Sikaflex over epoxy - fixing leaky fore-deck

[carioca1232001]

I am going to cut a long story - short !

Am in the process of carrying out a major repair to fix fore-deck leaks.

Used a circular saw followed by a router to weed out out 48 fancy strips of white wood ( marfim , 5x5 mm)that were set with epoxy-glue in 5x5 mm recesses on the mahogany planking of the fore-deck. A back-breaking job. :eek:

BTW, these recesses are due to the overhang of adjacent plank-ends butting-up against each other.

Having used a 5/16 straight-cut bit on the router, the resulting rectangular grooves on the mahogany-planking now fit the new white-wood ( marfim )7 mm wide X 5mm deep strips perfectly.

To-morrow morning, I plan to seal the new grooves on the mahogany planking by swabbing with two-part epoxy diluted down with 5-8 % acetone (by volume). Similarly, seal the white-wood srips too. The epoxy is a slow-curing type (7 hours).

Some 5-6 hours after doing this, that is, just before the epoxy cures, plan to squirt Sikaflex (polyurethane) sealant into the grooves and then tap-in the new white-wood strips. Is this OK ?

Would welcome any suggestions and/or advice.

[Don Kurylko]

It is my experience that polysulphide is incompatible with uncured Epoxy. Do a test piece to see what happens before doing the actual deck.

[formerlyknownasprince]

Why mix wet epoxy and Sika together - sounds like a recipe for disaster? Why not just epoxy the new strips in?

Sikaflex works well in one plane - eg, sealing seam edge to seam edge - where it will stretch up to 400%. If you add another plane to the equations eg, by having it touch both sides and the bottom of a seam, it will fail. That is why you should use bond-breaking tape in seams.

I'd go with the epoxied strips with plenty of ooze factor. I'd also omit the acetone.

Ian

Ian

[Gary E]

Originally posted by igatenby:
If you add another plane to the equations eg, by having it touch both sides and the bottom of a seam, it will fail. That is why you should use bond-breaking tape in seams.



IanWould you mind tell us where you get such narrow tape?

And how do you actually get it into the botttom of that tiny slot?

Does this require you have really tiny fingers?

Or does the sugestion "SHOULD USE" really mean nobody actually does..

[Scott Rosen]

I'm not sure why you would want to do it that way, but to answer your quesiton, polyuretane generally adheres extremely well to cured epoxy. (The reverse is not true.) However, I would wait for the epoxy to cure, as the solvents in the Sika might create a problem with partially cured epoxy.

[sdowney717]

Seems like from what he is saying the strips fit perfectly in the grooves before any glue is added. If the epoxy he is using as a sealer hardens, he wont be able to fit these white wood strips into the grooves cut into the mahogany.
So the idea is to place the strips before the epoxy has completely set?

If you are worried, I would simply test it out on scrap wood. Then see how strong the bond is. I think it should work.
Are you trying to save on epoxy by using the polyurethane?

[Bob Cleek]

Igatenby is absolutely right. Check the Gougeon Brothers' epoxy "bible" on this one. You are setting holly strips in the seams, as I understand your post. They should be epoxied in place. While CPES is often used in such applications to make sure the bond runs into the wood (forget thinning your epoxy... you're asking for trouble) epoxy adhesive is entirely suitable on bare wood for gluing purposes. Glue the strips in with epoxy. You may wish to thicken it with colloidal silica to prevent runs and mess and increase the strength of the cured epoxy. After it cures, sand the deck fair. There is no need for Sikaflex at all. If you properly epoxy the splines in place without voids, you will have a solid deck that should not leak. I say "should" not leak, because as you are using epoxy, this will depend on the stability of the deck itself. If it isn't stable, it will shrink and swell and no amount of anything will prevent eventual leaking. Holly splined decks are used on smaller surfaces and on runabouts which are often kept in covered berths, so it is suitable. For decks of larger surface area which will suffer the outrage of the elements full time, about the only ways to go are faux planking over plywood (better than nothing) or traditional laid and caulked decks (the best option).

[Adamant]

I've had experience with epoxy and polyglop and wish I didn't.

[formerlyknownasprince]

Would you mind tell us where you get such narrow tape?

And how do you actually get it into the botttom of that tiny slot?

Does this require you have really tiny fingers?

Or does the sugestion "SHOULD USE" really mean nobody actually does Locally - Scomars

How - read this: How to lay teak (http://www.robbins.co.uk/Pdf%20Files/teak_decking_guide_caulk.pdf)

Tiny fingers: try A 5mm wide stick - or some other tool about that size that you may have

Does anyone do it: Absolutely! I'm about to do 500+ metres of it. Seen too many failed seams to not prime and bond-break.

Ian

Edited to fix the link

[ 10-03-2005, 04:12 AM: Message edited by: igatenby ]

[carioca1232001]

My computer packed up yesterday morning. I went off to the boat hangar did some prep work and called home to ask what WBF had to say about my query.

As your helpful messages were relayed over my mobile phone , I decided to go it slow ! :rolleyes:

The white-strips are 7mm x 5mmm and they fit snugly in the mahogany substrate that are 5/16 " by 5 mm. No room in there presently for epoxy or polyurethane.

I do not wish to do this deck again for leaks , not in my lifetime if I can help it .

So on that note, let me tell you that the 5mm x 5mm white-strips I took out had been epoxy-glued into the mahogany substrate some 7 years ago .

That is why I thought of polyurethane sealant to handle the interface between the strips and substrate. You know, seal the strips and substrate channels first and then polyurethane them together. Please note that there is currently no room between these components for sealant to fill the gap

From what Bob Cleek says, seems that my deck is doomed to leak, if not now, at least in the near future.

What do I do ? For instance, don´t mind hand-planing the strips and turning them into say 5mm x 3mm, leaving some room for sealant - or even epoxy, if the latter is deemed better.Remember this is tropical, sweltering heat etc..

