They fit last weekend, but now...

[Greg H]

They don't.

I cut out and fitted the floors to a Whillyboat (glued clinker) last weekend. After a week of high heat and humidity, they don't fit any more, a 1/4 inch gaps in some cases.
Should I:
1)Trim them to fit and glue them before anything changes.
2)Wait and see if they change back.
c) Start again.

The keel is white oak, floors are yellow pine (is this the problem?) Occume planks.
Thanks

[casem]

Are you talking about the floors or the floor boards? I guess you wouldn't be gluing the floorboards but I can't imagine expansion that would give you a 1/4" gap on those floors (unless you started out with a 3/16" gap!). All I can say is that when I did mine, once I got the floors to fit (which was tricky), I glued them and had no trouble since. I haven't noticed any problems due to expansion of the floorboards either, even though most of them are screwed to the floors (the others have turnbuttons).

[casem]

Or maybe you mean the gap between the top of the keelson and the bottom of the floors? That makes a little more sense because if the outboard ends of the floor expand a little, the gap might end up being alot (because of the angle). If that's the case, then I'd have to say I had the same problem, only to a lesser degree, probably because I was inside my garage the whole time. I'd get them all to fit perfect and then the next day I'd have gaps (maybe 1/16"). But when I glued, I was able to close up the gap no problem with screws (3 total on each floor; one in the middle and one on each end).

[Greg H]

Hi Casem, did you launch yet?
I was so happy to get them (floors) to fit, but I ran out of time and left them to sit for a week, planning to glue everything at one go. The 1/4 inch is more like a combined 1/8 " at either end. It's like they expanded in the molded dimension and lifted at the ends toward the center, after I relieved the upper edge by cutting the arc.

Next time they are going in one at a time. smile.gif

[Greg H]

The outboard ends contracted in this case. Did you put the screws at the ends in from the outside? I was just going to glue, but screws would hold things together hmmm.

[Don Maurer]

I had the same problem on my Tammie Norrie. I ended up trimming them as best I could and then epoxied them in place. They seemed to take an incredible amount of filled epoxy to bed them. I put a radiused fillet on the joint so the bad fit wasn't obvious.

[casem]

I put the screws in from the inside just because I didn't think of going from the outside. That way your plugs wouldn't be visible. I used screws for gluing whenever possible because with clamps and weights it is too hard to clean up excess epoxy. But now I've got bungs visible all throughout the boat (inside is varnished).

I launched my boat back in April. I've been meaning to post a picture but I need to find someone to lend me a digital camera.

[Art Read]

Well... I kinda LIKE the look of well done, varnished bungs! (As long as they're in "logical" places... A few of mine will have knowledgable folks scratching their heads... ;) )

[Jim H]

Greg, it is possible that you had a problem with compression wood, wood from a leaning tree. It's called compression wood in softwoods and reaction wood in hardwoods. The wood will deform after cut. I had this happen with some purpleheart.

Jim

[Greg H]

I guess it was frustration as much as anything. I've been checking them every day now to see if they change any more and they seem to be about the same. So I'm just going to fit and glue them one at a time. She'll be apples.

Casem, Do you love it?
You've got to post pictures, I need inspiration, I think Ian's time estimate is a bit off. :D Most of those film drop off places will put your photos on a disk for you.

[thechemist]

Originally posted by Greg H.:
They don't.

I cut out and fitted the floors to a Whillyboat (glued clinker) last weekend. After a week of high heat and humidity, they don't fit any more, a 1/4 inch gaps in some cases.
<snip>
ThanksThe expansion of wood with moisture content varies depending on whether it is plainsawn or quartersawn. Plainsawn, theoretically, is perfectly tangential. Quartersawn, theoretically, is purely radial. The derivation of "quartersawn" is that logs were once cut in quarters, and then the first plank or two cut off of each sawn side had the grain orientation mostly radial: Stronger, more dimensionally stable, but somewhat wasteful of wood. It is less expensive by almost a factor of ten to buy a fir 2 x 12 plainsawn from Home Depot versus a "vertical grain" piece from a more upscale lumber supplier.

Per the Wood Handbook from the Forest Products Laboratory, Yellow pine does not exist that I saw it. There is Southern pine, which consists of Longleaf , shortleaf, loblolly, and slash pines. Green-to-ovendry shrinkages for these [radial] are 5.1, 4.6, 4.8 and 5.4% respectively. Tangential shrinkages are 7.5, 7.7, 7.4 and 7.6% respectively.

Shrinkage of wood from green to the Fiber-Saturation Point [FSP] is negligible. FSP can be assumed to be roughly thirty percent. Shrinkage from FSP to ovendry is pretty linear.

Let us assume that your wood started at twenty percent and baked to nearly dry at five percent.

You would expect under conditions of losing fifteen percentage points of moisture to see half of the total shrinkage, which would range from roughly 2.5 to 3.8%, depending on grain orientation. Look at the end grain of your wood to get an idea of what angle the growth rings run, roughly, and measure plank width and tell me what the percent shrinkage was.

Wood does things like this.

Some varieties of wood are more-or-less stable than others, but they all do roughly the above. Lengthwise, dimensional stability is within one or two tenths of a percent.

You gonna build boats out of wood, you gotta expect it will do that sort of thing. People build boats out of wood rather than other more dimensionally stable materials because they WANT this sort of behavior. Sort of like why people choose to have a cat versus a dog for a pet, probably.