Thread: recycled skin on frame

Lance, it looks to me like you made your own luck by keeping your eyes open - nice work either way .

Take lots of photos for us - I hope to do a SOF in the next year or 2 (or 5) so am interested in the process and local material sources.

If I didn't know who owned that ghost-arm in the tablesaw photo I'd be spooked out by it.

The frames are looking spiffy!

yeah, i thought you'd like a glimpse of your spectral self

ok...

so I made my scarf cuts this afternoon, mostly looking pretty good. For some reason the keel is a bit off-straight, but since it's going to get bent anyway I'm not really that fussed about it.

What I am a bit worried about is the size of some of the screw-holes in the chine stringers. at 18x18 they're not exactly beefy and those well (poorly!) placed old wounds certainly then take out a chunk.

My plan is to syringe in some thickened bote-cote and hope for the best. I have a feeling that this will make them very strong indeed but am I fooling myself? is the epoxy really going to make up for those voids? I'm going to have to do the same thing in one or two spots in the plywood cross sections (no... its not marine ply...) as well.

Do i need to re-drill the holes to get a clean edge (which will obviously take out yet more precious timber) or should I just goop it in to the old dirty rusty holes?

cheers!

Oh! by the way, how do I move this thread from design to building?
and how do you insert images into the thread body rather than as attachments without having them already online (ie with a URL?

Lance

I think your best chance of success with the chines is to place the holes on the inside of the bends—in compression. Cylinders of epoxy should be pretty strong in compression, so they shouldn't fail.
Converseley, if the holes were in tension, there is a chance that the timber will tear away from the cylinders. This shouldn't be too likely though. I think you'll be okay.

Do your thickening with strands of fibreglass if you can too, as it will strengthen the plugs in every other mode (tension and shear). I'll bring you some scraps of glass if you can be bothered.

From memory, you don't have a lot of length to play about with in those chines, but where possible get those bullet holes away from the bulk heads, where peak bending load will occur.

If you're still worried about them, you could add a strip or bandage of glass, or glue on a wee timber brace. It wouldn't need to be very thick at all, as it's really just moving the stress away from the holes.

I only just checked out your scarfing jig. Lovely work!

hmm youve pretty much confirmed what i felt mat.
I was planning on putting the holes on the inside as I figured an arch (or two stacked together to make a hole) is a compressively strong structure.

I dont have any fibreglass lying around here. are you in town soon? I had thought of doing a single wrap if I had to, hadnt thought of putting it in the hole as well... how much of a difference will it make vs sawdust or filler? I hadnt thought about glueing on a wee brace. I have plenty of 4mm thick bits laying around which would do fine and wouldnt get in the way at all..

that would give me a bit more confidance in taking out the grotty old timber first as well..

I was thinking of filling them up this weekend, although i guess it can always await a little. I can always start doing another section instead, or possibly even whack em all on the sections to get a glimpse of the shape then fill em later (as long as they dont snap!)

ta on the scarf jig. I'd had heaps of idea on how to do it simply with scrap studs, then suddenly kapow! simple concept wins! it worked great, although i couldnt use my new pull saw as it wasnt long enough & had to use the tip shop mitre saw...

So,

After an actual paddle this afternoon, I quickly set up the strong back wit hthe aim of putting all the timber together to get a look at what this kayak is actually going to be like.

The scarf joints have had a few days to cure. I cant say they are the greatest glue job in history, as I have very little experience of using epoxy, but i figure they shoudl be strong enough... I have been considering wrapping and epoxing (ie fibreglassing) the scarf joints themselves as Tom Yost recommmends for the actual cross section/stringer joints on the kayak. Amongst other things I got at the tip yesterday wasa roll of 'washing line' which is a plastic coating with a core of polyester fibres. The fibres are WAY stronger than my other potential lashing media (baling twine, an old deep sea long line, random unravelled cords from around the place, dental floss have all been discarded as not strong enough) plus it doesnt seem to stretch at all and once the outer sheath is off the polyester stands are not woven, whic hshould make the epoxy soak in better.
I reckon ill use some chopped up to bulk up epoxy for hole filling and I'm seriously considering using the bulk of this washing line as deck lines once the yak is finished.

Anyway, getting the gunwhales in place was way more hassle then I thought it would be, and bending them to fit in the middle section was frightening.
Once all 5 sections were in place (acheived only by lashing the bow/stern points tightly in place) I squeezed in to the cockpit and finally managed to get a feel of the shape and sizr of this boat! Yay! I'm no longer concerned about it being too narrow. It seems very short (approx 13 foot in the design) but since I was out on a 22foot double this afternoon its a bit hard to be objective.