Want a sure-fire solution ......the deck will wait till the many Wood Docs on this board come up with the best compromise .... :rolleyes:

Thanks a mil to all....will look up WBF later this evening

[sdowney717]

Carrioca, FWIW to you.
I have had good luck gluing wood together with permaflex. It is always flexible. If these strips are clean wood going into clean slots, it ought to stick well and not leak. It will also sand off. It will soak into the wood ever so slightly and is not a clear color so you might have to sand a little deeper to get the wood clear, but I am not saying it would color the wood deeply like a stain might do. I use the sand color which is a light yellowy sandy color.
I laminated some wood together and it does not come apart. I even glued 1/2 inch wood plugs into frames and they dont pull out.

www.sanitred.com (http://www.sanitred.com)

[sdowney717]

I wanted to add, those plugs in the frames are holding planks. Screwed planks up tight and under pressure they have not budged a bit. I was using epoxy but as it got really cold in december and january, the epoxy was not setting up and taking too long to harden, like weeks.

[Bob Cleek]

I don't think it really matters that your filler strips are a tight fit. Epoxy would hold them in just fine. Epoxy is "gap filling," but that sure doesn't mean it won't stick if there's no gap! I don't think polysulfide compound will be a better adhesive at all. Lay your strips in epoxy, finish fair and then apply CPES and several good coats of varnish. If you keep it covered and the varnish maintained, it should do alright.

[carioca1232001]

sdowney717 welcome on board and thank you for the tip. Sanitred, a polyurethane - and not a polysulfide , which I have had dismal results with - does seem promising, especially the high-UV formulation. Yes, the slots in my mahogany decking have been bared to raw wood, and the white-strips are newly cut but dried marfim wood.

Sanitred does seem to have worked wonders on your restoration as per your account. But as it is unavailable in Brazil, DHL or Fed Ex will charge me at least US$ 300 just for shipping and customs-clearing fees. Plus cost of purchase + customs fees.

Have you compared Sanitted´s holding tenacity, plus resistance to rupture, with that of say 3M 4200/5200 and/or Sikaflex ? Are you familiar with the latter polyurethanes ?

Bob Cleek, my boat will not be sitting under cover as of this coming summer as the restoration work is about done and I plan on leaving it out on its mooring.

After my sore experience in 1998 with gluing the white-strips with epoxy-glue on the same mahogany deck, I am not likely to do it again ;) And recourse to a circular-saw to bust the fellas, prior to weeding them out with a router :eek:

What if I, say, :

1. Shaped the rectangular X-section white-strips, some 50 in all - with a Dremel-type tool - to form a V X-section, 7 mm at deck surface tapering out to 1-2 mm at the bottom of the deck slot ?

2. To seal the wood, apply thinned 2-part epoxy (max 10 % acetone)to white-strips and deck slots; then let these cure.

3. Put a strip of 7 mm wide waxed-paper at the bottom of the slot for its full length, as Ian(igatenby) has suggested; some say parchment paper (draughtsman stuff) also works well.

4. Finally, squirt Sikaflex into the slots and tap-in the white-strips with a wooden mallet.

What objections could be raised, if any ?

Has anyone thought of this and/or done it before ?

What results could I expect ?

Anyone care to guess ? :rolleyes:

[wyndham]

Seems like you are making this a lot harder than it has to be. Dry fit the white strips with a tiny bit of play. Run some unthickened epoxy into each slot and along the sides and back of each strip. Smaer some thickened epoxy into the slots and tap the strips home with a mallet and a long block. let it all set and scrape and sand it smooth. CPES the whole shootin' match real well, let it set and then varnish.

[carioca1232001]

Wyndham,

Do excuse my frankness, but do you have on-hands experience of what you have proposed ?

Why not use Sikaflex, which should allow for movement - seasonal as well as structural - between the strips and deck substrate ?

Please note that epoxy-gluing was used in 1998, with dismal results. It could be that it was not done as it should have - I simply don´t know, as I was not present on location at the time.

All I can attest to is the unholy - and back-breaking chore - of undoing what was done.

And I need to do it right, now, once in for all.

[Gary E]

If you are using that insert strip of wood for the color efect I can understand, but if that is not important I will tell you how a fellow who worked at Egg Harbour made his teak decks.

FIrst thing is NO plywood or underlayment was used...just the cross supports for the deck at aprox 8 inches apart.

The teak was about 1 inch thick maybe a little thicker, call it 25 or 30mm for you metric guys..and maybe 3 inches or 75mm wide...each board was random length of 4 to 6 ft...or maybe 1 meter to 2 meters long..

He cut a rabit along one side with a table saw and as best as I recall that left 1/4 to 3/8 wood at the bottom, and the sawblade took away maybe 3/16 inch..

When these boards were laid next to each other he had what looked like a slot 3/16 or 4 mm wide and 3/4 or 18 mm deep.

Butt joints looked just like the side joint.

He screwed the deck to the supports allowing for wood plugs.

After the wood plugs were put in and I dont remember what he used but it was in a caulking gun and was black in color.

Deck was then samded with a belt sander to make the plugs level and look good. Vacumm up the dust.

He then covered the deck, not the bottom of the slot with masking tape and used a 2 part black thiokol type caulking compound to fill those slots. this was put in with a putty knife and a trowel much like spreading mastic for laying tile.

Knife it all off, as much as you can anyway, then pull up the tape so it left the black rubbery stuff just a tape thickness above the deck.

That's it, finished..

I didnt sleep under it, he did.
So I have no idea if it leaked or not.

[Bob Cleek]

Carioca, Wyndham is right. Also, Gary E. is describing the proper way to lay a traditional deck. Now, so far, I haven't figured out WHY those "white" wood strips are in there. That technique is used on finely finished, varnished decks and hatches on runabouts and such, not meant for much walking on. Is this the situation with your boat, or are these regular decks that some idiot put wood strips into instead of seam compound?

Anyway, look, do it your way if you want, but take it from somebody who has used a lot of Sikaflex on decks and doesn't anymore. Sikaflex doesn't hold up well in the UV (sun). It will dry out and harden. Also (another lesson from the school of hard knocks), if you don't put a barrier strip on the bottom to free the cured Sikaflex, it will pull apart and get full of cracks and be next to useless. (I've routed out my share of Sikaflex from between deck seams, too!)

