Sunday 28 October 2012

Spiling challenges

Although I managed to get a reasonable result with spiling the garboards, the broad strake and next plank proved more difficult.  I suspected a faulty spiling pattern (the bad carpenter always blames his tools, right?!!) so I recreated the spiling pattern using larch thicknessed to 8mm.  It is articulated in three places and seems to maintain its position securely with several short self tapping screws.


However, I notice that the resulting planks turn out to have more of a curve in them than required.  In other words the ends were pointing higher up towards the keel by some 2 to 3 inches than required.....

The culprit: Now I suspect this is because I did not rest the spiling pattern on the bevel of the preceding plank, but set it instead midway between the plank lines on the mold and the upper edge of the bevel. 
Here the spiling pattern is laid on top of the preceding planks bevel, about 1/2" away from the top edged of the bevel...time will tell if this approach solves the problem.



 Having made a couple of expensive dud planks, I started using hardboard as a test plank and refined this until it fitted and then laid this on the planking stick to mark points for fairing the baton on.  This produced accurate planks, but it is a slow multi step process, and I would really like to refine my compass spiling technique such that this intermediate stage can be eradicated.

Reading various forums on spiling, I really like the approach of tacking two batens onto the build lined us exactly to the upper and lower edges of the new plank and tacking a trellis network of light timbers between them to recreate the plank.  The only drawback I see is how to get a smooth surface to run the circular saw armed with John Brook's special jig and subsequently the router on the batten.  Maybe one has to nail the trellised batons onto the planking stock long the battens and then remove the trellis before cutting...

I used 10 second mitre glue to tack on the small pieces of hardbard - initially I was quite suspicious of this product which Brian had recommended - it looks like superglue with an aerosol can of catalyst hardener - but it worked miraculously - gluing extremely strongly in 10 seconds...I may use this on the trellis pattern approach instead of a pneumatic staple gun.

I will try one more approach with my articulated spiling template and compass, as per John Brooks GLWB excellent book, but if the template which ensues turns out cursed as previous iterations, I will try the trellised approach and record updates in later posts.



If anyone can pinpoint why my planks are turning out more curved than they should be, please comment...it may well be that this is a known repeated error of the first time amateur wooden boat builder...!

Monday 8 October 2012

More Planks

Today, I continued on with planking, having completed my keel mold and awaiting delivery of some melting equipment - more of which later.

My dilemma is to decide which boards to cut my next planks from. In the specifications there are one set of boards scarfed at a slight angle to accommodate a more "banana" shaped plank.  However, there is no reference as to which planks these boards are for, so I am going to cut them out of the same plank as I used for the garboards.  My wife casually remarked that the angled planks are probably for the mid section of the boat - she obviously has a better 3D mind than me and I suspect she is right!

[EDIT Jan 2013- I since found a reference in the plans as to which strakes are made from the angled boards - answer: nos 3 and 4.  Once again it proves to me that all the information is in the plans, you just have to search diligently!  However, I only made this discovery when fitting the final sheer strake.....but when I re-examined how I had used the boards, to me pleasant surprise, I had applied them to nos 3 & 4!!]

So I have just spiled the patterns boards and laid them onto the planking stock.  Marked out the various marks but there seems to be an ugly wobble in the lower line - I had a similar issue with the garboard around the same station - #6...I'm wondering if I have some issue with the marks at this mold.

It's dark outside, so I will go at it again in the morning and see if I can figure out what's going on.


12 Hours later.......

This morning, I eased some of the hard spots and with the assistance of Brian, who I recently discovered lives near me and also is building a wooden boat, we managed to fair out some decent lines.  Unfortunately, one of my battens was too thin so when I routed the final edge the batten bent inwards leaving depressions between the nailed points.  We had to re-trim the edge to take these high spots out, which meant the lap is more like 1 1/16th rather than 1 3/16ths - I can't imagine it will be too must of an issue.  So tomorrow, I will make a new Douglas Fir batten out of wider stock to make sure I don't have further incidents of the batten moving while routing the plank's edges.

