Mahna Mahna
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 endeavor 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.
March 2010 Start on Saloon furniture
As I hinted last month, I had grown bored with the fiddly plumbing work (I know I have to suck it up and get on with it sooner or later but I can do little bits at a time in between more interesting work) so I moved onto the saloon furniture. As I now have polycore panels glassed I have the raw material needed to make it all and it is very satisfying work, so for a while I will be doing this furniture.
Mar 15 First lounge frames glassed in.
Unfortunately half the month is gone and I have only managed 10 hours work on the boat so far this month. I have been in Queensland over last weekend with Jo so could not work on the boat for 5 days. Unfortunately Jo has had to move up there for the school year to help Jake through his last year of high school. It had been dreamed at one point that perhaps the boat would have been finished and we would berth at Mooloolaba Marina for the year so that Jo could be close by for Jakes last year but that was unrealistic. Little did we know that Jo would have to move up there without me but Jake needs a stable home environment in order to knuckle down and study and sadly he is not getting that without Jo moving there. And of course I cant go as I have to continue to run our businesses and finish the boat, so for a few months Jo and I will be apart. I spent last weekend up there with Jo helping her get set up.
Here and there I have been able to get a few hours done. As I mentioned at the end of Feb, I spent a day measuring and drawing plans of the saloon Jo and I have discussed for over a year since seeing Rob Shen's Alaskan 48ft power cat at the last Schionning Muster. It is an immaculately fitted out boat and although it is about half a meter wider than our boat, we loved the galley set up and I am attempting my version of it. So once I had the plan put to paper and then drawn on the saloon bridgedeck in marker pen I was able to start cutting parts out to turn the ideas into reality.
But first, it is that time of year again. The start of a new season. Summer is over, and as if a switch had been flicked the weather has cooled 10 degrees and the humidity has dropped from mid 80's to mid 50's and finally it is bearable in my shed again. But the reason I mention it is because it is time to see if Pureseal is still working. See for yourself.
Whilst there was more slime on one side than normal, and I put that down to the warmer water of summer, and I needed to use a small towel to clean the plates properly or at least in a reasonable time (up until now I just used the pad of my forefinger to clean but it was not really coming off as easily this time) I still feel that this product is still working. If I only had to rub the hulls with a cloth once every 3 months and still have them as clean as this after 3-5 years then this stuff is well worth while. It has been 2 years + 3 months (27 months) so far. If this is the result this time next year when the boat is getting close to launch, this stuff will be going on my hulls.
Ok, back to the lounge set up. Besides the critical dimensions such as seat height, back height, back angle, the other factor that went into the decisions are the sizes we want the lounge to be to accommodate our needs in both the lounge itself and the room left over for moving around, the size of the kitchen, where the steps are to be (this was somewhat determined by other factors such as slope of the ceiling) and just the general feel of the room. Every decision is a compromise to some extent. Space used in one place cannot then be used for another purpose. When we were laying out and making the cockpit we decided that space in the hulls was not as important to us as space in the cockpit and saloon, so we made the furniture as close to the edge of the bridgedeck as possible, which meant we lost some storage space under some of those seats as the underside of them becomes the room below such as the rear bunk or the bathroom, but we felt that living space was more important than storage space. The same principle applied as I set out the saloon, we dont value the space in the hulls as much as we dont think we will spend much time in them other than to go to and from the bedroom or bathroom.
Another consideration was the lounge itself. To us, we are building our home for a considerable number of years, so the lounge is very important to us. We spend hours each day on our lounge at home, working on our laptops, watching TV, even eating meals. We have not sat at our dining table for years, unless we have guests so in all likelihood, even though we will have a table we will still eat from our laps on the boat. So the lounge has to be as comfortable as we can make it. So a starting point was our lounge at home and then a photo of a comfy lounge from a furniture store so I had an idea of how to upholster the lounge and where panels needed to be and what size and shape. We wanted the saloon to be the best room of the house as it will no doubt be where we spend a great deal of our time.