If you want the white stips, epoxy them in place as described above. Finish bright as described above. If you are not planning to finish the deck bright (and I assume it is meant to be, since it is mahogany), then just tape the seam edges and use a good compound like Teak Systems for filling the seams. Sikaflex will not hold up as deck seam material. No way, no how. (Now watch somebody that did it last year and says his looks just fine... give it about three or four...)

When you read these posts, keep in mind that there is usually a right way to do something and then there are all the ways folks who are trying to figure it out think up so they can have something to post. If you read between the lines, you can see who's talking from experience and who's just killing time at the scuttlebutt.

[sdowney717]

They are similar and also different.
Permaflex is actually a harder substance than 5200
and cures shiny. It is also a thick liquid like paint.
I was also thinking there ought to be supplier of a liquid polyurethane industrial pipe and tank coating available in your area.
Here is another contact company for liquid coatings, so it is not anything special just to sanitred. Perhaps you can email them and see if they can point you to a local supplier.

http://www.madisonchemical.com/

I think the liquidness of the material would be good in helping it flow into the gaps and fully saturating the seams. That is one other difference between permaflex and 5200. I wonder if anyone has ever tried to thin out 5200 and make it more like a paint. Part of what makes the permaflex so usefull to me is being a liquid, I can paint it on and know it seeps into cracks and crevices that 5200 would not reach. Just imagine a material that fills and seeps into cracks, crevices, holes and sets up as a hard rubbery coating bonding everything together in a rubbery matrix and youve got it.

[carioca1232001]

....That technique is used on finely finished, varnished decks and hatches on runabouts and such, not meant for much walking on. Is this the situation with your boat, or are these regular decks that some idiot put wood strips into instead of seam compound .... The deck on my 32 ft motor-cruiser is exactly how you describe it. It is there mainly for the good looks, and a nice V-berth underneath it too.

Thanks for letting me in on the down-side of Sikaflex. The main cabin fore-windows that make contact with this deck were set with Sikaflex (around the perimeter) in 1998 and they were a real sod to take off. But I suppose Sikaflex can also shrivel up when left in seams on hot-decks.

BTW, whose seam compound is the best ? The deck-to-gunwale seams need redoing with something other than epoxy. As I routed out the old epoxy to a depth of 6 mm on the latter seam, a (gaping) crevice of 2-3 mm came to light.

[Bob Adams]

I'm with Gary E and Cleek. I did my cokpit coaming the same way, holding up fine. Use 2 part pourable polysulfide, (I used Boatlife).
Also, as all the materials in epoxy are intended to be a part of the cured product, and not evaporate away, I feel acetone in the epoxy is not a good idea.

[carioca1232001]

I have not used Boatlife´s 2-part pourable polysulfideseam compound, but would not use their 1-part polysulfide again.

[Bob Cleek]

I've had excellent results with Teak Systems seam compound. For small jobs, it comes in caulking gun tubes... expensive at about ten bucks a tube, but I've had excellent results in about five years of use. Others told me the same. Given the work it takes to reef and refill seams, there's no point in using the cheapest stuff. Do put down a bond breaker in the bottom of the seam, though. You want it to stay stuck to the sides of the seam. If it sticks to the bottom, when the wood moves, it won't stretch like it should between the seam sides, but will pull away from the wood. If you can't find skinny bond breaking tape, even a layer of caulking cotton will do the trick just fine. (This is one reason people find that traditionally caulked decks aren't as prone to leaking.)

[JormaS]

Carioca, I´m trying to figure out why you want to put the wood strips in the seams. My conclusion is that it is only because that is the way the seams were done before...and the deck looked nice. That is why, right?

You said they did not hold out, but you did not tell us why. What happened with the strips? What ever happened, it is going to happen again, unless you do something differently. (Probably the strips were splitting, and now you want to prevent it by making the seams more flexible).

Unfortunately, it is not going to succeed because flexible seam compounds do not work in your type of installation. You have to fill the whole width of the seam with the compound in order to make it work. A thin film of Sikaflex between the strip and the plank will have to stretch by more than a 100 per cent, because the seam width will move between zero and, say, 0,5 mm according to seasonal change in the plank´s moisture content. That depends also on the plank width; a wide plank will move more than a narrow one. It will also depend on the grain direction in the planks.

Most of the seam compounds are designed to stretch 10 to 15%, and some of them are capable of 30%. You are asking them to do a 100% or more. It doesn´t help to make the strip triangular, because at deck surface level there will still be almost no seam compound to stretch.

It is an interesting challenge to try to explain in a concise manner how these elastomers work. I don´t claim to be an expert in the field; I have only done my share of deck and other seams. It is still true, I think, that next to alcohol, Sikaflex is the most widely misused stuff in boats.

So Carioca, like almost everybody here has said, you are not going to gain anything by using Sikaflex or anything like that in your particular application. If you want to use the wood strips, you have to glue them in, and you have to paint or varnish the deck inside and out in order to minimize wood movement.

The other approach is to forget about the strips and fill the seams with something flexible. If you ask me, my first choice would be a two part polysulfide like Smith´s, or Saba, or Formflex. Next come good polyurethanes like Sikaflex 290 DC or high quality silicone sealants like e.g. General Electric´s Silpruf. What ever you use you have to bear in mind that these elastomers were originally designed for construction applications with seams 15 to 20 mm wide and 10 to 15 mm deep. Any manufacturer will tell you that the minimum recommended is 6 by 6 mm. There simply must be enough of the stuff in the seam in order for it to stretch without stressing the glue line too much.

[carioca1232001]

Jorma,

I was scratching my head about what I should elect to do ......epoxy or sikaflex ...or even seam compound ? .....when your message arrived and broke the ice !

The white strips that I weeded out last weekend were inlaid into the new mahogany deck in 1998, and some relevant deck data follow :

1. Fore deck dimensions: 2,20 metres wide at base with king-plank some 2,10 metres long; I took a picture on Sunday but with SonyImage Station not honouring its obligation with WBF forumites etc etc ..... . Deck also has a hatch some 70 cms x 70 cms.

2. There are some 8-10 deck beams, spaced some some 25 cms from each other in the above area

3. New mahogany planks were affixed on the above deck beams with screws (fasteners) in 1998; the planks were 10 cms wide and 15 mm thick, and as they nudged against each other - and epoxy-glue was used to glue them together - they created a 5 mm x 5mm space for installing white-wood strips. Another 5mm x 5mm channel was also routed into the centre of the 10 cm wide plank so there are 2 (two) white-wood strips every 10 cms, one embedded into solid plank, the other in the nudging region between planks. and of course, miraculous epoxy-glue throughout ;) .

4. The leaks developed around the mid-deck area, specifically, over the king-plank and central-deck area, and also where the new deck meets the gunwales. Water would seep through minute cracks in the white-wood strips embedded with epoxy-glue in the region between deck-planks - I am only guessing - and drop onto the white-wood ceiling in the V-berth directly underneath . The port and starboard areas of this ceiling got the worst of it, due specially to the leaking deck-to-gunwale seams - plus gravity and water finding its way to the lowest level. ;)

A friend who visited me at the boat hangar last Sunday said exactly what you said in your message above - not enough room between white-wood strips (7mm x 5mm) and substrate (5/16" x 5mm) to create a Sikaflex bond, even if I did sculpture the former to a V X-section.

He said to forget the white-wood strips and drop in seam compound. :rolleyes:

I need to solve this problem .......forever or as long as I live, because it would be a pain in the neck to go through the same rigmarole in the next 5-10 years or so.

May want to turn to plastic and forget wood :D

[Gerald]

I am getting ready to lay a complete deck on my boat, and internally coat 1,500 litros worth of fuel and water tanks. I had the Scuna rep here today, from Rio. He had samples of 6 different products that they carry. The thin product being something similar to what the guys here call cps..... something. Water being 1.0 the epoxy is not thinned and has a viscosity of 1.3. Darn close to water. The rest of their products fit almost every need that pooped into my mind.
If you decide to call Scuna, you can talk to Leonardo and probably get an answer to almost any question a person might have about epoxy.
Gerald

[Gerald]

I will be adding color to the epoxy for a black joint. Po xadras works just great and as I am sure you know comes in many colors or mix basic colors to get any color you want.
Gerald

[JormaS]

Carioca, from your last post we learn that in the middle of the plank there is another wood strip (like a fake seam). Obviously, you have not routed out that strip. If you now do the real seams with a black seam compound, you end up with a pretty colourful foredeck. Maybe you have to consider replacing those remaining strips with the seam compound, too?

To complicate things further, you have to consider varnishing the deck. Certainly mahogany will turn nicely gray exactly like teak, but I suspect that it doesn´t like to stay that way. Somebody here surely knows more about mahogany than I do, but my guess is that you should varnish the deck. If so, then you have to take into consideration that with time, the varnish will harden and start crumbling on top of the seam compound, thanks to the ever so small movements of the seams. Not a terribly big deal, but it will somewhat complicate the revarnishing you are going to do once or twice a year, or maybe even more often, considering your location.

By the way, I´m starting to suspect that you have been skipping varnishing the deck. If that is the case, we might be back in square one. Somebody earlier pointed out that your type of deck must be kept well varnished in order to keep wood movement to a minimum, and to seal eventual checks with fresh and soft varnish.

[Bob Cleek]

Yes, mahogany cannot be left unfinished. It will weather and eventually erode. While greyed mahogany does look like teak at one point, it doesn't last like teak. Mahogany decks are finished bright. Jorma's right about the varnishing problems with soft seam compound. The traditional mahogany decks had either a holly strip glued in over the seams, or white lead putty, which will harden fairly well and hold varnish better than any soft polysulfide.

[Gary E]

Carioca,

From what you said about the deck construction...

2. There are some 8-10 deck beams, spaced some some 25 cms from each other in the above area

3. New mahogany planks were affixed on the above deck beams with screws (fasteners) in 1998; the planks were 10 cms wide and 15 mm thick Supports spaced at 25cm or aprox 10 inches
Deck boards aprox 15mm thick or aprox 5/8 inches
Deck boards aprox 10cm wide or 4 inches

This may not please you but I am going to say that this is sorta on the skimpy side unless you are a very lightweight fellow. The reason I say this is that stepping in the middle of the supports will allow the 15mm thick deck boards to deflect, they sure as hell would if I stepped there. That deflection will cause whatever you place in the seam to move and eventually leak.

If that was my deck, here is what I would do. Mind you I think pretty is NO LEAKS, Can TAKE a BEATING and keep on keep on KEEPING THE WATER OUTSIDE..For example, in a rough sea, I can count on dropping the anchor and chain on the deck while getting tossed around, I am not gentile, and dont want to baby it, that deck must not dent, bust, or rust.

Which brings me to what I would do...
Fill the slots with a 2 part rubbery compound, forgit the white wood, or use the Caulk from Sanitred and then cover the intire deck with the sanitred paint on waterprofing.
http://www.sanitred.com/

If that is not to your liking, then I am afraid that the deflection that will happen will never allow that deck to remain waterproof UNLESS additional supports are added UNDER the deck between the ones you have now. That is a big job, one I would not do.

If you can not get sanitred in your country, I would look to the rubber roof coating or tank lining industry for a product.

Good luck

[ 10-05-2005, 08:41 PM: Message edited by: Gary E ]

[carioca1232001]

Gerald,
If you have Scuna´s tel. number, kindly forward it to me.
Actually I bought a litre´s worth of Tubolit´s laminating epoxy, a product that George (from Angra) had recommended a couple of months ago, when he also added that the proprietor is a chem. eng and pretty accessible too. I may give this guy a ring too.
I am still wary about installing those white-strips with epoxy , though. :rolleyes:

Jorma,
What I failed to add in my account above of the deck is that after it was first built (1998), the whole lot was sanded down and given around 4-coats of the finest 2-part clear polyurethane.
When the first leaks came to my notice in 2000, I combed the deck area to see if I could identify white-strips that seemed unfirm in the mahogany substrate - and I did ! I injected 2-part epoxy into and around these armed with a doc´s syringe and needle, sanded the deck with 120 wet-and-dry and then a couple of coats of 2-part clear polyurethane. Worked well for some time but leaked again - the latter got worse in terms of intensity, as the boat sat out in the water :rolleyes:
Yes, I have routed out ALL the white-wood strips, both over the plank-joints as well as in the plank centres. Must look homogenous, at least ;) . Wish I could post a picture for all to see.

