Auxiliary power ideas

In common with many sailors, I rather regret the need for auxiliary power, but of course it is an enormous convenience and a significant contribution to safety.

Haiku’s plans have an optional outboard well, but I have seen the outboard in Alastair Bremner’s boat and I have to say I was very surprised at how much of an intrusion into the cockpit it was. If I were to use the same arrangement, it would seriously call into question whether this was the right boat for me at all, since a day sail with six people would become very cramped.

One of the other criteria that led me to the choice of Haiku was the extreme shallow draft, and here is another potential area of conflict with the auxiliary power. There seems little point choosing a boat with a 1ft draft, if you then dangle a propeller in the water that requires 2ft. This led me through all sorts of wild ideas involving jet drives and the like, but not only does there seem to be nothing on the market of a modest enough power, I am also assured that jet drives are hopelessly inefficient except on high-speed craft.

A further constraint is my unwillingness to contemplate an inboard motor. Interestingly, Iain Oughtred is extremely scathing about the idea of an inboard on this design. I can’t be sure of all his reasons, but my objections include the following:

  • The modifications necessary to fit an appropriate inboard in the boat, e.g. a much enlarged compartment beneath/near the bridge deck, and the addition of a skeg to carry the drive shaft aft and protect the propeller.
  • Another hole in the hull to inspect and worry about
  • Noise, right in the heart of the boat, whenever motoring is necessary
  • The in situ maintenance required, especially bearing in mind I will not be a regular visitor to places that have such facilities

So where does that leave me?

The first thing that occurs is to go electric. This would eliminate some of my concerns above, but of course it brings its own problems, not least of which is cost!

cruiseR_abbildungBy far the simplest and cheapest implementation of the electric idea would be to go with a Torqeedo outboard. I could create the outboard well, and at least the head of the outboard is tiny compared with a 10HP petrol motor, so the intrusion into the cockpit would be considerably less. Another option would be to mount it on a bracket on the outside of the boat. However, my gut feeling is one of dislike for outboards both in terms of their inconvenience and looks, so I will only use this as my fall-back position.

ACV-NThe idea that is currently my front runner is to use an electric pod drive. An obvious make would be Mastervolt, but I did see some pods recently by Krautler, which looked very good. A folding propeller obviously reduces drag, but also helps in that there is otherwise insufficient draft to allow the boat to dry out without damaging the propeller.

p3000cexternalOf course this still leaves the thorny issues of power source and storage. Again, I have no firm conclusion here, but am thinking of a generator coupled with enough batteries to give me about 1 hour motoring at full power. This does not sound much, but the generator could be rated so as to enable motoring at reduced power for as long as the fuel lasted. One such generator would be the diesel-powered Paguro 3000 Compact. Fitting this in would require a minor modification to the space under the bridge deck, but nothing like the modification needed to fit an inboard motor of a suitable size. It also introduces something that needs maintenance, but my understanding is that it would not be difficult to remove and take somewhere for servicing if necessary. Another option of course would be a Honda petrol generator – simple, cheap and portable, but does involve bringing petrol onto the boat.

A few more components

20140411_115613I’ve been plodding on with a few more components, but much more slowly than I had hoped because work keeps interfering! Here are some cockpit sides photgraphed while back on the machine after gluing on pieces of framing.


20140411_115708During my construction of the centreboard cases I was using a technique of gluing (with epoxy) using temporary screws to hold components in place. Even though I used washers, the screw heads created significant dents in the plywood, so I had to find another solution. Here is what I came up with – clear acrylic washers. They are working very well: the epoxy does not stick to them and I am getting no more indentation. If things continue like this I will end up using less than a box of screws on the entire build, and none of them will be left in the boat. This of course means I don’t have to buy any stainless/bronze screws, which are expensive and pretty awful things to use.


20140422_151007Here is my first bulkhead at a similar stage to the cockpit sides above. Notice all the framing it will need is already in place. The edges are being cut at the appropriate angle wherever possible, to avoid the need for any fairing. It remains to be seen of course if any fairing is needed after all, but even if it is, there should be less to do. Notice also the recesses for the chine logs and even limber holes being cut. Having modelled everything in such detail I am determined to make the CNC machine earn its keep!


