Mahna Mahna
The journey 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.
February 2008 Cockpit set out
I am keen to make the strip planked cabin top but there are a number of reasons I should wait. First it is much easier to make the cabin top if I have more space and in a few months the other boat will be out so i will have much more space and there is no real hurry to get the top done, and the other reason is that to get the length and shape I want it will be easier to know the exact cockpit layout as the top mirrors the rear seat layout. So I am setting out and gluing in the cockpit furniture this month. I may also get a start on the daggerboards.
February 3 Port side seat set up
I had already glued in the first seat frames to the back of bh6 last weekend. Today I kerfed the curved seat front wrap around. It starts at the main cabin door and wraps around the cockpit to the rear bulkhead, I will then curve the rear seat to match the profile of the duckboard (and the cabin top will match this shape) and then start on the starboard set out, which is different for 2 reasons, the port side has a breakfast table the starboard side has the helm position. Even though it was raining today, it was hot and humid making work uncomfortable, but I am keen to get moving again so I just got stuck in, and finally I have something concrete to report on.
The plans also call for a layer of glass each side of the rear bulkhead, partly because the bulkhead was cut down to lay the uni rope inside, so the 2 pieces that were glued back together need to be glassed and partly because the rear bulkhead and the forward beam are the 2 most stressed members and hold the boat together square and the hulls parallel at each end. So before I can glue the seat panels in I had to glass the inside of this bulkhead, so I glassed the port hull and across the bulkhead to just before the starboard hull. I will glass the rest of it next week when I start on the helm position seating and around to the middle again to meet the port sides seating.
I started by measuring out where the turns will be and marking out the kerf lines. I had already cut kerfs into an offcut to test the number of kerfs I would need to make the radius bends I needed. Because the seat curves in both directions I need kerfs on both sides of the panel. I cut the first kerfs and then turned the panel over and cut the second and third set of kerfs. A tip when cutting closely spaced kerfs is to keep the peel ply on until after you have cut them, it minimises (it doesn't completely stop it but does minimise) the tear up of glass fibres leaving a neater panel once it is curved and glued ready to be re glassed. For those that don't recall, the kerfs are cut with a circular saw set to 3/4 of the depth of the panel. Basically you are making space on the inside of the curve for the panel to compress around the corner (the inside of a curve is shorter than the outside). I also cut mdf frames to the radius of the various curves (1 larger radius 2 smaller radius) to form the curves when it is glued and setting.
Once I had completed the kerfs I set about dry fitting the panel and mocking up the way the the area will look once I have completed the seats and fit the table. I also need to work out how the full rear seat will be, how I will shape it. The plans for an enclosed cockpit have the seat straight along the back bulkhead and no duck board, the plans for the walk throughs have the duckboard and a curved rear seat. I am having a combination of the 2, so I will have an enclosed cockpit, with the duckboard and a curved rear seat to match the curve of the duckboard.
I sanded the front of the rear bulkhead from the port hull (and down in it) across about 3/4 of the boat to the start of the starboard hull. I then glassed the panel using the off cuts off glass from the side panel glassing, about 500mm wide and from top to bottom overlapping them by about 50mm until I got to the top of the bridgedeck then I ran the 500mm glass along the panel in 1 strip.
During the week I will start to glue the seat front into position and glue the seat frames along the rear bulkhead ready to attach the curved seat front across the boat.
February 9 Seat back
Today was a good day to work on a boat. Cooler, about 20 degrees C and raining most of the day. Raining does not make boat building any easier physically but when it is raining you at least don't feel like you could be doing something else like you sometimes do on a sunny day! I worked pretty hard today, but I don't have as much to show for it as I would like, mostly because some of the work is invisible. I have glued, coved and glassed the rear seat webs in and before I could do that I had to glass the rest of the rear bulkhead.
A couple of years ago just before we bought our kit, we visited another Schionning builder who told us it had just taken 2 weeks to make the saloon lounge framing and we went away thinking no way that it could take that long. Now I know. I spent all day and whilst I have glued, coved and glassed all of the pieces on, it does not look like a days work. It is surprising how much time is consumed with coves and taping.
