Friday, February 26, 2016

Bullet Proof Hulls

I am a follower and fan of Chris Morejohn and his Hogfish designs.  His boats are planked with three layers of 1/2 inch marine ply glued together with epoxy resin.  They are bullet proof by virtue of the heavy fiberglass layers that go on over that, consisting of 4 layers of 1.5 ounce chopped strand mat, followed by a layer of 10 oz fiberglass cloth.  They are set in polyester resin.  I believe that the mat is also fastened to the hull with ring shank nails.  The combination makes for a very tough hull.

I have considered this but the polyester just gives me the heebie jeebies.  It is not quite as waterproof as epoxy.  Water WILL migrate inward through polyester - that's why fiberglass boats blister. I would prefer to use epoxy but epoxy is not compatible with chopped strand mat.  It can wet it out eventually but the styrene soluble binder in it makes it difficult to absorb the epoxy.  Plus, it would use an enormous amount of epoxy.

Rueul Parker uses Xynole fabric and epoxy, using multiple layers in high wear areas.  This is purported to be a very impact resistant combination.  If I were to consider it I would have to import the Xnole as Defender Industries is the only supplier.  If I were to consider Dynel, another contender, I would need to import that as well.

An option for me, if I want to buy locally and supply/re-supply myself with short drives to Vancouver is to go with 10 oz fiberglass cloth and Aqua Set epoxy.  I'm thinking two layers of cloth, wet out together using the 'dry' method.  A square yard of double layer 10 oz cloth will require 20 oz of resin by weight.  I figured about 12 gallons to do my hull... Aqua Set comes in 15 gallon kits for just under $1800 Cdn.  E glass cloth is just under $11.00 a running yard for the 50 inch wide stuff.

So it won't be cheap any way I go, but after having re-visited copper cladding many times and ultimately rejecting it - for me - I am committed to using epoxy.  I want that water barrier.  But which cloth to use to get the impact and puncture resistance I want is still up in the air.

A Rethink On the Raptor Nails

A long time ago I was flying a rented airplane (Cessna 172) from a small airport north of Toronto.  It was wintertime and the runway was icy.  I was coming back to the airport and on final approach.  I was high, and a little fast and  in fact I knew that before I even set up for the landing. I should have gone around.  I didn't.

On short final, I was definitely high and fast.  I really should have hit the throttle and gone around.  I didn't.

My usual greaser landing where you could not tell when the wheels touched down was very, very greasy.  The brakes had no effect of course and I was not high anymore of course but way too fast.  I ran out of runway.

I did not damage the aircraft.  It did stop after plowing through ten or fifteen yards of foot deep snow and everyone at the flying club was able to help me push it free.  I never went back there.  But I learned a very valuable lesson and that was not to press on with something if your intuition tells you not to.

So that is why I will not use Raptor nails to laminate the plywood.  I think that they are great but not for this application.  I will use them for sure when I do my interior joinery.

What I found was that they would let go enough to open a glue joint if under stress.  Not much but some.  What I was doing was putting in a screw when I could see the ply needed to go down a bit more....especially evident on my curved strips.  I'd fire a couple of nails beside the screw and then remove it.  I could see the ply flex a tiny bit when I did that.  It did not sit right with me so I put the screw back in.

Once the glue set up I have wound up with very tight joints using screws.  I have not left the screws in however (epoxy coated deck screws).  The first layer that is glued with PL Premium is screwed with permanent screws but the subsequent layers will have no fasteners...yet.

So here is what I am doing now.  The second and third layers are being glued and screwed very carefully.  Even on the flat sections I am using ply panels no more than 2 feet by 8 feet.  I KNOW that they are laying flat and especially with a lot of screws.  They come out a day later.

Once both layers are on I will nail the hell out of it capturing all three layers with bronze ring nails.  Better safe than sorry.

Tuesday, February 23, 2016

To Kerf Or Not To Kerf

That was the question.

My approach to getting a nice curve on the bow curve up has been working out this way:

I PL Premiumed and screwed the first lay of ply athwartships (love that word even though blogger spell check doesn't... athwartships).  the half inch ply complied well enough.  However the curve lacked for some fairness and had some flat spots.  Put it all down to my exuberant work pace and wanting to actually sail the boat some time before I croak.