Also, I am going to remake my spiling pattern.  It is made from ordinary 1/4" ply, which arrived from the store with a wicked warp  - delivered in my absence!  I used the warp as I thought to my advantage, to follow the curve of the hull, but I am not at all sure that this is working out correctly, so I am going to use some of my sapele 1/4" ply for this (once I have checked to make sure it's not all required for other parts of the boat.  


36 hrs later....
Finally manged to fit the board ready for epoxying to the garboard.  The Dory Gains were really troublesome, as they didn't seem to want to mate to each other.  Had to do a lot of fiddlying and fudging to get anything close to a fit, and still I reckon I will be relying on the magic properties of epoxy.  The angles of each Dory are the same, but I subsequently realised that I should have also calculated for the angle delta between the two planks to get the Dory gains to fit.  It is not at all clear to me how to get these cut without a lot of incremental guesswork.  Also I note the that the plank does not sit on the frames at stations 2 & 4 but rather kisses the frames at the lower side (sheer-side) of the plank .  So I am now wondering why I bothered beveling the cheeks which were attached to the plywood frames if the planks are not going to fit snug against them.
Station 2 - the gap is obviously going to be quite large, but should I fill it in or leave it?  Does the plank need to be screwed to the frame and if so where - probably at the laps.


Same issue at Station 4 where the frame and the plank is separated by a large gap.  I presume the gap itself is not an issue , although the cheek on the frame looks  strange. 
Here is a short video which shoes the challenge I've had trying to get the Dory gains to line up.


So John Brooks came to the rescue and wrote me an email of explanation....:-

"Dory gain is same width as lap. You will also make a dory gain on the underside of the next plank. Measure the angle between the landing for the next plank on the transom and the dory gain on the garboard, cut this angle on the underside of plank #2 where it meets the garboard, then make the dory gain to this angle. On the garboard, make the lap bevel flow into the dory gain"

Thanks John for the assistance,  it's beginning to makes sense now to me and by the time I get to the sheer plank, I may have a passable example..

Finally planks 3 & 4 are affixed.  I spent some time rechecking the offsets and made a large dividers to check for symmetry,  It transpires that the jig is perfectly aligned and level, and the molds are symmetrical.

I concluded that the difficulty I had fitting the last planks to their marks on the molds was due my spiling - relying on a warped spiling pattern.  So I decided to remake the spiling board out of 9mm larch planks.  So far they seem to pick up a fairer curve than the original 4mm cheap plywood.   Here are the old planks which composed the spiling pattern - you can clearly see the warp in the boards.

Here is the new spiling patter in action - I am hopeful for more precise outcomes.

 
The bow of the boat is hard pressed up against the inner wall of my garage, so it's difficult to sight the lines from the bow - my only opportunity is to take a photo holding the camera against the wall!   It will be interesting to see the boat when I take her out of the garage for the first time...

Notice where the blue F Clamp is holding the plank against the #2 mold - there is quite a large gap here - as if the mold is too narrow but checked the measurement and it seem fine.  So I'm wondering if that is as it should be or if I have not trimmed the inner stem sufficiently causing it to set the plank at a wider curve...
The transom is beginning to take shape.  The dorys look fine (at least to my eye).

Saturday 6 October 2012

Keel Mold

Having run to a standstill when a supplier of fasteners told me one month after ordering the screws that his supplier's factory was demolished..(yeh likely story Dave) I decided to start building the mold for my keel.

Using JB's plans for the keel, I ordered some pine from a local supplier, somewhat thicker than specified, in the expectation that it will be strong enough to contain the lead without having to bury it the ground, as John specifies. I want to be able to move the mold when pouring the lead - using steel tubing as rollers underneath the mold.

I read lots of threads on forums about lead keel pouring - and various solutions including coating the inside of the mold with water glass - but I'm going with a wood fire in a barrel enclosing the crucible.

I had been storing some gas cylinders which I planed to use as a crucible for lead smelting, I meanwhile came across a local company who was advertising some steel barrels for free - when I arrived to collect them he also had some old oxy-acetylene bottles which were also for the taking.  So when home with my new crucible, removed to valve to vent the bottle - it was marked 1970 - so it was old but still had the smell of acetone emanating from it.  Five hours later we finally managed to extricate the solid mass of firebrick from within...





