Sailing is Fun, But is Heeling Fun?

My theory on why some people love their monohulls is that speed is fun, and if you have grown up on monohulls speed is associated with heeling.  The only catamaran sailing I've done has been on beach cats.  A few times I've had nice windy days where I got to drop off the kids and get some actual speed (between them all their weight adds up), I didn't miss heeling one bit.  Since I'm on the subject of heeling, here is a picture of me and the kids heeling over a J-70 on a breezy afternoon.

A Plan Made in Haste.....

I cleared my boat stuff out of my boat shed to make room for my son's birthday party (see "Boat-Life Balance" 9/21/15). I thought I if I gathered the materials I could work on rudders in the garage until I get my boat shed back. I was wrong. I forgot to account for where all the boat materials would be stored.

As you can see I won't be doing anything in there in the near future. One good thing that did come from this is that I did think through how to make the rudders and I will still do that next. Somewhat simultaneously with setting up the level frame on which to build the first Ama.

Found Alaskan Yellow Cedar for Rudder Spars

So I'm in gather materials mode for the rudders. The rudder drawings call for spruce for the rudder spars, but the only spruce I could find near the house was a bit too thin 3/4 inch instead of 20mm. So I drove across town and found Sitka Spruce that would work, but for the same price they also had Alaskan Yellow Cedar. So I went with the AYC. Its really amazing how much this lumber does not weigh.

Next problem will be how to cut very accurately. Thinking I will rough cut it on the table saw and then work it down to size with a power planer.

Paper Scaling Vs Trig

So I used the scale printout for the rudder section to find the half angle for the rudder construction jig. At first I just took measurements and used trigonometry to find the angle. I got 31.6 degrees. I then laid out an extension line on the printout and measured it on paper with a protractor. Fully expecting my trig to be verified. It wasn't. By laying it out on paper I got 34 degrees. Then I looked at my measurements again and realized that very small difference in what you read off the scale make a huge differences in the angle calculated.  So I printed out a scaled up version and repeated, this time I calculated an angle of 32.6 and measured 33. I'm going to go with 33.

Using Draftsight for Templates (Scaling)

So Bernd's instructions for rudder construction call for you to print out the drawing at 1:1 scale and use that to find some dimensions.  Having had no end of problems with this sort of thing in the past I was all set to send this to a print shop and deal with the hassle of having to go out to pick up the paper. For giggles I tried to print it out at home. Sure enough I measured the rudder as printed at 17cm when it should have been 22. But as I was poking around the print interface in Draftsight I noticed the print scale is in the form of a ratio. So I plugged in 22:17 as the ratio and it came out perfect.  Not a huge deal but it saved me some hassle.

Why I chose a DUO 660

Start with the understanding that there is no better all around boat. Certain boats may be better for certain uses, so the place to begin in choosing a boat design is to be honest about how you intend to use the boat. Not so easy since sailing for me is aspirational and spiritual so how can more not be better.

So here are my considerations:
My family likes boats if they can jump in the water and play. They will tolerate me simply enjoying to relative silence and peace for awhile (not long).
We like to go crabbing in the summer, but don't like hauling the inflatable and rowing to the crabbing grounds.
Puget Sound is always cold to the touch.
My wife is prone to seasickness, although she is getting better.
I harbor a deep and abiding animosity for convention.
We still have to pay for three college educations so the bank must not be broken
Need to carry the family and hopefully a guest (6 persons although many are small)

So going from considerations to requirements I came up with the following:
Seasickness: Means it needs to either be a catamaran or a trimaran.
Capacity: Trimarans are not much better than monos for people carrying so it pretty much needs to be a catamaran.
$:Besides the build cost the truly scary cost to consider is moorage. In Seattle the sailing season is relatively short. So to avoid paying for moorage in the winter, the boat must be trailerable. That way I can store it either in the driveway or in a much less costly storage yard.
$: Building the boat myself saves money in two ways. First the labor is "free" but also commercially available catamarans seem to be either not trailerable or beach cats. It seems the only way to get the boat I want in the first place is to build it.  Also building myself also has the benefit of spreading the cost over time.
Convention: I really like the bi-plane rig. It puts the structural loads in the place that makes the most sense and is apparently easy to sail with no jib to mess around with when turning.  Ease of sailing is also of great benefit when sailing with only mildly alert kids.

