Mahna Mahna

2009 building logs

The story of Mahna Mahna started the moment we decided we wanted to build our own Catamaran and then sail the world on her, but the actual building started in September 2005. The initial materials for our Schionning 1230 Wilderness Catamaran arrived from ATL composites and some other suppliers, over August 2005 and work on the strongback, the frame upon which the hulls are built, started in September. The journal starts with the building of the strongback. We will endeavour to pass on what we learn in the building process as we go and we welcome any questions or advise from anyone either following us or ahead of us in the journey. There are many different methods used by builders and the methods we use and describe on our site are suggestions only. You should always consult your designer and materials supplier for the best method of construction.

July 2009 Under sole work begins

It is time to get inside the boat and start doing on some of the work needed for systems on the boat. I cannot glass the soles in until all under sole work is done. And I have much more light and air with the side decks off so perhaps it is a good idea to get onto some of this work before the side deck goes on. Before I do this though, in preparation for Nine Lives being painted we are going to have a massive clean up to try to remove as much accumulated dust as we can. This could very well take an entire weekend! They are almost finished fairing it (and yes it is true, there are months and months of fairing on a boat!) and if I move inside the boat for a while, the dust levels in the shed may reduce a bit.

July 1 Starboard case exit faired.

Today I created more dust. There is nothing more ironic than bogging and fairing. You slap this stuff on just to sand 99% of it back off again. I applied a bit more bog to this hull than the other so it took a little longer to get it all off again. To save a bit of time I ground some of the really thick parts down before I started sanding with a random orbital. This side was much better in terms of bubbles under the glass and also for splinters up inside the case. I still had a couple of bubbles though and did the same as I did on the port side, I sanded the glass away and filled the slight low with glue and smeared some up inside the case along the glass edges and along the edges of the exit. This will be sanded again but leaving a thin layer for added strength along the edges.

After a little more sanding of the glue smears on each hull, the hulls will be ready for recoating first with some highbuild to fill the tiny pits in the bog, then the copper epoxy back on to finish.

July 5 Ensuite rough in.

After nearly a week the glue that I used as filler to fill the tiny bubbles in the glass and splinters inside the case I had had still not gone off due to the extremely cold weather. It just refused to kick off. I did them both at night but thought the shed would warm enough during the days for the glue to set off. I was worried that perhaps I had mixed it wrongly but on both sides on different nights? Anyway after a week it had finally hardened. If it had not hardened on its own I was going to hit it with a heat gun but it was sufficiently hard enough to sand, which I did, so it is now ready to apply copper epoxy. I am not going to bother with highbuild, I am just going to give it a coat of epoxy, let it tack off then apply the first of 2 coats of copper epoxy, all one after the other while it is green (when Nine Lives gets its copper epoxy).

I spent a lot of today (Saturday) cleaning up a bit, rearranging offcuts to stack a little more neatly and getting some of the dust out of the shed (by vacuuming and blowing it off vertical panels).

It is time to start on the internal furniture. I have decided to start from the bows and work back because in order to glue the soles down (which is needed in order to continue with the mast bases and any hull furniture) I need to plumb in any pipe work or electrical wiring. So before I can do any of that I need to know where the plumbing will need to start or finish. It is amazing where the hours go when all you are doing is measuring and cutting cardboard, remeasuring, re cutting more cardboard until you get the set up you like. It felt at the end of today that I had not really achieved anything. But I guess you have to get these things right and unless everything is pre-laid out (a kit) you have to go through these periods that feel unproductive but are in fact just part of the build. And a lot of fun.

With the doors moved to the outside of the hulls by 150mm for the mast posts, the room in the ensuite changes. It isn't any bigger but the new door actually makes better use of the space. You usually would not have any furniture against the outside hull in an ensuite so usually the door cuts the usable space for a vanity on the inside hull side, but the added 150mm means I can fit a deeper vanity top and because of the slope of the hull sides you don't really lose any floor space. And you need to have the vanity cover at least some of the floor so you can run waste pipes down the inside of the vanity unit and under the sole to keep them all hidden. The water in pipes will come through the bulkhead inside furniture in the bedroom and also stay hidden.