I wanted to have the next layers as best as I could running fore and aft.  There was no way to bend 1/2 inch sheet of Douglas Fir 1/2 inch ply in this manner without kerfing it.  But kerfing the ply across the longitudinal fibers would defeat that strength!

My decision was to rip the plywood into 8 foot long planks about 4.5 inches wide.  I experimented with some different widths - and used them all - but the 4.5 inch strips seemed easiest to conform.

About the flat spots.  There were two that ran athwartships... full width across the boat.  One of them was negligible and I was able to force the strips into full contact, but the other one caused the strips to bridge a void about 8 inches long.   I decided that this was ok, because the next layer will be in full contact with these fairer strips in that location.

The material I used was all left over from planking on the first layer and I ripped them up with my cordless handheld circular saw.  That is why the joinery looks a little rough.  I also planked the first 20 or so inches athwartships so that my 8 foot strips would be stepped aft, so that when I plank on the third layer of strips they will end that distance forward of the strips in under them.

I will rip up the last layer of ply for this area at home on my tablesaw so it should look a lot neater.  I will make the strips in two widths though, 4 inches and 4.5 inches so I can always select a piece that will cover the gap or joint below it.

The Raptor nails are working out well, however I've had to drive a screw here and there, which I will remove once the glue cures.

I have also decided that I will rip all of my 4 by sheets into 2 by 8 sheets for all the flat sections.  They will be much easier to handle, and knelt on to conform to the flatness.

As a completely unrelated aside, our Canadian made Cubic Mini wood stove arrived a few days ago.  It is very well made!  I am quite impressed.  Can't wait to use it.  I have an earlier post with a link to their site... worth checking out if you need a wood stove for your boat.  It would be nice to see some finished, value added products exit our borders instead of raw logs, ore, bitumen, and water.  But I'm not bitter...

Saturday, February 20, 2016

Titebond III Second Test

I made up a test sample of two pieces of 1/2 inch marine fir plywood approximately 3 feet square.  I applied Titebond 3  to one piece only with a paint brush, and spread it out to a reasonably heavy coat.  I waited about 7 minutes before laying the second piece on top.  The second piece had a 6 inch grid penciled there upon.  Using my knees to apply pressure as close as possible to the nail position, I drove 3/4" 15 gauge Raptor polymer nails at each grid line intersection.  The nail gun was set to countersink the nail about 1/8" below the surface so there is a bout 3/8" grip into the bottom piece.

I let it cure for a day and a half.

I then got out the table saw and ripped the sample up into strips approximately 1-1/2 inches wide.

All of the strips were perfectly glued without voids.

Conclusion is:

I'm going to laminate my subsequent layers with Titebond 3, nailing with Raptor nails on a six inch grid while applying manual pressure at the nailing location.

Wednesday, February 17, 2016

Time To Laminate Some Plywood

Here's where we are now...first layer of 1/2 inch ply glued and screwed to the bulkheads and stringers.  Just some cleanup to do with the belt sander left, and I still haven't put on the aft transom yet.  That's a quick job though.

So now I have to make a decision as to how I will laminate the subsequent two layers of 1/2 inch to the bottom, and the one layer to the sides.

The safe and sure way to go of course is to use epoxy.  But I will be using epoxy for sure as a final layer with either Dynel or Xynole cloth, and that will be expensive enough.  Do I really, really need to use epoxy to laminate the ply together - especially since it will all be well protected from moisture (barring collision damage) by the epoxy/cloth barrier?

In a previous post I documented a test I did with Titebond 3.  It is strong enough without a lot of clamping pressure (in the test none at all) to exceed the strength of Douglas Fir plywood across the grain.  In other words, when I broke the sample apart it was the plywood that failed and not the glue joint.

However, it was generously pointed out to me by Dave Z that voids can be a problem.  So I think I may have come up with a way to deal with it.

If you have been following the blog I indicated that I will nail the laminations with Raptor polymer nails.  They are quite strong in tension, don't rust since they are plastic, and can be sanded and cut with power tools.  So they have very distinct advantages when used in a marine situation.

What they won't do however is act like a screw, and pull the ply together.  So I need to apply pressure somehow at the location I wish to fire the nail, fire it, and move on.  I thought of driving a screw and extracting at each nail location but that would take a ridiculous amount of time, and also would perforate the plywood badly.

