Atomic Shrimp - Building A Boat

Building A Boat - Page 3

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Glass tape techniques

Teaching yourself to do a skilled job like this - fibre glass lamination - is interesting. I can tell that I've learned quite a bit even in the last couple of days - for example:

Tucking the frayed threads at the ends underneath the tape as it is laid down - this stops the brush from picking up an unruly bunch of strands at the end.
Getting just the right amount of epoxy onto the seam before laying down the tape.
Working the epoxy through the tape with a vigourous dabbing motion with the brush.

I'm sure these are all basic skills that anyone would learn on their first day of the job, if doing this professionally, but still it's fun to discover them for myself.

Things that make you go 'Hmmm...'

I stumbled across this picture today - it's a model of something Leonardo Da Vinci sketched:

I hardly need say what went through my mind when I saw it. By sheer serendipitous happenstance, the strong central rib in my boat will, I think, be just perfect for mounting add-ons like this (or maybe oarlocks).

I'm not planning to do this as part of the initial build, but if I design it right, I can bolt on and remove stuff like this at will.

Clamping angular assemblies

The bow and stern posts are wedge-shaped and are glued into the convergence of the extra panels at front and back. Epoxy glue - although it is an excellent adhesive when set - is a reasonable lubricant when liquid. If I tried to just clamp the posts into the ends of the boad, they would just squeeze out of places due to the angles involved.

To prevent this happening, I drilled small holes in the side panels (more to fill later) and pinned through with long panel pins - I didn't hammer these home all the way for two reasons - they'll be easier to pull out later if they're left protruding, but mostly, because I pinned it all up 'dry' - the ply faces can be slipped up the protruding shaft of the pins, opening the joint to allow glue to be spread in it, but with the pins in place, the joint can't fail to drop perfectly back into alignment.

The pins stop the timbers from sliding against one another when the clamp is applied.

Here's a plan view diagram of the assembly arrangement:

Here's how it turned out when the glue had set (but before the pins were removed:

Epoxy bread dough

I still can't quite believe using wheat flour as a filler for epoxy glue is OK, but it really does seem to work. I add about 1 part flour to two parts pre-thickened glue

If I was using ordinary epoxy resin, I'd probably need to add more filler, but 1:2 seems OK for this stuff. It produces a nice manageable doughy paste

More clamps

I bought myself another batch of clamps

Five trigger ratchet clamps and two very strong spring clamps - bringing my total collection to somewhere around twenty in number - which should just about be adequate for sorting out the gunwales - I need to apply both sides at the same time, to prevent the tension introducing a twist in the boat.

Mixed feelings

The glue I used to fill the outer seams has cured leaving a concave glue line

Two-part glues like this don't typically lose volume when they set (they don't work by the evaporation of solvent), so I think the explanation for this is that the resin has wicked into the surrounding wood.

That's good, really, because it means the bond will be a strong one - the glue will be forming a single plastic entity that extends into the fibres of the wood, but it's a bit of a nuisance practically, as it means I have to go along and fill again.

Why buy?

Why buy glue spreaders? - sliced-up margarine tub lids are great - they're flexible for smoothing down, they are nice and thin for skimming excess glue off, and you can make them whatever width you need.

You really never can have too many clamps

Repeat after me:

You really never can have too many clamps.

I used twenty-one clamps to fit a single outwale lath and to be honest, a couple more would have been quite handy

Gunwale construction

I'm building the gunwale as a lamination of three laths - I want the outer part of the outwale to be rounded, so I prepared this by cutting a quadrant on two edges of one of my 38mm spruce pieces, then I ripped the rounded end off with my table saw

The gunwale will then be built up like this:

I'll be deliberately leaving the top slightly proud of the ply edge, as this will then be capped with epoxy (probably loaded with microballoons, as these make an attractive, lightweight fill - this will serve to seal the top edge of the ply, cover any irregularities in the top edge, and also to bind the gunwale together as a coherent unit (additionally to the polyurethane glue used to build the laminations)

I'll probably sand the sharp corners off the inwales before finishing.

Paint setback

The paint I ordered finally arrived - a 5 litre tin of military surplus marine brushing paint in deep bronze green, BUT... I can't use it! - it is based on Lead Chromate, which is highly toxic/carcinogenic and would be a serious hazard if I have to rub down and refinish in the future, or even when I de-nib between coats.

The eBay seller made no mention of the toxicity, even though there's a big bold label saying so on the tin (yes, the side not shown in the photograph!)

That's £29 including carriage wasted - I can't return it, because it's illegal to send this stuff in the post (conveniently ignored by the seller). I don't even know how I'm going to dispose of it.

This has been a costly exercise. Ouch.

Advertise your site on Atomic Shrimp - Right here in this slot!

24 June 2007: I made good progress on the rest of the glass taping tonight - nearly all done now

The camera is actually pretty forgiving here - in real life, the inside of the boat looks quite messy now - it's almost impossible to avoid dripping a bit of epoxy here and there whilst working and even though I brush it out smooth when this happens (to prevent leaving a raised blob), it darkens and wets the timber surface, so at the moment, it looks like someone has done a rather amateur job of varnishing it - which of course isn't terribly far from the truth.

