Building Logs

Cabin extensions

Posted by Paul

For quite a while I have been tripping over the side cabin extensions. I clamp them in place, kick them as I climb up onto the side decks and they fall over. I clip them up again only to kick them again and have them fall. I have put off gluing and glassing these very simple panels waiting to find out if there would be any implications for the sheeting points. There wont be and I have known that a while too, but I have put off doing it because it did not seem like an important job that just had to be done now.

I decided I had kicked them one too many times as I was continuously climbing over the decks to the catwalk. So I glued them on, reshaped them a little and glassed and bogged them in preparation for fairing. These side panels are really just cosmetic appendages. They were designed to provide some protection from the elements at the helm but because of the extended roof, I need to have the ability to stand on the side deck and reach the helm to steer. I would need to be standing on the side deck in order to be able to see the port bow, it cannot be seen seated at the helm looking through the cabin windows across the saloon. Because of this requirement I have cut back the size of the side panel extensions so that the wheel is accessible from the side deck, and at the size it is now, it does not offer much in the way of protection from the elements. To combat this loss of protection I eventually intend to fit clears to each side that will extend from the back of the saloon around to just behind the helm and matching on the other side. They will clip to the roof and to the cockpit seat tops.

So the side panel shaping became an extension of the roof edge line and the cabin side profile. The transition of the roof edge line down the extension panel is complicated by the fact the roof is 3 panels thick (60mm), the roof itself is 2 panels thick but the sides protrude above the roof surface to form a ridge line that stops water from dripping or flowing over it and is directed along the edges and down the sides. But the side extension panel is only one panel thick plus the edging which means that the joins needed shaping down from 60mm down to 40mm. I could only really do this job once the panels were in place.

So going back a few months, I had already decided on the side shape by experimenting with cardboard shapes until I had the look I liked. I cut the kit parts down to the template shape I had chosen and then glued foam around the edge of the curved shape on the outside edge to make the continuation of the roof edge ridge, and after some shaping I glassed them with thin surfboard cloth to protect the soft foam. I didnt do a very good job and knew some extra work would be needed at the time of bogging and fairing but didnt worry much more about it.


I glued the side panels on the boat last week and the next day glued some foam onto the side and front edges to shape that transition of thickness. The other area I had to shape was the transition from side panel to deck. I used glue to create this edge as it tapers out to flat. I used glue because it is harder than filler and this edge could get stepped on a lot so I wanted it to be hard and durable.

Glue is much harder to sand than foam and the foam additions were glued to the base edges so inevitably I would be grinding or shaping foam and or glue at much the same time. And as a result you must be extremely careful when shaping transitions from foam to glue as the different hardness means if the grinder blade touches the foam it rips away very quickly whereas the hardened glue takes more effort and time. But eventually I had the basic shape worked out and all I needed for it to be finished was some filler here and there to fill gaps or straighten lines (actually the lines are curved but here and their the constant radius would break into a flat section that needed filling to re round it). But this shaping takes time. Each time more filler is needed, so is 24 hours minimum while the filler sets. Fortunately we have had warmer weather which ensures 1 day is time enough for it to set.




Once the basic shape was created, I glassed it all again, glassed over the glued edges and re-glassed the foam shaped edges. I waited for resin to tack off and then covered it all with bog in preparation for fairing. The reason for the wet on wet bogging was because the curved edges are very hard to cover with peel ply and I didnt want to have to hand sand all of that by hand more than the once or twice that the fairing will require anyway!



The cabin side extensions follow the cabin lines which are angled slightly toward the middle of the hull decks. I made sure to extend the taper toward the outside of the boat. This helps deflect flowing water (not so much rain but higher volume flows such as perhaps if a wave washes down the hull side) away from the cockpit coaming.


Whilst this work was going on I also started dry fitting some plumbing and electrical items such as light switches into walls and mixer taps and water outlets into the bathrooms. And the start of the outboard wells construction started with the creation of the outboard leg boxes.

Now that they are done they have become another of those shapes or angles that I just love staring at and admiring in this build. The way they sweep around and complete the roof line and the way they fade to nothing at the deck impress me. Imagine how excited I am going to get about all of these parts when they are all shiny gloss white!

Whilst this work was going on I also started dry fitting some plumbing and electrical items such as light switches into walls and mixer taps and water outlets into the bathrooms. And the start of the outboard wells construction started with the creation of the outboard leg boxes.



