NRG 18th Century Merchantman Half-Hull - by JacquesCousteau

[JacquesCousteau]

Here's another reposted old build log of mine from ModelShipWorld that was lost in that site's crash. As far as I can tell, there are no build logs of this model here, so I thought it may be useful to post it. This will be a simplified re-post, missing a number of helpful discussions I had with other forum users, which would be difficult to re-create here.

By January 2024, I had completed two models (the Model Shipways Dory and a Xochimilco Trajinera scratch-build) and had two builds in progress (a Lake Chapala Canoa de Rancho and a cross-section model of the Spanish fishing boat Juana y José). All but the Juana y José were flat-bottomed, flat-sided boats, and I was interested in learning more about how to plank a curved hull--the Juana y José had given me a taste of this, but as a cross-section, it was missing a lot. I saw that the Nautical Research Guild (NRG) sold a half-hull planking kit with a detailed instruction set on how to spile planks. I thought that a half-hull would be easy to transport (I was moving frequently those days) and display, and would simplify planking because I wouldn't have to worry about getting everything even on both sides, so I decided to give the kit a try. It helped, too, that there were a number of build logs on MSW with a lot of great advice and helpful photos, including one by the kit's designer, Toni Levine.

Overall, I found the build to be a very useful learning experience. There were a few issues I had with the kit, as will be seen, but I was pleased with the result, and more importantly, I learned a lot about hull planking, making me feel better-prepared for further builds.

The kit itself is pretty basic: a plan drawing to be placed on the building board and used to properly set up the bulkheads, some basswood parts (keel, keelson, stem, sternpost, and some others), thick plywood bulkheads that are hollowed out and effectively thick frames (theoretically to make clamping easier, although practically all of my clamps were too small to do this), and some sheets of 1/32-inch thick basswood for planking stock.

You begin the model by making a buildboard--I used foam board with the plans glued on--and assembling the keel structure. Right from the start, I ran into a bit of trouble figuring out how to fit the foreward keelson into place. The pre-cut notches (which the kit purposely leaves too shallow so as to not weaken the piece, you're supposed to deepen them later) did not line up with the plan lines, unless the part was placed to overlap the main keelson. There were also a few notches in the keelson that were slightly off.


Ultimately, I decided that it would be best to trim the aft end of the fore keelson and position it so it best matched the curve of the stem, ignoring the notches as they could be re-cut later. The issue with the notches is a potential stumbling block for builders, but as you have to reshape the notches anyway later, it's really not a big deal if they don't line up perfectly. With that, I had the keel basically ready for assembly, although the parts were not glued yet so as to allow for shaping the rabbet and bearding line.


I had been a bit worried about carving the rabbet--it seemed so complicated from everything I had seen, trying to get the right shape as the angle of the planking changed across the hull! But it actually was pretty straightforward. The kit instructions were detailed, and while some photos in them were a little blurry, I was able to find photos in other build logs that helped clarify any parts I didn't understand (of course, that can't be done now thanks to the MSW crash...). I used a compass to mark 1/32-inch on the keel, keelson, stem, creating a groove I later drew over with a pencil. I then drew out the approximate curve as the rabbet narrows over the fore keelson and eventually disappears on the stemson, which is necessary because the planking low down intersects the stem at a sharp angle, but by the top of the stem, it has transitioned to intersect it nearly perpendicular to the keel direction and hence needs a smaller rabbet to slot into.


I started carving the rabbet on the keelson with an exacto knife, as it is hidden in the final model and any mistakes would not be visible. It worked all right, but was a bit uneven. What worked better, on the keel, was to carve the rabbet nearly to the line, and then finalize it with sandpaper. One challenge is to remember to stop the keel rabbet at a notch where the deadwood starts, as it takes a different shape after that.


And the rabbet at the stem:


At that point, I glued down most of the keel assembly, although the deadwood is still unglued as it needs to be shaped. I then began deepening the notches so as to bring the bulkheads down to the deadwood. I started on the keelson, as being flat, it was easier to start with. Deepening the notches was mostly simple, although in some spots it was hard to cut due to glue spots between the keelson and build board. I took the opportunity to better align the notches with the drawing, although I also noticed that the D-frame was marked a bit wider than the others for some reason.


Next, the fore keelson, which was a little tricky to get sorted out as I wasn't sure how deep the notches should be--all the way to the keelson, beveled...? I went with the shape as seen below, which worked out all right.

