New Build. Bay River Skiff 15

[rstanley]

New build, new builder. I have limited woodworking experience so hopefully this will resemble a boat when I'm done instead of just a pile of lumber. Time will tell. I've spent a good amount of time going  through this and other forums, so much so I feel I already know many of you. Going through this process I'm sure I will need to lean on many of you so thanks in advance for your advice. Hope to hear from some "amateur" BRS builders. Speaking of advice, I guess it's time to start asking questions. Just 2 for right now.

 

For a BRS,  should I use Okoume or Meranti? I'm not terribly concerned with weight, my last sailboat was around 11,000lbs. The boat will spend most of it's time on a trailer in a garage.

 

For the sides and bottom should I scarf or use a butt joint?

 

Thanks,

Robert

 

 

[brigait1]

If weight isn't a big issue for you I would suggest Hydrotek 1088 Meranti. It weighs a bit more than okoume but my understanding is that it is much more rot resistant. Over the two years that I spent building my CS20, I left scraps of it laying out in the weather. A few pieces lived in a bucket that repeatedly filled with rainwater for many days. These same samples also went through several freeze/thaw cycles. After two years of this abuse they only showed some ragged edges but no signs of rot or delamination. Very impressive stuff. Of course your mileage may vary, but I've been very happy with the stuff. The only issue I had was that the bending characteristics are a bit different than okoume. Hydrotek is a bit stiffer and the bow sections took a bit more coercion to get things into the right shape. 

[Hirilonde]

I don't see rot resistance to be of any significant advantage.  These boats are sealed in epoxy.  And if you damage the boat, it occurs where it is visible and you will want to repair it immediately any way.  Meranti is more abrasion resistant.  This might be an issue if you beach it a lot.  But again, if you damage the finish right through the epoxy you will want to repair it immediately as well.  I would always choose Okoume.  To me weight it everything.  Okoume works better (works as in cuts, mills dresses etc.)  And as Pete points out is bends easier, which for stitch'n'glue boats makes folding easier.  Both have been used for these boats.  There is no definitive "best", it is a matter of priorities, and price and availability in your area may play into this as well.

[Howard]

On the plywood issue, I'm using both on the Princess 26 I've started. Mostly meranti. Stronger, said to be more rot resistant (as Dave said, should not be an issue) and less expensive. As I needed somewhere around 45 to 50 sheets, total cost was an issue. Meranti is also heavier, but since the Princess will have about 750 pounds of lead hanging on the bottom of it, I didn't see weight as an issue. However, anything I'm leaving bright, and everything above deck level, I'm using okoume.  Other differences, meranti, if left bright, will finish much darker.......about like walnut vs. the lighter color of the okoume. Meranti also seems to have a stringy grain pattern that leads to splintering. You notice it on saw cuts and when you drill through it. My solution has been to use a 60 tooth saw blade on my circular saw and 20 tpi blades on my jigsaw. For holes, I using old school brace and auger bits, with a piece of scrap as backing to prevent tear out as the bit punches through. That cuts holes faster and cleaner than anything else I've tried.

 

Having said all that, for your BRS, I'd suggest Okoume. Cost is not that big of an issue and I think the lighter boat (still plenty strong) will perform better. As long as you stick with known brands, such as Joubert, quality of the plywood should not be an issue.

 

Most meranti is sold as Hydrotek, said to be made to the BS1088 standard, but as it turns out, Hydrotek is more like a generic product, nearly all of which comes from Asia and quality is an unknown variable that cannot be predicted. The meranti I'm using came from a reputable supplier, but has two different brand stamps on it.......both from China. (Indonesia would be better). One is better than the other. If there is a comparable brand of XXXX Hydrotek to say Joubert okoume, I'm not aware of it. Suppliers only call it Hydrotek and you really don't know the source or manufacturer.

