Sunday, September 30, 2007

Transom taped

Today I only got a few things done: taped underside of cockpit floor to aft cabin bulkhead join, placed and taped the transom (I did get it bagged last night), and spent a lot of time trial-fitting the aft cabin bunktop.

The transom is interesting because the plans specify that it be canted 5 degrees forward, instead of just in parallel with the form frame. To accomplish this, I clamped a batten parallel to the edge of the form frame, and dropped the plumb bob down from the end of it, hanging over the hull. By measuring how far the plumb bob was from the angle point, I could use the Law of Cosines to determine far the point under the plumb bob had to move, in order to rotate the batten onto a 5 degree angle. Here's a picture of the setup:

This was taken after the batten was rotated from right to left and is already in the final position for the transom. There's probably easier ways to accomplish this placement, but this seemed to work out okay. Then it was taping time:

I didn't know about or even remember the Law of Cosines -- I was just pretty sure there'd be some piece of trig magic that would work, but it took about fifteen minutes of hunting around on Wikipedia to to finally find it. :-)

Also, you can see that I've left the transom full-width, rather than cut it down the middle. I wish I could do that with all the bulkheads -- frankly I'm not looking forward to making the bulkheads match up, during hull join.

After the transom, I worked on trial-fitting the aft cabin bunktop. This took awhile because for some unknown reason, the bunktop center line was higher than the hull center line by about 1/2" - another unexplained mystery:

After more fitting I trimmed the center line down and I think it's just about ready for taping:

I also already routed the fwd edge of the main cabin bulkhead where it meets the bunktop, so there's a nice gentle curve there.

Saturday, September 29, 2007

More port bulkhead taping, part 2

Since last post, I've continued work on taping port hull bulkheads. Here are some pictures to show the progress.

Aft cabin stern upper bulkhead:

Cockpit floor:

I used a router to put a nice curve on the bottom leading edge of the cockpit floor, you can kinda see it in the picture above.

Yesterday I taped in the fwd bunktop. Unfortunately, I started the job off with an Oaf Moment (tm): I placed the bunktop in position, slid my jigs against it but didn't clamp them down, climbed into the hull (this was fun, squeezing between the jigs), and started bogging and filleting the long outer edge against the outer hull. Did around five feet of fillet before running out of bog, started climbing out of the hull, and ... kicked the damn bunktop with my foot, knocking it out of position and ruining the entire fillet. Lesson learned: always clamp bulkheads in place before starting to fillet - don't just trust to "I'll be careful".

Here's some shots midway thru the bunktop taping:


See the handle of the blue scissors in the picture above, off to the left? I use them for trimming wetted-out pieces of tape, that end up too long. They were once a very nice pair of scissors, now they're gunked up beyond belief.

Here's the area between the rear bunktop bulkhead and the fwd beam bulkhead; this was a tight area, and I'm proud of how it turned out:

Not that anyone will ever see it again, after the hull halves are joined. :-)

Fitting in a strip of foam to fix the gap up by the bow:

And now all taped over:

This was taken today, as I was inspecting the tape job:

Here I'm contemplating how I'm gonna tape the inside bottom of the aft cabin front bulkhead (it feels mighty roomy in there!):

The outside of the aft cabin front bulkhead:

Here's the inside:

You can see that I haven't yet taped the edge next to the cockpit floor; this is because they didn't quite line up perfectly (don't ask me why - stuff happens), and so I am going to wait for the other tapes to cure so I can neatly trim it before taping it.

Finally, here's the little aft cabin bunktop support bulkhead:

I was disappointed to discover that my bulkhead collection in the basement did not contain a ready-to-go I've got a foam blank (with the h/d insert) curing for that now, and might try to vacuum bag it tonight before bed. I did have the stern deck pieces done from earlier this year though. Tomorrow I'll also try to get the cabin settee flange done -- I'm not going to glue the settee in place until after the hulls are joined, since I have a suspicion that I'll be needing the extra manuevering room.

Well, that's enough boat stuff for now -- we're off for some pizza.

Tuesday, September 25, 2007

Trial fitting more bulkheads

Been having fun getting more bulkheads ready to tape, and I thought the trial-fit details might be useful. I've been working the last couple evenings on the fwd bunktop, cockpit floor, and the aft cabin stern upper bulkhead, and I think they are about ready for taping.

Here's an aft view of the fwd bunktop being dry-fitted:

The fit from that view looks great IMO. However, I did somehow end up with a screwup near the bow:

Seeing this was quite depressing -- where did I make a mistake? Bow battens? Bunktop cutout? Who knows? So I fired an email off to Ian describing the situation and he sent the following reply which I thought was worth sharing:

[This is] not unusual, as it is very hard to always have a good fit, and particularly in bows which are hard to draw on the computer. Just fill in gap with a foamstrip or bog and tape over. These are not unusual problems in boat building particularly with hulls - it is not a precise science yet.

That made me feel somewhat better -- just have to keep moving along.

