Norglass is Wattle.

Is this a carvel planked jarrah yacht? If it's carvel then stick to single pack paints so that the paint does not crack as the planks move. Any of the aluminium oxide type grey primers will do. There is also no point to stripping off all the paint. Sand smooth, touch up bare spots and paint.

Not sure how the jarrah planking is going to absorb enough water to keep the planks expanded and the sea out!

Some background information for you guys.....

Yes, it's jarrah carvel planked. When I built this boat I did some tests to confirm exactly how jarrah behaved when absorbing moisture since I couldn't find anyone who knew how much a plank would expand under water. Unfortunately timber boat building knowledge is in very short supply and I suspect some of those who did know were not willing to share their knowledge.
I wanted to build a boat using both traditional and modern techniques. I did not like the idea of allowing "natural/raw" jarrah planks to expand and contract as they wish so I prepared my own test samples.

Test results: with no treatment raw jarrah expanded a little less than 6% of its width. After sealing with 2 coats of epoxy timber sealant (Everdure at that time) and then 3 coats of primer (no top coat) the expansion was about 0.7% of its width after 38 days immersed in salt water. All expansion occurred within the first 5 days.
So that's what I did for the whole boat - at least two coats of epoxy sealant on every piece of timber (including all ply) internally and externally followed by relevant primer and topcoats.

I butted all planks tight on the inboard edge and left a bevelled gap on the outboard edge of about 3mm ready for cotton caulking. Seams were payed with Sikaflex.
Although I strictly followed the advice of the Sikaflex wooden boat technical "expert" the most of the seam edges failed with the Sikaflex not adhering and I had to redo a few of the under-the-waterline seams. I removed the Sikaflex entirely on a few seams and used a product called Fixtech and it worked perfectly. I'll never use Sikaflex again.
After 5 years in the water I never saw any movement in the planks. That means to me that sealing planks against moisture, even when under water, can work.

For planks under the waterline I added two coats of grey (Intl Paints) primer then antifoul. Topsides were single pack Intl Paints white.

After 5 years in the marina the paint on almost all seam edges above the waterline started to crack and peel. After 2 years on the hardstand at home some of the antifoul and primer has peeled off exposing raw timber and the topside paint at the seams is continuing to peel.
So that's where I'm at and hence my question about which sealer is better .... Wattyl or Norglass ?

jarrah moves a lot we are timber boat builders and because of jarrahs movement about 8 to 10 % it is always hard to hold a good paint job here in Brisbane with jarrah ,so the boat we are restoring at present has been splined with QLD cedar to allow for the movement ,none of this will affect you to much as long as you only leave her in bare wood for a few days and only keep her out of the water for a couple of weeks
if she has been out of the water for an extended time she may have dried right out and this wood have caused complete failure of the coating brand wont matter no paint will like this a full recaulk or hardening up of seams at least will be required or a splining job . don't get to carried away with topside finish as it will move when she gos back in and tightens back up and will then require a sand back and repaint within 6 months even if you use epoxys
the reason we use wattyl on all our topside work weather enamel house paints or epoxy's and polyurethanes is service and price also there epoxy highbuild undercoat uc230 is amazingly cheap builds well and sands like butter all things a boatbuilder loves

LooseChange said..
Wattyl or Norglass ?

Why not ring both companies and speak to their technical devision. From what you have already deduced by trial and error you seem to have a fairly good grasp on what seems to work. Therefore based on your knowledge you should be able to work out who is offering good advice and who is spinning their product. Play one against the other so to speak.

On the bottom of the Norglass tins label you will find Wattyl's address and details.

The best paint I have found for carvel workboats above the water line is White Knights oil based paving paint. 3 coats no primer. Below the water line Jotun grey primer.

Norglass is an Australian owned company (there are still some) from their website:

Norglass was incorporated in May 1979 in Sydney, and current ownership acquired in May 1982. It is 100% family owned by Les Baker, Janice Baker and Brett Mould.

Wattyl is now owned by Valspar (US)

I worked both as supplier and user to the paint industry for many years, and the continual banning and restrictions of the additives are difficult without the back up that the big manufactures have. They do put a lot of training into their sales staff....so if you do buy from one of their outlets you may get good advice.{well better than Bunnings).

zilla said..
I'd like to use the same manufacturer for all coatings on the boat, just to keep it all simple.

Boty... from your experience in a humid environment like Brisbane I have two questions:

(1) for planks under the waterline: following the Seapro sealer, which Wattyl primer/undercoat and which Wattyl antifoul do you find works the best?
(2) for planks above the waterline: following the Seapro sealer, which Wattyl primer/undercoat and which Wattyl topcoat do you find works the best?

below the waterline we favor hempel antifouls either olympic or globic which is there better range i find the wattyl antifoul doesn't perform to its price point i also like the International antifouls micron extra or 66 though dear performs well and we use the epoxy tie coat of that brand to match though all tie coats work with differing antifouls

above water line if using tp80 as a primer i would use wattyl uc230 epoxy high build and if singel pack wattyl easy flo gloss white with a bit of penetrol to help it flow NO THINNERS roll and tip or if 2 pack poly u 400 make sure undercoat is sanded to a 180# finish no finer as if you sand to fine you will achieve a poor mechanical bond
remember if you have shrinkage of planking already when she goes back in the water and it tightens back up all of your paint will move and will need another sandback and repaint