Stepped out to get some more snaps and .... SNAP! one of the scarf joints gave out. It seems I was right to be anxious aboutthe amount of force I had to put through the gunwhale to get all those sections in place.
I now remember reading I should position the joints NOT right inthe centre of the yak as its under alot of bending stress there. I actually have enough length to reposition it better next time but hadnt done so in my quick check.

Lookign at the joint I can see that is was actually the timber that gave way, not the epoxy, and I can see from the difference orientation of grain in the two pieces that one of them exposes a large amount of softer wood. Too late now! I'll recut it again sometime this week (quick job with the circular saw was close, but not close enough for me to reglue it now) and in the meantime, all those other scarfs are going to get reinforced.....

Plus I'll need to actually make the strongback level and fix my thick nesser... So it unfortunatley going to be more than a week I reckon before I can consider myself back at this point again..

cheers!

LAnce

Lance i love what your doing here, I'm looking to make one of the yostwerks sea riders, the problem im facing, i cant make head nor tail out of the cutting list
any suggestions?

hey,

havent updated this in a while, but i have almost finished all the major glues now. certinaly has been slowed down by my habit of having too many projects on the go at once...

what exactly do you mean by the cutting list? do you mean you cant work out how to plot the offsets to make the plywood cross sections? or is it cutting down the planks to make the chines/stringers/etc/whatever?

cheers

LAnce

Hmmmm im not up to par with the lingo, but i mean measuring out the bulkheads...
i had another look at the site and saw the pic by pic build so i might run off that

Also where did you get your skin from? i want to get the clear stuff, im thinking i might visit my local clark rubber, but if you have a source in sydney im keen eyed hahaha

oh yeah, following the manual is very valuable...

I justlooked at it again last night and realised now why cutting the fore/aft plates was such a nightmare and done pretty badly (by me - I didnt glue to keel/deck ridge first, i did it all freehand, so they twisted out of place all the time...

some more tips from my experience : make sure your gunwhales are as close as possible to identical. I couldnt be arsed fixing my thicknesser and went with uneven ones and the whole boat has a wobble in it, which means Ive had to re-jig the keel to make it straigt as well as pack out the fore-aft plates a bit so they are vertical (ish!) as well as midline. If I'd just thicknessed the things it would have been much better!
obviously working with recycled timber makes it a bit more of a challenge but this one was pretty much my fault. We'll call it learning for next time..

Also, just yesterday I managed to score (sight unseen so far) a billboard pvc tarp for the skin. I've seen a friends and they seem tough enough. I had an old truck curtain but it was a bit stiff and in pretty bad condition - very hard to get it looking pretty. The billboard curtain i think will be around 400-500gsm which is around about the same weight as Tom Yost recommends.
I dont know if you're going recycled as well but its worth calling around some billboard companies to get a skin if you are.

I'm not going to glue it either, as the glue recommended comes only in 4ltr tubs! the truck tarp can be heat welded with a heat gun, so I'm planning on doing that on all my 'glue' joins instead. ITs pretty much the same end result - ie melted pvc smooshed together. Might be a bit messier/uglier but its more in ethos with the project. I'll probably also staple down the deck after glueing then if I cant get any stainless staples, I'll run some thinned out clear silicone (+turps and drill-mix for ages) over all the staples (and glue edges) to protect from the sea water..
This might not be as tough as tom yose recommends but it should be fine for my requirements (good weather fishing and playing

cheers

Lance

oh, whoops, just noticed that i didnt actually answer!

if you meant actually tracing the shapes onto the ply - follow the manual! dont forget to measure twice and cut once takes a while but it's good. I couldnt initially be bothered with putting in nails and bending thin strips to mark the curves right, but in the end its actualyl very fastand much easier than any other way I think...

if you meant the spacing between bulkheads on the actual kayak, I moved mine fore/aft a few cm each as I stretched the whole kayak out about 30 cm, and repositioned them to be about equall tension throughout. they're not perfectly aligned (in fact the ply itself was a bit twisted from age) but they'll be ok

I had a look at a clark rubber catalogue, i think they stock some PVC (it might not be thick enough though) and some contact glue stuff that sticks pvc.

as far as where im struggling, Im looking at the offset table and i dont understand it. HAB, HB,
I dont get why they dont just have chines x2 - 30mmx20mm - *length* and so on with the gunwales deck ridge etc.

wish he had photos of each bulkhead with measurements shown on the photos... or have i still not stumbled on that section of the site? or do you have to buy his plans? so far ive looked at the construction photos from start to finish...

im not going to use the glue either i dont think, and just seal it up with silicone. im also planning on putting in like a rail up the front and rear stem, and putting an external gunwale either side to hide the staples (which ill staple along the gunwale)