Friday, 24 April 2020

More rigging

Much of the rigging for the mast is done now. I have a vang, mainsheet and outhaul. The virus has made a real mess of things. I’m waiting on rudder fittings, boom end fittings and more cleats. From the sound of it I might not be getting those for months.

So today I assembled everything I have for a test-fit. It took us about half an hour in the driveway to put it all together. First views from the side, aft, and forward:

A closer view of the bowsprit arrangement, with cleats added for tensioning the bobstay and forestay:

Here’s the vang. I did it as a 4:1 using a 40mm fiddle block with becket and cleat at the mast end, and a 40mm fiddle block at the boom. I wrapped a dyneema line around the mast to secure the bottom. At the top it’s got a loop of 6mm double-braid through a hole in the boom.

You can also see the missing bronze fitting that’s supposed to go on my boom, plus a bunch of cleats. At the bottom is my 3:1 centerboard lifting line, using a 29mm double block and a sheave with becket in the board.

Here’s a pic showing a dinky little 22mm block that runs inside the boom to give me a 2;1 outhaul:

Here’s my mainsheet. I’m using 8mm double-braid, in a 3.5:1 system, using a 40mm block with becket on the bridle, running to a double 40mm block at the end of the mast, then a 40mm block mid-way along the mast runs the line down to a 55mm high-zoot factor ratchet block at the back of the centerboard case, which I hold down with a dyneema soft shackle.

I’m holding off until I get the sails before I install the jib sheet blocks, so I can locate them just so.

Sunday, 19 April 2020

Meet Katie

So I made a decision in record time and have ordered plans for Katie, by Harry Bryan.

There's a lovely video tour of Katie available at Off Center Harbour.

Katie is a good compromise between draft and stability. She makes use of a lead keel plus a centerboard. My only reservations with Katie is that the cabin is a tad small (Harry designed her to have a big cockpit instead) and I can tolerate a bit more draft than she has in order to improve stability. So some quick doodling on the picture of the plans that I have to illustrate my changed:

Firstly I scaled her vertically by 105%. This small change adds about 25mm of draft (from 480mm to 505mm) and 25mm of freeboard. It also gives me an extra 50mm of headroom in the cabin.

Then I add ballast to bring her waterline up by 25mm. That resets the freeboard to 480mm, and now my draft is 530mm.

My keel extension will add about 50mm on the bottom of the boat, giving me a total draft of around 580mm. I reckon this is still trailerable. It's certainly a lot less than the 900-1200mm draft of other designs I've been looking at.

Harry mentions that Katie originally suffered from mild weather helm. He cured that in the original by adding keel at the rudder end. I propose extending the centerboard back by around 250mm to deal with this. Additionally because of the taller keel we're able to drop the centerboard down a tad so most of the centerboard case inside the cabin is at floor height.

Finally we simply extend the cabin by moving it's bulkhead back around 500mm.

The results of my doodles is shown below:

Friday, 17 April 2020

The dawning realisation of life without a boat to build.

One of the truly shocking realisatons of late is that shortly Elena will be built, and then I won't have a boat to build any more.

That's utterly unacceptable.

I'm thinking now of starting on a small "pocket cruiser". Something that I can pull out of the water and keep in the back yard under the pergola when I'm not cruising in it, but still with enough size, weight, and cabin to really go places.

Also I'm fed up with plywood, so I want to make a boat from cut timber. Clinker is the romantic ideal, but strip built is probably going to be a lot more amenable to keeping out of the water for extended periods, so I don't completely get away from epoxy.

I asked for ideas on the woodenboat forum, and have been inundated with suggestions. Seems a lot of people have been thinking along these very same lines.

Here's a spreadsheet tabulating most of them.

Monday, 13 April 2020

Shroud attachment details

Being stuck in the house, and being almost out of epoxy, I’m working on odds and sods. One of these is the shroud attachment. My copy of “Sensible Cruising Designs” by Herreshoff, shows a short cut for attaching shrouds using two plates and a clevis pin, rather than a shackle. Ditching the shackle eliminates a potential rattle, so it sounds good to me.

