Frame D’ — Building the Compression Gate

I’ve started working on frame D’ (also referred to as D1 in the CNC kit), one of the most important frames in the entire boat. This frame will carry the compression loads from the mast above, and it does so through a compression gate — essentially a strong beam supported by vertical posts and a solid wooden block at the bottom. This post covers the work done so far in preparing and assembling the components of that gate.

Compression gate

When I first studied the plans, along with photos and blog posts from other builders, I noticed some discrepancies, as different builds seemed to use slightly different configurations. I asked in the builders’ Facebook group and got mixed responses, with someone pointing out that the original plans themselves show two different versions: a generic compression gate on page 2 (bottom right), and a specific version integrated into frame D’ on page 4.

Frame D' - 60cm between the posts

Compression gate (page 2) - 72cm

To get a definitive answer, I went straight to the source and contacted Janusz. He clarified that page 2 shows a generic compression gate not tied to any particular frame, while page 4 presents frame D’ as both a bulkhead and a compression gate. This flexibility exists because the plans allow for different interior layouts.

Interestingly, the CNC kit appears to merge both concepts: it uses the bulkhead-style frame D’ from page 4, combined with the wider compression gate geometry from page 2. That wider spacing between the posts makes sense, as it allows for a larger hatch. I asked Janusz whether this hybrid configuration was acceptable, and he confirmed that it was. Unfortunately, this clarification came a bit late, and I had already cut some pine pieces based on the page 4 measurements — a small waste of material, but a valuable lesson.

I also asked Janusz about material choices. He explained that the beam and posts can be made from pine, while the floor block should ideally be oak or another recommended hardwood (I’ll cover that in a future post). Since I already had plenty of pine, I decided to use it for the beam and posts — which meant laminating multiple boards to reach the required dimensions.

The method I settled on was straightforward but required discipline. First, I cut the required number of boards to approximate size, deliberately leaving generous extra material — as much as 1 to 2 cm in both width and thickness. For the beam, I used seven boards; for each post, three. This excess is crucial, because laminated pieces almost never come out perfectly aligned, and you need material to remove later.

Thickened epoxy on half the pieces

Flip and place the other half on top, repeat

For the glue-up, I prepared two containers: one with unthickened epoxy and another with thickened epoxy. I laid all the boards side by side and coated them with unthickened epoxy. Then I applied thickened epoxy to half of the pieces, flipped the remaining boards over them, and pressed each pair together. Repeating this process quickly stacked the entire laminate. After carefully aligning everything, I clamped the pieces until I got a healthy squeeze
of glue — firm, but not excessive — and left them to cure.

Clamp and leave to cure

The next day, everything was solidly glued, but the beam wasn’t perfect. The pieces had slid slightly during clamping, and the beam was visibly crooked — it wouldn’t sit flat on the table. Thankfully, I had left enough extra material to fix this.

Jointer planer - flattening the bottom

With help from the yard staff, we ran the beam and posts through the jointer planer to flatten one reference face. After that, a few passes through the thickness planer brought everything down to the exact dimensions required. The result was excellent — the laminated pieces looked and felt like single, solid timbers.

Thickness planer - trim thickness to exact measurements

None of this would have been possible without leaving excess material. I can’t stress this enough. The yard owner told me they typically leave 1 to 2 cm extra when laminating pieces for exactly this reason. This episode also reinforced how valuable it is to be building in a boat yard: experienced people, proper machines, and practical advice make all the difference. Doing this alone in a garage simply wouldn’t be the same.

Very good results

With the beam and posts now dimensioned, I trimmed them to final length on the table saw. All the individual components for the compression gate are ready — but assembling them into frame D’ will be the topic of the next post.

Last step - adjust length