From these references I got the seat height, although I have decided to lift it by 100mm on the boat over our lounge at home so as to enable faster and easier stand up and better access to table height at normal table height and also the idea of an island end (no back), kickboard and front panel sizes and the way the seat padding's are contoured. It should also be noted here that there are 2 ways to get the seat back rake (angle), you can either build the seats with an angled back and then use flat (non shaped) cushions or you can make the seat backs flat and build the angle into the cushions. I have opted for the latter for 3 reasons: I feel the space taken up in an angled back is of no useful purpose so it can be made in the cushion rather than a usable space behind the seats and another reason is it is much easier for me to make using the bulkhead as the 90 degree vertical panel and then just building the angle into the cushion work and finally we just feel that unless we have shaped and contoured cushioning then the lounge looks cheap and nasty. No offence to those that have plain slab foam cushions but if you analyse pictures of stunning boats and workmanlike boats one of the first differences is the way the seats are padded and contoured. Even the difference between our cheap slab like lounge suite and the plush one below is a result of the work in the contouring of the cushions. It may end up that these cushions are permanently attached to the boat, which is fine unless you wish to easily change the decor of the boat using the color of the cushion materials. A friend, also building a Schionning happens to be a marine trimmer/upholsterer and he will be visiting soon to start quoting me on making our lounge cushions.
Once I had the outlines of what we want drawn out on a plan and an outline drawn onto the saloon floor I started measuring and cutting parts. I started with the easiest parts, the dividing panels that form part of the frame of the saloon lounge chair. There are a few considerations in the placement of the dividers, the most obvious of them is they have to structurally bear the weight of people sitting on them, and we could sit as many as 8 around our saloon chair and that is about 600kgs so of course the structure has to be up to the task. Another consideration is the convenience of the space below, for example most people position their batteries under their saloon seating because they are big bulky and heavy and ideally should be centred on the boat, so the size and shape of the space and openings to them are critical, if they are not big enough to get batteries in there you cant store them there.
I decided on 600mm centres and cut the panels to size. I settled on 150mm kickboard, but will end up with an 80mm kickboard once I put the 60mm false floor in. 80mm is the height of the kickboard of all of the furniture so far so I am keeping it consistent. Then there is a 200mm front panel bringing the the depth of the underseat area to 350mm. The rest of the seat height is then made up with the seat cushion. The depth of the seat is also governed by the usual lounge seat depth. Most are 500mm. So will ours be but then you have about 200mm of seat cushion at the base tapering up to about 50mm at the top (actually the very top will have a roll so it will be back out to about 100mm) giving the seat the right angle back. So with the panels cut to size and shape it was a simple matter to glass them in.
The bottom front rebate is deep enough to have a 20mm kickboard on and still be recessed 15mm. Above that the front panel will go on leaving a small gap invisible from outside that will act as breathers to ensure that should the batteries ever outgas (unlikely as I intend on sealed non maintenance batteries, either AGM lead acid or if I have the money left Lithium Ion) the gas cannot build to dangerous levels. The front panel will probably also be upholstered but I will await my discussion with the trimmer before making a final decision.
The next step was to make the larger panels that drop down into the starboard hull. The bottom of these panels would also form the walls of the cabinet space in the hull. The first step was to measure all of the relevant lengths and angles (chamfer panel) and transpose them to a sheet of 3mm mdf in order to cut a template. It is just too difficult for me to get any of these types of panels exact off taking measurements and plotting them because the chamfer changes angle and shape slightly as the hulls widen then taper off again from bow to stern so a template allows for any miscalculation to be corrected without wasting material. Surprisingly though, the template was almost exactly the right size, I deliberately made it a bit too tall so it would wedge in under the deck but in the end needed to cut it back to exact size in order to get it to stand and not buckle from being wedged in.
Once I had the mdf template right (and I have 2 panels to make one at right angles and one at about 45 degrees to the chamfer at the stairs, I transposed the the shape to the poly panels and cut the first of them out. I made notes and marks on the mdf where the panel needed to change shape slightly for the 2 different panels. As you angle a panel in relation to another panel the length of a particular angled section changes.
Jo also has a couple of requirements that I am trying to accommodate. Jo hates the claustrophobic effect that dark hulls have. So as a result she really likes the way most cats have a space between the edge of their saloon furniture and the cabin sides leaving a gap for light and air to circulate into the hulls. But because I want to maximize the living space on the bridgedeck and I have the furniture starting close to the chamfer panel instead of inboard as others do, the top of my seat back is too close to the cabin sides to leave any meaningful gap. I also like the structural strength I add by glassing a panel all the way to the cabin side.