Bob Cleek,
Talking of varnish on mahogany decks, would varnish fare better than, say, 2-part clear polyurethane ? I mean in terms of durability, holding the whole lot together in the face of load-induced flexing etc etc ?

Gary E,
Yours was a good and succint acccount on how decks were built at Egg Harbour in days gone by.
As for my current deck, we did think of reinforcing the deck-beams, but that would entail taking off the ceiling-lining, the port and starboard lockers etc... quite a big job, specially as we are looking forward to being able to avail of the boat this summer... The boat carpenter did his eye-ball-cum-foot testing and concluded that it would be overkill to do so.
If I had to lay Sanitred or another opaque (industrial) liquid polyurethane on the deck surface, it would kill the good looks - but probably solve the problem !

I shall contact Tubolit´s chem.eng. proprietor tomorrow, though I do not expect him to admit that epoxy will eventually crack if used in the contruction of a wooden deck like mine ;)

[Bob Cleek]

Varnish is much better than polyurethane. Polyurethanes do last longer than varnish and if applied correctly (which can be tricky) look very good. The catch, however, is that when they do break down inevitably, they are extremely difficult to remove and you end up practically having to grind them off. The best claim to last five years and probably do. In the end, though, most everyone I know who has tried them has gone back to varnish, which is easily maintained with a new coat over a light sanding every six months or so.

[Gerald]

The site for Scuna is.......

http://www.tubolit.com.br/

The phone number etc. is in the within the site.
Gerald

[Matt Cohen]

Originally posted by carioca1232001:
sdowney717 welcome on board and thank you for the tip. Sanitred, a polyurethane - and not a polysulfide , which I have had dismal results with - does seem promising, especially the high-UV formulation. Yes, the slots in my mahogany decking have been bared to raw wood, and the white-strips are newly cut but dried marfim wood.

Sanitred does seem to have worked wonders on your restoration as per your account. But as it is unavailable in Brazil, DHL or Fed Ex will charge me at least US$ 300 just for shipping and customs-clearing fees. Plus cost of purchase + customs fees.
If shipping is the issue,
System Three Standard Resins and Hardeners (http://www.jamestowndistributors.com/to;ID;,Epoxy...Adhesives,System.Three.Epoxy) are non-hazmat, so there would not be a huge shipping/customs fee. Just my $0.02

[chucksw]

Hazmat is not the issue with Brazil. Shipping costs are 2x normal, 20% VAT taxes and additional duties charged by their government are the main problem. A quart of anything imported from the US can quickly add up to $500.

[Gary E]

Originally posted by chucksw:
Hazmat is not the issue with Brazil. Shipping costs are 2x normal, 20% VAT taxes and additional duties charged by their government are the main problem. A quart of anything imported from the US can quickly add up to $500.I dont think that is the problem...


If I had to lay Sanitred or another opaque (industrial) liquid polyurethane on the deck surface, it would kill the good looks - but probably solve the problem !
It looks to me as the apearance of the deck is more important ...

But if it's not, and sealed is more important I would be looking for a company that applies rubber roof's or a tank lining company to talk to.

[JormaS]

This crossed my mind earlier but I thought it would be too much trouble for you. I´m thinking of coating the deck with a clear polyurethane coating (somebody already suggested Sanitread, but they don´t have a clear version, as far as I know).

There must be tens, if not hundreds of one-part polyurethane coatings on the market, but there are only two that I know of that are without pigment, namely Coelan and Oldodur. They both come from Germany. Coelan has a product series expressly intended for boat use. Many decks are covered with Coelan in Europe, and many boat owners swear by it.

These products are, generally speaking, like "5200 in a more liquid form", i.e., moisture hardening one part polyurethanes, mostly with a Shore A hardness around 80, which is harder than the polyurethanes used as seam compounds. Mostly they seem to be very elastic indeed, with an elongation at break of between 300 and 500%. They also glue very well; many of them can actually be used as glues. They are claimed to be very resistant to UV radiation.

At first glance they would seem like the ideal substitute for varnish, but there are downsides like pricing, storeability, slipperyness, abrasion resistance etc. I will not go into more details here. I have done one 36 ft deck with Oldodur two years ago, and so far I`m happy, but that´s only two years.

If you are interested, go to www.coelan.de (http://www.coelan.de) to find out more. At the same time you will learn that for some reason, the Germans still have some things to learn about how to do a web site... ;)

[Chris31415]

Have you thought of doing the best job that you can setting the strips in epoxy, sanding the deck to acceptable levels of fairness, and then covering the whole deck with a suitable weight fibreglass cloth/epoxy resin?
I think that no matter what you do the strips will expand and contract differentially with heat and moisture, more moisture will seep down, and the whole deck will progressivly deteriorate.
Teak is used in decks because it is very moisture resistant and a large enough gap to ensure flexibility can be achieved. Near perfection in workmanship and top quality materials would be necessary to get a watertight job. It does not look like you can do this with mahogany and marfin.
The only way to stop this would be to seal the entire deck with epoxy, sand lightly and then lay the thin fibreglass cloth on top.
Thin fibreglass cloth should be transparent when properly wetted out. This can then be lightly sanded and varnished with a UV varnish.
It would be wise to do a few test runs on scrap wood to get the technique right before getting stuck into the main job. Laying the cloth dry onto a thin coating of wet epoxy, alowing to at least partially set, and then filling the cloth with the resin, may be the best way to go.
Thin epoxy resin and lightweight fibreglass cloth should be available locally.
You may have to choose between a permanent waterproof result and one that looks really good.

[carioca1232001]

Gerald,
Scuna is the brand name of Tubolit´s marine products line, so I learnt this morning when I checked the writing on the epoxy package.
I have left a message for their product support and am awaiting for them to call back.

[carioca1232001]

Bob Cleek,
The nice thing about 2-part polyurethane is that it imparts a wine-coloured tan to mahogany over time.
I suppose you were referring to the old-fashioned sort of varnish, Chinese tung oil et al ? If you look at the sales brochure on most current brand names of varnish, they all claim to be based on tung oil + high-solids (?) and one-part polyurethane.
I have used Cetol - a one-part polyurethane based varnish - and it looks great for a couple of weeks, but after soaking in the sun, the whole lot gets amber coloured.

[carioca1232001]

Matt Cohen and chucksw,
Chuchsw hit the nail on the head. Air-transporting HAZMAT should be way over 300 US, which is the basic flat-rate for DHL/Fed Ex to transport the smallest goods parcel from the US to Brazil. Pricing for documents is substantially lower, though.

[carioca1232001]

Gary E,
This morning the carpenter and myself took out the port and stbd deck-planks, by the gunwales, as the main-cabin bulkhead beneath these showed signs of rot at the extremities (very common in wooden motor boats). We also took out the end-column frames that lodge the fore windows, as the former were also rotted at the base which sits on the deck.
As we took off these deck planks that were epoxy-glued in 1998, the carpenter commented that either the epoxy-glue used was no good or that too litle was used. They came away from each other much easier than expected.
Another thing that we noted was that the epoxy-glue on the gunwale perimeter clung to the latter but there was little or no sign of glue on the underside of the deck planks at this location ! Maybe they installed the deck planks after the glue set on the gunwales !
Another finding - all the deck beams had been sistered in 1998 ( my memory goes fut at times !) with 2cm thick x 6 cm deep ipê frames. That explains why the deck passed the carpenter´s go/no-go structural test.
As for liquid polyurethane, Coelan sprung to mind, but Jorma beat me to it

[carioca1232001]

Jorma,
I was introduced to Coelan some months ago by a WB forumite, who swears by it as it solved the problem on his leaking deck. I visited the site at the time and stored their tech literature.

Another forumite commented that it was no good as it peeled off his deck as large chunks of poly film. Perhaps he simplified the application instructions ?

I was warned that it costs as much as Rolls-Royce does in comparison to a standard 4-door family car ! :eek:

Is the other German supplier cheaper and the product on par with Coelan ?

Neither have reps here so I would need to ask my pilot friend to do the needful :rolleyes:

[carioca1232001]

Chris 31415,
True, Brazilian marfim is not the most dimensionally-stable of white woods,but it can be kept in check by sealing it.
Yesterday a friend tipped me off on an epoxy-supplier in Brazil who caters to a wide spectrum of users, including sailors ! I sent them a whole dossier on my deck and am awaiting a response.
Yes, some friends at the Club have suggested what you have, that is, glue in the white-wood strips with epoxy, sand the lot down and epoxythe whole deck with a layer or two of angel hair fibreglass.

[sdowney717]

How UV stable is that epoxy? If you coated the deck with it and glassed it. Most epoxy has poor UV resistance and eventually fails. this deck will probably get a lot of sun exposure.
There is another possible product for you to consider.
NYALIC
www.nyalic.com (http://www.nyalic.com)
A crystal clear nylonic polymer which is UV PROOF! Totally pure clear and will show all the wood. It stretches with the surface and only disaapears off the surface due to erosion. Lasts 10 years on metal and several years on wood with no discoloring of the wood.
It is thin like water and will soak into the wood and need several coats. It is infinitely recoatable without any sanding, new coats melt into old coats. A gallon covers 260 square feet I think. It ought to do everything you want but is pricey. On the other hand in use it is really tough and easy to reapply.
From the site,

'Nyalic is a single pack polymeric resin coating that provides envelope protection against chemical and ultraviolet corrosion on ferrous and non-ferrous metals, galvanized, anodized and painted surfaces. Nyalic can also be used on concrete, stone, wood and fiberglass.'

What Makes NYALIC® So Good?

OPERATIONAL PROPERTIES

Formulated for use on ferrous and non-ferrous metals, painted surfaces, plastics, hard vinyl, fiberglass, tile and Formica, stone, brick, concrete, marble, and wood
Easy to apply -- sponge brush, compressed air sprayer, H.V.L.P. gun, airless sprayer, wiped on with lint-free cloth, poly foam sponge brush or roller
Self leveling, self annealing
Easily re-coated: self-priming
Dries to the touch in 15 to 20 minutes
Reaches dry cure in 4 days, and full hard cure in 30 days
Cleans up fast with just soap and water
Indefinitely maintainable
Application tools and equipment clean up with lacquer thinner
Single Pack - No mixing, straining or thinning required

SURFACE CHARACTERISTICS

Flexible - Expands and contracts with host substrate across a wide temperature range -- so NYALIC won't crack or peel!
Impermeable, smooth, clear finish -- NYALIC won't chip!
Thermodynamic to 350° F
Non-conductive, prevents harmful electrolysis
NYALIC will never chalk or yellow
COVERAGE

One gallon covers 1,200 square feet at a 0.5 mil wet film thickness (3-5 microns DFT)
Multiple coats are necessary when coating porous substrates such as concrete or wood
PROTECTION AND RESTORATION

Impact resistant
Blocks ultraviolet radiation, will not yellow
Prevents oxidation
Protects against damage from corrosion, acid rain, salt water, salt air, bird droppings, bugs, fertilizers, and battery acid
Resists dirt, dust, mold, mildew and algae
Protects against bleach, corrosive salts and other damaging agents
Restores faded or oxidized surfaces to a like-new appearance

[carioca1232001]

Welcome on board again, sdowney !

Your out-of-the-ordinary solutions make you somewhat conspicous on WBF, a pretty conservative congregation, at least when it comes to boat- repair techniques. ;)

Yes, I had heard of nyalic already and you may have been the person who tipped me off in the past.

