wood deck and baltic birch

[Al Stead]

Well, I just went to our local big box lumber store and I have another scheme to throw out for comment.  My local Menards stocks a baltic birch underlayment that is 1/4 inch 5 ply ext glue, good both sides, no voids for $25.00.  I am thinking about gluing two thicknesses of it together to make up the bottom of my  Weekender so that I have no joiner piece in the cabin.  I would of course stagger the joints between the two layers.  I am thinking that I should be able to cut out the bottom in one piece at one time.  I am considering using titebond III for this purpose because it is so strong and the plys are very nice so the joint would be tight.

The other thing I am considering is making the deck out of this 1/4 inch stuff and laminating 1/8 inch redwood planks onto it before cutting it out.  I figure this would simplify fitting the planks as well as giving me the required 3/8 thickness for the decks.  I could make the planks out of redwood decking by resawing the 5/4 decking on the table saw.  This idea appeals to me because it is a wooden boat after all and bright decks would sure reinforce that notion.  I would of course glass the deck and apply some kind of non slip, so the softness of the redwood would not be an issue in the end. 

Anyone see any big problems with these ideas?

Al

[Frank Hagan]

The underlayment will probably work as well as or better than the 1/2" exterior fir plywood (which a lot of us used).  If your Weekender is going to live on a trailer, you are probably OK with that type of ply.

As to the side decks, I'm not sure.  Redwood is fine for decking but it has a weird trait (in regards to other wood, anyway).  Instead of moving across the width, at 90 degrees to the grain, redwood moves in line with the grain with seasonal changes in humidity.  And it is pretty soft.  I'll wait to see what others say, but for the decks on the Weekender, I'm just not sure.

[PAR]

If you can use vertical or nearly so, grain redwood then you'll have better wear, but it's not a wood I'd use. I'd use a more dense species of lumber for your decking.

A double bottom makes good sense and eliminates the butt blocks or need for scarfs. Be careful with birch, which is typically a "cabinet" grade of plywood. It may have a WBP glue, which is good, but the outer veneers are usually very thin, making for pretty weak panels.

TiteBond III can work, but it just barely passes the WBP test, isn't considered a structural adhesive and isn't recommended for use below the waterline (continuous submersion). On a trailer sailor, this is less of an issue (continuous submersion), but it can cause issues later in life.

TiteBond requires a great deal of pressure to provide a good bond. This is easy on parts that can be clamped, but on large panels of plywood, much more difficult to provide uniform and sufficient pressure.

Lastly, TiteBond III doesn't let epoxy stick to it very well. So if you're going to 'glass the outside of the boat, be especially neat with the TiteBond and not get finger prints or drips on later to be 'glassed surfaces.

[Al Stead]

Thanks for the advice guys. 

My plan is to glue up the panels before lofting and cutting out the bottom, so there shouldn't be any drips or excess at the edge joints.  Maybe I could seal the edges near the single butt joint with shellac before gluing up and then take it off later, or mask it off.  This stuff is real nice.  The plys are uniform and it is quite firm for its thickness.  I have used it in part of my motorhome restoration where I needed to save weight and still have some structural strength.  My biggest concern with birch is that it doesn't resist rot all that well.  I will have to be diligent about sealing it up.  I do intend to keep it on the trailer and not at an anchorage, so it will get a chance to dry out. 

I used a scrap of redwood decking in the last canoe paddle that I made special for my wife.  It turned out to be much more attractive than I could have imagined, and with the epoxy and glass over it, it has withstood a fair amount of abuse.  However, I am not wedded to redwood.  I like it because it would be easy for me to resaw, and it is fairly cheap.  If there is a more traditional wood to use for this application, I would be interested in suggestions. 

Al

[PAR]

Teak, cedar (heartwood only) and pitch pine are the usual choices. They have high oil contents, wear well, can weather naturally with a uniform color and are less prone to checking or splitting (except some cedars).

Teak veneers aren't especially expensive, can be had in reasonably thick (1/8", 1/6", etc.) pieces, which permits some sanding and long lengths. I'm using some on a project right now (okay in a few weeks).

It's common to use mahogany veneer on transoms too. Prices range, depending on thickness, backing (get it without a backing) type, grain and species type, etc. Roughly, "utility" grades of teak veneer will range from about $2.50 to $4 and quality veneers up to $6 a square foot. A CS-17 transom has about 8 square feet of area. This means a high end, thick veneer would cost about 50 bucks to cover the whole transom.

[Frank Hagan]

Epoxy might be an easier choice for laminating the panels.  You don't need as much clamping pressure, so you could lay down some heavy plastic (visqueen or equal) and put the bottom layer on it, roll on some epoxy, lay the top layer on it and cover it with another layer of plastic and then weight it down with blocks.  Epoxy sticks to nearly everything except heavy plastic sheet, so you want to be careful about epoxying things to your garage floor (like I did).  Don't use the thin painters' plastic; it has to be pretty thick.