The rear seat is curved to match the duckboard, and to achieve this curve the webs are smaller in the middle and then each web is slightly larger, the same size each side and the same distance from the last one, this creates a curve that the seat front will be pulled into, the panel will have a uniform gradual bend in it. Then the seat top can be glued on. I will then make hatch lids out of the seat top rather than seat front making the size of what can go into the hatch larger and easier to get in. I intend for some of the seat back to be for the outboard tanks and life jackets.
I have a plan for the rear seat back, for the centre part. The open section in the pics above should be filled with a curved seat back but I may leave that section open, and fit a curved seat back made from chromed tubes with round padded cushions around them, this way the seat is see through making visibility aft from a seated position in the saloon better, and also the back of this seat back is also a seat back to the duckboard. I can sit on the duckboard with my back on this padded seat back with my feet over the edge fishing or just enjoying the view. I first saw this idea on the Schionning Alaskan 41, except it has this seat back on either side from a centre duflex bbq stand so mine will be reversed, the seat back across the centre only.
I have a tip I have been meaning to pass on for some time but keep forgetting. You don't need any special tool for coving, you can make your own out of 3mm ply, just shape the end to the radius you need and then taper the top like a chisel, then just throw it way and make another next time rather than cleaning a purpose made tool.
Tomorrow I should get the rest of this seat front made. I have to measure and kerf the starboard side seat front and when it is done, glue it to the port half and glue it to shape and to the seat webs.
February 10 Starboard seat front
The starboard seating is going to be much different to the port side. The helm requires a different arrangement and there is no need for a table on both sides. The helm position needs to be raised so that you have visibility from a seated position as well still as being able to chat with everyone else on board, see into the cabin and the electronics etc. and for docking I need to be able to see all four corners of the boat. My solution is to have a raised helm and I was originally going to build all the way up to the raised position but instead I have decided to go for a the helm seat on legs so it can be raised or lowered to the height required and when at anchor can be lowered all the way to normal (or just above normal) seat height. I will still have my original idea of a hinged seat back so that the seat can face forward or back. Jo was trying to think of the correct word for it and came up with Swivet, she was thinking pivot and swivel at the same time and the 2 words mixed as they come out, so I think we will use that. The seat raised on legs also gives the cockpit a less closed in look and feel.
I "borrowed" a couple of helm pics, one from Lightwave and one from Perry, but because both of those put the helm on the port side, I have reversed the pics to give a better idea. I hope they don't mind. The Lightwave shows the raised helm idea a little better although I don't intend to have a soft raised roof and the Perry shows the seat back style and how easy it is to change the look of the boat with seat covers.
The first thing I did today was to mark out on the cockpit floor where the seat would wrap around to. This gave me the length of the panel I needed (the seat height is the same right around at 500mm with the top on), it also allowed me to take the measurements of where each curve would start and finish so I could mark out the kerfs and it also gave me the feel of where it would all fit. You can see the helm island in the pic below being shown out by the tape.
I have a panel in the walk through kit that is the correct height but is 660mm too short, so I have to glue an extension on. I found an offcut the right size and cut it to the right height and length and I glued it on last after I had cut the kerfs. I measured out the the kerfs in all the places I wanted the panel to bend. There are 3 small curves (all on the same side of the panel) and 1 very large curve (on the other side of the panel because of the direction of the turn) at the end of the helm base. Once all of the kerfs were cut I tested the curves to be sure they could make the shape I needed. It did as I thought so I glued the extension on and called it a day. All of this still took 6 hours. Tonight when I was typing up this page and looking at the pics I realised I don't now need to make the island like it is in the pictures and I now have too many curves in the panel and it is too long. It will now go from the start of the island curve and from the middle it will extend into the back of the bulkhead and not back around in an island. I will fix it tomorrow and also try to figure out how to utilise the space underneath the raised helm box properly.
