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Top sides paint time -- what to use?


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Last spring I realized re-painting was overdue but too late... So this season instead and last fall I decided to do what never happened when we built the boats 30 years ago -- longboarding:

slipad_för_mars.jpg

 

If all goes according to plan tomorrow will be the last day of longboarding and painting will start next weekend. What to use? My current thinking is epoxy primer followed by 2-part polyurethane top-coat. Spray painting is out of the question, I think (not enough space between the hulls).

 

Thoughts?

 

TIA

 

/Martin

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If you can't spray then use perfection by international over interprotect.

 

Having done this with my GBE I'd recommend getting it sprayed though. 2 coats each of primer, undercoat, topcoat is a hell of a job rolling and tipping.

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I painted the tri with 2 coats of Altex No.3 primer/undercoat and two coats of Altex Elite 2 pot rollered. Got the best results with lots of thinners - around 20% and small foam bullet rollers. Never tried tipping, seemed overly fussy to me. 

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Yes, spraying is very tempting even though I have no experience of it but as you see in my photo the space between the hulls is less than 50 cm for most of the hull length.

 

Any particular reason for recommending International?

 

/Martin

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GregW, interesting observation regarding thinned paint and rolling it. In some resent paint projects I have noted that the first rolled coat comes out very nicely -- pretty much the same as sprayed. The second coat is never that good for some reason but I have never tried that much thinning.

 

Never heard of Altex. Over here we have a choice of International and Hempel plus whatever car paint shops use.

 

Aditional information: I am only doing the 'inside' topsides this year. I expect to do the 'outsides' next year.

 

/Martin

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Martin, looks like a similar low-ventilation low light shack like I had - I should have added the primer is pretty evil and chops through rollers like you wouldn't believe. The top coat not so bad. You thin it right down and it looks so thin and runny it shouldn't have any coverage, but once the second coat goes on it looks ok. Worked alright for me, but I was only working to the 'boatlength' rule :-)

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I did the beams and cabinside with International Perfection and it was super easy to get at good finish and its very hard durable paint. The biggest challenge is keeping the dust off it as it stays tacky for ages.

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The first boat I restored some years back I went nuts trying to get it perfect, then some chap introduced me to the boat length rule - it's a good rule and you can get very good results that you'll be happy to live with.

 

If I'm perfectly honest, these days I'm getting lazy and it's more like the two boat length rule (if your boat length is at least 9 meters)... However it still applies roughly speaking.

 

I've never had luck with rollers - ok for undercoat that you're going to sand but if the temperature, humidity and thinning isn't right you end up with uneven, poor coverage orange peel or tie-dye effect.  Which could be cool in a hippy kinda way...

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I am having problems wth the boat length rule. First coat of paint went on on Saturday (rain on Sunday) and I am clearly out of practice.

 

Sanding again -- yeah, it's that bad :-(

 

I *think* my problem was I did not control the viscosity well enough but I have a plan for the next coat that I think will make me less dependent on varying evaporation rates (wind, sun...): Keep the properly thinned paint in a big PET bottle. Make small *small* hole in cap and pour paint right on the roller -- keeping nothing in the roller tray.

 

What do you think?

 

/Martin

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As someone used to diy house painting I have just finished painting the topsides of my 31ft yacht with Transomarine 343 2pot polyurethane. My 2 boat paint advisers didn't even mention a viscosity cup which may have made some difference. I used Wooster flawless rollers which are awesome and followed their advice, basically Be Patient for the calm warm days, only paint when humidity is less than 75%, temperature between 15 and 20 degrees c and don't paint after 2pm here in Akl NZ.

From 1 metre away you can't tell it was painted with a roller. I was also told that the paint does flatten as it hardens. This is correct. I am a first time topsides painter and I am happy with the result.

Good luck.

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Test painting already done, sort of. The very first square metre or so painted on Saturday came out really nice. This was when I had good thinning accuracy having added a known quantity of thinner to a known ammount of paint. Then I lost track of viscosity and didn't manage to fully compensate for evaporation. Or at least, this is my theory and why I think keeping the thinned paint in a closed bottle and none of it in the roller tray may help. I did keep a lid on the container for the paint but there was always some paint in the roller tray.

 

Temperature between 15 and 20 degrees? I see nothing that warm in the forecast until May 22 and we all know about long-term forecasts.

 

/Martin (living at N59 and some)

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Work progresses and I may be in the positions to launch next weekend.

 

I do think I finally reached the level of the one boat length rule. Keeping viscosity in check by keeping the paint in a bottle and squirting paint on the foam roller as I went really helped. Some non-timely rain did not help...

 

And that long-term weather forecast actually came true. This weekend has been really nice weather-wise.

 

/Martin

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OK, I don't have any photos of the end result but this is the second to last coat in the making. International Perfection with ~20% thinner and at some 8 C. Only the port hull was painted when this photo was shot.

International_Perfection_lager_ett_1.jpg

The last coat was put on the day after and did not come out this good. Because it was a little warmer? Because it is harder to judge how much you apply when there is no shift in colour or gloss? Because paint flows differently on a sanded surface? Becuase I did not hit the correct viscosity as accurately?

 

Anyaways, it looks OK from even a modest distance -- at least while still under the tarp. :-)

 

The very first and failed coat was done using Hempel's 2-pot paint. I don't blame Hempel for the failure but there are differences. Hempel's product 'dries' much quicker which makes it easier to work on the second hull but I guess that may have contributed to my failure -- unless keeping the thinned paint in a plastic bottle had saved the day even with Hempel's paint. I like the whiteness of Hempel better than International's which I would call cream- or milk-white even though International would like you to think of snow.

 

The reason for switching from Hempel to International was availability.

 

Finally, comparing the newly painted 'insides' to the partially yellow 'outsides' today I could see that my long-boarding efforts have improved things.

 

/Martin

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That looks really nice!  Martin, in your long boarding efforts, was there a net gain in filler used?  I wouldn't mind going through the effort on mine, but worry about cutting into that first layer of glass.   How far did you take it down before laying on filler?

 

We are looking forward to seeing the final product!

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Perfection was not the goal and I don't like adding weight to my boat so I added almost no filler -- less than 100 g for sure. I sanded until reaching high spots of the laminate and did not fill in lows. I then undid some of the longboarding as I removed the 60 grit paper scratches by machine sanding with finer paper: exposed filler sanded quicker than old paint. Still fairer than before.

 

/Martin

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