20140415_112017The next three bulkheads I want to make throw up 2 problems:

  1. They are bigger than the plywood sheet size
  2. They involve laminated cabin roof beams

So, a pause was required while I made the roof beams and worked out a good way of joining plywood sheets.

The laminations are all different curves – essentially 3 different radii. Being horribly lazy, I wasn’t about to do three separate glue-ups, so I opted to make a multiple-curve laminating jig out of 38mm MDF and glue up all three at once. Cutting the strips of Douglas fir was standard procedure like I do for furniture: using the table saw, but flipping the stock end over end before each cut to counteract any compounding error if the sawblade is not cutting at exactly 90 degrees.


20140415_112028Before actually gluing the beams together I put each stack through the thicknesser whole – that way, any hollowing or bulging created by the saw is eliminated, and the beams will be of an exactly even thickness. This is particularly important when using 2-part laminating moulds. Here is one of the stacks ready to glue up.


20140415_152459Here is the actual glue-up


20140416_114847And finally the beams are being skimmed to remove the dried glue before thicknessing.


20140425_182618The other problem with the next bulkheads was their size. Of course most builds involving plywood require joins, typically employing a scarph joint. I was keen to develop a method that would suit my equipment and be easy and quick to do, as there will be a considerable number of such joints to do. I opted for the joint shown here – I’ve no idea what it would be called, but the important elements are that it is staggered over 12x the ply thickness like a scarph joint, and is also self-locking like a dovetail so that I can put it in a veneer press without worrying about it slipping apart. I have seen a similar lobed finger joint like this before, but never in multiple layers. I dare say I’m not the first though!

20140425_182623

That long-awaited sawdust

At last, the sawdust has started to fly! I decided to start with the centreboard cases.

20140402_171138.resizedFirst I cut out very shallow recesses where the framing was to go. These are purely for location, and the depth is kept to an absolute minimum to avoid weakening the ply (although I suppose anything removed is filled again with wood anyway).


20140404_104918.resizedThe next step was to cut the pieces of solid framing, which are mainly made of Douglas fir, but with some black sucupira where the pivot is attached.


20140404_105659.resized20140404_114936.resizedA bit easier than doing it by hand!


20140405_113741.resizedDry run assembly of framing onto plywood. The wood is held with temporary screws from below.


20140405_150118.resizedThis might look like an effortless result arising 5 minutes later than the last shot, but it’s not! Anyone reading this who might have been thinking ‘smug git with his fancy machine!’, will enjoy this bit…

Very first glue-up, and it was all looking so promising, but I just had to rush in and cock it all up – and it was just a bit of simple maths that let me down. I somehow managed to mix up the epoxy 2:1 instead of 5:1. Of course it would have been no fun at all if I had noticed straight away, so my brain naturally had to wait until I had glued the framing into place before it suddenly twigged. So, off everything had to come, and a mad panic scraping off all the epoxy ensued, before having to mix up a new batch and start again from scratch. Good job I had nothing better to do with my time!

After wiping off the excess, there was a terrific mess of epoxy smeared everywhere, so I thought I might as well coat everything with a thin layer neat epoxy, which I would do at some point anyway. Still not sure if this was a good idea, but you’ve got to try these things.

The next job will be to put the sheet back on the machine to cut out the overall shape, followed by glassing the other side and bringing them together with spacers to form one of the cases itself.

 

 

Wood

After a frustrating week, I have finally started actually making something! As soon as there is something interesting to see I will post about it, but until then, just a quickie about wood, which is now all here.

I was gripped for weeks in my usual paralysis of indecision about the plywood. I’m sure anyone who has made a boat will recognise the symptoms – total fear that the decision at hand might ruin thousands of hours of hard work. Before the work starts, this fear is especially crippling, as every decision is yet to be made, and most of them need making now, before one has gained any experience on which to base them. It’s a wonder anyone ever starts.