I also learnt something else today. The kerfs splinter because I have been using my battery powered saw. Either it does not spin the blade fast enough or the blade is blunt. Today I used a power saw as my batteries were flat and the result is a much cleaner inside radius because of far less fibre splinters. So my tip is use a mains power circular saw.
During the week I am hoping I can get the seat front panel in position so that it meets up with the port side panel ready to be glued in.
February 11 Starboard seat front in place
I quickly re-measured where I wanted the helm island to finish, so that rather than being a complete island, it is now going to be more a raised helm box. I will place a half height step up into the helm position to make getting up and down easier. I will also put a step up from the seat top to the deck, which is a similar size rise as the floor to seat height and again this will make the transition up onto the side deck or back down much easier. I will also put a step in the middle of the rear bulkhead seat front to again make that step into or out of the boat much easier. It will be curved reverse to the seat back. It will mean that the 2 middle hatches will only have half the size openings if I go with my original idea of having these open fronted for life jackets so that they are in an easy place to grab them for such things as bar crossings etc. If I decide for them to stay solid fronted I will just have the lid in the seat tops like all of the other cockpit hatches.
Once I had re-measured, I marked the new position for the kerf and where the panel should end, I cut the kerfs and the excess panel off. Once that was done I put mdf planks across the kerfs to try to keep the panel stable while it was lifted onto the boat. Once on the boat I removed the mdf planks and bent the panel into place and using the mdf as blocks screwed to the cockpit floor to hold the panel in place I had my cockpit roughed in. It will still need to be pulled back into the curved rear seat and once fully roughed in I can prepare to glue it in.
I am very pleased with the way the cockpit is laid out. The cockpit is very wide, as wide as I could make it without impacting on the internal volume of the main bathroom on the port side or the bunk on the starboard side. As well as being spacious we also have a heap of seating. I think we could easily and comfortably seat 20 people in the cockpit, 6 will be able to eat at the outside table.
The boys have also started on the fairing of Nine Lives. In the next few weeks, the ply boat will be transformed into a shiny white boat, and some of the hard lines will soften.
Hopefully I will get the seat back glued in soon. I have to go to Melbourne on Thursday and will need to stay over the weekend for a family Wedding on Saturday, so no work this weekend, so I doubt I will get it glued in until the following weekend as it is a big job and will take a day.
February 12 Rear seat curved
I did not have much time to work on the boat today, nor could I do much with the little time I had, not on the cockpit seating anyway. The next part of this job will take the best part of a day, that is gluing the now full length wrap around seat in place and coving and taping it all. One small tip to remember when making a curved seat is that the front has to stretch a little longer across the front before it is curved because a curved length is longer than the straight line from the widest points, how much depends on the amount of curve so it pays to check it with a flexible tape first.
Today I did get the panel dry fitted into place to reveal its final shape. The only thing that will change once the seat tops go on and the seat backs in place will be that the tops will overhang about 40mm. I cant explain how happy I am with the way this seating has turned out. It is quite a thrill to design something yourself, albeit within the parameters of the space available, and then to measure it out, and to see it come together and turn out the way you want.
Unfortunately I wont get back on the boat until next week.
February 18 Rear seat kerfs glued and glassed
Unfortunately I did not get anything done on the boat this weekend, but I did manage to get the kerfs glued and glassed today. I also gave the outside ones a light coat of bog to fill the grain of the glass and to fair out the ends of the glass to the panel.
I decided it was too big a job to glue the very long seat back panel down and glue and glass the kerfs in one go, and also I thought having the curves formed and set would make it much easier to glue the base of the panel by simply raising the panel on blocks and glue buttering the bottom with a scraper, the panel would be able to be easily lifted when it is set into shape but very difficult when it is a floppy panel as it is before the the curves are set.
