Friday, February 2, 2007

First float half

This post will cover my observations on planking my first float half. This is written from memory, about six weeks after the fact.

Ian has commented on how long it should take to to plank a float: it should be done in about two hours. I wish either that I could do it that fast or perhaps the truth is that I wish I had the guts to do it that fast. I didn't do my first float half in two hours -- maybe 6-8 hours, but I was going slow. A couple parts of the process I found semi-frustrating, I'll detail those as I go. I do think I'll be a lot closer to two hours next time. It is definitely not rocket-science. And always remember, "you're not building furniture".

First thing was to mount the keel strip, easy enough:

I then cut a bunch of plank blanks on my table saw at about 8" wide (and ~48" long, because that was the length of my offcuts). The initial procedure was then:

  • Hold the blank in place, flat end against the deck mold piece, pushed down as close to the battens as possible, and make a mark about where the blank should be cut to fit against the keel strip.
  • Go cut the blank at the mark.
  • Push the blank into the float mold, and re-trim the keel cut as necessary. At this point I was only aiming for the keel cut to be "close enough", or maybe just a shade too long.
  • Take the heat gun and use it to heat up the plank while molding it against the battens. Outside temperature was about 35-45 degrees F, so conditions weren't the best and the corecell was slow to heat up and mold. I didn't time myself, but if memory serves I was spending at least 8-10 minutes on each plank.
  • Once the plank was reasonable curved into the right shape, I would then turn my attention to the keel cut. The plank foam is supposed to meet the keel foam at the angle given it from the battens; it's your job to miter that join so that the two foam pieces meet evenly. I may have been too anal about this, but it was certainly the most frustrating part for me. Kinda hard to use any kind of precision mitering tool (at least I couldn't think of a way, and precision isn't really called for), so I ended up just using a RO sander: I'd eyeball the joint, then sand down the keel end of the plank to about where I think it should be. Test-fit, then repeat as needed. On a couple of planks, too-much sanding\mitering resulted in the planks no longer meeting the the keel foam at all; these I re-did and saved the blank for a shorter section of the float half.
  • Once a plank was as good as I could get it, I took a cordless drill and drilled two screw holes through each batten so that each hole was an inch from the sides of the plank. This goes fast.
  • Then I would grab a handful of screws and get one started in each of the holes from underneath the float. Then it was just a matter of holding the plank down with one hand from above, and running the screws up and in to the foam with the cordless drill from beneath. At first I was using temporary clamps on the foam, but quickly discarded that step. The F22 float planks are short enough and narrow enough that you can do the job by hand.
  • I was not edge-glueing as I went. For now I've butted all of the edges together, and will cut a groove later on between them.
  • Things to look out for: 1) don't try to squeeze a slightly-too long plank into the mold; when I did this, it would push against and sometimes distort the keel foam; 2) make sure your screws have adequate holding power. The screws I have been using do not penetrate the foam very far and I sometimes had problems with foam under tension pulling out from the screw, unless I had adequately heat-formed it into place; 3) consider planking the float without the deck mold plate in place (see Ed's site for example) and just cut it to fit after all planks are in. I will do this on my other float halfs.

Here's a picture at the beginning of the job:

And somewhere in the middle:

(I seem to be missing a shot of the fully planked float half, will add one to this post later.)

Other float-related things I've done already are 1) make the chainplates (haven't cut it into two yet); 2) vacuum bag all float bulkheads, plus transoms; 3) make up all 4 stringers, and 4) cut enough 3/4" x 3/4" deck support angle pieces for all four float halves. So there's a big pile of stuff ready to go.


Anonymous said...

Hello Jay, nice site!

I agree on your frustrations on the planking when it comes to fitting the planks to the keelplank.

What I did from half #2 was i plank without the keelplank in, then you can be quite rough on the keel end cutting. Then leading a sharp knife with a 10mm spacer (piece of foam) between it and the keel batten to make a clean cut along the whole hull.

Then just slip the keel plank in place and screw. Works well for me at least.

F-22 #11 in Norway

Jay said...

Thanks Tor. Yes, I am planning on doing that for the next one. It will be much easier I'm sure. :)