25 June 2007: More progress - the temporary braces are no longer needed, so those came out. I took off the masking tape from the outside of the seams (bit of a nightmare that - it left its glue on the patches of epoxy, so I had to remove this with a rag and white spirit)

The four small extra panels were stitched in place and tack glued.

There's a distinct gap at the bow and stern, but I did plan it that way (honest) - this will be filled with a solid timber post that will protrude a little past the end and will bear the brunt of any forces in the event of minor collsion, etc.

I'm not all that happy with the overall look and shape of the boat now, but I think it's because it despertately needs the gunwale to make it look like a proper boat. Time will tell.

26 June 2007: I ripped the 38mm pine into thin laths - I think it's going to bend OK for the gunwales, but I'm going to have to do something clever for the bit where the extra panels meet the main hull. I have a plan - more later.

I also made up some posts for the bow and stern - these currently have wedge-shaped packing pieces being glued to them.

27 June 2007: The glue on the bow and stern posts has set well - I thought I'd try Gorilla (polyurethane) Glue for this job, as the pieces are close fitting and there's no gap-filling required. It worked a treat - they feel really solid - as if cut from a single piece of timber.

It's a little bit frustrating now, because I'm at the stage where a series of smallish jobs need doing in succession and I can't plough through them all because I have to wait for glue to set in between each stage. So today, all I was able to do was to glue in the posts

Tomorrow, I need to turn over the boat and do another couple of fiddly little bits - tidying up and gluing in the pointy ends of all the panels.

28 June 2007: I fixed up the ends of the panels to the end posts today. I drilled small holes, spread glue under the ends and pinned down the panels with copper plated hardboard pins that will be left permanently in place

It's a bit grotty-looking after gluing, but it will be trimmed and filed to shape, filled a little more and I think probably glassed over - the ends of the boat are likely to take a bit of abuse so they'll need to be strong

While I had the boat upside down, I took the opportunity to fill some of the long seams - about half of them are done now

Later on this evening, the previous session's glue was pretty dry, so I turned the boat - by which I mean turned, not flipped on its long axis (which was not easy in this cramped space) and filled the seams on the other side. That's all the main seams filled now.

Here's another picture:

This series of all-too-similar photographs actually illustrates a cause of minor frustration at this point - work continues on the project, but doesn't make much visual impact, leading to a feeling that nothing is really getting done - it's a false impression, of course - all of these jobs are important and need completing, but I'll just be glad when it starts looking like progress is underway again.

29 June 2007: I filled and radiused the internal seams on the extra panels today, along with a bit more filling at the ends - now that everything is mated up to the end posts.

No picture today, because as stated above, it would just be another barely different photo of the hull.

30 June 2007: I've filled all the remaining seams now. I've also shaped and filled the bits where all the tapered ends meet.

I may not need to refill the slight concavity in the glue lines after all - one of the next jobs is to sand the joints smooth anyway and this will entail removal of a small amount of wood immediately adjacent to the joint, like this:

-in which case, the bottom of the concave glue line will become the top of the convex smoothed joint, or that's the plan.

I had said I wouldn't bother, but I'm thinking I might glass the outside of the seams, at least the bottom three, that are most likely to suffer abrasion if the boat is beached. I have a hard roller to press down the tape on these joints, but it will probably also need filling and fairing afterwards.

I also glassed the inside ends today - the only remaining internal glassing is along the seams of the extra top panels, and I intend to leave that until after the inwale is fitted - as it needs to clamp flush to the wood.

01 July 2007: I fixed on one of the outwales today - possibly the trickiest work of the whole project - the curvature of the gunwale line demands a bend in more than one direction, which the wood just really doesn't want to do. I don't have facilities for steam bending of wood, so here's how I did it:

First, the laths to be used were ripped into three sections along about two thirds of their length:

Next, the outer pair of sections was removed from one lath, and the inner one from the other:

Then they could be glued and clamped onto the gunwale line - the solid timber at each end, the slimmer fingers interlocking in the middle and permitting an upward bend as well as an outward one.

Clamping was a really tricky business, because I essentially had to start from both ends of both pieces, creating a bulge in the middle, although this wasn't too hard to work to the ends and bring the timber flush with the boat.

This part of the job would actually be ideal for two pairs of hands.

02 July 2007: I fitted the opposite outwale lath tonight - this one went a lot easier - I suppose I just knew what to expect this time. No photo as it looks just like the other one.

I also did a bit of gap-filling on the lath I fitted yesterday.

Tomorrow, I hope to fit one of the inwales.

03 July 2007:

The second lath looks really good - here's a picture showing the way the fingers interlock (just ignore the voids - they'll be filled before the outer beading goes on).

And in this one, you can just about see the compound curvature that made all this jiggery-pokery necessary.

Anyway... it's time to move on to another page now...