I am trying to sort out re-varnishing an NSM IV and have a couple of questions if anyone can help. 

I have read the varnishing guide on this website but would also appreciate any other tips or advice as i dont want to mess it up.I have spent some time looking into this and have some ideas already but any experience or advice would be gratefully accepted

I will be re-painting the hull as it appears the easiest option, can anyone recommend what paint would be best to use and give me some idea of the coverage area.

As for the decks they are currently varnished and i intend to keep them this way as i think they look fantastic. I have been advised that Epifanes are the varnish of choice and have been looking towards this. 

I intend to recover the decks, transom, centreboard casing and thwart. I'm opting not to recover the inside of the hull as the varnish there appears to be sound and it will save me a huge amount of time.

Is it better to strip the varnish back to the wood for this and if so is this as arduous as it sounds or would i be better just roughening the surface and recoating on top of the old (I might add that the current varnish is pretty sound and there is no peeling or blistering).
Again if anyone can give me a rough estimate of the coverage area it would help a lot.

For decks if you are going to use a single pack varnish I think that Blakes Dura Gloss is excellent - a polyurethane alkyd based varnish which is extremely tough.  Apply by roller and jenny brush gives a great finish.  For coverage and overcoating times search on the net for specifications.  The CVRDA website has an excellent varnishing guide too - link below

I am revarnishing with epifanes at the moment, and the results are excellent. If it's a bit cold use 5-10% epifanes flow enhancer and warm the varnish a bit by standing it in a bowl of warm water. This will help with the wet edge too. Use only enough for the session in a clean plastic paint kettle and don't return the surplus to the tin (reduces dust polution picked up by the brush). Use epifanes thinners rather than anything else - or the appropriate one for the varnish you choose. All the big names are good, but in my experience the build and depth of gloss is better vs blakes or international.

They say it's not necessary to cut back between coats providing the recoating times are observed. I'm not sure about that and flatten the surface with 240 or 320 grit between coats then vacuum and wipe clean with a cloth wetted with thinners and well wrung out just to dampen the surface and remove any remaining particles. Clean the cloth regularly. Sanding between coats will also help remove brush marks, minor runs and other misdemeanors. If well prepared; 6-10 coats over the existing base should give a deep pool finish!

Hi
I have renovated a couple of wooden boats before. I actualy use 2 pack west epoxy which is a fairly evpensive but fabulouse looking option. For example, on my N12 I owned, I stripped the deck back down to wood to start with, this is important as to give a good finish-If not it can often look blotchy as the wood under the old varnish will turn out lighter, even if recoated over the old varnish. I made sure that any dodgy looking wood was allowed to dry out, then sanded to remove the different colour (This is the part where you replace the wood if you need to). I then sheathed with epoxy mixed with the suitable thinners as to allow the wood to soak it up. I then applied about 7/8 layers of epoxy resign that was warmed up using boiling water (you must be careful here-any water in the epoxy will be a mistake you will regret!) Remeber-Put on a thin layer, I found the easiest way to do this was to put on the layer, then keep going over it after every time, empty brush on container Even consider using a roller. odviously sanding between eack layer with p400-600. The result was amazing! It looked really good, I would recomend this option to anyone and everyone.Just remeber-75% preperation, dont rush your surface prep just because you want to slap some varnish on and go sailing! It is well worth getting a warm sealed workship with no leaks or draughts (Excuse spelling if wrong).

What top coat, and how many, did you finnish the expoxy with to UV protect it?

If you have bare wood patches, then I would suggest sanding back to bare wood for that area (be very careful with ply - it's the veneer is very thin and it's easy to sand through it). That way you will not have a major colour change on one item (e.g. thwart).

I bought 2 x litre tins of the International paint (& 2 tins of varnish) - using about 7% of flow agent gave much better results than without. Enough for about 5-6 coats of varnish (inside of hull, underside of decks, transom, decks + gunwhales) - about 4-5 coats on the hull - with about 1/4 tin left over.

Rub down (lightly) with 400 grit wet & dry between coats, then rub the penultimate coat with 400 grit wet and dry paper Wet - use clean water with a couple of drops of Fairy detergent - allow to dry, clean all the dust off and apply the last coat.

Colin (NSM 2)

Yes - be VERY careful not to sand right through the top layer of ply! The worst bits are edges and curves I find.

Thanks for the advice from everyone, its nice to hear others experiences when approaching something which is a little daunting to me :)
I have been slightly confused when looking as lots of paint is sold as for use above the waterline and as i am painting the hull this obviously wont be the case. Also its been suggested to me that the polyuerethene can be a little brittle and can flake away from the hull?
Can anyone recommend any specific paints to use please, i am assuming that if i use a more traditional type that i will not need to remove all the previous paint?

Hi,

You can use a conventional (non-polyurethane) finish on 2-pot paint/varinsh or on one pot or conventional finish

you an use 1 pot on conventional finish  or 1 pot or 2 pot

You can use 2-pot on 2 pot only.

The polyurethane finish is harder (less flaxible) than the traditional finish, but is much better as protection (needs re-painting less often).
Don't worry about "topside" finishes - the industry is biased to yachts which spend all their time afloat. These need waterproof finishes + antifouling. The "topside" is the bit that's usually out of the water. Your Merlin will be out of the water for most of the time (they don't sit on moorings well), so topside is fine.

My experience is that 1 pot polyurethane is fine - provided the primer and undercoats adhere well to the wood. If they don't, then you'll need to rub them off anyway...

If you do have a dampish bit of wood, then the traditional varnish will let it breath (and dry), whereas polyurethane will tend to blister.

HTH

Colin