So this is what that looks like for Elena:

I’m not super happy with the forestay attachment. I had a lot if difficulty bending the bronze strap neatly, and it shows. It’s not a particularly good fit, either.

I’m wondering if perhaps a cooler way to do this might be a loop of Dyneema rather than bronze.

Edit: I made a 20cm bridle from 5mm dyneema. This is the shortest I could do maintaining 20:1 bury in the brummel lock splices. The eyes go over some 12mm dia bronze tubes, which sit under the shroud attachments. I reckon this is much nicer.

It’s certainly miles simpler, not to mention lighter. If I want to easily detach the forestay, I could even use a small gaff saddle shackle.

Saturday, 11 April 2020

Apocalypse craft

Here in Australia, the public health advice has gradually been changing regarding the wearing of masks by the general populace.

We started with "Masks don't work, and they'll probably increase your risks of getting the virus", accompanied by pictures of health workers wearing (you guessed it) masks, and newspaper stories about the incredible shortage of masks and other PPE for health workers.

Any idiot can tell the reasoning for the message is that while masks do work for reducing spread of the virus, if everyone tries to buy them then those who need them the most (health workers) can't get them. So it makes good sense that the health authorities would lie to us here.

Now the conversation is getting a bit more honest. There's a grudging admission that masks do work, especially when worn by people who have the virus and aren't showing symptoms yet. So the advice is to make something, using multiple layers of t-shirt cotton or teatowels.

It's straightforward arithmetic. A certain percentage of people have the virus but are not showing symptoms. The public health response around people who are showing symptoms is quite good, limiting transmission. It's the asymptomatic carriers that are responsible for an increasing amount of spread. Social isolation works in general here, and widespread wearing of masks in public also helps.

In general, act in public like you have the virus. If you have the virus, the first thing you'd want to do is stick something over your face so you can't breathe droplets of it over everyone.

Being an engineer, I'm not convinced of the efficacy of a piece of woven cloth. The weaving pattern makes uniform sized holes in the weave, through which stuff is easily able to move. I've previously used non-woven poly cloth (specifically engineering wipes) as efficient filters, so a bit of google-fu revealed that this material is the secret-sauce in real facemasks.

So let's make some facemasks. They aren't going to be N95 or P2 certified, but they're going to be a whole lot more effective than something made from t-shirt fabric.

We start with the ingredients. My fabric is electrolube ECW engineering wipes, which are widely available, from for example Farnell. Each wipe makes two masks. I also use some 6mm elastic for holding it to your head, and some 1mm magnet wire for forming the nose bit.

Cut the wipe into an axe-head shape and sew two pieces together along the rounded bit of the axe head, leaving a small seam allowance.

Unfold it, seam side up, and sew the top and bottom with a more generous fold, to allow the nose wire to be inserted.

The engineering wipes make really good fabric. They don't fray, they're strong and don't tear, and are just super-amenable to sewing.

Make the nose wire from a piece of magnet wire, or really anything that you can stick in that will bend easily and retain it's shape. I whack a little loop in the end before insertion so that it doesn't poke into your face.

After pushing the magnet wire down one of the seams to the middle, the last seam goes at the ends of the mask, again leaving a generous pocket for the elastic to go through.

And tada. A non-certified, comfortable, durable, and hopefully effective mask.

Saturday, 4 April 2020

Rigging, rigging, more rigging.

I’ve entered an interesting phase, whereby each pay I trot down to the local chandlery, give them the current content of my bank account, and go home with fancy things that spin to screw or lash to Elena.

It’s getting closer and closer.

And after attaching the spreaders:

I just use some bronze rod through some bent brackets to hold the spreaders to the mast. This makes them straightforward to remove for storage, and allows them to pivot fore-aft to line up nicely in use. The vertical angle is fixed at 15 degrees.

I’m liking using thimbles as deadeyes for the rigging. I think I’ll put a couple of cleats on the bowsprit just forward of the gammon iron to tie the bobstay and forestay lines off to.

I think this deserves some celebration: