Fillets Fixed, Building Rudder

I retired Oct. 10 so am finding more time to get some work done on the boat.  I finished chiseling and sanding the bad fillets and have now covered them over with new fillets.

You may remember from my previous post that I had applied the fillets when it was too warm and I was unable to smooth them out before they set.  I chipped and sanded out the bad spots and re-covered the fillets--this is a huge improvement--not as good as some I have seen in other blogs, but they will serve the purpose of both strengthening the joint and allowing the fiberglass cloth, to be applied later, a smooth curve to bend around.

Yesterday I began building the rudder, which seems fairly simple, except that it is tapered from the front to the back, but not at the top where the tiller will slot in.

The rudder consists of two sheets of plywood with wood "blocking" separating them.  The wider blocking at the top of the picture is 3/4" thick; the bottom blocking (to the left) tapers from 3/4" at the front to 1/4" thick at the rear of the rudder.  The  vertical blocking is tapered from 3/8" to 1/4" all along its length.  The more complicated part is the "triangular" block, which has a compound taper from 1/4" to 3/4", so that it is supposed to be a full 3/4" thick all along the edge that butts to the wide blocking.  I was a little over-zealous with my sanding so the triangular block is a little too thin at the bottom edge.  So it does not make good contact with the plywood there, but only for less than 1/2", and I am filling the gap with thickened epoxy so I don't think it will cause a problem.

Here the blocks are glued and clamped (the wider block at the top was glued yesterday).

And here is a closer shot of the compound-taper area clamping on the triangular block.  You can see the gap, but again it is very narrow and I am going to fill it. The block is in full contact with the plywood from the less than 1/2" to the top.   I clamped blocks of wood on the outside top and bottom to keep the triangular blocking in place and help the plywood conform to the curve.  At the top right you can barely make out the slot where the tiller will fit.  Another sheet of plywood will be glued to the top after these parts cure.

A "Not So Fun" Job

In an earlier post I talked about the weather being relatively cool and deciding to do some filleting work, which was a disaster.  More about that later.  The fillets are thickened epoxy used to round or soften any corners in the hull so the fiberglass cloth has a smooth curve to bend around.  It will not adhere well at all to sharp corners.  These fillets have to be as smooth as possible, not only for appearances, but because any bumps or voids will leave a "bubble" under the fiberglass causing a weak spot.  Weak spots, especially in boat hulls that are going to be bouncing around on a trailer, can be disastrous.

On some of the fillets I was at least able to do the initial smoothing and today I chiseled away some of the roughest areas on those.  After filling in a few low areas I should be able to sand them smooth enough at this point.

A not too bad fillet with the worst areas chiseled off--ready for sanding

There were one or two particularly bad areas where the epoxy started hardening before I could even start to smooth it out.

Very bad fillet, most of which has been chiseled away

 It is hard to tell from the picture, but in this case I have chipped most of the fillet away.  It will be sanded and a new fillet put in its place.  I'll post the results when I am able to get the job done.

The way the fillets are supposed to be done is the thickened epoxy is laid in, then smoothed and sculpted with a flat, rounded stick to get it as close as possible to the finished shape.  Then any spills and excess material are cleaned up with a putty knife.   After an hour or two, depending on the temperature, the fillet has started to gel, but is still malleable.  At this point the final smoothing and shaping is done with a gloved finger dipped in alcohol.  This can be done very nicely if the temperature is anywhere between 60 and 77 or so degrees F.

According to the epoxy manufacturer's literature, at 77 degrees the pot life of their resin, using slow hardener, is 23 minutes.  That's how long you have to spread the epoxy before it becomes unworkable.  What they refer to as "thin film set," where the epoxy feels fully hardened but is not yet cured is 5 hours at 77 degrees.  Full cure at this temperature takes 5 days.  So, at that temperature it is best to wait about two hours before the final smoothing.

Again according to manufacturer literature, at 86 degrees the pot life is about 17 minutes, thin film set (TFS) occurs at about 3 hours, 45 minutes, and full cure takes 3.75 days.  At 95 degrees pot life is 11 1/2 minutes and TFS is at 2 1/2 hours.

So to me this means I should have had at least an hour to an hour and a half before the epoxy became unworkable.  That tuned out not to be the case.  As I said, most of the fillets from that "pot" only gave me time for initial smoothing and the last fillets didn't even give me time for that.  I would estimate the actual pot life at about 5 or 6 minutes and the TFS time at the end of pot life at about one more minute.  The temperature when I started the project was 85 and I don't think it climbed above 87 before I was finished.

So what went wrong?  One possibility is that I accidentally added too much hardener.  But according to the manufacturer, this does not make the epoxy cure any faster, but can make it weaker.  As I learned today when chipping away at it, it was definitely not any weaker!  So I don't think that was it.

One response to my previous post was that epoxy starts to become unpredictable above 80 or so degrees, meaning I guess I can't trust the literature completely.  So, one more lesson learned the hard way.  If I remember all these lessons my next boat will be perfect!

Gluing Up the Mast

It was finally cool enough (70s) this weekend to glue the mast together.

Here I am cleaning up some of the squeeze-out after epoxying three sides of the mast together.  I didn't get pictures, but there is a 32" piece of 2x2 inside the base of the mast and a 16" piece of 1x1 tapered to fit in the tip-top end of the mast.  A pivot will be inserted through the mast near the top end of the 32" piece so the mast can be lowered for trailering and storage.  Several pieces of hardware will be installed near the top and bottom of the mast, so the the 16- and 32-inch plugs will strengthen those areas for that purpose.

The fourth side has been added and glued in place.  I used every clamp I could find that was large enough to fit.  Even so, I'm not sure I used enough.  The instructions are not clear on this but I think you are supposed to glue all sides at the same time.  I didn't have nearly enough clamps for that, so glued three sides and the plugs yesterday and added side four today.

Odds and Ends

Sanding Bowsprit

Not a lot going on with the boat--too hot for epoxy work and there are tons of other outside jobs to keep up with during the summer.  I did find time to work on some of the spars.  Rounding over and sanding the gaff, then filling in tiny gaps where the two parts are glued together.  Then chamfering and rounding over on the bowsprit, and sanding both.

Sanding Bowsprit

Here I am sanding the bowsprit.  The gaff (spar that lifts the upper part of the sail) is lying beside it.  If you click on one of the photos it should become quite a bit larger and you can just make out some of the chamfering about a foot back from the small end.  All that means is that I have used a 45-degree router bit to bevel the corners.  This gives it a nicer look, but more importantly lowers the weight a little.  There are several parts of the boat where measures have been taken to lower the weight, especially higher up where there is more moment-arm.  Ballast is added at the very bottom and weight reduced higher up, so maybe the thing     will stay upright.

I hope to start again in earnest when the weather cools, and then devote much more time to it after I retire in October.  The plan is to get it on the water by sometime next summer.

Filleting and Gluing

It's Independence Day weekend and I'm trying to get a bit more done.  One thing that is working out really well is a new way of doing the filleting.  I've been trying to do it with "pastry bags" made from freezer bags, which might work really well standing at a bench, but not so good in this situation.  After filling a bag with thickened epoxy, I would have to clamber into the boat and get in some really contorted positions to get at the floor fillets.  The bag was flopping around and dropping epoxy here and there, and with the fatigue factor I was finding it really hard to get a good bead going.  

So I ordered some fillable caulking-gun tubes from West Marine.  This is much, much better.  I have a lot more control and it is nowhere near as tiring so I end up doing a better job.  Here's a photo:

West System Fillable Caulking Tubes

An unused tube is shown below the gun.  You fill it with thickened epoxy then put in the cap.  I found it is best to have the tube in place before pushing in the cap and installing the gun--quite a bit of epoxy is ejected while doing that.  Also I have a gun that has about a 6:1 mechanical advantage.  Even something like Gluezilla or Six-10 is extremely hard to push out with a standard gun.  This gun makes it very easy to do--just a lot more trigger pulls.

