The best varnish finish that I have ever achieved was on a full size boat, a fibreglass sailing cruiser. The boat was a cancelled order that we put to one side as our boat show display boat, as such it was cobbled together from various items that were lying about, items like rubbing strakes and hand rails come in pairs and, when one is damaged, the other tended to be put on a rack as a spare. My partner and I sorted through this big stack of mahogany items and found some nice pairs which had been quietly seasoning for years.
Once fitted we were extremely lucky because our very small boat was ready weeks before the larger boats being fitted out on the other side of the factory.
Our last job every night for weeks was to rub down all the woodwork with 400 grade wet and dry (dry) and apply a water-thin coat of traditional (International brand) yacht varnish.
The resulting shine was breathtaking, like glass, and there was a very satisfying side to the situation, The team working on the larger show boat were a bit behind and the weeks of polishing (we compounded and wax-polished the hull as well) on our little jewel were driving the chargehand of the other team crazy. Of course we smiled sweetly and told him that, as we were so far ahead, we were more than happy to help bring his boat up to scratch, he exploded, told us to shove our assistance, etc. all good fun.
So, a long winded way to say, patience, dry, well-seasoned timber, good quality abrasives, good quality brushes, or careful spraying, buy enough finish to complete the job to avoid different batches, more patience, and check out SailorGreg's build log of his Dumas 1930 runabout on the forum. Good luck.