 

If I was going to use meranti for anything, I'd ask the supplier to send me samples of what they are selling. Purchase a 1' x 2' piece if you have to.......and do boil tests and inspect them close for defects, up to and including overall thickness and thickness of the face veneers. Look for any variations in the ply layers themselves.  Ask for a piece with the brand stamp if you can get it.......so later on, if you do order in quantity, you can be assured of getting the same thing as your sample. If the sample you get doesn't look right, keep looking. Above all, do not let price be the controlling factor. In the big picture, the overall cost of the plywood is not that great, so saving a few bucks per sheet won't matter much in the end. But it will matter a lot if your boat falls apart.

 

On the issue of scarfing or butt joints........butt joints come in two versions. The original was to butt two sheets of plywood together and on the back side, fit a length of plywood of equal thickness over the joint. The surface on the other side was left flush. But that left that butt block on the back side to deal with....unsightly and generally in the way. Enter the "Payson butt joint", which replaced the plywood backing with fiberglass tape, which is installed on both sides. The original descriptions of doing that suggesting grinding or routing in a shallow depression, same depth as the finished thickness of the glass you were using to cover the joint and same width as the piece of glass tape, such that when the joint was completed, the end result would be flush with the surface. Modern versions eliminate that step, leaving the raised "bump" of the glass tape on the surface. To hide that, you need to feather and fair out the edges. Remarkably, I've heard is said that without the tape, a glued butt joint alone......just epoxy hold the two edges together.......is so fragile it might not even survive a rollover. But supposedly, a layer of tape on either side improves the joint to nearly the same strength as the plywood itself. If true, that is impressive and indicative of the strength of glass tape.

 

True scarf joints are more work as you have to create as near to perfect as you can, long, straight, square bevels that come to a feather edge. Get this right and the only evidence of a joint is a straight line where the two panels overlap. In practice, this is not as difficult as it might seem if you make them in stacks, doing several panels at the same time. Measure the offsets for your 8:1 scarfs, support the leading edge of the bottom piece to get a feather edge, then let the plies in the plywood be your topographic map showing you the high and low spots. Straight ply lines and a level edge, front to back across the entire stack should leave you with near perfect scarfs. If you use a plane, power plane or belt sander, this goes pretty fast. Lastly, some will also argue that a true scarf joint will leave you with something closer to the original plywood sheet itself, so if you bend a long panel, the bend will continue through the scarf joint resulting in a fair curve. How noticeable that might be would depend on how tight the bend is.

 

So it pretty much boils down to if the joint is hidden (as would be the case on the bottom), or if you don't care that there might be a noticeable bump, or if you want to spend about as much time grinding and fairing out the bump as you would spend on grinding and fairing out the scarf.

[Hirilonde]

........................ or if you want to spend about as much time grinding and fairing out the bump as you would spend on grinding and fairing out the scarf.

 

As much?  Not sure what you mean here.  I found scarfs took very little time to bevel and virtually no time to fair.  I think most people spend more time being confused as to how they will do it than it takes.  If you stack pieces off-set by the length of the scarf it is a lot easier than it would seem.  I use a surface hand plane for most of the material removal and finish with a belt sander. 

[Howard]

Dave:

 

I think we are in agreement on this. It seems to me that glass butt blocks are often suggested as offering a faster way of joining plywood panels vs. the true scarfs. Perhaps I'm sloppy about it, but I have found it takes me as long to grind down and fair out a glass taped joint as it takes me to cut the scarf bevels, so in reality, I don't see any time savings by doing glass butt blocks. You also have to be careful sanding down your glass butt block to avoid cutting into the glass tape, or there goes the strength of your joint. And you also raise a good point......don't try to do scarfs one at a time. Stack as many as you can comfortably handle and do them all together. It will go faster and be more accurate to boot.

 

As long as you are careful about it when gluing them up, both should end up equally square. In true scarfs, you do lose the length of each joint from one panel, such that if you needed two panels of 1/2" plywood to finish at over 15' 8", you would not get that out of two scarfed 8' panels, as you would loose 4 inches to the overlap of the scarf. Butt blocks would finish at a full 16 feet.

[rstanley]

Thanks for the advice. Hope everyone has a Happy and Safe New Years!