I'm also having to do a not-so-fun job and may as well get it over with.  The mast is made from four "staves" that form a very long (16 feet), square box.  Rabbets are cut along the length of two of the staves for the two others to fit into.  Well, I cut them 3/4" wide according to the plans, but what I did not realize is that the boards I bought are slightly less than 3/4" thick (a standard 1 x 4 is 3/4" thick, these turned out to be non-standard).  So, I am filling the rabbets with epoxied-in strips of wood.  When I get that done I'll cut the rabbets again to the proper width.

Gluing Wood Strips into Rabbets

Filleting and Glassing Bow and Cuddy

There is not much to report but Jan thinks I should keep people up-to-date.  Around May 18, I did some filleting in the bow area.

The fillets are pretty ugly--you have to practically stand on your head to get at the lower ones.  Some of the builders do a beautiful job in here although I don't know how they do it--I did the best I could.  This area will be filled with foam and never seen again so I'm not too concerned about appearances--mainly I need the fillets to be strong and provide smooth curves for the fiberglass cloth

Here I've added the fiberglass cloth and resin on May 20:

Looks pretty horrible.  Again, I did the best I could.  As I said it is very hard to reach and there are some tight compound curves for the cloth to conform to as much as possible. In the very bottom corner where I want to make sure there is a good seal, I poured in some more epoxy, approximately 1/2" deep.

Today (June 15), the weather was unseasonably cool.  It was about 77 degrees in the garage, so I decided to get some more filleting done in the "cuddy" area.

I was able to get the fillets smoothed out fairly well, although still having to get into some rather contorted positions to get to the lower fillets on the floor joists.  They don't look all that pretty, but the cloth should go on fine and they will be hidden under the floorboards.

I did the upper fillet to the port side back in early June when the garage was about 84 degrees.  I don't know why, but at the end you can't see in this photo the epoxy began curing much sooner than I expected.  I should have had about four hours before it set to the point I could no longer smooth it, but after waiting about one hour it had become way too hard.  So there will be a lot of sanding and grinding to do there.  I won't do any more of this kind of work until late September, unless we get some more very cool weather in the summer.  There are other things I can do in the meantime--e.g., more work on the spars, and I may start on the floorboards even though the cuddy filleting may not all be finished.

Odds and Ends

I haven't been doing much since the last post that was worthy of pictures--just gluing more seams, so that's why I haven't posted any new blogs for a while.  Also my wife and I just returned from a trip to L.A.

Today I removed the stitching wires from the bow stem end back to bulkhead 2.  Since there is so much pressure on the panels at that end I decided to fill the gaps that were left with more glue.  I will probably also put in the fillets and fiberglass before I climb into the boat to fillet the remaining joints.  Pictures will help clarify the filleting later.   From bulkhead 2 to the stern all that is needed is to pull the wires.  There is no need to fill in the gaps because there is plenty of glue between them, and most of the joints are more "vee" shaped, allowing more gluing surface.  Up near the bow, the joints are almost flat, so the only glue is a little between the panels and a thin film on the inside.  

Glued Seams in Locker

Above is a shot of the "locker" between bulkheads 1 & 2.  You can see part of bulkhead 2 on the right and bulkhead 1 (with the round hole) on the left.  Not much to see here, but if you look carefully you can see that the gaps for the stitching wires are no longer there.

After I get all the wires pulled the next step is to start adding "fillets" over all the seams.  This adds strength and allows the fiberglass cloth a smoother bend when it is applied.  The fillet material is made from epoxy thickened with wood flour and silica powder, and is applied with a "pastry bag" made from a freezer bag with a corner cut off.  (I will of course show all this later.)

Fillet Sticks

I also took time today to prepare the sticks that will be used as filleting tools.  The three on the left are some of the sticks supplied by Chesapeake with the kit and will be used for smoothing and shaping the fillets.  They are just flat pieces cut from marine plywood, but I have prepared them by beveling the working edges similarly to a chisel.  It's hard to see the bevels, but if you look closely you can see the individual plies where they have been beveled.  I also prepared the two "chisel sticks" on the right from thin strips of scrap wood.  The beveled ends are easier to see.  They will be used mostly for cleaning up excess fillet material on the edges.