Materials and Construction – getting my head around what to use and how to do it…

So I am starting to develop a better understanding of the materials I will be using and construction methods that I can use.

I will be adding the appropriate page tabs above around materials and one for construction.

By way of an introduction to these pages I will highlight some of the decisions made and progress towards goals.

First of all materials.
I am now fully fixed on all structural components being made of 25mm CoreCell, double sided slotted with 1000gsm fibreglass fabric each side. Teh superstructure will be of lighter Corecell with the appropriate glass fabric.
And on the subject of fabric I will be using some strips of Kevlar/Glass fabric at certain points of the boar including the widest points of the hull, the bow waterline, some of the keel, etc to give that extra puncture resistance. Some carbon fibre will be included especially around the mast seatings but generally glass will suffice. I am building an expert team around me of materials experts and have been really enjoying the help of Dick Garrard, who apart from being a funny bloke knows a sh1t load about composites.

Next construction mathods.
Well I have thought long and hard about this and although all the experts done agree with me I am going to go with a modular construction philosophy. In addition I intend to resin infuse the vast majority of parts. The combination of these two facts means that the structural manufacturing sequence is as follows;
– Each hull will be identical and the main hull will be made of 6 major parts, excluding the bulkheads.
– Each hull will be divided longitudinally down the centre-ilne of the hull (see FRAM blog for an example of this);
– Each hull will be split transversly into three roughly equal parts of 6m long each;
– Each of the 3 hull modules (front mid and rear) will comprise of the the two halves of the module and all bulkheads including a stub major bulkhead (more about that later);
– Each module will be joined to the other via a structural secondary bond using kevlar;
– ALL components (or at least the VAST majority) will be made using vacuum infusion and in-situ building minimised;
The bridgedeck will follow a similar path with many modular parts being constructed and se3condary bonding used to fix the modules to the hulls. Currently the plan is…
– Bridgemodule one will include bulkheads 1 and 2, from the front of the forward salon to the forward wall of the cockpit.
– Bridgemodule two will include bulkhead 3 and 4 and take in the entire aft salon;
– Bridgemodlue 3 will include all the parts in the cockpit not covered by 1 and 2.

So there you have the outline of where I am going. The mast layout and design is still a gaping wound in my plans and is causing me lots of headaches

Ok, keep well until we catch up next.

Mick

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A lovely sunny day

Well today is a lovely sunny day and that is good, we seem to have started the climb back out of winter towards spring. But Melbourne weather will assert its authority again later this week with 14 and raining. But as we say here…”did you don’t like the weather…wait 10 minutes, it will change!!”

So progress on the boat.

Design wise…I have lots and lots of drafts of lots and lots of varients on a theme. Sound familiar?? There are, as is normal, a number of competing aspects to the design.
So whats settled? The size to a large extent is settled for me. Somewhere between 17~18 meters. I think the cost structures of bearths and the layout will determine the actual length. The width of the hulls are settled. I want to be able to place a full Queen sized bed at 400mm off the hull sole so I’m aiming for a width of 1700mm at 400mm over waterline at the rear bulkhead. The maximum hull width will be 1950mm located near the centreline of the hulls. The bow will be an axe face shape or possibly an 8 degree slope forware from top to bottom. The beam will be 8.5~8.6 Meters. I am not a fan of the long sloping windows i some cats and will change them for windows at about 8 degrees to the vertical. Additionally these will have the salon roof overhanging to provide shade. Another aspect that I am fully behind is the main bed being on the bridgedeck. The actual location is still fluid but we are working on it.

OK, so what are my design problems to be solved/decided.
AS is the way of things a lot of the design aspects are interdependant. A change in one alters many others. Which is the first decision, well due to the interdependancies there is not a first decision, there are scenarios to consider.
So lets start with the mast scenarios. There are basically two that I am considering. The traditional bermuda setup and the aftmast concept being championed by a good bloke called Brian Eiland.
Scenario 1. This can be summerised by Malcolm Tennants Vega design with the traditional bermuda rig. I really, really like it and with a few updates I think it is a winner. Updates would be the bow, the windows adn a change to the rear bedrooms, I would just have one large one with a rear access. And possibly some different deck access arrangements.
Scenario 2 Aft mast config. This makes some significant changes to the Vega. Because of the location of the aftmast base (on the vega close to the middle of the aft bedroom) there will need to be changes to the layout. So what changes? I like the large open front area salon that the vega has so maybe its just a swap of the centre cockpit to the aft location so that the bedroom moves forward to accommadate. When I say just, this is a major change to the structural layout and will mean a full structural redesign. The hulls skin will stay the same shape but the bulkheads will move. Access from the rear cockpit to the front salon is a challenge given the location of the aft bedroom but that is just a layout efficiency problem. Anyway that is secnario two.
Scenario 3 Aft mast config 2. Similar to Scenario 2 but swap the bedroom to the front salon location and vis versa. I have a location sketch of this and although there are problems with this layout it will create a super master bedroom which I beleive is very important both for us living abard AND resale…rememebr its the woman that makes most of the buy choices!!! Anyway thats scenario 3. Just a note on 2 and 3, the cockpit at the back will be a dual level thing. There will be part at the bridgedeck level and there will be part which will be at a similar level to the standard VEGA cockpit level, maybe a little higher. But it will be in the same area as the lower cockpit so communcations will be cool and the skipper will be part of the group.