Before filling the kerfs with glue, I sanded off the glass splinters. I then released the seat back from the upright seat panels in order to move the panel around to straighten out the kerfed area so that I could scrape glue down into the saw cuts. I put peel ply down so that the panel does not glue itself to the bridgedeck until I have glued the whole panel down. I then put the panel back into place including curving the kerfs back into place and using screws screwed down into the deck tight up against the seat panel back and front to hold it in the correct places (be careful not to screw them all the way through as the bottom is faired). I then scraped the excess glue off the panel that was squeezed back out of the kerfs when the panel was re curved. I had the panel screwed in place for the weekend and it retains a little memory of where it has been and went back into place really easily, I had marks on the floor to remind me where the panel should be.
Once the entire panel was in place and the excess glue removed, wet out glass and placed it on the kerfed curves. Once all the glass was on, I mixed up some bog and spread a thin layer of bog over the outside kerfs in order to fill the grain and to fair out the glass edges.
Once this is all set I will raise the panel on blocks, give the corners a sand whilst it is still easy to get to the corners by moving the panel around. Then I can give the entire bottom edge a butter up of glue, as well as the forward faces of the seat uprights and glue the panel into place onto the bridgedeck. I may get that done tomorrow, but there wont be time to cove and glass it down, that is quite a big job. I will get that done on the weekend.
The boys have also been getting on with the fairing of Nine Lives. They have long boarded the bog lines and are in the process of back filling with bog to the sanded bog lines. Once that is on and set they will then fair that again but it is a lot neared to fair and will only need a light sand, a lot less sanding or at least a lot easier work than flat bogging and sanding.
February 19 Rear seat front raised
I did not quite have enough time to glue the seat front down today, but I did sand the bog back down on the kerf glass and generally clean up the panel and bridgedeck ready for gluing. The panel is very easy to work on now that the kerfs have set and it can be released from the seat uprights and can free stand. The seat retained a bit of its shape by being screwed into place as seen in the photo, however it will need to be screwed back into place when glued to set in place.
Once the seat panel is glued down, coved and glassed I can start work on the seat tops, then on the seat backs.
February 23 Rear seat front glued down
It is amazing how time consuming some jobs are. They don't look like much but they take hours. Today I worked for 6 hours on gluing down the seat front and starting on the coving and taping. Before I started on the taping I put some bracing in under the boat to ensure that my weight did not cause the deck to sag and be glued with that sag, I figure it would be better to keep the deck flat. I doubt there would be much movement from my weight but better to be sure. There is still some movement in the deck when I walk around on it but the furniture will stiffen the floor up.
After bracing under the deck I started to butter the bottom of the seat front with glue, then once that was done I buttered the front of all of the seat uprights and lowered the seat front down into place. Because the seat back is curved it is difficult to get it into place without getting some of the glue on the deck where it will not be glued to if you are working alone.
I had pre-marked the deck when I dry fitted the panel so I know where the seat front should be. I attached the 2 ends to the bulkhead and worked around along each side until the seat was glued and screwed down up to the 2 rear corners with just the curved sectio to go, and then I went to the middle and pushed that in and screwed it down and screwing down to the rest of the uprights was easy. I then scraped off any glue that got smeared out of place and using my finger made a glue cove and removed any excess and filled any gaps.
I had lunch for about half an hour and then started on the coving and taping. I have managed to cove and tape all of the inside edges, both along the bottom and up each side of each upright, effectively sealing each compartment. The seat top will enclose them and then, I wont be gluing that down all over as some parts of the seat top will be hatch lids into each compartment, so wherever there is balsa edge exposed I will need to core out and backfill.
Nine Lives is slowly being faired. The backfill has been sanded back to almost fair. The way they check for fairness is to spray a mist of black paint (auto black) on then sand it off, any area that stays black is low meaning they need to keep sanding until it is gone or back fill it more if it is too deep, the lighter areas of black (grey) are almost fair.
Tomorrow I will cove and tape the 8.5 meter long seat front in one continuous tape and the last few areas I didn't get to today. After that I will start to find the parts to make the seat tops and backs and glue them together (I will need to make them out of the parts left over from the walk thru kit) ready to fabricate the tops and back. Once that is done I will need to get back to some of the parts of the build I have skipped or avoided, such as the keelsons and fairing the forebeam. I really want to make the cabin top but it would be better to wait until Nine Lives is launched in a couple of month.