With the vanity shape selected through trial and error of different shaped cardboard cut outs of quarter circle shapes some more elliptical and longer, one bigger to fill more of the ensuite and starting closer to the door until I settled on the shape I have. The ensuite is also a shower so you want to keep as much floor space as you can. I have freed up a little of the space by having the toilet inside a cubicle on the other side of the forward bulkhead so the showering space is very generous and does not feel cramped in anyway. I will also have a hatch through to the underside of the tramps as well as a port on the outside hull and a hatch above so plenty of ventilation which keeps the mouldy smell that some bathrooms can have, away. I will have a mirror fronted sliding door shaving cabinet in the panels that go into the forepeak. I was thinking of putting a black water tank into the space but have decided to put it into the space to the side of the toilet cubicle.

Which brings me to the forepeak filling walls. These are pretty much the last of the pre cut (kit) panels to go into the boat. I was thinking I would leave them off the boat all together in the port hull walk in wardrobe and use the space for more clothing, but with the masts moved inboard I feel they are more critical to add stiffening to this section of the build now so I will put them in and utilise the space in that void by accessing it from the bedroom via either a door or a large drawer on pot drawer runners.

July 11 First plumbing in.

I got no work at all done this week. To be honest I have just been a bit lazy because it has been so cold in the evenings. So today I got stuck into running the first of the plumbing into the starboard hull. I have decided to try to keep the plumbing as simple as I can. I will have 3 fresh water tanks each one 200 litres. I have decided that for the sake of 1 extra pump it would be better to have a separate tank for each hull and 1 spare that will only ever be filled if I am going on a long cruise to areas that may not have water available. If I ever get a contamination in a water tank I will still have the other hulls tank to rely on until I can refill. I can also use the pumps via taps to pump from one tank to another. And the same goes for waste. I will have separate holding tanks in each hull for both black and grey water, that way if a toilet ever breaks down which I am sure they will, and at the most inopportune time (usually when guests are onboard), I wont have to affect and immediate repair because I have another fully functioning toilet albeit in the other hull. I do like redundancy!

So with all of the roughing in done I had to decide how the waste grey water would be extracted. I have a space in front of the toilet, above the waterline where I can hid a small grey holding tank (the port sides grey tank is behind the dagger case and at 1000mm x 600mm x 120mm it will hold 72 litres which should be ample) of about 50 litres. It is a little smaller than the port side but wont have the kitchen sink draining into it, and is not likely to see anywhere near as much use. In fact I doubt it will be used unless we have guests aboard. And with gravity out the tanks will rarely be closed and called upon to actually hold any water. About the only place would be in a marine national park (Great Barrier reef perhaps). The black tanks will be used as tanks but will have pump out ports on the deck.

The space under the sole in the ensuite is not very deep so I decided I would lead a pipe down to a sump in the bedroom but I could not put is directly behind the bulkhead because a lot of that space is taken by the mast post. It does not go through the sole but I wont have much space left for an inspection port in order to access the submersible pump. I will also have steps up to the bed in the middle section so the best place for the sump is at the back of the bedroom hull. From there a pump will send the waste up to the top of a holding tank and from the bottom of that out through the hull just under the waterline. With a breather at the top of the holding tank that will double as an overflow through the inside of the hull under the trampoline, it (the breather) ensures I can never have a siphon back up into the tank. I also avoid a common problem on directly exited waste, blow back from wave action back up the waste pipe creating a geyser from the sink hole whenever waves form in just the right way to blow water at pressure back up into the boat. I might still have them but they will form inside the holding tank then fall back out again once the pressure stops.

When I set the pump out pipe I ran it level because fall is not needed when under pressure, the water is going to be pumped up to the top of the holding tank about a meter above water from below the sole which is below the waterline. But when I set the larger diameter drain pipe I needed at least 1mm per meter fall. At first I cut the rear hole too high so I cut another hole and will just glue the piece back in, and to be absolutely sure I have 10mm per meter fall.