The kitchen has been waiting on me buying the convection microwave and then fitting a rail at the appropriate height just above it then making and fitting a cutlery drawer above that. The space I have is tight, it will fit a regular microwave easily, but a convection microwave is somewhat larger or at least needs to be so as to be big enough to fit a roast in it for example. I settled on about 32 litres being about the optimal size. There are a couple of brands that fit one way but not another. The most critical size deficiency I have is depth of the cabinet.

Directly behind the kitchen back is the bathroom, so the backwall position was a compromise between saloon space, bathroom space and cupboard space. Cupboard lost. Anyway, the LG is the right width and height isnt an issue for most of them, but the depth is about 40mm too deep so that the front will protrude about 20mm beyond the drawer fronts above and below. Not a big deal but not ideal. Other brands are not as deep but are too wide for the space I have. I made the space a little bit too narrow for most brands. I have had the dimensions of the cavity in my phone for months and every now and then I check out a different brand for size. And the other day I was walking through Aldi and they have a convection microwave on sale for $150, 30 litre, and the dimensions are as close to the cavity I have found. Tight width but ample depth and height. It fits into the cavity but the overhang lip I left on the curved front needed to be trimmed off. Its fun to fit some of these items that have been planned for so long.


Being such a tight fit I will need to remove some of the side panels inside the cavity in order to allow breathing space for the oven. I have space each side of it on the other sides of the cabinet walls, on the right hand side is a void that is perfect for the purpose, its not used for anything anyway. On the left hand side, the other side of the cabinet wall, the space is deep inside the undersink cabinet which will store larger kitchen items such as big pots etc. This area can also act as a heat sink but I can also fit a bilge blower (to rapidly remove heated air) to the outside of the boat from the other side of this cabinet which is the main bulkhead, and it would emerge inside an outside hatch well. I probably wont need a bilge blower, but it would be very easy to fit at any stage so I may wait until I have used the oven a while and see if it is needed. The oven has an over-temp cut out and of course I will be able to feel if the spaces either side are overheating. I find it very unlikely. Lets face it, have you ever burned your hand on the outside of a microwave regardless of how hot the food inside got?

Another job that took me way longer than I thought it would was glassing ply pads onto the cabin roof for mounting the solar panels to. It didnt help that I made a basic measuring mistake. I made the mistake of measuring from a front face or edge on one measurement and back face/edge on another and I have made it many times but usually I catch it on the measure twice part of the saying. This time it got by me  and I marked the positions after taking a measurement off the wrong edge of the front pad, which meant that each pad after that could be effected by the mistake. And unfortunately a change in plans compounded or at least allowed the mistake to go un-noticed.


Here’s what happened. First the reasoning behind the ply pads. Solar panels get hot. The hotter they get the less efficient they become. Its not by much but its there. A normal solar panel has a frame around it which raises the actual panel and the backing substrate off the surface the panel is mounted to. The frame around the panels makes them rigid, or even more rigid than they already are, because normal panels have a glass cover. The panels I have dont have either a frame or a glass cover, which allows them to bend. But the frames in rigid panels serve another useful purpose. They allow air to circulate under the panel which dissipates heat from under the panel. My panels are designed to bend around the curve of the roof. I dont want the underside of my panels in contact with the curved roof though. If they were, the panels could not dissipate heat fast enough but perhaps worse, they will dissipate heat through the roof and into the cabin. Or enough heat will be generated to damage the paint on the roof under the panels.


My solution is to glue and glass plywood pads to the curved cabin roof, so that only the first 30 or 40mm of each panel on each side is in contact with the ply pad, then a void is created by the height of the pad under the panel to the actual roof line. I used 12mm ply and put spacers under each end so that the top and bottom edge of the panels is 15mm off the roof. Thin pads like this are easy to bend around the curve of the roof. This allows hot air under the panel (heated by the dissipation of the heat in the panel) to rise up the curved roof and out from under the panel and this in turn would draw in fresh cooler air from the bottom of each panel. This constant circulation will achieve 2 things, keep the panel cool and keep the hot sun off the roof which in turn would keep some heat out of the saloon. The pads also provide a fixing point that does not compromise the integrity of the cabin roof glass skin. If a ply pad gets moisture into it eventually via a fixing screw and eventually rots then it can more easily be replaced rather than the structural danger that the roof getting moisture into the core presents. And it also means there is a very large footprint on the roof that will be permanently covered by the solar panels, which in turn means I dont have to fair it to the same standard that a fully visible roof will need to be.

