Wa'apa Build - Part 15 (Making hollow beams #4)

I left off with both boards and spacers glued up waiting for plywood sides..

With glue cured I planed and sanded the excess spacer and got everything ready for the plywood.

Remnants of side panel sheets provide enough for side caps with still some left over.

Plywood sides cut and everything hit with a coat of epoxy ready for gluing.

Glued spread, caps stapled down. Stapling turned out to be a bit of a pain, but got the job done. Once cured I flipped and repeated for the other side. After that came pulling lots of staples...

Staples pulled, excess planed, and corners rounded.

Not counting filling all the little holes and such, sealing, or painting...beams are complete! They came out to 16 pounds total..or 8 pounds each. According to my calculations, based on using this radiata pine, that is a total of 6 pounds lighter than solid beams with dimensions per plans, or a total of 10 pounds lighter than solid beams of same dimension used here.

Very labor intensive, but I'm happy with the results. They don't weight a lot and they are nice and stiff. I laid them across the saw horses and sat in the middle of them, was quite solid with almost no flex at all.

On to the next!

Wa'apa Build - Part 14 (Making hollow beams #3)

Carrying on from last time...

First up was to get the spacers dry fitted, which as usual meant lots of drilling and placing temporary screws...

Spacers and board labeled to keep track of what went where...

Preparing for epoxy coating and glue up...

Coated and gluing in progress...

That was left to cure overnight and the next day it is time for cleanup and trimming to bond the next board on.

Spacer over sized on tapered end.. 

Planed flush.

Double checking spacers flush and square. 

Board dry fitted....

Taken apart, epoxy coated, and glue spread.

Then screwed back together and squeeze out scraped off.

Next time, the plywood sides...

Wa'apa Build - Part 13 (Making hollow beams #2)

Continuing on...

It took a few hours but the 4 main boards are all whittled down to size. I have a number of lengths of western red cedar 2x4 I can make use of for the interior blocking. Of course its rough and over sized, so more thicknessing to do...

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Cutting didn't go so well...think I'm overdue for a new blade.

Planed and sanded..

Then I measured and marked the boards for the blocking. Made sure to get blocks to cover where the beam goes over the gunwales, then spread the rest around at regular intervals.

Then I got it in my head I should taper the ends a bit just to give it a little shape...and for better or worse it's all done now...

I still need to mark for, and get the blocking prepared for the other one...then should be ready to glue it up.

Wa'apa Build - Part 12 (Making hollow beams #1)

I decided to leave the hulls alone for a minute and work on the iako (cross beams). I am building them hollow like Gary Dierking wrote about here.

I decided to just use some cheap and readily available radiata pine boards for the iako, and grabbed them from the local big box store. I also dug an almost clear (one knot towards one end) 2x4 with good grain out of the $3 pile. I'll be able to rip some good lengths out of that for things like the rudder mounts and some other stuff later.

The radiata boards are 8' x 3.5'' x 3/4'' (2438 x 89 x 19 mm). In Gary's article, he commented that as a rule he makes the hollow beams 10% larger than their solid counterparts. For me that will equate to beams of 77 x 62 mm. Since I'm using 4mm ply for the beam sides, I need to reduce the board width by 20mm, down to 69mm.

So I set up my ripping sled for 20mm cut and ripped a length off one of the boards; then promptly realized I forgot to take into account the size of kerf...so I ended up with 67mm instead. Oops, so my beams will be 75 x 62 mm then, no big deal I think.

The article used 5/8'' / 16mm boards, mine are currently 19mm. My beams will just be straight boxes, no bending or anything, so I could just leave them at 19mm I guess. However, I'm trying to keep things as light as possible; for one because I'm adding extra weight elsewhere with the self bailing cockpit, rudder stuff, etc; and secondly because the lighter it is, the easier it will be to move around, lift on a car, etc...and be all around more enjoyable to deal with I think.

So anyway I weighed the boards, did some calculations, and came to the conclusion that reducing the boards to 15mm will shave off just over 3 pounds. Doesn't sound like much, especially when I think about the work I'm in for using a hand plane to do it...but every little bit helps. Save me a trip to the gym anyway... ;)

I work the plane down the board at an angle, across the grain. When I reach the end, I work my way back with opposite angle, making an X like pattern. Going straight across grain results in tear out; a scrub plane or at least a cambered blade would probably do a cleaner, quicker job. Starting with largest cuts I can get away with without knocking my makeshift work bench around to much, and getting lighter as I get closer to the line. Then I switch to long strokes with the grain to smooth and flatten it out, and finish with a sanding block.

Marking gauge set for 15mm.

Board marked on both sides.

Trusty jack plane put to work.

Done yet?

Looks good!

And only three more to do! A lot of work, and a bit time consuming, but enjoyable and rewarding in its own way...