I have decided I will put a small vanity basin in the starboard aft stateroom, just for a drink in the middle of the night, or brushing teeth. So its waste will run forward to the sump and its supply (cold only) will come through the furniture, under the sole and back up to the faucet along side the waste downpipe. So today I went to Bunning's and bought some conduit (a plumber told me that it was exactly the same plastic as used in plumbing) in 3/4 inch for the pump out and 1 inch for the waste to the sump which needs to be a little bigger because it is just gravity but the pump is under pressure. And then I proceeded to cut holes in the webbing and bulkheads to lead the pipe-work through. I have cut bigger holes than needed with a holesaw so that I get a 5mm glue bead to seal the balsa panels. I cut the pump out pipe in first.

And then the strangest thing happened, one of those Murphy moments that must happen to all builders and have them scratching their heads and muttering under their breath about why these things happen to them. In the toilet cubicle I had glassed a ply base so as to have a level base for the toilet because the hull is starting to V in this section. For it to be bedded down I first glued and glassed a piece of ply in a triangular shape to the shape of the V of the hull and then level and flat along the top. I then glued the ply base to it and back along each hull side to the bulkhead, forming a sealed box underneath it. But I now needed to run the pump out pipe through. So I cut a hole in the ply front with the holesaw and the moment I pushed through the holesaw came out of the chuck into the sealed box. What the!!!. How the hell am I going to get it out? I was convinced I would have to cut a hole into the base to get it out and re-glass it. Not a major problem but really annoying. It just wastes a few hours. I have to get it out for 2 reasons, the holesaw isn't mine but more importantly you cant leave solid sharp things like that banging around in there because it might punch a hole in the hull. Unlikely but you just cant risk it. Year after year, wave after wave banging around. No it had to come out. Then Greg, who owns the holesaw asked if I had a magnet. Dennis did so we tied it to a string, attached that to a stick, fished around for about 20 seconds until the magnet grabbed the holesaw and I gently manoeuvred the shank to the hole and gently worked it out of the home. Over as fast as it started but one of those amusing moments that have you shaking your head.

July 12 First steps roughed in.

In order to figure out where the plumbing needed to go for the aft bunk sink I needed a rough idea where it would go, which is against the wall (non structural bulkhead) I have yet to fit that will also have the doorway into the stateroom. I know where that wall will go so I ran a beam of timber to act as that wall, clamped a door cut out to it to simulate the doorway and that gave me an idea where the steps would run down into the hull. Because of the angle of the wall to the hull (about 45 degrees to centreline) the steps naturally lead you on an angle forward into the hull. This is critical. As are the step heights. It is hard enough climbing up and down them on a boat on the hard, let alone into a hull pitching in a seaway so getting the steps right is very very important. It took me all day to get this right.

First I needed to make some mdf braces upon which anchor the steps temporarily to the hull (they will be glassed in once I am satisfied with their shape, height and position). The kit includes pre cut step treads so as a starting point I used some of these. There are a couple of different shapes, I am not sure why, I didn't mark them when I cut them from the panels, I am not really following the plans for the furniture as I did not buy a furniture kit so it does not really matter, if their shape works I use them if not I adapt them or make my own from offcuts. I actually found that the shape worked well, it has the angle of the wall already cut into them, also the angle of the cupboards that butt to them on the inside of the hull and allow for the natural angle that I need for the stairs to "work". By work I mean direct you down them in the most biomechanically efficient way. But I did not know this when I started, the process of setting the steps taught me.

The stairs on a cat or any boat for that matter, often require contortionist like manoeuvring down them. Getting up them is easy as the gap opens up as you climb but coming down is much more difficult. And you need the steps to draw you down them in such as way as to turn you as you go down them so that you naturally avoid hitting the cabin side as you go down them. And because the platform to which the steps jut out from is the angled chamfer panel it is all the more difficult to get the tread heights right, the shape right so as to lead the feet and the body down correctly. I started with the obvious starting point. I centred the first tread on the middle of the chamfer panel. It is aesthetically the best position but the fall from bridgedeck to the first step is about 200mm and the fall from the first step to the next step, which falls right on the chine is about 250mm. But because of the angle away caused by the chine, the further down you put the step the larger the gait needed to hit that next step so although the fall is less the stride is greater.