My compromise is to have the furniture meet the cabin side for part of the way then dip down and inboard to leave a big gap to let light and air in for about half the length of the lounge return. It also allows for the cupboard to ease in inboard widening the space as you reach the bottom of the stairs then narrowing down to the width of the doorway at the bedroom door opposite the dagger case and matching the shape that the dagger case and cupboard aft of it against the outside of the hull giving a kind of symmetry to it but more importantly not making the stair well seem like a narrow space. You lose some cupboard space but as Schionning constantly point out to its builders, the more cupboard space you have, the more the temptation to fill it adding weight to their performance designs.
With the 2 major upright panels cut to size and shape (the third is the actual bulkhead between the saloon and bedrooms BH5) I started on some of the horizontal panels such as the seat back. Having settled on the spacing of the 2 vertical panels, or I should say the middle panel as the front is the bulkhead and as such already set and the rear is the stairwell so that is also already set (when I glassed the steps in I had already decided then how deep the starboard lounge return would be) so the only variable was where the middle upright would be and this was decided before I cut the panel as moving it changes the angles of the chamfer slightly. I decided on keeping the sizes consistent so the gap between the middle panel and the bulkhead is the same as the spacing of the under seat frames, 600mm which incidentally is also the depth of the dagger case opposite in the hull. Perfect symmetry which will be obvious when the door are on and the cupboard closed up.
Once I had the basis of the next stage of framing cut from poly and stood in place temporarily, I measured off for shelves and seat backs. I cut some of them and was starting to run out of time and I wanted to be able to glass some parts in next time but before I can glass them in I need the front edges decored and back filled. As polycore increases in popularity (it is a relatively new building product) more and more builders are starting to use it in their builds and I am receiving emails about how I am finding it and how to work it. One common question is about decoring the edges. Although I have covered this earlier in my blog I will go over it again as I dont have an index by topic yet (I am working on it but it is a long long blog so inserting hyperlinks so that an index can be made is a big job) it is easier for me to blog it here then point people to this page.
I have found the best way to decore poly core is to use a router with a parallel to table saw blade which is about 15mm from edge to shank (you can fit a collar to reduce that but I find 15mm a good working depth) and set the table so the blade just skims the inside of the glass. Then cut a slot both sides of the panel. This tool is only useful on flat or straight edges but most are so it is used for most backfilling. I do this for balsa panels too but after the slots are cut, a chisel is all you need to remove the balsa as the end grain means a slight twist of the chisel in a slot and the balsa simply falls out. But this is not the case with polycore and whilst I have not used it, I imagine this would be the case with featherlite, which is pretty much the same stuff as polycore except the honeycomb core is paper rather than plastic. So for the next step, actually removing the core I have found an air powered die grinder to be the perfect tool. And as I pointed out at the time, I was not impressed initially with the die grinder but I dropped it on its blade once and it put the shaft just a slight micro millimetre out enough so that it wobbles slightly and the end result was it cut much better. There are a variety of different die bits, some designed to remove lots of material. I have found that the cheaper ones that grind more than cut are much better as you can push really hard against the inside glass skin and not cut through it, in fact you just grind it clean of any remaining core that the router bit missed. There are also a variety of bit shapes, I prefer a tapered bit or a round head bit, the round head is great because not having any edges the chance of cutting the skin is reduced.
Once the edges of any composite material is decored the method of filling is pretty much the same and I used microsphere paste. I overfill the slot slightly so that the core material can be sanded back to square and fair along its edge. It is important to remove all traces of the core whether poly or balsa or foam, because you want to get a glass to glass fill, it adds strength and completely seals the edge to moisture.
Next step is to start glassing some of the vertical panels into the boat. These will start to define the shape of the saloon space and the starboard hull space. A task I will enjoy as it has high visual impact.
Mar 25 More lounge frames glassed in.
As you can see from the dates on the 2 posts, I am not updating the site as frequently as usual. Unfortunately I have been having computer issues and as a result I am working from my old laptop which is a bit slow and clunky but more importantly besides uploading it I also keep a back up copy of the entire site on my computer and because I am now working on an older computer I was trying to avoid having different versions on different drives. Anyway, I am still making the updates albeit less frequently for a while and getting work done, even though it is still not enough work.
I have continued with building the lounge furniture concentrating first on the starboard hull end so that the cabinet that is formed below the starboard end of the settee is completed also which would then just leave the finishing of the aft bunk room to finish that section of furniture and then the starboard main bunk bed set up and the furniture for the starboard side of the boat would be pretty much done (I still have the glass the ensuite vanity in and final fit the toilet so still a lot of work to go really).
