For the past fifty years I have varnished my boats with International one pack and have had great success. When I recently redecked Laurie Smart's "Smart Cookie" I decided to use Epifanes as only the best would do for such a lovely boat. Unfortunately I didn't find it at all easy to work with (and I am not a beginner). I must have put on about five "final coats" as I wasn't happy with the results. I am currently revarnishing MR 3285 Venus in Blue Jeans which has survived 12 years unscathed since I varnished it with International one pack. However I thought I would give Epifanes another try. It's just as bad this time. I find that I can't get it to flow out to a smooth surface unless I put it on heavily whereupon it sags. I have tried it thinned (Epifanes thinners); I've tried it unthinned, warmed, unwarmed. I've got up at dawn to put it on in the morning cool with a rising temperature gradient. I've watched every varnishing YouTube I can find. I've bought expensive Hamilton Perfection brushes. I have not tried using a roller and then tipping it out as this is not a suggestion made by Epifanes. I put the varnish on using diagonal and perpendicular strokes and then brush it out with the grain, followed by a light tipping. When the varnish has dried, if I sight along the deck I can see the start and end of the brush strokes in a slightly rippled surface (each coat is rubbed back as in Epifanes instructions). My only thought at the moment is that I am perhaps "working" the varnish too much before leaving it to settle. Is anyone able to help (I'm due to get up early tomorrow to try again!!).

It sounds to me like you haven't thinned it enough.
 
The Paint Police have been very active in the last 10 years and something has definitely been going on with single pack polyurethane products as they all know seem to take an eternity to dry, need to be thinned 20% to stand any chance of flowing out and crinkle up you dare overcoat them inside 72 hours.
 
They are now an absolute swine to work with, and I avoid it wherever possible!! 

Hmmm. That definitely sounds familiar. The Epifanes DEFINITELY takes much longer to dry than I am used to. Even the instructions say to overcoat not before 24 hours at 18 degrees celcius (which is not a common overnight temperature). 24 hours often leaves a less than robust surface to rub back. The only times I have had smooth coverage have been the priming coats which are heavily thinned. I have been reluctant to thin the top coats so heavily as it means a thinner protective layer for each coat but if YOU have found the same problems as me, then I suspect you may have hit on the solution. Interestingly one of the reasons that I decided to give Epifanes a trial was that I had become less than impressed with the latest versions of the International offering (Compass?). I would also say that when I did Smart Cookie I first epoxy coated the deck and then, as recommended by Epifanes, used a two pack varnish to seal it prior to proceeding with the single pack. I didn't achieve a faultless finish with the two pack either, but at least I could have flatted it back and buffed it up! What varnish do you prefer to use these days? Thanks for the input Chris.

We prefer to use two pack varnish these days, and there doesn't seem to be much to choose between the topcoats. Hemme do a very good primer varnish with superfast dry time and high build rate.
 
With these too drying time is a problem, but the other way around! Use of a retardant thinner gets around this and helps keep a wet edge.
 
People are terrified about mixing systems, but my experience is that you can overcoat with two pack all but the very softest single pack varnishes without reaction. Most built post 85 will have been done in a polyurethane varnish (one or two pack) from new. Its the old fashioned tung oil varnishes that cause issues because they never really go hard. 
 
International Blue Peter Deluxe and Blakes Dura-Gloss were fantastic. Ive not used Blakes for a long time and gave up with International at the second iteration of Goldspar (Had a funny smell, fresh tomato?). Topkapi from Hemme seems to me the best of the one pack products if you have to use one - I used it on an old 12 on Wednesday, it'll get its second and final coat on Monday if its hard enough. 
 
 

Having re read your second post I would rub back to the two pack, get yourself a can of Acriglass and put a coat of that on thinned with their 205 thinner approx 10%.
 
 

This thread is of great interest since I'm about to do the wood finish on a 1961 Vrijheit,- Dutch Sports Keel boat  built in strip planked Mahogany. As it seems everyone, I liked the old formula Goldspar but find the newer alternatives decidedly poor in comparison. I had thought of Epifanes, simply by reputation, but now have doubts.
 
Can you be more specific about Acriglass. A web search here showed this as a automotive product. A specific search in English suggests this is a Hemme marine product, but when I then do a web search for a supplier in France and type, 'Acriglass vernis Hemme' Google gives me all sorts of reasons why men (homme) should use nail varnish!
 