I experimented with moving this first step up and down but in the end I settled back on the original position in the centre of the chine. It works best and looks best. I used a milk crate to simulate the bottom step but next job is to set the bottom step. This took some time.

At first I could not get down the steps without turning my body as I went down and kind of crabbing down. Going down those steps will become second nature and learned behaviour but for guests that will only experience them every once in a while I want to make them as easy to negotiate as I can. I could not understand why I could not get down the steps easily at first. And then it occurred to me. The position of the bottom step, at this stage a milk crate was not drawing me down the steps correctly. I had it positioned for minimal footprint in the companionway and directly below the step above it. It needed to be forward of the step above it so it turns you down the steps after you have cleared the side deck to cabin side corner with your shoulder.

So next I had to ascertain the correct shape for the bottom step. The milk crate had taught me that my foot wanted to fall out from the hull so another step of the same shape would not do. It would need to be bigger at one end. The downside of this is that it protrudes into the companion way meaning anyone walking from the rear bunk to the ensuite would need to walk around that step that protrudes a long way into the hull. And with any sort of cupboard against the hull outside making that squeeze even tighter. I cut a piece of mdf to what I thought would roughly be the shape I needed. I was pretty close, but the milk crate was not quite the correct height. I split the difference and came out with 2 325mm steps. This wasn't working. It was just too far to step. But having 650mm fall from the chine step to the sole meant that ideally I need 2 more steps. But this has its own problems. Each step has to protrude out from the step above, it cant just be directly below the step about. And there is not much width in the hull to accommodate this. I worked out a solution. I settled on 250 mm drops for each (from chine to bottom step and bottom step to sole) then I would raise the sole height in this section by 100mm. Problems solved.

After a bit of experimentation with the step shape I had it. I made the duflex step much bigger than the mdf step and slowly worked down with a series of curved lines until I had the shape that would work. I watched where my foot wanted to fall naturally and ensured I did not have my toes over the line when I stepped. I tried the steps over and over until I was satisfied I had it right. I then cut the most appropriate shape. The other consideration I had was the way the aft stateroom door would swing. It was easy to decide it had to hinge to the outside of the hull so that the door did not have to be walked around to get in or out. But it could swing out into the hall or into the room, there is enough space for it to go either way but it would be very cramped inside the stateroom if I put the planed step up into the bunk in place. It will double as a chest for packing clothes or a duffle bag and a seat to sit on to put shoes on or just sit before or after bed. So out was the optimum. In order to swing out I had to be sure the swing of the door would clear the step, so i put a curve in it to accommodate the door swing and the shape worked aesthetically too and also worked ergonomically as a step. All good.

To finish I put timber and panels in place roughly to simulate the furniture that would surround the steps when all of the furniture was in place around it, then retried the steps over and over. When Jo arrived to pick me up I had her try them too. She is much smaller and had no trouble at all clearing the angles and getting down the steps. Getting up them is a breeze for everyone.

It does not seem like much work for an entire weekend but it was a lot of fun and I did spend a lot of time daydreaming about how various walls, steps, doors, sinks etc would work in practice. And not a piece of it was actually glued in yet.

July 26 Steps glassed in.

I have had a frustrating 2 weeks and little got done on the boat despite me working on it for both weekends. I couldn't seem to get any actual work done. I did a lot of mocking up and a lot of staring at it but not much actual construction. We also had a bit of bad luck with our car, the auto transmission causing a breakdown which we are being quoted half of what the car is worth to fix. We think we could get $8000 as a trade if it was running but the quote was $4000. And at a time both of us have shipments being made so we have to pay for them very soon. My hatch shipment is $18000 so money is very tight. We were rescued though, a customer of Jo's has a cheap car she sold us in exchange for stock instead of cash. That buys us some time so that we can fix the car at a time when cash is not so tight and we can also look at buying a transmission from a wrecking yard and have it fitted by a home mechanic rather than the shop it is in now and perhaps get out of it a bit cheaper. We were going to trade it later this year after the shipments were paid for, we had been looking at cars online for weeks. Anyway, these things happen.

