Rascal Finishing Schooner varnish and deck seams

[Speedboy]

I have recently completed varnishing the bottom and topsides of the Rascal runabout. Here are some pictures:









The stain was Minwax Mahogany 605 Gel Stain. Put on with foam brush, waited 3 minutes and wiped off.
I put down 14 coats of Interlux Schooner Varnish over 2 coats of Interlux 1026 Sealer, with 220g wet sanding after 4 coats and 8 coats. Then 320 g wet sanding after 3 more coats and then after each following coat for a total of 14. The boat is now flipped over, and if it ever stops raining, I will stain and varnish deck. The designer recommended mahogany colored Sikaflex 241 for the seams on the deck, but a recent thread on deck seams indicated Sikaflex may not be the best choice. I checked the spec sheet for the Sikaflex 291 LOT that I purchased (replaces 241 Sikaflex) and it did say that it is not recommended for deck seams. Since I would like mahogany colored deck seams, what material is preferred? Here is a close up of the deck:



Seams are about 1/8" wide and 1/8" deep. I was planning on putting down about 4 coats of varnish prior to adding seam material, and then another 6 coats over everything. Any recommendation on the best method of filling seams is appreciated. Note that boat will be trailered and stored indoors, so UV exposure will be less than most boats. Could the Sikaflex work?

Thanks, Speedboy

[pipefitter]

looks very nice....great work.

[pcford]

Looks like you are doing a fine job.

I've done this stuff for a living for some years now.Sikaflex will be fine. Sikaflex warning is for "real" deck seams, like on a sailboat for example. Polyurethanes do not tolerate teak deck cleaners.

[BRobinson]

Speedboy,

The boat looks really, really good.

Most restorers I know fill the seams mid-way through the varnishing process as you describe (with Sika). Personally I prefer to fill the seams just before the final sanding of the bare wood. I final sand, stain, seal, and varnish right over the top of the caulking.

If the color of the caulking will show through as your finished seam, don't do it. Paint the caulked seams the color you want when your done varnishing. Mahogany colored Sika (or any brand) will fade quickly in this application. Worse yet, it turns purple-ish. Besides it's not really a good color anyway. If the look you are after is for the seams to blend into the deck, mix some of the hull stain with varnish and paint the seams with that. Personally, I prefer when the seams are chocolate brown.

I guess its not the end of the world if you go ahead and leave the Sika unpainted with a few coats of varnish over it like it sounds you were planning on, you could always paint them later. I just don't think you will be happy with how it looks in a year.

[pcford]

Yes, the seams need to be painted. Most prefer white. Some clients like yellow to make it look like varnished white caulk. You use a yellow paint about the color of a legal tablet. A few boats have mahogany seams. I like more contrast, but that's your choice.

Seams have to be painted because the varying thickness of the varnish in the seam changes the apparent color.

[Dan McCosh]

Last I looked, Sikaflex is not recommended for use in sunlight--it degrades in UV. That's the reason for not using polyurethanes in deck seams, rather than deck cleaners. Mahogany colored polysulfides are available--3M makes one.

[JimD]

That's some shiney wood, Speedboy

[Speedboy]

If it is recommended to paint the seams, what brand and type of paint is used? The Sikaflex is a one part polyurethane, and the varnish is Interlux Schooner. Is an artist brush recommended?

Thanks, Speedboy

[BRobinson]

Sikaflex 291-LOT is fine to use for this.

Any enamel will work fine, you can tape off the seams with fine line tape and paint (any decent small brush) or you can use a striping wheel like a buegler. Or you can pay a pinstriper to come over and do it, should cost no more than $100 for a deck your size.

[DavidS]

I thought that some guys had filled the seams with thickened epoxy. The epoxy can be colored to be white or can be thickened with silica and will be an off-white. Is this method not as good for some reason?

[pcford]

By the way...if it is not a live seam you can use glazier's putty mixed with one tablespoon varnish to quart.

Nicer to handle.

[BRobinson]

Speedboy,

Are you planning on staining the covering boards and king plank with the Minwax Gel walnut color?