February 24 Rear seat front coved and glassed
The weather is warming again and it is still very humid. But not as hot as it has been and bearable, however it was still warm enough to mean I had to hustle to get the taping done before the resin went off. I decided with such a long length to wet out (the front of the seat is 8.6 meters in continuous length) that it might be easer to wet the tape out in the wombat, but whilst it did mean I worked faster it put pressure on me that would not have been there if I wet out with a brush as I went. That said I got it all done and am happy with the job I have done. It is the best coving and taping I have done so far and good timing too as it is also the most visible so far.
I had a visitor today so I waited until he had gone before I started the taping, just so that I was not half way through when he arrived as you cannot stop once you start. It is always fantastic to get visitors and to chat about boats, today's visitor has already built a Waterline 1320 cat and has extensively cruised the Pacific so it was great to chat to him. We had read his story (written by his wife) in Multihull World so it was nice to meet someone we had read about doing what we want to do. He is living on board his boat with his family, in fact he is living our dream!
Honourable mention today for Jo who decided to come in and help today by vacuuming some of the dust in the shed that has been building up for a while especially since Nine Lives started to be faired. It is a full time job and not a fun one, so I am very grateful. The strangest thing happened while Jo was vacuuming, she screamed and dropped the vacuum saying she had an electrical shock in her foot. I checked everything and it all seemed fine and I used it a while with no shocks. The as soon as Jo touched it she was shocked again. Apparently the fibreglass and resin dust going up the hose creates a static charge that builds up and then when you touch something that grounds you it zaps you. She was continually zapped for the next hour or so.
The coving took about 2 hours and the taping about 2 hours today. I gave the cockpit floor another sand just to remove any dags of glue that set hard and sharp in the glassing area and then gave the cockpit a quick vacuum to remove the dust. I then coved the entire seat front and the 3 small sections that I had not finished yesterday.
Then once the coving was done I changed gloves, I find that a couple of hours with the same gloves on and my hands sweating inside them and they look like prunes and need a few minutes to dry and recover. I mixed up a little too much resin in the wombat and wasted a few pumps worth. I hate that. It just went off in the wombat before I could use it all, I got the long tape through it and another smaller tape but I could feel it getting hot on the roll so decided that I was better off getting the wet glass off the roller and onto the boat before it set on the roller. The tape super heats much faster when tightly rolled on the roller than if it is unrolled so I got the tapes unrolled roughly in place as fast as I could to slow the set off, and then got a brush and mixed some fresh resin to use the brush with resin on to push it down into the cove and against the panel and to get the air bubbles out. I went to the wombat to see if I could use the resin in the bag but it was rock solid!
Once I had all of the glass down and wet to the panels well I got the taping roller to roll out any remaining air bubble. So another 2 hours with the gloves on and I was relieved to get them off. And I had really moved fast, time seems to fly when you are under pressure. The 8.5 meter tape took an hour from the time I filled the wombat to the time I had the last air bubble out. The rest of the tapes took another hour, the rest of these I wet out with the brush on a flat offcut before applying them to the job. The one thing I probably should have done that I didn't was to put down some peel ply or to apply a thin layer of bog. I didn't have any ready and just forgot about it. It is not a big deal, it just means I have to give it a sand up to get the bog to stick. I only have to fair the seat fronts not the cockpit deck as I will be laying cork down and this will negate my need to fair the deck. I may still need to give it a bit of a sand to remove the inevitable spills bound to happen over the next year or so.
So with the cockpit seat front finished save for some sanding of the tapes inside and out, I will start on the seat top and back although I may not glue this in for a while, I will just need to have all of the panels made to shape ready to. I am particularly pleased with the way the cockpit is working out.
Time Spent: 46.00 Hours
Total build time so far: 1368.00 Hours Total Elapsed Time: 2 Years 5 months 3 weeks