 

[JacquesCousteau]

The next step is to begin fitting the bulkheads amidships. It was a little tricky to get them in place, because some of them want to fall over due to the large hollow space. The kit includes a number of spacers to hold them accurately apart. I used rubber bands to clamp every other frame pair first, and then added in the missing spacers, clamping across longer spaces with rubber bands. One important word of warning: make sure that the spacers are placed such that you can later mark at least one side of the wale from the drawing.




I then prepared to add the frames fore and aft. The aft frames are placed temporarily and used to mark the bearding line. You then draw the bearding line and thin the deadwood aft of it, in order to create a proper landing for the planks in this space.

And then you go ahead and cut the rabbet under the deadwood, which should here be a 90-degree notch rather than a v-cut. (As can be seen, I messed up a bit by marking the rabbet line all the way to the end of the keel, which was not necessary. Ah well.)


With the bearding line and rabbet set, you can start adding frames aft.


The bow was tricky, as you have to cut a new notch and shape the bulkheads to follow the rabbet. I found that the plywood used sanded pretty well, but often crumbled when cut, which took some getting used to. Below, the notch for the 5a frame:


And the 5a frame in place:


The last fore frame just sits on top of the stemson. The instructions in the kit say to add another bit of basswood ahead of it to run directly into the rabbet, but I didn't have space on my build. Adding the spacer was also difficult due to the serious curves at the bow, so I angled it kinda weirdly (but it worked!).


Aft, there's a huge stack of frames in order to provide a good gluing surface for the complex curves there. A spacer gets added somewhere in between them. I think I placed mine in a slightly different place than given in the instructions, but it didn't really matter in the end.


One area where I felt the kit could be improved was that it could be a little confusing how to handle the stern, especially as some photos were not very clear. The instructions, for instance, say that frame H (the final frame) should not be sanded, as it's supposed to form the bottom of the counter, which I missed until I had already begun sanding it. I then realized, thanks to other build logs, that it's fine, in fact it's necessary, to sand the bottom of the frame to properly run into the rabbet, it's the rest that should be left unsanded for now. Below, a picture showing how I handled the aft frames at this point, and how the transom should be oriented.


At that point, the model looked like this:


I then used a razor saw to trim the frame tops to match the drawing.


With that, I was ready to begin fairing!

 

[JacquesCousteau]

Fairing. This took way, way longer than I expected. Here I had thought I was getting a kit to learn how to plank, and instead I got stuck spending two months sanding the thing before I even got to plank anything. It was a dreary, frequently frustrating experience. But, I learned a lot!

I began with a 150-grit sanding stick, and a bit of 100-grit sandpaper for areas that needed to have a lot taken off. After a week or so of this, I had the following:


Some frames, like B, had been reduced quite a bit, while others, like C, had barely been touched. I kept at it, using a batten to check for fairness. After a while, I concluded that I needed to build up frames C and E, at least, so I added some thin basswood to the outer side of these and kept sanding.




The bow needed to have a lot of material removed. It was also extremely hard to check for fairness, as battens kept breaking whenever I tried to use them to check. I mean, it's a clear sign that it's not fair yet, but it would be nice to know that before you break a batten. In the photo below, you can also see how I placed tape over the keel to try to save it. In hindsight, I should have gone with a sturdier tape, as some parts of the keel still got banged up during fairing and the little slivers of clear tape were a pain in the neck to remove.


If the bow was hard, the stern posed its own difficulties. There were such major height differences between the frames that many parts were still left untouched. Meanwhile, the instructions say to not touch the bottom of frame H (the aftmost frame) so as not to mess up the counter placement, which I found almost impossible to avoid.


At one point, I decided to use a bit of chart tape to get another look at fairness, especially in the areas that were hard to check with a batten.


I realized that I would probably need to shim frame D, which sat between the already-shimmed frames C and E.


At the bow, I had initially thought that I needed to shim frame 4, as it seemed too low, but the chart tape helped me see that the real problem was that the upper part of frame 4a needed more sanding:


Around this point, I began to test-fit the counter to try to get a better sense of how to properly fair the stern. I found that the counter didn't really match well with the frame, and would not have even if I hadn't occasionally accidentally sanded the frame.




And I kept working at fairing, shimming here, sanding there. By this point, the hull was looking pretty ragged.


At the stern, I started shaping filler pieces to fill some of the gaps between the frames and provide more area for gluing planking.


I still had a hard time visualizing how the planking, or battens, should run at the stern.


While I was getting close at the bow: the battens finally stopped snapping!


I also significantly reshaped the counter to better fit (still not glued on though), although the whole counter area still needed a lot of work:


It was finally getting close....