Rod & Jo 

it is a Hemme product. Skipper are the UK distributer.
 
Im not sure its significantly better than the various other to part products, but it works well for us. 

 I completely identify with the problem highlighted by the original post. I have experienced the exact same when re-varnishing our very dear Salcombe launch. I too, have been down the "thinned/un-thinned/waiting-for-a-blue-moon route". I even applied a coat in high summer in totally ideal conditions. Result: exactly the same.  I also, have varnished many boats in my time, all with better results than currently. 
IMHO Epifanes is dire to work with. International Gold, Schooner et al, are all just as recalcitrant. 
 
And another thing: I reckon the UV protection of these products is not up to much either. 
 
Otherwise, brilliant. 
 
Trouble is, to my knowledge it is not possible to overcoat two-pack over single pack unless anyone tells me different. So having started with single pack, one is where the sun don't shine: you simply have to live with a poor amateur looking varnish finish all year. Though in our case, when en route to the pub, and certainly back from it, I never notice it that much.  Admittedly the net effect at 50m range is acceptable, but this is hardly the point and certainly not what is promised by Epifanes in their very misleading blurb. 
 
Annoying.
  

 the only single pack we use is top kappi...another hemme product....but...you have to stick rigidly to the specs and over coating times, dont pre clean the surface (activates the subsrata) and do exactly what the instructions tell you, correct thinners , etc...dont use crap brushes = crap job.....i have heard that the old blakes now hempel 1 pack is ok but as we havn't used it cant comment....good luck!... d.h ...

OK so I hope this might help......I am now beginning to hope that I might finally have hit upon a route to a good result. My problem was that the varnish would not flow out to a smooth surface and that I could always see where my final brush strokes had ended. I noted Chris Martin's assessment that it sounded as though I hadn't thinned enough. I then watched yet another Youtube video, this time of a guy getting a great result with single pack on a strip-built canoe wherein he worked on areas no bigger than about 1 - 2 square feet at a time and wherein he only brushed quickly in two directions, ending in a light tipping off (he was using foam brushes but I have tried them and don't like them). This all fitted in with my theory that I was over-working the varnish and was therefore still moving it beyond its (very short) "flow time". I have now got very smooth results as follows (forgive the extreme detail but I can't be sure which bits produce the results!):
 
As I have to varnish outdoors, I make sure that I varnish in full shade to avoid the surface starting to set in sunlight. I pour the varnish into a plastic milk bottle so I can measure the depth of varnish, calculate the thinners required and mark the level on the side of the milk bottle. I thin the varnish a generous 10% (twice Epifanes recommendation for final coats....but maybe working outdoors flashes off the thinners more quickly?). I apply across the grain quickly over about 1 - 2 square feet....this feels ridiculously small. I then brush out quickly in the direction of the grain, I then tip off from the dry edge into the wet area and ONLY go into the preceding 1 square foot patch (no nice long arms-length strokes along the deck!). I tip off at a shallow angle of about 30 degrees using ONLY the weight of the brush (2 inch Hamilton Perfection) and I lift the brush off the varnish AT THE SAME ANGLE effectively continuing the stroke into the air (like an aircraft taking off!!). This seems to avoid the final "dent" in the varnish. I then continue along the deck 1 square foot at a time making sure I only ever touch the wet varnish in the previous patch. In this way I never touch any varnish that is more than about one minute old. This has consequences when varnishing the foredeck but with a bit of planning and ingenuity you can keep adding wet edges as you extend the varnish patches both laterally and longitudinally. This all sounds very precise and fussy but in reality it is a technique that is fairly easily accomplished. It is certainly very different from painting but I now no longer have any evidence of brush strokes in my finish. The thinned varnish doesn't sag (it just goes on thinner and the single 90 degree cross-brushing seems to even it out). I can now sight along the deck and see a smooth gloss all along the deck (just the odd pesky insect that I'll brush off when everything is good and hard (they do have VERY tiny footprints!!). However, I still maintain that I never used to have to be SOOOO precise in the past. I am also not denying Chris and D.H.'s points about the use of two pack......I was just already too committed to my Epifanes program. Sorry for the length of this post but I hope it helps.