The plywood probably should be nailed every six inches.  If I include nails at the borders of a 4 by 8 sheet, then I need 153 nails per sheet, each nail being fired in with that location clamped somehow.

It would make sense to draw the grid on every sheet.

Most of the ply is being nailed down on a horizontal surface so applying body weight makes sense at each location on the grid.  A knee won't do though.

Here is what I'm thinking:

This would be a piece of plywood with a one inch dowel glued into it, which I could strap to my chest.  If you can now imagine me crawling around the bottom of Autarkia, placing the end of the dowel as close as possible to my nail target and leaning into it hard, I figure I can get almost half my weight on to that one localized spot before driving the nail.

I could likely get a nail in every five seconds so my sheet would be fastened down within 12 minutes.  The question is do I have enough working time with the Titebond to do that.

Another test is in order.  I think I'll make up a 3' by 3' sample, apply the glue and wait ten minutes before leaning/clamping/nailing on the six inch grid.  I'll let it dry for a day and then saw it up into 1.5 inch strips and try to get them apart.  If I'm happy with that test it will be a go I think.  Stay tuned.

Tuesday, February 16, 2016

Outboard Motors Part Two

I am a consummate tinkerer and love building, designing and inventing things.  The video below has me completely inspired for an ultimate drive system for Autarkia.  However, she must be built first and I have lots of work to do to get to that point.

In that regard, I will be buying a used 2 stroke 20 h.p. outboard to power her - for the time being. 

So, within the hour I will be heading back up to the hull to continue planking.  She's coming along pretty good though.

And here's a really cool video along the lines of what I'd do.  What with the availability of dead outboards around here to cannibalize, and the availability of surplus dc motors, my tinkering ability, electrical skills, and some interesting stuff I already have in my various junk boxes....this is something I'll be working on!

Saturday, February 13, 2016

Outboard Motors

I grew up around outboard motors.  We fished with them, water skied with them, and fixed them the rare times they needed fixing.  The old Evinrude and Johnsons from the fifties and sixties were bullet proof!  The Mercurys not so good but in my opinion better and more reliable than what is made today.  Yes they were two stroke, and they smoked.  They also guzzled somewhat more fuel than the modern ones.  But we would put regular motor oil in the gas, keep the carb clean, check the points and spark plugs and made sure there was hypoid in the boot.  If you did those things your motor would never let you down.

Fast forward to modern times.

Our last sailboat had a 9.9 hp Yamaha four stroke.  If you did not run the gas out of the carb, and drain it completely, it would not start if left for more than a few days.  The little, tiny, minuscule jet that allowed for the fuel economy demanded today, would varnish up.  It did not matter what you added to the fuel either.  I'm told this was a common problem with these motors.  Pain in the ass.

My son has a 60 hp four stroke Mercury on his boat.  The last time we were out - and thankfully we made it back to the dock before this happened - the engine caught fire.  Actually it was the voltage regulator.  Made a heck of a mess.  We were out on the Fraser during freshette, and my four year old grandson was with us.  If that had happened while we were out we would have been swept down to Vancouver.

We never had problems with the old motors.

So now I have begun to look for a motor for Autarkia.  I'm thinking a twenty horsepower will be good - a little reserve power for the Fraser current when we need it, and partial throttle, low rpm any other time.

But dammit, what to buy?

We have the budget to buy a good motor.  I simply don't know what to get, and may wind up with a two stroke from the sixties.  At least I'll feel confident in its reliability.

Meantime, here's little Autarkia with a rig.  I just need to make a leeboard and rudder and put in the RC gear and then I can play with it.

And planking continues on big Autarkia...

Tuesday, February 9, 2016

Keeping My Mind Open

When I first started this project I felt quite committed to a junk rig for all of its advantages.  I even went so far as to commit to it with the URL of the blog.

Now, I'm not so sure given everything I have been reading about other rigs and especially with regard to the functionality I want with being able to lower the rig and get under bridges.

I find myself quite intrigued with the sprit sail.  In this comparative test the sprit sail proved to be superior to other rigs when tested on the same boat under conditions deemed fair.  One of the things discovered in the test was how much improvement was gained by the use of a small, non-overlapping jib.