[Speedboy]

I am planning on staining the deck one color. All of the deck planks are bookmatched so there will already be some color variation due to the different planks used. For some reason, I prefer the more uniform look of one color stain, and I also prefer a mahogany colored seam that blends in more. I first saw the Rascal design in the book "The Wooden Boat" by Joseph Gribbins. On page 118 is a picture of a Rascal runabout built by Ken Basset and I really liked the way he finished it. That is the look I am going for. He used limited deck hardware so the deck isn't too cluttered and the seams are just slightly lighter than the stained wood. I have seen the boat finished as you describe, and that works well also.

Speedboy

[Alixander Beck]

That is an absolutely beautiful finish.

[Speedboy]

Thanks for the feedback and information. Here is the picture of the boat that made me want to build the Rascal runabout. I spent about 2 months searching for a boat to build before I saw this picture. I was fortunate that Woodenboat sold the plans.


I am hoping the boat will look similar to this when I am finished.

Thanks again,
Speedboy

[Speedboy]

Oh, and here is some of the hardware I have collected so far for the deck. Windshield brackets are from Maine Classics, chromed by New England chrome, Atwood gas fill, and Perko cleats.


Here are some more build pictures that may help future builders:




Speedboy

[BRobinson]

No way I would ever use sikalfex on that boat or any flexible compound if you intend on having a varnished deck.

Mike,

That's how runabouts are done.

[BRobinson]

Mlke,

Then what do you suggest using? I know epoxy is a mistake.

[ 10-12-2005, 07:04 PM: Message edited by: BRobinson ]

[DavidS]

Regarding epoxy being a mistake, I had asked this question above but no one has yet responded.

Would it be a mistake to fill the seams between planks with thickened epoxy? I had thought that this would last a long time and if the epoxy is thickened with silica and/or colored white then this would look like traditional seams. Is there a problem with using thickened epoxy for this type of filler?

Thanks.

[pcford]

Regarding epoxy being a mistake, I had asked this question above but no one has yet responded.

Is it a live seam? Will there be movement in the seam? I did not notice if the deck planks solid wood or not.

Sikaflex is prefered to "Thiokol." Thiokol is the manufacturer's name of very early polysulphide. Twenty five years ago people used that term instead of polysulphide. Polyurethane sticks better.

[Speedboy]

Mike, Just for the record, I seriously comtemplated using no stain on the mahogany, since mahogany looks great varnished natural. However, the construction method for this particular boat requires that the outer planking layer be stapled in place with 18 gauge narrow crown SS staples while the epoxy cures. Each staple divit is filled with wood putty(FAMOWOOD was my choice). But the wood putty is not a perfect color match for the mahogany, so the stain helps to camoflage the wood putty over each staple divit. They pretty much dissappear. I was concerned with a "freckled" appearance if I justed used varnish alone. As for the decision to use Sikaflex for the deck seams, the General Specifications that come with the boat plans recommend the SikaFlex 241. However, since the plans are 16 years old, I am open to all possible improved methods of doing the seams. I will probably default to the designers recommendations, since several forumites have also suggested this method. I am leaning toward painting the seams as well, as recommended above.
Note that I did use thickened epoxy filled with graphite to fill the seams on the veneer (1/8") teak cockpit floor and it was pretty labor intensive and messy, but it does look OK for a flooring material.




Unfortunately, I don't have any image of the final picture of the flooring.

Speedboy

[pcford]

So, the deck is a lamination and the seams, thus, are not live seams. You could use epoxy for seams. However, I've seen this kind of deck buckle if allowed to become high in moisture.

In my humble opinion, mahogany does not look good without a stain. Rather flat. Also, you should not depend on stain to "camoflage" anything. Should be transparent as is possible.

[BRobinson]

However, I've seen this kind of deck buckle if allowed to become high in moisture.

Me too, that's why I don't think epoxy is the best choice for deck seams. The wood will move, whether its 1/4" or 1/8" thick - it will move some eventually. By caulking the seams with something flexible you are at least giving the wood some place to go. Laminated decks certainly slow expansion/contraction down, but I don't think it can be totally eliminated in dimensional lumber.

If it were a total plywood deck (1/16" veneers) I think epoxy would be fine in the false seams because expansion and contraction would be almost nil.

[Tom Lathrop]

I would wonder why pigmented epoxy is not suitable for seams in thin laminated decking over a plywood substrate. Works for me and I've have never had a problem with it. The trick is to seal the unsanded planks before they are installed to prevent color bleeding into the planks. There is no need to staple these planks. I like to use temporary screws through plywood washers (duck taped on bottom to avoid sticking) in the seam gaps.

