Floorboards, Pt.1

Where to start?

I have a whole lot more to go in this build but at least to date this has been the most challenging piece by a long shot. According to other blogs, I’m not alone.

Part of the difficulty is simply discerning what the goal is, much less how to accomplish it. As the manual says, this is indeed a ‘project in itself.’

So What is the Goal?

In my mind, the big question here is…where the floorboards meet the hull bottoms, how flush do the boards need to be to the hull? Or more precisely, how flush do you WANT them to be??

With very little effort you could rough cut some boards, screw ’em down and use a batten to scribe and cut a nice curve. But there’s no telling what the gap between the boards and the hull bottoms will look like. It’ll likely be really wide in some places and narrow in others. Do you care? Maybe not. If not…lucky you. Throw ’em down and keep trucking.

For those who do care, the questions then become: Do I care if the gap is large or small? Do I care if the gap is uniform from fore to aft? Those are simply preferences of degree. Either way, you’ve got some figuring to do.

Here is what I decided my goal was…to have a uniform gap from fore to aft and for that gap to be no larger than 1/4″. I figure having a gap at all is good since if you were to get water in the cabin (maybe from an open porthole) it couldn’t run down the side and pool where the floorboards meet the hull. But I wouldn’t want the gap so large that I could easily lose small items into the bilge. 1/4″ seems reasonable.

So What’s the Problem?

At some point you’re going to have to affix a batten so you can scribe a nice fair curve. The boards have to be laying pretty flat to do that. So you have to do some cutting. But…if you’re going to be particular about the width and uniformity of that gap between the board edges and the hull, you should probably be real conservative with how much you cut off before you actually see them in a dry fit. With several different dimensional planes at play here, it’s unlikely you can get to your final cuts in one fell swoop.

My method was to go very slow and make a series of incremental cuts and bevels.

Start laying down boards and you’ll get the picture.

So How Is It Done?

I’ll tell you how I did it. It’s certainly not the only way and there are likely better ways. This is what I came up with only after a lot of time staring into the hull, ciphering, and kicking ideas around with some buddies. Many thanks to Gil, Michael, and Harvey.

Step 1: Ensure you have enough board length

First of all, I simply laid down the 16 floor boards that came in my kit to see what I was dealing with. It was immediately obvious that some of the lengths were too short if I wanted a gap no wider than 1/4″. I’ve heard complaints of short boards from other builders as well. The kit boards come in pre-cut lengths. I wish they would have simply sent all full-length boards (~103.375″). If you’re reading this and plan on ordering a kit you may try requesting that. Having them pre-cut by CLC doesn’t get you anything.

You can see from the picture below that there is no way to cut a fair curve that would yield a gap no larger than 1/4″ with the board lengths sent in the kit…

I know that’s a straight line, not a curve, but you get the point. The boards are too short. And this pic doesn’t illustrate that I have also laid these out with nails in between the boards to account for the space the gaps between boards contribute. Doesn’t matter, the boards are still too short.

I needed longer boards. All it would take is 2 longer boards on each side. That would ‘push’ all the short boards out where they would then be long enough to fill in the big gaps. Pic above shows ‘big’ gaps.

My local box store does have some nice oak boards. So I bought four (two for each side) and that easily gave me enough coverage. In fact, too much. I would need to reduce the width of all the boards. And in addition to that, I even discarded the outermost kit board (the shortest one) altogether. If your eyes haven’t glazed over at this point, you’ll notice I now have 9 floorboards for each side of the centerboard trunk. Seven are original kit boards and two are new oak boards.

Step 2: Determine width of boards

The widest part of the sole will be at Floor #4. So the boards will have to cover from the trunk at least to the end of Floor 4. In my boat, that distance is 22″. I’m going to increase that a tad to give myself some slop and to account for the fact I’ll want to bevel the underside just a little so the edges of the board aren’t totally vertical. This is aesthetic only. So let’s add a half-inch and call it 22.5″ out. That’s distance out from the trunk. If I’m wanting total width of all my boards (which I do) I need to add in the part of Board #1 that wraps around the trunk. Half the trunk width is 3/4″. Those two dimensions total 23.375″. See graphic below…

Note the slight bevel on the outermost board. I think this bevel is what will allow me to better control the uniformity of the gap, fore to aft. And I like the look better than a full side face of board.

With 9 boards I’ll need to subtract out 8 gaps of 1/8″ between each board. That gives me 22.375″ of total board width. Divided by 9 boards gives me 2.49″.

I called that 2.5″ and then ripped all of my floorboards down to a width of 2.5″

Ripping all the boards based on a calculated total board width also ensures my outermost board will be as wide as all the other boards. Some builders have bemoaned that usually that outermost board winds up pretty narrow compared to the others. Some care, some don’t.

That was a lot. I’d be surprised if anyone is still reading.


Time to start making some rough cuts and getting the boards to lay flat enough to put down a batten.

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