I have glued and glassed the steps into each hull. I had to, I am not getting any younger and with lots of work going on in the hulls now climbing in and out was getting harder and harder. Now it is really easy. I have not glued in the bottom steps as I have not finished the under sole work yet so cant glue and glass the soles down yet. I cannot lift the soles out if I glue in the bottom step.

Before I could glue and glass the steps on I had to de-core the front edges as they will be exposed. You cannot leave exposed balsa anywhere on the boat. That includes inside the boat. De-coring is really easy on panels you can get to with a router. I have a blade that cuts a slot in the balsa as close to the inside face of the glass as you can safely get. Then once the slots are in (to a depth of about 10mm) you can twist a chisel or screwdriver in the slot and the balsa breaks out in chunks because the grain runs from slot to slot so it just breaks along the grain.

Once the balsa is removed including running a chisel blade along the inside glass to be sure there is none still on the glass, then it is just a matter of mixing up some thick coving compound and filling the slot, slightly over full so that it can be sanded back down smooth. You also have a much better surface on which to round the edges. I de-cored all the steps and under step bracing pieces and filled them all at once, clamped together so it was an easy fill job.

The port steps are further forward than the starboard steps. Both steps have a wall to aft and furniture on the forward edge, in the starboard hull the wall is the bedroom wall and angled at about 45 degrees, in the port hull the wall is the bathroom and will be at 90 degrees to centreline. It is further forward (and not angled) because of the position of the kitchen on that side of the hull. The kitchen bench top forms part of the bathroom roof and the wall is and extension of the side of the kitchen cupboard and forms part of the stair wall with a handrail on it. So the step positions were determined by where I wanted the kitchen cupboards to be. I have a plan for a bench top that runs along the rear bulkhead and then at 90 degrees along the hull with the top against the saloon walls, interrupted by the stairwell then starting again on the other side and around 90 degrees again will be more bench top over the fridge freezer. Over the stair well I want to have a hinged top that can join the two bench tops to form an uninterrupted bench top all the way around so that the kitchen when needed can be as big as the one in our house. This can be very useful when preparing larger meals for larger groups when entertaining. You can sit 8 around the saloon dining table and another 4 at the outdoors breakfast table so we could conceivably be preparing a meal for 12.

Another task I have managed to do which also was decided a long time ago based on our plans for the kitchen is to resize the saloon cockpit doorway. The standard size is 1200mm wide, which is a great size but we felt we could sacrifice 300mm of it to make the usable kitchen space that little bit bigger. We have seen (on a Schionning Alaskan 45ft power cat) a floor to ceiling pantry against the doorway and we are going to replicate that in the space I have reclaimed from the doorway. I have known about this since building the cockpit furniture and made the seats accordingly. The plan for the doorway is to have a double sliding door, sliding to each side by 450mm to create the 900mm opening. We can also have insect screens do the same.

The other resize job that has been on the cards for a long time was the rear bunk opening. The chamfer panel angle makes the hull wider as you get higher. The bunk if set to the opening that was originally cut into the bulkhead would have the bunk as a single bed or a king single at best. In order to make it a double bunk I needed to raise the bed height which in turn required the doorway to be raised by gluing (and glassing) duflex into the space. The raised bed height means less headroom but we would rather a double with less headroom than a single with added headroom, and it also means added depth to the under bed storage area which could house pushbikes or even a moped motor scooter if we build a lid to the bunk that can be opened and we use the boom as a crane to lift it out (and swing it over onto the jetty wherever we want to unload it). I have not settled on the shape of the opening yet. I may square the shape up or make it symmetrical, or leave it as it is. I will decide that once I build the bed base in and try out the opening. I will also build a step to make getting in and out of the now raised bed, and this step can double as a storage chest (the lid would be hinged) and as a seat in the bedroom.

So although it seemed like I got very little done, some big decisions have been finalised and put into practice by the fitting of the steps and the resizing of the openings. At the very least I can easily climb in and out of the hulls easily now. I have also crossed 2500 hours.

Time Spent: 57.00 Hours

Total build time so far: 2507.00 Hours   Total Elapsed Time: 3 Years 10 months 3 weeks

August 2009 logs