Model Boatbuilding - Stem rabbets

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[@JH-lo9ut]

Don't cut all the way to the rabbet line in the first go, or you'll cut away too much material. The planks won't come in at 45•, and the angle will change over the length of the curve. You need to take the planking thickness into consideration. Use a block of wood of a plank's thickness, cut at 90°. Set it to paper and draw it's shape. Rotate it and note how the back rabbet and the inner corner move as you change the angle. Now, this would help you if you had a completely staight perpendicular stem, but you don't, do you? There is a method of getting the exact angle in any given cross-section from the plans, but it is quite tricky to wrap your head around. You also need a lofted, full-scale plan to do it accurately. Angles run away quickly on you, once you start to rotate them in 3D. Even with this technique, I think it's better to air on the side of caution. If you are somewhat confident with your rabbet line, you can cut it roughly, but shallow, with a round tip router, or make a scalloped cut with a hollow chisel. It will remove some material and makes the chisel work a little less exhausting, especially if you are working in oak or ash. But take it easy. Good stem material doesn't grow on trees. (Pun intended) Cut it roughly at first. Test out the angles with a good batten that has some stiffness to it. Cut some more, and save the last for when you have the plank cut out, bent and clamped in place. Cutting the rabbet is the single most difficult thing in boat building, and it sucks that it's among the first things you have to do. I've had many a student in tears over this, but you know what, they all managed it in the end.

[@Nomadboatbuilding]

All excellent recommendations. This video was just intended to give the viewer a very basic idea of the chopping method and obviously the scale prohibits detailed guidance but everything you mention I employ on full scale builds and teach in my hands on courses. Thanks for adding hese details.

[@donsanders9863]

I smiled when I saw your cereal box models. I have built many boat and kayak models from cereal box cardboard, and now I hesitate to throw any boxes away 😀. But this year I finally used a real set of plans (Steve Redmond’s “Tetra”) and build a very nice sailboat. It’s great to be retired!

[@poepflater]

doing my first model from scratch I would not have thought of this... Busy with sawing wood for the stem so I watched your video....

[@Nomadboatbuilding]

Be sure to read the pinned comment at the top which has a bunch of good tips for getting this detail right. Of course working at scale has challenges for accuracy and maybe it isn't important to you to get everything just perfect but model making also offers great low time and materials cost education as so many tasks are pretty much the same regardless of scale.

[@poepflater]

yeah , I priced out building the full one, and yeah, a model is best I can do at this point. I swear I have more time into CAD on this boat than they say it takes to build the full boat.@oatbuilding

[@Nomadboatbuilding]

Computer machines can be a real time suck

[@poepflater]

for real, but also amazing feeling whe nyou tell that virtual concept to move down the wifi network in your house to the 3d printer.... I printed a big arse boat stem yesterday just to see how it fits on my drawings. in real life. @@Nomadboatbuilding

[@Nomadboatbuilding]

@@poepflater well that’s very cool. I've never been able to envision much use for 3d printing or even cnc in what I do but a friend of mine has recently started playing with it and I can now see some interesting peripheral applications. Still there’s the cad time to consider and I'm so far out of practice that I can’t hardly use it anymore. I gave up cad when I went into boat building almost 30 years ago.

[@gwheyduke]

Good information. Up 'till now I had mostly avoided this process on my model boats by just gluing the planks to a V shaped stem. Doesn't look to terribly difficult to do if you have to proper tools.

[@Nomadboatbuilding]

While I am all for finding simpler solutions, I also believe there is value in cracking the code on more seemingly complex processes. There is often some unforeseen gains hiding in there. Even better at a model scale where the cost of failure is so very low.

[@loki7441]

Hi Mark, I found the video very informative and wish I had seen it before I built the model of the french tunny boat in my profile picture. I was catching up on your Bouchie Dory build on the cut water. Watching you scratch marking the fixing hole through the cut water, reminded me of the accessory / tool I recently found. Its called the "Marxman". It's a little aerosol of green chalk with a tapered applicator. About 4 inches long and 1 inch diameter, its compact for getting behind objects to mark a hole. You center the applicator and push the aerosol and it fires a dart of chalk to mark through your screw hole in your timber. The guy who came up with the idea is a domestic service engineer, an ordinary guy cheesed off with one or two holes off center like the second hole which went slightly off center on you. They make two types, one for 0-2 inch depth and the other 2-4 inch depth. The estimate is 250 shots of chalk per tin, unless the kids get to it. They are quite inexpensive, I used it last week to put a tiny latch on a cabinet. I got 4 little green dots all aligned and no farting about hoping the pilot drill will get you sorted. You will find it on amazon uk but I haven't seen it on amazon.com. Its also shown on youtube, on "The Dragons Den" an enterprise program on TV over here. Love the videos , keep them coming ; its never a good day unless you have learned something new!

[@Nomadboatbuilding]

That’s an interesting product. I'll keep my eyes peeled for it.

[@robertrowse1028]

A good cheat on the full size is to use a biscuit jointer from the frame to the keel. Obviously you have spare material on the back rabbit , but is does put you in the ball park and give you the correct angle at each frame. I have never tried it on small craft, but on 10m and above it worked rather well

[@Nomadboatbuilding]

That’s a really interesting idea Robert. I’ll keep that in mind.

[@andreattazanella]

Dear Mark, excellent video as usual! Please, how do you determine the position of the apex line? Thanks, mate!

[@Nomadboatbuilding]

That is usually figured out in the lofting stage by working out cross sections of the stem and subtracting plank thicknesses from the outer surface of your lines. The plank ends are assumed to 90 degree cuts so you project that angle back from the rabbet line in those cross sections and your plank thickness determines where on that projection the apex or back rabbet lies. You can do it without the lofting right on the work if you have the bearding line as well as the rabbet. This very hard to describe in words that make any sense. Read the pinned comment. The writer describes the process fairly well.

[@andreattazanella]

@@Nomadboatbuilding that's perfect! Thank you so much! All the best!

[@andreattazanella]

Valeu!

[@Nomadboatbuilding]

Many thanks.

[@Starboatbuilder]

Hi : good description but it looks a lot of work; my technique is just screw ( with glue) the planks to a stem and then glue a pointed end stem to that, ( probably the reason is I only have dull chisels). But, may try the idea. What is the time table for the Catalina skiff? Will it be the same format as the 2.4M ? Totally looking towards the next build

[@Nomadboatbuilding]

I call the technique you describe as an applied cutwater. I use it often but in traditional construction we often find a chopped rabbet and so it's good to know how to approach such a construction problem. I plan to start the Catalina wherry videos after I wrap up the Bouchie dory series. Probably somewhere early in the new year. It won't be the same as the 2.4 series. I'll have an emphasis on some different concepts. It will be a little more self critical, looking at good and maybe bad ideas for productivity.

[@Starboatbuilder]

Whoops ; trust you are dry with all this rain

[@Nomadboatbuilding]

barely

[@MikeAG333]

Fun little video, Mark. I need to pull you up on your units of measure, though. "A hair" is just not good enough. The standard units of measurement are a gnat's c*ck, a double decker bus, a blue whale, a swimming pool, a tennis court, and Wales. Obviously the one which applies to model boat building is gnat genetalia, but if you are describing how much rainforest is felled in a certain period of time, for instance, then "an area the size of Wales" comes into its own. Now, do try to stick with these official units, there's a good chap.

[@Nomadboatbuilding]

My bad Mike. I'll check my units conversion chart in the future.