That got me to thinking.  A jib, for all intents and purposes acts similarly to a leading edge slat on an aircraft wing.

I participated in the building of a homebuilt aircraft called a Zenith CH801. The fixed leading edge slats on this airplane vastly improved the efficiency of the wing.  We were up in the plane one day and with power on were able to slow the aircraft to less than 30mph indicated prior to a very gentle stall.  First used on the famous WWII Storch the slats made for an aircraft that could get in and out of places that would be unthinkable without a helicopter today.

But if a jib makes the airflow around a mainsail so much better, then its triangular shape must certainly be a detriment the further up the sail you go.

And a big square sprit sail would not benefit much up high, where the wind is, with the tiniest bit of triangle that such a jib would provide.

So why not a square jib, for a square sprit sail, on a square boat?

In this latest fantasy (which I intend to test with little Autarkia) the boat has a square jib.  There is a boom fixed to the top of the mast extending forward, with a fore stay running straight down to the bow. The jib has a 'yard' on top and a 'boom' at the bottom.  It also has a controllable sheet at the top as well as the bottom.  It in effect, becomes a fully adjustable leading edge slat for the main sail.

The main sail, is a pretty standard loose footed sprit sail.  The nice thing about the whole rig is it would come down easily.  Since the mast would be stayed (fore stay, either side and running back-stays) I could use a lighter mast, and in a tabernacle could be lowered with simple and light rigging.  The sprit itself, while quite long could be made in two sections, allowing the whole rig to be stowed horizontally without extending past the stern.

Reefing would be accomplished in the typical sprit sail fashion of 'brailling up'.

I could have well over 500 s.f. of sail area in a compact, low aspect and possibly quite efficient rig.  I'll be playing with this idea with the model.  But for today, it's back to work on full size Autarkia!

Monday, February 8, 2016

Progress And Still Thinking Rig

I spent some time on the weekend throwing together the sailing model of Autarkia.  Mainly I used scrap wood, and some doorskin for the curvy parts.  I had to soak the roof panel in hot water to make the curve and it worked fine.  I did not make any effort for an authentic paint job, and cheated with electrical marker tape and aluminum tape to approximate the windows.  Once I've played with it enough and am happy with the final configuration I can sand it down and paint it up authentically and with care. But, next step is to make a rudder and install the R/C gear.  The lee board can be installed anywhere I want because the sides are 1/2 inch ply and will accept a wood screw for the pivot no problem.

But the rig.... where to start...what should I try first?

In the meantime big Autarkia is progressing.  I made the motor well on the weekend and today I will go up and start installing the first of 3 layers of 1/2 ply on the framework.  There will be some shimming to true up the curves cut in the fir 2 by 4's.  No matter how careful you are with a sabre saw, it's impossible to go along the grain in fir lumber and get it to track the line the way you want.  It'll be fair when I'm done though.

Later today...

Friday, February 5, 2016

It Won't Work Because I Read It Won't

I'm sure that even down at the Skunkworks when this project was first proposed there were those who had strong opinions about whether this bird would fly at all.   It did of course but needed a computer for control and stability.

That got some of the homebuilt aircraft people thinking.  Now the people who build homebuilt aircraft are somewhat different from the yacht club crowd - in my opinion (and I would like to make it clear that I don't include the visitors to this blog in the 'yacht club crowd').  They don't buy airplanes - they build them.  At the flying clubs those pilots that buy airplanes hold the airplane builders in high regard.   And in even higher regard if that person designed the aircraft as well.  In fact all homebuilt aircraft are deemed experimental aircraft by Transport Canada and the FAA.    Experimental aircraft.  Here's one that worked quite well.

The Facetmobile was built and flown by Barnaby Wainfain - without computer assist I might add.  The aircraft was stable, easy to fly and in general performed quite well.  It was lost due to engine failure unfortunately - something that can occur with any airplane.  It had nothing to do with the fact that it was a square airplane.

I've been around this community off and on over the years and have participated in the building of some homebuilt aircraft, as well as owning and flying two factory airplanes over the years.

In all that time in that community I never encountered someone laughing at an airplane, or ridiculing its lines, or predicting how poorly it would fly.  I never saw a flying field or airport that would disallow someone to tie down his odd looking homebuilt airplane.  Different crowd I guess.