Going from requirements to design selection:
I tried to treat the bi-plane rig as a bonus rather than a requirement since that would have severely limited the choices. Actually it came down to selecting either a Richard Woods or Bernd Kohler design.  I chose Bernd for a few reasons; his designs seemed to weight ease of build more than the Woods designs, he has an easy to detect reputation for after sale support of his designs, and his designs are more unconventional. He has Gunther, Biplane and even "A" frame mast rigs in his stable. With Bernd I could get the right sized, trailerable, easier to build, Bi-plane rigged catamaran and get awesome support.

Other notes:
The 660 uses anti-vortex panels instead of a centerboard or daggerboard.  I read Bernd's paper on them and everything I could find online.  The physics make sense and I think the trade off is that you are accepting a bit more wetted surface area (vs board up) for alot more simplicity. Given that this light catamaran should already be plenty fast I think it is a good trade.

Biplane rig. The reason this is so cool (besides the  easier structure on the boat) is that it allows for a lower heeling moment on the boat for the same sail area.  Basically more of the force on your sails can be put to work propelling the boat instead of tipping it over.

Radical Bay: Schionning Designs of Australia has a Biplane Rig design. While I like the thing I think there are issues. It is too beamy, its been thousands of years of testing that has shown a 2:1 length to beam ratio works for a sea-kindly catamaran.  Not sure why they chucked that out the window.  That is my main complaint, as for my build it is too long for me to build at home and uses strip plank construction. Stip planking while not impossible, is more difficult than I want to deal with now.

So here is a picture of what the finished catamaran should look like. This is taken from Bernd Kohler's website: http://www.ikarus342000.com/CATpage.htm .  His site has many designs for various needs.

Slow Down for Rudder Preparation

So I haven't posted lately because I've been studying rudder drawings and trying to strategize how I'm going to approach the build.  After a couple of days of flipping back and forth with the rudder drawings, rudder construction instructions and rudder pictures on the k-designs Yahoo group. I think a have a good handle on what needs to happen. I have an e-mail out to Bernd for a few clarifications but I'm feeling good enough to start buying materials and tools (finally going to get that planer).

Transom, and a lesson on how not to do this

So in an earlier post I talked about needing a way forward on how to cut stringer relief on the transom superstructure.  I thought I could just cut the superstructure away where needed and leave the exposed side of the transom unscathed. I was wrong. Since the chine and deck stingers have edges that stay within one piece of the superstructure, I would have had to either mill inside corners or cut away more than needed and then put back some extra pieces.  So as usual when confronted with an either or proposition, I chose both. For the stringers where I could do a clean(ish) cut, I cut way the superstructure. Where I could not do this I cut through the transom. Like this:

Note that I used clamps instead of the polymer brads, since I'm still trying to keep the outer face of the transom as clean as possible. Here is another look showing the cut away for the stringer and the cut through for the deck stringer (shear).

I am concerned that seating the end of the stringer in its relief and flush against the inside face of the transom will be tricky. Since the stringer will be "moving" both laterally and vertically from BH6.  I think I'll just be ready to cut several test parts on the compound miter saw until I match the angle.

Boat-Life Balance

So I'm going to have to change plans a bit. I was hoping to set up the bulkheads so it could start to look like something, except my son is turning 7. See the connection? We will have a birthday party for him here at the house. We have a small house. So my boat shed will temporarily become a kids party play area. So no setting up the ama until after the party. Since I no longer know how to live without working on my boat, I'm going to see if I can fit working on rudders in the garage until the party is over. Space is tighter in there but should be enough for rudder work.  Can't sleep tonight so I will be going over Bernd's instructions on rudder construction instead.

Another Day, Another Bulkead

I'm getting close to being done with bulkheads now, finished cutting BH6. It still needs some epoxy coat in a couple of areas but I'll do that when BH7 is ready as well.

Bulkhead 5 Done

Two more to go!

Bulkhead Needs to Survive Build Process

I finished Bulkhead 4 yesterday and ran into a potential issue. On Sept. 1st I wrote a post about alignment holes. The discussion was that some of the alignment holes would be drilled in areas of some bulkheads that would theoretically not be there if the center cutout of the bulkhead were made prior to setting up the ama.  The outcome of that discussion on the k designs group was to drill the alignment holes but then only partially cut out the center cutouts. That way the material is still there to do the alignment but also make it easier to complete the center cutout when access is restricted. Seems reasonable right?

But then it turns out if you do this with any aggressiveness at all on BH4 you will be left with the entire bulkhead being supported by only tiny sections of thin plywood. I think you would break it in anything other than very careful handling.  Hopefully some pictures help. Here is the entire bulkhead.

Here is where the section of remaining bulkhead gets really thin.

As you can see I stopped the cut well short of where the center cutout comes close to the relief for the stinger. I ended up making 5 short cutouts being careful to stay well away from where the center cut out gets close to the stringers. Here is one more pic of how I started these cuts with a drill and a jig saw.

I'm a bit worried about access to finish these cuts when the time comes, But I would rather be worried about that, than a broken bulkhead.

Bulkhead 3 "The Magic Bulkhead" Cut Today

I got another bulkhead cut out today. I'm getting the routine down now.

1. Find the next bulkhead and remember what I was doing.
2. Re-check the dimensions for the chine and stringer cut outs
3. Cut out with jig-saw and check fit.
4. Prepare things for epoxy coat.
5. Epoxy coat.
6. Take picture.
7. Write blog post.

So here is the picture of BH3 all cutout and with epoxy applied.

This is the magic bulkhead. This is where the keel goes from forming an outside part of the boat to becoming an inside structural only piece.  My plan for this is to build the keel out of 6mm and 9mm sheets and then step the 6mm sheet from the bottom of the 9mm sheet to the top to make room for the 6mm bottom planking.  I had hoped that by doing it this way I could have a clean transition that was all done at bulkhead 3. The only hitch is that as you can see above the bottom the bulkhead still has a marked, if gentle, V shape.  I tried to bend 6mm sheet around it and it didn't look promising.  As usual Bernd was right. He said I would need a filler piece.  So now I think the bottom planking from BH4 to BH3 will have a U shape so I can get the tops of the Us flush onto the bottom of BH3, I will still step the Keel as above but will add a filler to fill the relief in the U shape.  I know this is wordy but hopefully will make sense when I have some pictures.

Back in Action

Its been awhile since I could break away to work on the boat. I got a couple of hours in today and am happy with the results, but also have a mystery to think about. I did the cut-outs on bulkhead 2 including the cutout for the keel. See Below.

I have some scrap pieces of stringers and chine that I'm using to test fit as I go. Below is admittedly one of the better fitting stringer cutouts. While this one is one of the better ones the worst ones are not too different.

So I'm back to letting epoxy cure. I am getting worried about how I'm going to fit workspace and an ama in my boat shop. But I suppose I'll fix that when I get there.

The mystery is how I'm going to do the cutouts for bulkhead 7 (transom). Since I don't want to cut through the entire bulkhead. So far I only have the two side pieces of superstructure glued onto the bulkhead.  I'm going to leave it like that until I come up with an approach.

Video From Vimeo

So the K designs website had this Vimeo video posted (thanks leevogtman). I love everything about this. It's flirting with danger but obviously he was prepared, he is very close to massive natural formations and forces but manages to eek out a joyful life experience, he is not alone but there is no crowd. For me this distills what I love about sailing. Even the music strikes the right tone.