The 64 k $ question that any such (nyalic) supplier needs to answer is as follows:

Are you able to supply a list of references and referees, who have purchased and used your product for the intended application ?

Coelan (from Germany)can. Can the other suppliers also follow suit ? :rolleyes:

BTW, the majority of boat carpenters at my Club share views similar to yours, as regards the use of epoxy on wooden decks.

[sdowney717]

Yeah I know.
Sometimes you just have to take the plunge and get wet.

[carioca1232001]

Nyalic would seem to be the equivalent of Coelan, that is, to provide a flexible,impermeable, weather resistant, and clear, topcoat.

I wonder if you have noted that on the Nyalic site there considerable mention of metal - and fibreglass - substrate applications. Little or no wood.

What might a quart cost ? And a gallon ?

Nevertheless, I would still need to solve the white-wood strips to mahogany-substrate gluing problem.

[sdowney717]

What is Coelan made of?
And yes, wood is not a primary goal of those who make Nyalic.
What drew me to this was someone using this on their wood boat trim and years later looked just like it was freshly varnished. Also I was looking for a coating for aluminum wheels and found out about this stuff. Very highly recommended as a metal coating. On wood it will soak up some on the first coat. Additional coats ought to be just like going on a smooth surface. I was thinking more coats would build up layers which would be desireable. I think the first coat would not cover as well as additional coats.
1260 sq foot per gallon on surfaces which are smooth seems like good coverage.
You could always email the company and ask them what would multiple coats of Nyalic do for a tight seamed well attached wooden deck?

[sdowney717]

http://www.mrsimpson.co.uk/ghost/coelan.htm
Yeah it looks good this coelan
It is a smmoth flexible polyurethane and looks like it would work great to sealing a deck. This site shows it on a boat deck

[Gary E]

Originally posted by carioca1232001:
Gary E,
This morning the carpenter and myself took out the port and stbd deck-planks, by the gunwales, as the main-cabin bulkhead beneath these showed signs of rot at the extremities (very common in wooden motor boats). We also took out the end-column frames that lodge the fore windows, as the former were also rotted at the base which sits on the deck.
As we took off these deck planks that were epoxy-glued in 1998, the carpenter commented that either the epoxy-glue used was no good or that too litle was used. They came away from each other much easier than expected.
Another thing that we noted was that the epoxy-glue on the gunwale perimeter clung to the latter but there was little or no sign of glue on the underside of the deck planks at this location ! Maybe they installed the deck planks after the glue set on the gunwales !
Another finding - all the deck beams had been sistered in 1998 ( my memory goes fut at times !) with 2cm thick x 6 cm deep ipê frames. That explains why the deck passed the carpenter´s go/no-go structural test.
As for liquid polyurethane, Coelan sprung to mind, but Jorma beat me to itDont you think you need to fix the cause of the deflection / spring / weakness in the deck before coating it with anything?

or maybe a tarp will work on non sunny days.
Sorry about the sarcasim but ya got to have a firm foundation to start with or you are screwed before you start.

[Gerald]

Please call Leonardo at Scuna. Having a non flex base is using thinking from 50 years ago. Scuna has products that will flex with the deck.
Gerald

[carioca1232001]

Yes, Coelan seems to work wonders at sealing wooden decks.

Downey, you said that epoxy is prone to UV degradation. Does this get more critical when epoxy is applied over a wood substrate ?

The reason I am asking is that there are tons of all-epoxy fibreglass boats out there doing pretty well. :rolleyes:

BTW, do you know of a US supplier for a good-quality plug cutter for use with a drill press ?

[carioca1232001]

Gary E
The deck did pass the carpenter´s stomp-and-eyeball structural test .
We also noted that the first three deck beams - bared as a result of pulling out 1 1/2 deck planks, each at port and stbd. of the deck/gunwale perimeter - had been sistered. I was able to recall that I had agreed to have the whole lot of deck beams sistered in 1998.
So rest assured that the deck structure is pretty sound.
BTW, what particular function does the king plank play in the deck´s structure ? The king plank is the only plank mounted in the fore-aft direction over the skeleton of the deck beams.
My king plank tends to bob up and down as the boat is removed from it´s cradle and put in the ocean and vice-versa. I have a feeling that one of the major deck leaks may be due to this, which obviously affects the mahogany deck planks immediately over it. Perhaps I should cut out the ceiling lining in the V-berth and constrain the king-plank in some way ?

Gerald,

It may be easier to have President Lula - or even G W Bush - call back than it is to have Scuna´s reps do the same. ;)

Cariocas are great people, but I simply cannot digest this kind of informality which is typical of us. :rolleyes:

Yes, Scuna´s flexible epoxy sounds interesting.

[Gary E]

You say that it passed the carpenters test... well it may have, but since the deck still moves / flex's / deflects... what ever you want to call it...and it STILL LEAKS... IT WAS A LOUZY TEST, and not good enough..


what particular function does the king plank play in the deck´s structure ? The king plank is the only plank mounted in the fore-aft direction over the skeleton of the deck beams.
My king plank tends to bob up and down as the boat is removed from it´s cradle and put in the ocean and vice-versa. I have a feeling that one of the major deck leaks may be due to this, which obviously affects the mahogany deck planks immediately over it. Perhaps I should cut out the ceiling lining in the V-berth and constrain the king-plank in some way Since I can not see what you are calling a king plank I have no idea, but since you say it moves, I will say that ANY PART of the deck that moves is bad, fix it.

Removing the ceiling covering from below is a start. Then firm up EVERYTHING... unlike someone else that thinks my thinking is from 50 yrs ago, well... it probably is because I learned it from people that were most likely 50 plus at that time so it makes the ideas 100 yrs or more, it worked then, it works now. Flimsey never works.

I will say it one last time...