The space under the seating at the starboard end of the settee will be split between some on bridgedeck under seat storage and the cupboard space in the starboard hull. In order to separate the 2 sections off, the next task was to fit a dividing panel into the framework. Then shelves could be set into the space accessible from the starboard hull. All of the width dimensions already having been set by the spacing of the upright framework walls, leaving only height of and spacing of shelf considerations. One of the shelf heights needs no consideration, so that there is consistency, there is a shelf at bench top height as part of the shelf will form a bench top and this height is traditionally 900mm from the floor but in the boat it is 880mm from the floor and an 80mm kickboard height.
Notice with the 90 degree cubic framework above I had chosen to make the fore/aft panel one piece and cut the upright panel, the only reason I did this was to maximize efficient cutting from a sheet. I had considered using the slotted cross (cross halving joint) where you cut a slot for each panel half way from the top of one cross and half way from the bottom of the other, its a bit stronger but at the end I considered the slight added strength not worth the sacrifice in extra material.
Next panel I glassed in was the starboard end seat back, this went in before the stairwell end upright panel because the anchoring points to set the seat back correctly were there in the bulkhead and the middle upright but the only guide or anchor point for the stairwell end panel was the steps, so I felt it better to have another point to anchor it whilst the glue and glass set. This panel is not the original rectangle originally planned but a rectangle with a rectangle cut out of the top right hand (aft) corner). Because I am building the furniture out over the chamfer panel and to side deck height there is no space for a gap between the furniture and the saloon walls as is common in bridgedeck cats. The reason for the gap is to let light and air through the hulls and it gives the hulls a more open feel. Jo quite likes that feature and wanted me to try to incorporate it. I did not want to sacrifice seat back height so the 2 features are in conflict. The solution was half and half. Half way along the seat at the point of the middle upright panel I cut away the height of the seat back (and also the depth of the cupboard below but that wont become apparent until the next step) in order to give Jo some of the feature she wanted and I think the outcome of our collaborative compromise is better than the outcome either of us would have had if we went completely one way or the other. The best of both worlds is more than the sum of its parts! As well as the more light and air in the hull feature there is also a shelf or arm rest behind the seat and makes a feature of the area.
In the pictures above the seat end is just sitting in place, it is not yet glassed in. I still had to angle the front edges back to square to the centreline so that the cupboard door that will eventually be hung on the front of that cabinet all line up, and then the ubiquitous decore and back fill. Also note the seat back edge overhangs slightly. This is deliberate so again I could back fill and then round the corner once the end panel was glassed in. The set back of the top half of the end section of the cupboard as mention in the previous paragraph is to help with the feel of opening up that corner of the stair well. There will be a bench top that continues behind the set back door.
The stairwell end panel is glassed onto the hull and stair risers and to the seat back and frame inside the under seat that separates it from the cupboard. Next step to finish the hull side of the cupboard is to fit the top and the shelves and base (kickboard) so that all that is left to do is hang doors (the same state the other cupboards are in) although I may still put drawers and the angled pot draws in to make best use of the chamfer panel, other wise the bottom 500mm of space is virtually useless as the shelf below it is only 150mm deep).
I then have to start working my way around to the other end of the sofa by putting the kickboard and front panel on. I have made a mold for making the curved sections and started with an unglassed strip of poly to see if that was the best way to achieve the curves I need. The first attempt could safely be called an abject failure. The lessons from this are that you cannot form the curve with both sides wet out together, it has to be one side at a time, and perhaps this mold can only do curves one way, that is outside of the curve on the outside of the furniture, inside of the curve outside will need to be done with another mirroring mold. The action of pulling the shape to the mold and clamping it down (trying to avoid screws) creates creases in the glass against the mold. Or if all else fails I will have to kerf and fair.
Then once the port end of the framing done and the front is on all the way around I can make the tops which will include access hatches to each section below.
Mar 28 Under seat shelves glassed in.