Anyway, today I'm working on big Autarkia.  I'll play some more with little Autarkia this weekend.

Thursday, February 4, 2016

Netflix, Red Wine, and Alternatives

I like to drink wine.  I like to watch stuff on Netflix.  It can sure eat up the evenings though.  So I thought I'd do something else tonight...

Scrap wood, Bondo, some radio control gear (even got a sheet servo!).  Why not make a sailing model to test out my rig?

Wednesday, February 3, 2016

Making A Leeboard

I bought a lot of two by four structural Douglas Fir lumber and a whole lift of 1/2" Douglas Fir marine plywood when I began the project.  So I may as well use it to make up my leeboard.

Here's how I'd glue it up...

And then trim it so...

Dynel and epoxy to sheath the works.

It will likely be somewhat buoyant so some weight in the lower end would be in order.  I'll have to work that out...

In the meantime framing is almost done.

I still need to box around the outboard well and put in a few more structural pieces.  Then the whole thing needs to be cleaned up anywhere the plywood touches with a belt sander. There's lots of cured PL Premium that has oozed out of the seams.  Also,  I may have to glue in some shims in a few places to fair things up.  She turned out pretty straight so far though.  I'm stoked.

Tuesday, February 2, 2016

Single Lee Board

I'm thinking that since Autarkia is so beamy and will have very low heeling angles there is no reason to have two lee boards.  One should do the trick.

I think that mounting it on a pivot pin - in this case a 1 inch bolt (could be bronze) with lots of bearing surface provided with nylon or other plastic bearing plates, should handle the loads in either direction.  I have some black plastic (not sure of the type) already that I can use.

I can build up a board with wood, aluminum and fiberglass pretty easily in my shop at home.  I figure about 25 s.f. in the water should be enough for around 500 s.f. of sail.

If I bolt in from the outside it is no problem to house the threaded portion inside the boat to make it water proof.  Or, making more sense I think, is to have the bolt coming out through the hull and holding the board on with the nut outside.  It can be cottered there as well.

The nice thing about this idea is that wherever I mount along the hull it will not impede the view out the picture windows - board up or down.

Monday, February 1, 2016

Mast Hinge Idea

I have been kicking this around for quite some time but have been reluctant to broach it the with boat-building community because I have never seen it done before with a sailing mast.  It is essentially a means of joining two pipes or tubes with  flanges and radially spaced bolts.

It's done with aircraft - in some examples to hold on a cantilevered wing - and with high pressure piping used in oil and gas .  It  makes complete sense from a structural standpoint since the lines of stress - in tension as well as compression - remain in roughly a straight line through the joint, unlike a tab and fork style hinge where the stress lines must make abrupt right angle turns through the joint and in greater force since they wind up well inside the radius of the structure.  In these examples where I have seen such a hinge used on an free standing mast the tab/fork hinge weakness is taken out of the equation by a sleeve that slides over the whole shebang.

aluminum pipe shown shiny - steel shown red

In my fantasized hinge the aluminum schedule 40 6 inch pipe slides over a steel mandrel that forms the upper part of the hinge assembly.  If the fit is tight, and both the aluminum and steel are properly etched, epoxy primed and fit together with pro-seal there should not be any corrosion problems because of the dis-similar metals.  Steel and aluminum are mated in this manner in aircraft all the time.

The lower part of the hinge assembly is made of steel as well, and continues on through down to the keel (or my equivalent).  Eight 1/2" high strength bolts hold the flanges together and a 1/2" hinge pin allows the hinge to open with the bolts removed.  A bracket could be included to accommodate a gin pole as well.

I selected steel for the hinge structure because it can be easily fabricated and welded up with steel plate and pipe or tubing.  In order to use aluminum the upper hinge mandrel portion would have to be machined from a solid billet at great expense.  The reason being  is that welded aluminum joints are weaker than the aluminum itself and that would preclude making the piece up with aluminum plate and tubing.  It would have to be machined from one piece.  You will never see welded aluminum used structurally in an aircraft with conventional and traditional construction.

So I picked steel for these parts because steel, unlike aluminum welds up as strong as the host material.

I can't see why this isn't viable...

Meanwhile, framing up Autarkia continues...

I'll clean her up with a belt sander before planking on the plywood.