It is a change of mind of fixing method that caused me to be in a position to attach some of the ply pads in the wrong place. My original idea was to mount nuts called T nuts to the underside of each ply pad in each corner. A T-nut has teeth on it so that it grips into the ply and cannot rotate so that when you apply a bolt from above it can secure tightly without being able to spin in the hole. So I bought 40 of these nuts (10 panels one nut in each corner of each panel). In the process of planning out the positioning of each nut I decided that it was too easy to get the ply pads down in the wrong place (how prophetic!) out enough that over the course of the 5 panels some of the bolt holes would not line up with the holes in the panels. In fact I noticed a very small discrepency with the position of the holes on 2 different solar panels which convinced me that if I was out 1mm on 2 different ply pads and the hole on the panel was 1mm out that would be enough to mean that the hole centres would not line up and I might have trouble having all the bolts find the then permanently fixed nuts.

I decided that self taping hex head screws 10mm long x 4mm or 5mm shaft would be much easier to make fit. I wont need pre-determined fixing points and just have the ply pads to screw down into when final fitting. So not having the precision placement that the nuts required may have caused me to be, lets say, less diligent with the placement of the pads. I glassed down the very front and very rear pads first, then the next pads inside each (so second from front and second from back). The front and back panels dont share one pad with another panel on the other side of that pad (the very front or very back pad), but as there is no panel on the other side that pad is just for that panel , there are 5 panels so 6 pads each side in all and 2 sides of the dividing centre brace. My intention was for the panels on the front and back to be fit just inside the front or rear edge (depending on if we are talking about the front or back panels on the array) so I made these pads 60mm wide with the expectation that 40mm of the pad would be under the panel and 20mm exposed. The middle pads that had panels sharing them either side would be 120mm wide with 40mm between each panel and 40mm under each panel edge.


I had 4 of the 6 pads down each side and decided to lay the solar panels on the pads to see how things were working out when I discovered that some of the pads were too far apart for the panels to reach deeply enough into the pad to ensure a meaty support for the 4mm screw that would be holding the panel down. WTF? How could I make such a silly mistake. I thought for a moment about ripping the pads up again, but I had glued and glassed them down, it would be near impossible to remove them now.

So I set about trying to figure the best way to remedy this. Most pads were the correct difference apart one way or another but not both. Each way I placed them (front edge of panel 20mm in from the edge of the front pad or back edge of the back panel 20mm in from the back edge of back pad). In the end I figured out a way to mount front and back panels in 20mm and the front panel 10mm in from the edge of the pad and what would be needed would be to make one pad just forward of centre another 40mm wider and another pad just behind centre a full another pad wider. The panels would all be equal distance from their neighbour except for one pad that would be much wider. What it allows for is a path between the panels to be walked on up on the roof should I ever need to go up there.

From time to time I may need to stand on the cabin roof to work on either of the booms that might be over the cabin. The solar panels can bend enough that they can be stepped on and that they will just bend the 12mm or so until the cabin roof stops any more bending as they are stood on. But these panels will get super hot, so much so that perhaps standing on them would not be such a good idea, barefoot would simply burn your feet and with rubber soled shoes, who knows perhaps hot enough to melt them, so perhaps having standing room between some of the panels is not such a bad thing. Not planned for, but the path is a nice justification for the gap should I ever be asked why its there. That will be the story anyway! Not too big a deal really. It will look as if it was by design.



Having all the pads down, next step is to bog and fair the roof and pads so that the glass edges are faired out. As I mentioned, very little of this area will be visible, just a strip along the top of each pad about 40mm wide, about 40mm at the top of each panel before the centre strake (this space is needed to provide the ventilation needed to remove heated air from under the panels and to hide the wiring) and for 20mm or 30mm under each panel which would be the limit of your ability to see under the panels. Because roof below each sides panel array is highly curved it is not an area you could comfortably stand or walk so I will have that faired properly and painted high gloss white. The roof under the panels will also be painted gloss white but I wont be as fussy about the finish under the panels between the pads.

Next blog report should have the outboard wells finished, rudders hung, and maybe even rear steps at the very least dry fit ready for glassing. This will complete the final appearance of the boat and I cant wait. The only other big changes to the overall appearance to the boat after that will be the entire boat being shiny white and maybe the windows fitted. Yep, I cant wait.


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