KVARK – the homebuilt microcruiser

Breaking the rules of posting a post without pictures, but not only that. I was down at the build today. One of our gunwale stringers has snapped during pre-bending. Again, at the knot. The hunt is on for knot free wood. The slightly ripped bulkhead is now very solid, with two additional layers of plywood at the weak spot, a roughly 4 cm laminate. We will do some CAD analysis and design the forward bulkhead based on the results. I now own a white X-Files style white “bio suit”, which is basically an overall for keeping away nasty fine glass-epoxy dust. I was sanding away with a Dremel at a sloppy glassed fillet, feeling irritation on my arms. Later it felt like I had sanded my arms instead. Hence the upgraded protection for future work.

Our stem redesign is proving to be not as effortless as initially believed. Since we can’t go to the workshop on the weekend I spent some time building a CAD model in Solidworks of what we’re trying to do. Kind of an overkill, sure, but it never hurts to think more before cutting. We will need to adjust the forward bulkhead so that the top stringers run nicely.

As a side note – anybody have any tips on where to get relatively knot-free timber for stringers?

Another productive day at the workshop. We started dry-fitting the stringers to see how the forward stem is going to look like. Bending the 2×4 cm pine stringers was made much easier by pre-bending them, but the ideal stringer should have very few knots. We have some 3-4 smaller knots on the 5 m stringer, and that seems to be pretty much the limit.

A side view of the boat with two of the top stringers in place.

Probably we might have to hit the lumber yard once again to get some extra stringers to replace the bad ones. So far we’ve managed to bend two of them to place on either side.

The stringer is bent using two chairs and a tire.

The bulkheads are holding together quite nicely, but we were fortunate enough to discover a hidden weakness in the central, hollow bulkhead. While stress-testing it (read: sitting on it while it is being pulled apart by 4 stringers) developed a miniature, 1 cm by 1 mm crack on the thinnest part of the bulkhead. Turns out the stringers are pulling the central bulkhed apart.

The crack from the floor's side.

Fortunately we can now exploit this discovery to make the bulkhead stronger. We took the central bulkhead and will rebuild it a bit. Once that is done, we’ll finish dry-fitting the stringers. Then we can lay down the forward plywood stem. There is lots of work to be done, but there is nothing better than lots of work. One of the great things about building the boat is that you can never go backwards. Every screw you put in is a step forward.

The ships skeleton