IF YOU ALLOW MOVEMENT / DEFLECTION / UNSUPPORTED / FLEX...what ever you want to call it... and expect varnish to protect it so it looks pretty, IT WILL LEAK..as it did last year, it does now and it will tomarow and next month ..unless you firm up the boards, supports, deck beams what every you want to call those parts and cover it with a rubbery type thick film substance that stretches much like a rubber roof...

I have always wondered why it is so easy to skimp on structure and then complain of weakness.

[ 10-08-2005, 08:06 PM: Message edited by: Gary E ]

[sdowney717]

I Just bought a great plug cutter.
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/plgtenon.html

I bought the 1/2 inch tennon cutter and it is really heavy duty. 1/2 drive shank for the drill press and long so you can cutlong plugs. I was really pleased with the quality and the heft of this piece, it is not a wimpy cutter. The tennon cutter will cut plugs or tennons. And it is on sale now.

[sdowney717]

Epoxy as a coating by itself wont hold up under intense uv exposure. But when mixed into a fiberglass matrix must become somewhat shielded from the UV. At least this is what I understand.
How well does coelan hold up to UV? You know the Nyalic is UV proof.

[carioca1232001]

downey,
I bought a set of plug-cutters from MLCS a couple of years ago - mos of their stuff is exceedingly good value for money. These cut plugs all right but you need to pop the latter off the mother board to release them. Not as convenient as the types that eject plugs, once cut.

As for Coelan, I cannot vouch for it´s UV resilience. But as a v.good German friend - and high-level chemist - has told me more than once: "Chemistry is..... German, you know" ;) I believe we could be in for some luck, but need to dig deep into our pockets too :D

[carioca1232001]

Gary E,
I should be posting some deck photos shortly.
My rig is down and am at the mercy of the son´s. But I will get round to doing so.

[JormaS]

When considering resistance to UV radiation I think we have to be careful. If Nyalic or Coelan say their products are "UV proof", do we know what they are talking about?

The coatings themselves may be resistant to degradation by UV radiation. But to my mind, that does not mean that the coating acts as a filter and protects the underlying wood from deterioration.

Also, Coelan claims that their coating "breathes". Latex paint is also said to breathe. If this means that water vapour gets through, does it mean that...well, what does it mean?

I´m not a chemist, nor an engineer, just a simple sailor. Lots of things in this world that I don´t understand. smile.gif

[sdowney717]

Well from my reading of Nyalic it says UV radiation is not passed thru the coating.
If it passed UV and allowed damage underneath it would be almost useless.
Nyalic will not pass any water thru the coating.
I was surprised to see Coelan says it does. Also surprised to read it is self healing to what extent I dont know.
I think if you put a coating on a deck that wont pass water, humidity from underneath will more likely swell the wood and keep the deck tighter since it cant evaporate off the outer surface.

'Rockwell was seeking -- a coating that was very durable, blocked ultraviolet rays, prevented corrosion and oxidation, and performed at film thicknesses as low as one half of one millimeter'

No UV radiation pass thru means no greying damage of the wood from sunlight as long as the coating is intact. Also on wood Nyalic will poentrate somewhat so it will need 2 coats. And this may also be a good thing yielding a thicker coating. I also was wondering if has any adhesive qualities on tight seams.

[sdowney717]

Does anyone else when reading how Nyalic works get the sense this is some kind of miraculous coating.

Extraordinary Features:

7.1 The dry film coating remains flexible throughout its life. When properly applied, Nyalic will not chip, crack, peel or yellow. Nyalic will not “track”.

7.2 In the event of damage to the coating, the damage should be repaired by the further application of Nyalic. First clean the affected area and reapply Nyalic as needed.

7.3 Nyalic vapors off @ 660° F.

7.4 Although it is a clear, Nyalic provides U.V. block.

7.5 Rejuvenates oxidized painted surfaces giving them a new paint appearance on vehicles, metal buildings, tanks, etc.

8. Maintenance:

8.1 Nyalic is self-annealing. At any time Nyalic can be applied to a clean surface and it will bind through itself to form a new one-part coating. The life of the coating may be extended with the application of additional coats at regular service intervals. Nyalic is indefinitely maintainable.

8.2 Maintenance painting, using the techniques described in sections 10 and 11 should be conducted as needed.

8.3 Localized repairs of damaged or abraded areas should be conducted as necessary using the same techniques described in sections 10 and 11.

8.4 The smooth envelope protection of Nyalic prevents the adherence of and lessens the build-up of algae, bird droppings, diesel carbon, dirt, fingerprints, marine growth, etc. Although dirtying agents may settle on the surface, they will not adhere to Nyalic and can be easily washed off with soap and water (HBI 128, Right Rinse, a low pH soap, is recommended for cleaning Nyalic coated surfaces.. In most instances, marine incrustations and splattered bugs wash off easily. It is not necessary to use high alkaline content cleaners to clean Nyalic coated surfaces. Avoid using solvent based cleaners on Nyalic coated surfaces.

[JormaS]

It certainly looks like we should use Nyalic in stead of varnish. I remember having had the same thoughts about Coelan. Now that I have done one deck and various spars and other items on a wooden boat with Oldodur (which I consider equal to Coelan), I am convinced that it will outperform any oil based varnish or other one part varnish when it comes to longevity. Granted, it was only two years ago, but so far zero maintenance, except when
- there has been a dent
- when moisture from underneath has been unable to escape through the coating.

These coatings are not as abrasion resistant as one might be led to believe. After all, they (at least the two mentioned) have only a Shore A 80 hardness. For the same reason, they become fairly easily dented or damaged otherwise.

To repair "ordinary" varnish, you need to sand and coat small areas with between four and eight or more coats, which is frustrating. The number of coats depends on your location. To repair these polyurethane coatings, you need to do the sanding and plus four coats. They are a bit difficult to sand because of their elasticity.

Each time, you need to open a new can unless the repairs are a few days apart...or maybe a week as a maximum. Now that is frustrating, because the stuff is expensive. Being a moisture curing product, it starts curing the moment you open the can. Some package innovation will be needed...but it will make the product still more expensive.

As soon as I can lay my hands on a can of Nyalic, I´ll try it out. Will report back. Anybody else tried it on wood?