Next, to deciphering the plan.  At first it seemed a cryptic document, but I persevered and finally made sense of the plans.  No doubt a seasoned boat builder would grasp it in an instant, but to add to the complexity, you need to make a special pattern ruler which accounts for the lead shrinking.  


150 screws later, I have a mold ready for pouring...time will tell how successful it is..

Having used spacers to define to mold profile, I had to cut them out as the top of teh mold is narrower that the base..
 Copious use of clamps were used to bend the 1 1/2" timbers to shape.  Plenty of screws where used to keep them in shape and so far it seems robust.
 I used a large coach bolt at this end to keep the timbers together.


 The finished mold, including vent for gasses to escape the enclosed portion of the mold, as specified by JB.



Friday 5 October 2012

The garboards

Having read JohnB's GLWB, it seemed to me that the planking was going to be a watershed stage in the build.  If I could figure out the spiling technique and master the cutting of the planks, and if they fitted, then I was well on my way to building this boat.

Well the good news is that the spiling techniques which John recommends using a compass, is much easier done than read.  So I was quite pleased with my efforts, although I decided to fair one station mark about 1/8" larger than the mold marks.  I'm hoping that this will be a good decision, but since it is the garboard, only the fish will be my critics...

This is the spiling pattern I made in action.

The spiling pattern is articulated in 3 places, thereby allowing it to fall onto the molds without too much torture.

This is the jig with JohnB recommends for the skill saw...I used an old acrylic display stand, hence the odd glue marks on the sheet - but it came for free and worked perfectly.

 Rather than nailing and screwing the planks temporarily to the keelson and molds, I screws blocks to the side of each mold station and used to clams to dry fit the garboards using clamps.  Seemed to work fine and allowed me to re-position the planks until I was satisfied it was aligned to its marks.

My test attempts at cutting half lap gains....

Half lap gains...

And again, using chisel and Quangsheng block rebate plane

Dory gains for the transom, using a spoke shave.  I've come to really enjoy using the spokeshave.  Initially all it would do was scrape and bounce off the wood, now having persevered with it, I can make really nice shavings, and it is a real pleasure to use.


I have opted to have curved planks at the transom rather than notching the transom, so JohnB recommends to make re-leaving cuts on the underside of the end of the plank.


 Garboards in place.

A short video on the garboards clamped to the molds and keelson before final attachment:


A view from the transom of the fitted garboards.  

Close examination will reveal I am using straight slotted screws.  This was to avoid a further 4 week delay in sourcing Frearson #10 1" screws.  Although JohnB warns of the horrors of using straight slotted heads, in fact they worked out fine and I didn't have any difficulties using an electric screwdriver to send them home.



Tuesday 2 October 2012

Laminating the inner stem

This was my first attempt at creating saw dust from my lovely stock of Sapele.  I bought a new (secondhand) 17" bandsaw for this project so I was eager to put it through its paces, cutting laminates.  I was chuffed at how well the laminates came out, and before long I had 15 lengths prepared for my stem.

I glued up the laminates without incident, although I did not use any fillers in the epoxy mix, but so far the stem seems to have held together fine.


Flushed with early sucess, I then laminated up the outer stem on the inner stem.  It wasn't until I re-read the specifications  that I realised the import of the sequence of John's instructions - i.e. shape the inner stem after it is cured and THEN laminate the outer stem to the inner stem.  My outer stem is a little off as a consequence, but I am confident that it will bend back to mate with the outer stem, when the planking is complete, or failing this I will have to get out my lamination blocks and plans and re-do the outer stem.  Not the end of the world...

One small word to the wise....dont cut off the excess timber from the top of the inner stem - you will need this to attach the stem to the jig, only when the boat s off the jig should you cut it to its finished lenght.  I thought I knew better, I trimmed it back to about 2" longer than the finished length - had to re-glue the cut-off back on so that I could attach the stem to the jig.  Epoxy glues and wood flour make for a very strong joint!