I edited out the video since the quality on my site suffered, here is the link instead. Something like this should be enjoyed with proper resolution.   https://vimeo.com/133833096

The teachers union is on strike here in Seattle (I blame the school district). So I've been trying to do all I can to keep the kids busy. Which means no time spend building my catamaran. I'll should be able to squeeze in a few hours this week, I hope.

Re-Charging the Batteries

The weather did clear just enough yesterday to get in a good sail on puget sound. I joined a sailing club here in Seattle and so can check out a variety of boats (all monohulls).  Yesterday we had the Ericson 26.  It was a nicely windy day in the morning (my guess around 10 kts sustained), but the wind died in the afternoon so we had to motor home. It was nice to be out on the water again and remember why I'm building this boat. There is just nothing like sailing to make you feel so liberatingly small.

Bulkhead 1 Done!

I wasn't going to start cutting out the bulkheads until I was done putting the superstructure pieces on all of them but I couldn't help myself. All the cutouts for BH1 are done. There are still a few areas to epoxy coat but I will work that in as I go.

I made this little stand so I could epoxy coat edges without accidentally gluing the bulkhead to its support.

This is the view of the bottom edge of the bulkhead. Turns out the dimensions on the offset table include the keel, (confirmed with Bernd) so I cut 15mm off the bottom. I had accounted for this when I placed the bottom piece of the superstructure and the results are pretty.

Of course there is still tons to do, but for now I can hardly wait to get the bulkheads set up so it starts to look like a real ama instead of a pile of sheet parts.

Putting the Superstructure on the Bulkheads

This will likely be my last post for awhile since I will be turning the crank on getting all the superstructure pieces installed on the bulkheads for awhile.  I'm doing things out of order again as it seems like it will be easier to put the superstructure pieces on first and then cut out the reliefs for stringers, chine, and keel. Not to mention where the middle of the bulkhead needs to be cut out.  Note the lack of clamps due to the use of polymer brads.  The tool did act a bit weird where some brads did not sink all the way. I think where I left an extra thick layer of epoxy on the bulkhead the tool struggled. It still penetrated enough for my purposes, Just not as uniform as I had hoped.

First use of Omer brad nailer with polymer brads

I invested in an Omer Brad nailer that can use polymer brads.  The main advantage of this is that the brads (which basically turn into columns of glue running through the joined parts) can be left in the boat.  So I won't removing screws, then filling and sanding the holes left behind. I used it for the first time today and am very happy with the purchase.  An unexpected feature is that it has an easy to use depth setting. I thought I was going to control depth by changing the regulated air pressure on my compressor. This is much easier an insures you wont just shoot a Brad straight through your relatively thin marine plywood.

Its a bit hard to see below but I was reducing the depth setting in this test piece. I left it where I could see the head of the brad from the top, but so the head of the brad was still below the surface of the plywood.

Drilling alignment holes

So after some discussion on the K-Designs Yahoo Group. I laid out locations for two alignment holes in each bulkhead. These will help to insure that I build a straight ama.  I used the offset table to insure that the locations I chose would actually be on each bulkhead and kept both on the centerline for simplicity. I drilled tiny holes in each bulkhead at locations measured from the keel of each. I calculated these individually for each bulkhead since the CWL (datum for the holes) is not a physical feature.

On the transom (bulkhead 7) I just marked where the holes would go with a marker. These will be my laser targets when I set these up.  I used a trick I learned when laying tile. When you strike chalk lines on the floor you spray them with hairspray to keep them from smudging as you proceed to walk all over your carefully laid out lines. I did the same thing to my target on bulkhead 7 and the hairspray seems to have locked in my target marks.

Bulkheads Epoxied Finally

I finally finished applying two coats of epoxy to the bulkheads.  Naturally takes awhile since I did at most 5 at a time. 7 bulkheads 2 sides 2 coats per side, 24 hours minimum between applications, you get the idea.