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).

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