Varnish for wood floors vitrify

Hello everyone!

I want to build my first boat by myself. Now I have a Victoria and a IOM, but I want to build a RG-65.
This weekend I saw a RG-65 built using the usual balsa wood method, but the fiberglass was replaced by varnish for wood floors vitrify, and the boat looks very good. The owner say that he expect that the boat will have a 3 years life, that is more or less the design obsolescence.

To apply the varnish is very much easier than the fiberglass without discussion.

What do you think about this idea?

For the way I build boats, I dont see the advantage. I normally glass, then fill the glassed hull with epoxy to get a smooth enough finish for varnish. I glassed my RG with 15g cloth, adds a little strength and is easy to do.

My normal glassing method is to apply the cloth to the hull with a light layer of 3M77 to hold it in place. Once I am happy with the way the cloth is on the hull, ie no wrinkles or puckers, then I apply resin. Once the resin is cured, I sand, then apply system 3 clear coat, repeat until it is smooth.

You can just paint wood boats, but after seeing a couple of stars get holed, I like having glass to add strength.

My RG’s are all built without glass cloth - but have been coated with epoxy - and THEN varnished. It will take some time for varnished balsa to deteriorate unless the water sits in the hull and isn’t emptied/drained and dried. If you are careful when handling the boat, glass cloth is really not needed. Not sure about the Star class, but RG’s are required to have a bumper to be legal for racing. The one I built for my son-in-law does not use a bumper. Yes things can happen, but if you are sailing in a bumper-boat class club, I would move to a different club, or push to have members carry their own personal insurance to cover any “accidents”. Anything you add increases weight - but so does water if you don’t seal the balsa.

I guess my thinking is, if I am going to add resin to the wood, why not add some cloth. At 15g per yard, I am only adding 2 or 3 grams of cloth weight and a lot of strength since resin really doesnt have any tensile strength.

Stars have bumpers, but that doesnt prevent damage from happening. I have had two boats holed now. One on the deck (1/64 ply) on a port/starboard disagreement. the other I dont know when it happened, but it was through the 1/16 ply sides. Sailed and won the regatta with the hole in the side of the boat. Amazing what a little dacron can fix.

After seeing the success of an RG-65 built here in Chile with this method today bought the materials needed to build mine.
Keep you posted, but only the terminations, the first part has been documented many times on this forum is not worth the effort.
I’m going to build the ultimate design of Maximo Lange, the Pakinto.

Don’t put away your vrnish yet!

All the Footy hulls I have built, except for the Kittiwake, have been covered with very light glass cloth (0.5 oz/15g?) I first painted the hull with the polyurethane floor coating to seal it inside and outside. Then I put on the glass cloth and instead of using the polyester or epoxy resin, I used the poly floor coating again. The floor varnish I used is for gymnasium floors, so it is very good for the Footy hull, and probably the RG65 too.

That is what I will be using when I get to build an RG65 hull.

If this system works I probably try to build a IOM with the same system. I want to try it with a heavy boat. If works probably I will start a revolution about how we build our boats!

I think I forgot to say a couple things that would explain to you what I am doing.

I used the polyurethane floor coating because it has a water-base, so you can use it inside the house without a lot of bad smell, and it (your paintbrush or spray gun) will clean up with warm water, so there is no waste like when using epoxy or polyester resins.

I only use the lightweight glass cloth and floor varnish to seal and strengthen the balsa wood Footy hulls that I make. I don’t think I would use the floor varnish to seal a hull only by itself. You should try a test with some small pieces (15x15cm) of different kinds of cloth and paint it with the floor coating, then let it cure (about 40 hours total) to see if it is strong enough, or if there is a way, to use by itself in the way you would use epoxy or polyester resin.

I do think a 1m sailboat could be sealed with a layer of light glass cloth and the polyurethane floor coating, because the balsa-planked hull is what makes the hull strong. The lightweight glass cloth will add a little strength, but is better for an outer protection.

Tom -

not to shoot a hole into an idea before it is tried - but varnish of any kind has no adhesive or hardness properties - even if designed for a wood floor. It is for protection from spills and “some” scratches, but I would guess it isn’t recommended for holding wood floor boards in place - nails are usually used for that. Likewise, epoxies are the best solution for glass cloth or for wood saturation. Polyester resin is stictly for glass and not recommended for applying glass to wood.

Also, it was reported by someone that an RG65 showed up at the recent “Worlds” (I think) that supposedly weighed 50 grams. If so, I would suggest your recommended 15 gr cloth might be nearly 25% of the total weight of the boat which doesn’t leave much for other things. (I would guess the 50 gr was hull only - but that sure is light for a 25-1/2 inch boat).

I will look forward to the idea of saturating “WOOD” with varnish - but I would lay odds it would strengthen glass to any great degree.

Will look forward to seeing/hearing of the results. Cheers

Remember that I’m referring to a Polyurethane floor coating, and not a varnish. I also think you haven’t done the testing that I did.

I agree a Polyurethane polymer floor coating (NOT a varnish) is not intended to be a glue or adhesive, but it does totally stick to itself well. In testing, did successfully laminate a layer of 1/2 oz. glass cloth to a balsa sheet and it would not come off without tearing. Some extra coats added to the protection. I had the same success to 3/4 oz glass cloth on balsa sheet. I didn’t try anything heavier than that.