Making the epoxy too thick is a mistake since bubbles cannot get out through the surface. Use a slow hardener for the same reason. Leave the epoxy high above the plank surface and sand or scrape the whole thing down together.

I can't imagine painting the seams either. Too tedious. I'd rather be poked in the eye with a sharp stick.

Varnish over everything or use a couple coats clearcoat epoxy for quick build up before varnishing.

You can see the result in page 18 under Misc Boat Related. For some reason, copy and paste is not working on the WB Forum.

Edited to say that 1/8 veneer will not move when epoxied and sealed to plywood, at least none of mine ever have.

[ 10-12-2005, 09:20 PM: Message edited by: Tom Lathrop ]

[BRobinson]

Edited to say that 1/8 veneer will not move when epoxied and sealed to plywood, at least none of mine ever have.

Try taking boat built in say...Florida (or N.C), and using it for a summer on Lake Tahoe - wood moves at any thickness.

[ 10-12-2005, 09:34 PM: Message edited by: BRobinson ]

[Speedboy]

The deck of the boat is 4 mm okoume with 6 mm mahogany for the second layer. There is a 3/32" rabbet on one edge of each plank that is 1/8" deep. This creates the "seam" when adjacent planks are placed next to each other. So the depth of each seam is about 3mm. I am not keen on the idea of trying to tint thickened epoxy consistently from one batch to the next to create a mahogany colored seam. I have final sanded the deck in preparation for staining. The plan was to put down 2 coats of Interlux 1026 sealer, then 4 coats of Interlux Schooner, then mask both sides of each seam and run the Sikaflex in the seam. Next take the curved end of a hacksaw blade, and run it down the seam to remove excess Sika and create a slightly concave surface on the Sika. After the Sika starts to set up for 20 minutes, remove the masking tape. Then, after 4 days, wetsand everything with 220 grit in preparation for the last 6 coats of varnish. That was the plan.

Speedboy

[Tom Lathrop]

Originally posted by BRobinson:
</font><blockquote>quote:</font><hr />Edited to say that 1/8 veneer will not move when epoxied and sealed to plywood, at least none of mine ever have.

Try taking boat built in say...Florida (or N.C), and using it for a summer on Lake Tahoe - wood moves at any thickness.</font>[/QUOTE]Of course we are all aware that wood moves with humidity changes, or at least it tries to. Thin veneer can be stable when locked down to a substrate even without being sealed in epoxy. It that were not so, all marquetry would destroy itself. Also plywood would destroy itself just sitting on the rack, while we know it does not even when going from water to dry as when a boat is hauled.

Thicker and wider boards turn that reasoning around and at some point the stresses will overcome the bond and it will split. With your thicker and wide planks, a flexible seam might be the prudent way to go. In any case, I would not like to look at a future where I had to paint the seams and varnish the planks separately every time they needed maintenance.

Anyway, I congratulate you on the beauty of your boat and know that you will enjoy it. I have driven a Rascal with 60hp and can attest that it is like a GTO or Shelby Cobra on the water.

[ 10-13-2005, 12:36 AM: Message edited by: Tom Lathrop ]

[pipefitter]

You can also load thickened epoxy in empty caulking tubes with the tip cut to the right size for the seams.Plus,compressing it through a caulk gun gets most of the air out of it and it goes quickly and you can also buy some time by keeping the loaded tubes in a cooler with the frozen blue cooler packs.

[BRobinson]

In any case, I would not like to look at a future where I had to paint the seams and varnish the planks separately every time they needed maintenance.

That's pretty much the way it goes on runabouts with white seams. Even one coat of varnish will yellow the seams more than most want to look at. In any case, re-painting the seams is not a big deal.

Fortunately for Speedboy, he is wise to the fact that brown seams (or any color but white) will not require repainting each time the boat is re-varnished. Because the seams are concave, when the time comes to re-varnish, only the varnished wood will get hit by the sandpaper, not the painted seams.

Actually Speedboy, in your situation it would not be a bad idea to paint the seams just before the final coat of varnish, so long as you varnish with a bristle brush or spray. If you use a foam brush, paint the seams after the final coat.

[ 10-13-2005, 03:00 AM: Message edited by: BRobinson ]