Here's one more bunktop dry-fit view:

The cabin settee has to wait for the fwd bunktop to be taped, so I moved next to the cockpit floor. After some very minor trimming to get everything squared up and vertical, it was looking like this:



It's hard to tell from these pictures, but when I sighted along the bunktop and the cockpit floor, they looked nice and parallel, as they should be.

Finally, here is the aft cabin stern upper bulkhead:

And from the other side:

Some of these arrangements could benefit from more positive retention, but I think they will be okay as long as I'm gentle while taping (once you've got them bogged and filleted into place, they tend to stay put). After they're taped in place and the jigs are removed, I'll re-check them all with the level and see how good a job I've done.

Tip: if you have a straight bulkhead horizontal or vertical edge that just needs trimming by a half degree or so to be true, a flat sanding block works great - more control than the electric sander.

Finally, since the weather is getting colder lately, especially at night, I've moved all of my epoxy resins into the Great Carpeted Hot Box (aka my office). This makes my office a bit cramped, but I've lost more resin in the past than I want to admit, to excessive crystallization. (Yeah I've used the hot water bath trick before but the crystals always seem prone to reappearing, once they've shown up.)

Sunday, September 23, 2007

More port bulkhead taping

I made good progress today, spending about ten hours outside in the tent working on bulkheads -- got the fwd beam bulkhead, both front bunk bulkheads, the main cabin bulkhead, and the aft cabin stern bulkhead, all taped in. And my aft beam bulkhead from yesterday turned out great - finished curing in perfect alignment.

First was the fwd beam bulkhead. Here's all the tapes for this bulkhead (both sides) ready to be cut out:

With the exception of the temporary ones, all tapes were cut double-bias. DB tape is a pain to work with (always wants to shrink in one direction, and elongate in the other). At first I tried carrying the wet tapes out to the tent as one long piece, but this doesn't work so well -- it's best to roll the tape up for transport, then unroll it as you place it over the fillet.

Here's the fwd beam bulkhead taped in place (except for the temporary tapes, I added those a bit later):

Fwd fwd bunk bulkhead (this gives you a good idea of my strategy for holding the bulkheads in place too):

Temporary tapes added to fwd beam bulkhead:

Like yesterday with the aft beam bulkhead, I hope that's enough "tacking".

This is the aft fwd bunk bulkhead, getting an initial bogging on its foam edge:

The bog in the picture above is supposed to be just enough to fill the space between the hull and the bulkhead. After positioning the bulkhead in place and clamping it down, I would then form fillets...

...and then lay down the tape:

The main cabin bulkhead was about the same as the others, but slightly more challenging due to its size (plus the fun of clambering into the hull over the deck side). When doing the fwd-side tapes, I brought my taping wet-out board into the tent to minimize the number of times I'd have to climb in and out of the hull:

Here is the fwd-side of the main cabin bulkhead after taping:

I did not apply tape to about 5" below the deck, nor above the bottom drain hole, to allow for minor adjustments when joining the hull halves later.

The last bulkhead for today was the aft cabin stern bulkhead; I won't show any more pictures of taping since it's all the same after awhile. Here's some pictures though, that show the hull is rapidly starting to fill up now with bulkheads:


Pretty cool, eh? Still a lot to do though, before I can even think about unscrewing this hull half and popping it out of the mold.

Saturday, September 22, 2007

Port aft beam bulkhead taped

Due to a late start today, progress was minimal.

I had some small work items to get done, before I could really get started taping in bulkheads. First thing to do, was tracing out the new beam mount cut-lines on the beam bulkheads. Ian sent this update back in April or so, but I never got around to updating my lines. I only had the PDF version of the new lines, but fortunately Kinko's can accurately print large documents - laser-printed, even - super cheaply.

Here I'm tracing out the new lines for the fwd beam bulkhead:

After finishing the tracing and cutting out the helper holes, it looked like this:

Similarily, the aft beam bulkheads looked like this:

It was interesting to compare the old trace-lines to the new ones -- the beam mounts obviously got much bigger!

After that, I got into the hull and sanded down all of my bubble patches, and all of the bulkhead mount lines. I now have essentially all of the hull interior laminate sanded down.

The last small work item was edge-filling the exposed foam edges on some of the bulkheads. I decided for now to only do the ones that for sure had to be done, or that would be very difficult to get to once the bulkhead was taped in.

I've read on other websites that sometimes builders will add chopped glass fibers to their bog when edge-filling, to give it some extra strength. I tried it today just for fun - but you can't over do it. My first filled edge looked like a shedding cat:

So I reduced the fiber ratio on the following mixes. Other than the bottom-most section of the fwd beam bulkheads, I also filled the access holes on the aft cabin aft bulkhead, and the drain holes at the bottom of the main cabin aft bulkhead, for both port and starboard bulkheads.

After that, since most of the bulkheads were set aside with curing edges, I decided to look at the aft beam bulkhead. The dry-fit was remarkably good, and the beam would even stand up on its own after being wedged in a bit:

This was pretty exciting, so although it was getting late I went ahead and taped it into place. I didn't have time to build a nice jig to hold it in place, so I went low-budget with a stick across the top to keep it from moving around, and also a screw through the hull into a batten, just in front of the bulkhead, to keep the bottom from moving around. I think it will be okay, but if you hear a scream from my vicinity in the morning, it's because it fell over in the middle of the night. :-) (if that does happen, I'll just grind it all out and start over)

Here's what it looks like:

The upper-most tape (two layers) are the ones that will actually stay in the boat; the two lower pieces are temporary, just to help the bulkhead hold the hull's shape. I hope this is sufficient enough for a "temporary tack" -- I didn't want to over do it.