So they are the big design considerations I am working through. The standard is cheapest, but if I go Aftmast (which I would really like to) it will cost money to get the redesign done.
Credit for VEGA design see here..http://www.tennantdesign.co.nz/index.php?page=vega

The Model: Well the model has started. See the model page. But what design am I going to use, what layout. Well that will evolve as the model evolves. Right now the hulls are common so will be the starting point. Have a look at the model page for an update.

Materials:- This has been an interesting journey. I have learned so much about materials in the last couple of years. Materials and composites. I now realise that you have to be very very careful with checking the date of any article as the technologies in both materials and composites have changed quite a bit. Acceptance of change talkes a very long time which at face value might seem to be a bit stoggy BUT when you dig further there is a very valid point to this. A new material or combination needs at least 10 years of real world application before we can truely understand the good and bad of it. Therefore when going with “new” materials like corecell we are to some extent covering untested ground. Thats not to say that it is wrong….just had limited real life experience. There seems to be two components that stand out in the discussions, below waterline usage and Heat distortion. The below waterline one is very very valid. How does a material/combination react to long term submersion and as importantly is the QA of the workmanship going to jepordise the material through little fault of the material perse. Quality of layup seems to come up time and time again when discussing boat hull faults. So my conclusion is that whatever material is decided that is only half the story, ensuring true quality of the layup is even more important. I wonder if the hull shoe should be treated differnetly when it comes to construction…don’t know, will eb exploring.
Regagrding Hear distortion, this one got me by surprise. A particularly good boat surveyor source focused on this and I was surprised witht he results. A boat hull or deck left out in the sun (and Australia’s got plenty of that) gets up to the mid 200 degrees F. Wow. But I can understand that. I have tried to walk across a hot deck only to do the beach bunny hop to stop the soles of my feet from burning. So this IS an important factor for Australian boats. I was then surprised to see that some of the excellent core products only go to the low 200 degrees F in their Heat distortion ratings…!!! Wow again.
POLYCORE. Current my favourite material for part of the construction….why? no factual reason but it seems to be a very sensible approach. Weight wise it seems to be similar to corecell, so no big advantage there, strengths, somewhat lower than corecell. Resin soak, seems about the same?? So right now I am trying to compare Polycore (or any equivlent) to Corecell (or any equivelent). Boy is that hard to do. Try to get some small samples of either and a sales prson who actually knows both well. Its very hard to do and I am struggling. But I will persist. Regarding Polycore, I have the name of a guy who is building a polycore boat about 5 hours drive from me here. I am goign to try to get over to have a good look at the stufff. i really dont understand enough about it to decide what is best. Mark from Compositepanelsaustralia has been very good to be and has chatted about things freely. I like that.

AFT MAST. Oh boy has this been fun. First of all big cudos to Brian Eiland who is a good bloke. He has been very much a champion of this and freely discusses with anyone who wants to hear. I have created a discussion document that I will upload discussing aftmast configs. I am trying to mimic luffing jib construction cranes with fling jibs. Thi sis along way from being settled. The ONLY thing that is stopping me from deciding today to go AFTMAST is cost. Two components…the cost of the redesign of the VEGA design and the cost of the loss I will make due to lower resale value because of the “unusual” mast configuration. But I want to take the chance if I can afford to. Regardless I want to help develop this concept with Brian.

MONEY:- I still dont have the money to complete the project, but I am going to start anyway…if I dont its guarnteed not to finish but if I do start it has a change…

So there you have the latest gossip on the boat. Talk soon.

Mick

Needs analysis

The nice to have analysis

All designs require a needs analysis adn here is mine. Should not be called a needs analysis more like a nice to have analysis…but here goes…
I added a usage analysis jsut to try to develop some reletive priorities. Yes I know that we could drive a truck through the gaps in this but its something for me to work with.
Also not that I have really focused ont eh accommadation side. The rigging etc will take care of itself when I talk to a designer.
Mick