Unloading Bruynzeel ply

Unloading Bruynzeel ply

Anyway, plywood needed choosing. I was clear that I would go with decent marine ply, and had heard good things about Bruynzeel, so that was a start at least. Next, should I use okoume (gaboon) or mahogany? Mahogany was my first thought, but it is a lot heavier – maybe as much as 30%. I knew that the original Haiku had had weight issues, and Iain himself says sharpies should be ‘lightly built’, so this didn’t seem such a good idea. On the other hand, okoume is not a durable wood, which worried me. However, I always planned to sheath the hull with epoxy and glass, and have been convinced that given the right maintenance, there is no reason why okoume should be a problem – there are certainly a lot of boats made of it. Lower resale value is another thing people mention in connection with okoume, but I have no intention of ever selling Luely, and I don’t think the British market is receptive to second-hand sharpies anyway, whatever they are made of. The bonus is that I have saved thousands, since okoume is much cheaper than mahogany.

One problem though, was that Bruynzeel don’t do 9mm ply, but do 10mm instead, so I had to amend my CAD drawings. You might think that a) 1mm difference in a few components is hardly worth bothering to reflect in plans for a 30-foot boat, and b) even if I insist on making that change, it surely couldn’t take more than 5 minutes. Because I want to make maximum use of our CNC machine, I really do want millimetre-perfect parts so that they all fit together first time. Unfortunately, my software (Rhino) is not parametric – a feature of the most advanced and expensive modelling software, which enables changes like this to ripple through a whole plan automatically. For 99% of the time, my trusty non-parametric friend Rhino is fine: it is remarkably good value, and is very quick to use – much quicker than the disciplined way in which parametric drawings have to be done… until you need to make a change that is! So, in this case it bit me badly, and I spent several days rebuilding sizeable portions of the model and swearing loudly.

Douglas Fir arrival

Douglas Fir arrival

The solid wood was much easier: Iain speaks highly of douglas fir, and given that it is easy to find, reasonably durable and quite inexpensive, it seemed silly to look any further. Naturally, I did not miss the opportunity to make things hard for myself, by forgetting to order one of the thicknesses I needed!

I am using small amounts of other woods too. The plans call for ‘oak’ floors. However, I have some fantastic stuff called black sucupira, which is stronger, stiffer, stabler, more durable and cheaper than oak, so I am using that. It is somewhat denser, but the extra weight will be as low down as the internal ballast, so I can simply omit some of that if necessary (and it is only a tiny amount overall).

Heavy centreboard woods

Heavy centreboard woods

The only other woods are those that I am using in the centreboards, and again, I happen to have something already that will fit the bill. This time it is a selection of various timbers I had left over, including coracao de negro, preciosa and muirapiranga. They are all woods we bought years ago when we were researching sustainably produced exotic timbers for use in our furniture, but never really found they were suited to much of our work. What they all have in common is that they are denser than water (i.e. they sink) and ridiculously hard: perfect centreboard materials, and a perfect way to use them up.

 

Keel: an idea

I was just thinking how useful it would be to have some lead weights to hold things down as they glued. So, given that I will need lead to make the ballast keel and bricks at some point, I started to think about a supply of lead, and as usual this train of thought got me totally side-tracked. I am nowhere near ready to be making keels, but when eureka moments strike, they need to be given a bit of space.

I have given at least some thought to most aspects of the build already, and one that has been worrying me was the casting of the keel. Casting small weights and the like holds no fear, but the idea of pouring 455kg of lead has been troubling me. But that was before my idea. Like most ideas, it will either prove to be a good one and has therefore been done a million times before, or it will turn out to be the ‘other’ kind. However, to date, I have not come across it elsewhere.

Here is my thinking: instead of finding an enormous crucible of some kind, making a wooden mould and then risking life and limb by trying to pour the molten lead in, why not use a mould that can be heated up, and lob chunks of lead in until it looks about full? The shape of Haiku’s keel is essentially a couple of flat bars, each one about 10′ long, 10″ wide, and 2″ thick, with the lower two edges rounded over. So what, I asked myself, is about this shape and is made of something that I can heat up? The dazzling flash that came to me was… the web of a steel beam. If I can find an I-beam of the right sort of size, I can weld a plate to each end, mount it on its side on some bricks, put some burners underneath, and voilà!