Time for another rant. Almost a month after the end of summer and yesterday was 35 degrees and today 38 degrees in Gosford. And that was outside, it must be another 10 degrees warmer on the boat. If anyone doubts that climate change is happening, start building a boat. You will soon agree. In just the 5 summers since I started building I have noticed the really hot days start earlier in the year, last longer in stretches and still occur 4 days out from April. I am also thinking of hiring myself out to influence whatever it is you want influenced because whenever I declare something the opposite happens. I note at the start of this months blog that as if set to the calendar the temperature dropped dramatically and that I could now look forward to a few months of productive work due to the cooler weather. Wrong! As a result although I managed 8 hours yesterday I could only manage 6 today and both at half pace because of the relentless heat. I heard on the radio that the humidity had tipped into the 90's and I defy anyone to get anything done in such conditions. The irony of it is that despite slowing because of the heat, you must work faster because resin goes off so much faster, so the remedy is to make smaller pots but that means making more of them in order to get the same work done, which takes longer. I barely got some of the tapes onto the job before they were hot and going off today. And all because the petrochem industry acted much like the tobacco industry for the past 30 years and stifled development of alternative technologies. Pretty soon we are going to have to redefine the tropical lines from 23 degrees to 33 degrees! Ok rant over, for now.
I have got most of the shelves into the starboard hull cupboards under the seats. There is one I have deliberately left out for now, as I am undecided if the space would be more useful without the additional shelf, I will ask Jo. I have just one more shelf to glass in (I would have had it in if not for the heat, dont get me started again!) and then the bottom shelf/kickboard set up. Then I will clean them up inside and give them a coat of white epoxy to finish them, in one section I have a couple of drawers to make and of course for the entire cabinet I still have the doors to make and hang, but that is true of all the cupboards so far. I will make all of the doors in one door making session (that may last a couple of weeks or more if it falls in summer, now there I go again...) and hang them all toward the end of the fit out, after they are finished, not sure yet whether that will be paint or laminate.
I will also be finally putting the side decks on very soon. Probably in the next few weeks. That is a milestone I am looking forward to very much. Essentially closing up the boat. So in preparation for that I have bogged the inside of the curved strip planked side decks over the area that will be the shower in each hull, so aft of bulkhead 6 on the port hull for about 1200mm (about the half the way to BH7) for the main bathroom shower (although the rest of the bathroom is in front of BH6) and between bulkhead 3 and 4 in the starboard hull over the ensuite. The reason for this is that I am not sure if I can have linings inside the showers, for if fairing and painting wont be the best finish for these wet areas. I intend to line the rest of the boat so fairing is not necessary and I may still be able to line the showers, but if I cannot I would rather that I fair the curved insides of these side decks off the boat rather than finding out later and having to do them upside down inside the boat. Life is so much easier right way up and off the boat. At least 5 degrees cooler for a start....yes I am still on this rant. So yesterday I marked out the bulkhead positions and from there bogged them leaving about 100mm all around so that I can still tape the panel to the boat without there being bog in the way, and today I managed a few minutes of fairing before my body quit and politely asked me to wait for a day at least in the high 20's.
There is no easy way to fair a concave curve. The bogging is easy enough, my method of bogging was to key the glass underneath, in the case of the port deck I added a thin layer of surf board cloth (200gsm plain weave glass) because I had a number of bubbles in the glass that sanding out left unglassed sections, on the starboard hull I did not have such bubbles so I simply keyed it then brushed a coat of resin on, then bogged both when they had tacked off using sweeps with a trowel from one side to the other keeping the blade as square to the panel as I could so as to get an even layer of bog, then repeat until you have bogged enough of the panel trying to keep the bog layer thin. You cannot trowel along the panel for obvious reason. When sanding you must use a curved long board, in my case it is just a swimming pool noodle with hookit glued to it to hold the sandpaper. So with a long curved board you push in zig zags across and along the curved section until it is fair. The zig zag motion is important, without which you could end up with a series of parallel troughs require rebogging and resanding. The zig zag ensures you dont dig holes. It still may, like most fairing require a couple of runs with bog. But even with only 10 minutes manual fairing in each section the tops are knocked off the highs and the panel is almost fair. Hopefully if I do a few minutes each day I will get it done soon.
I managed to get 57 hours done this month, not bad considering I missed a weekend which is 14 hours so if I had not I would have got into the 70's which for me is a good effort. I was also striving to get to the 3000 hour mark before the end of the month. According to Schionning it takes about 4000 hours to build this boat and I pretty much agree with that. I think I have about 1000 hours to go. It has taken me 4.5 years to get 3000 hours done and my goal is to get the final 1000 hours done in 18 months tops. A big ask, considering I have averaged only 700 hour or so a year, but the way I intend to achieve this feat is to hire some man hours to help me finish especially the fairing and with that help I am now getting confident the boat is going to be finished and in the water next year. Only a little over time budget.