A very thick (on purpose) coating was able to hold up to some impacts. I have no equipment beside some steel balls to quantify compressive/puncture tests, but since I didn’t notice any significant stress marks or fractures it supports my use on Footy hulls, and probably for the RG65 hulls I may build.

I use the same coating on my home floors and after two years, I still don’t see any scratches in the traffic area. It reflects the manufacturer’s recommendation to use the same coating on gymnasium floors.

I don’t think I would recommend using a polyurethane floor coating straight from the can as a substitute for for the usual resin in a fiber glassing situation, but it did make a good laminating agent for protection on hulls.

I would like to ask the OP to see specifically what ‘varnish’ he was considering, because if it is a polymeric coating, then he may have something useful.

The RG-65 that is sailing here in Chile was built of balsa wood and polyurethane floor coating and nothing more, not fiberglass, and in Chile’s National Championship finished fourth behind three Little Best. The boat received normal impacts of any race, both days ran rigged B and C, the wind was really strong, and the boat had no problem. It was after seeing these results that convinced me to build mine. I think fiberglass is overkill.

The Pakinto in first place in the first race in the morning.

The start of another regata with strong wind and C rig. The Pakinto have sail number 77 with red numbers. Sails 4, 5, 11 and 37 are Little Best.

You seem to be missing one of my points - glass over balsa is NOT necessary for an RG65. It adds unwanted hull weight, and like a FOOTY, when you are talking “grams” for weight, anything added (glass - or several coats of thickened polyurethane or varnish, or paint) simply removes available weight from the bulb and puts it at waterlevel.

I don’t think I would recommend using a polyurethane floor coating straight from the can as a substitute for for the usual resin in a fiber glassing situation, but it did make a good laminating agent for protection on hulls.
I’m not sure “what” you are saying in this quote - … you don’t “recommend” polyurethane floor coating to replace resin - but it makes a good “laminating” agent ? Ummmm - laminating resins and epoxies are used for laminating in most building circles that I am aware of… both big and little boats. I have heard of polyurethane (2 part) paints being a subsititute for gel coat - but even gel coat isn’t considered a “laminating” agent… at least as far as commonly referenced in building of boats.

Also a note - your floors are probably oak as are most gym floors (or possibly maple) - not a soft balsa. Balsa panels, protected from water by any means is sufficient to be used as a hull for an RG65. For strip built hulls, I would “guess” epoxy would work, since it glues the strips together as well as encapsulating them from water. Even the very thin glass hulls use a minimum of materials to prevent weight gain.

I’m not suggesting your idea doesn’t have merit, but presented as you did for other new builders of RG65’s seems a bit premature - don’tcha think?

The point here is that the polyurethane floor coating makes a very good sealer for a balsa wood hull, both inside and outside. It can also be used to laminate light fiberglass cloth to a hull. If you are concerned about the extra weight, that is your decision, but anything you add to a boat hull involves extra weight. I’d rather build a boat hull that’s on the heavy side for the first time, and I think most or all beginners will do that. After you learn to build a good hull, you can start to look for ways to save weight.

The OP was considering using a varnish or a floor coating as a resin for making hulls from fiberglass, and I think we all agreed that the varnish or floor coating straight from the can probably won’t work.

Tomo - in his first post he specifically indicated REPLACING glass with varnish for wood floors.

Yes. Sr. DiasDePlaya noticed someone else had done it (apparently sealed a hull with the floor coating only) and was asking if it’s OK to just use the floor coating instead of the usual fiberglass outer laminate. In #7, it seems he was considering using either the varnish or the floor coating to make fiberglass-only (not balsa) hulls.

I do not know who agree that the polyurethane does not work as a replacement for fiberglass, but here in Chile there is an RG-65 in which the fiberglass was replaced by polyurethane and works very well.

(Sorry for my bad English, but what is the meaning of “OP”?)

Sorry again for my bad English. The idea is to use balsa covered only with Poliurethane, no epoxy nor fiberglass.

Hi Friends:
My english is not good, but I will try to explain how I paint my hulls.
I have made 35 RG65 in my life and all with the same method.
I Use Poliurethane for floors only, one component. (not varnish)
Do not fill the holes with adhesive!!!
Do it with brush not spray.

so, here we go…
1- one layer inside (leave the sections)
2- one layer outside.(no sand)
3- one layer inside. (no sand)
4- 2 more layers outside.
until here all the layer must be done roughtly to fiil all spaces between wood

5- sand outside (use sand 150, middle weight)
6- 2 more layers outside
7- sand outside (use sand 200)
8- 1 more layer outside
9- sand outside (use sand 300, light weight)

until now you will have 7 layers outside, (really 3 or 4 layers after sand) and 2 inside.

10- you can take off the sections.
from now on, 1 layer+ sand until you got a perfect texture and no “holes” are seen.
11- when you can´t see any “holes” sand with 600/800 sand paper.
12- polish with “car-polish”

the final result must be a hull of 50/60 gr., strong and shine with great resistant to the water.



I understand what is being done by the builder.

Instead of painstakingly sanding the edges of each strip of balsa to the correct angle so it leaves no gaps at all, the thick floor coating is used to fill any gaps by painting many times, and no fiberglass louter layer is used at all.

My new boat today, thanks to Maximo Lange for the plans.