If you have not yet seen the pictures of Oliver Dom's main hull yet, I would suggest taking a peek -- it turned out gorgeous. I was worried that the aft-cabin cockpit would turn out really small, but in the pictures it looks perfectly sufficient. I know that in the end it's still just a small, 22' boat, but those pictures sure make it look bigger than that. It's a nice shot of extra motivation to get my boat done.

Thursday, September 20, 2007

Power of the plumb bob

Just to get it out of the way: no, I have not yet taped in any bulkheads. But I have been busy preparing for it, and I wanted to post some details on how I'm doing it.

Doing this kind of work (bulkhead alignments) is when I realize what a crap job I'm doing: none of the bulkheads fit just right, and gaps are everywhere; this isn't new of course, over time I've started to figure out that the boat, when completed, will be a huge amalgamation of compromises and "split the difference" compensating errors. That said, don't let me discourage anyone else from building.

Before I get into the bulkhead details, I have a mea culpa. I've been reluctant to admit it here on the blog, but my lower hull half lamination did in the end suffer a bunch of bubbles (I didn't actually see them until the next day). It was a hot day when I did that work, although the temperature was fairly stable - still haven't pinned down the reason for it. So Tuesday night I sanded them all out and laminated a bunch of patches over the holes:

I have to admit that the devil in me kept saying "why bother patching them, it's just a few bubbles, they won't hurt nothin'" - but my better side finally won out. The good news, is that the lamination I did on the upper hull half turned out spectacular! Not a single bubble anywhere to be seen. As mentioned before, the differences were a) cooler temperature; b) pre-wetted the foam; and c) used Fast hardener. I can't always control the temperature, but I will definitely be pre-wetting the foam from now on.

For the bulkheads, I wish I could say that I was able to whip out a laser level and a protractor, do some mystical math tricks, and then line everything up with millimetric precision, but it never seems to work that way. So please don't laugh too hard, when you see my primitive methods.

Here I'm digging a hole in the side of the boat right over form frame #5, in order to expose the gunwale line (for aligning the fwd beam bulkhead):

Tip: don't mount the @#$*&! battens right over the gunwale reference on the form frame. And keep a sharp razor blade handy -- thick, cured laminate (due to the overlaps in this particular area) is tough to cut!

To locate the the fwd edge of the fwd beam bulkhead, I made the following alignment thingy (to call it a "jig" would be too grandiose):

The 3/8" ply, plus two popsicle sticks, makes exactly 1/2". Or close enough, anyhow. I then carefully mounted this utensil so that it poked up thru the hole I'd made above, aligned with the edge of the gunwale line:

And from the top:

The other reference point for the fwd beam bulkhead, is that the fwd bottom corner should be 9/16" in front of frame 5's fwd face. For that one, I decided to take the easy way out and drill a small hole from the outside of the mold, at the edge of the frame; I then marked a small line the appropriate distance in front of it:

Looking down, here's what the popsicle tool looks like:

After I had the above two reference points, it was then just a matter of jiggling and trimming, until I had the bulkhead reasonably aligned and vertical; I then marked it for later taping:

Now, let's all pray that I've got this thing aligned accurately enough. Count of three: 1, 2, 3 ... pray!

Now for the plumb bob part. I borrowed one of these from my neighbor (thanks Scott!); it's a big, heavy, yellow thing with a really sharp tip, looks a bit medieval in fact. I needed it so I could locate the aft edge of form frames in the middle of the hull, by hanging it from a straight edge (my level, in this case) that was aligned with the form frames at the keel and deck center line. E.g:

Once you have the frame aft edge marked somewhere in the middle, you can easily line up the bulkhead; the main cabin aft bulkhead turned out pretty good I thought:

However, here's that gap by the deck that I mentioned before; I have no clue how this showed up:

I'll just fill it in of course, and hope that the starboard side has the same problem so it lines up correctly. :-)

I have not yet marked the final location of the aft beam bulkhead; however I think I came up with a cool way to locate the aft edge of its form frame, by using a ladder to hold up the deck-side edge of the level, and locating the level (fwd and aft on the deck\ladder side) by dropping the plumb bob right at the frame's stub aft edge:

You got to admit, a plumb bob is a pretty cool tool!

Once I had it perfect, I clamped the level to the ladder (no-one better bump the ladder though - I had to shim up the legs with scraps of foam), and was then able to move the plumb bob back over the hull to locate the frame edge farther inwards. I didn't get around yet to digging a hole over the gunwale line, but I suspect I'll end up having to drill through a batten to expose it, just like I did with the fwd beam bulkhead.

Anyway, I hope this will give other builders a few ideas on how to locate these bulkheads (and I'm sure my techniques can be improved upon).