coat depending on what top coat you are using.
My top coat is ppg deltron 2 pack and mixed in a ratio of 3;1 and it is extremely nice and easy paint to use. Not cheap but not crazy I used approx 5l per hull thinned down to 15%. it is VERY important to use the correct masks and filters preferably air fed masks. We used 3m vapour filters and sprayed outside as we couldn't find air fed masks. These were the best we could get and were recommended by the ppg agent. Not cheap at around 100 use per set of filters.
Once the top coat has set up and has dried for a minimum of 4 days. Flat it with 1200 and then polish.

Hope this helps


Marty

[Manos Amanakis]

Thank you all for your advice! Despite the fact that it made things much more clear in my mind, it also helped me remember one of the principals of these designs: simplicity. Often, in a building process that seems to have no end, I find my mind trapped in details that probably won't make my boat sail better but are certainly delaying my work and postponing the launching day over and over again.

I think I will use what I already have and know how to use it and that is Low Density Filler for the larger hollows (these aren't so large after all). Can anyone tell me if I have to give the fairing compound a final coat of epoxy after I have sanded it and made it fair or should I go on applying the primer directly to it?

There are also some spots where I had some runs of excess epoxy underneath the glass cloth (no air bubbles. Just runs of epoxy on the vertical surface of the upside down hull that cured underneath the cloth making it uneven). Is this a problem to the bond of the glass to the plywood? Should I sand these areas to bare plywood and apply the glass cloth again or should I leave it as it is and just fair it with some fairing compound? 

Manos Amanakis

[Manos Amanakis]

Hi John,

 

Thanks for your answer. I think I will go for a sooner launch and live with the 1/100 of a knot less in boat speed ;)

By the way, you are doing a great job with the Amatasi!

 

 

[Marty Peters]

HI Manos,

 

I think the hardest decision is to know when to stop, you can keep perfecting and sanding and sanding until the moon turns blue and the stars fall from the sky, you will always find another imperfection. In hindsight i spent way too long on this fairing lark and knowing what i know now i could have had just as good finish if i stopped 6 weeks ago.

I am working on my Tiki 46 in the yard of a very luxury catamaran builder here in South Africa and their latest all carbon-fibre 60ft cat has just been launched. Even with a huge team of 40-50 guys working non stop for over 2 years, when i cast my critical eye over her hull i still find imperfections and that is a boat with a retail of 35,000,000 South African Rand. Will the new owner ever see these imperfection... I don't think so...

Anway good luck with your build, at the end of the day don't get caught up in the really small details because honestly, you'll be the only one to ever see them...

Cheers

Marty

[paul anderson]

Marty i second your sentiments wholeheartedly.Carbon fibre hulls hey,well that would be a tad more than the ole epoxy and ply on the budget;}