Getting out on the water this year

What does your design brief look like? What are your requirements for the boat? What do you want to use it for? What does your budget look like?
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Manik
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Getting out on the water this year

Post by Manik » 28 Jan 2015, 14:19

Hey guys,

I've decided to set myself the rather ambitious goal of getting out on the sea with a proa of my own design this year. Due to other obligations I can't start construction before the 1st of May, and if I want to be able to get any sailing in at all with the new boat this sailing season, then I'd have to get the boat in the water for final fitting out by very early September. That's 3 months, in which I can build almost full time, to try and get the boat done.

The thing that becomes immediately obvious looking at the time plan, is that my design is going to have to be optimized for low construction time. No more endless speculation and pondering over armchair performance gains. ;) While you may lose a few percent in performance by say opting for a flat bottom instead of a semicircular one, not getting out on the water, means no performance at all. The mantra here is keep it simple, keep it easy to build, stick to the essentials only, and not to worry about making it perfect, I can always build a better one next year, or do incremental upgrading. The goals are similar to what they were before, so much of this will be familiar to those who know my Firstborne posts on proafile.

The design brief is:
  1. Coastal cruiser for the Baltic and North Sea (including the intertidal Wadden Sea)
  2. Optimized for single-handed sailing
  3. Daysailable with 2 people
  4. Suitable for sailing in cold weather (below 10°C) to extend the sailing season
  5. Seaworthy enough to sail in force 5-6 in the intended waters
  6. Re-rightable single-handed without outside assistance
  7. Construction time of no more than 500 hours
  8. Cost, ready to sail of no more than 4500€ -- incl. EPIRB & VHF, excl. trailer, and excl. setting up workshop (already done)
  9. Suitable as a testbed for future boats
Optional / stuff which could be done without for the start:
  • Suitable for singlehanding at night
  • Active radar reflector
  • AIS
  • Camper cruiser for two
  • Man-powered propulsion (prop, paddle, oars, or something)
The next post will be about what conclusions I have drawn from this design brief, and how I plan to tackle the whole thing. The CAD model is still in the works, but more soon! ;)

Cheers,
Marco
"Man's mind and spirit grow with the space in which they are allowed to operate." - Krafft A. Ehricke, rocket pioneer
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Re: Getting out on the water this year

Post by old school » 28 Jan 2015, 17:48

I can understand your sense of urgency and reason for compromising design and build method to achieve quick results. From previous conversation I also understand that plywood will probably be your material of choice, so will not even make further mention of the speedy build benefits of table laid foam core composite panels.
Also, I have been a long time fan of Wharram, so have an idea how his design has evolved to suit both form, function and build method. On top of which there is my own experience covering a range of design/build craft from single chine flat bottom to the present hybrid construction effort.

This latest design construction method I won’t go into any further discussion on in this thread, because it has not been fully proven. But the basic concept can still be applied to the scenario you propose…………………..rather than creating a canoe of compound curvature, a plywood V bottom is an excellent compromise.

Look what Wharram has done with his Tiki designs to see how the basic V form can be extended, creating a relatively light stiff structure with a sea-kindly shape.

Once you have the light and structurally adequate shape of the bottom boards with bulkhead support, you have your essential vaka to build on.
skyl4rk
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Re: Getting out on the water this year

Post by skyl4rk » 29 Jan 2015, 01:12

Good project, I will be watching
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Amati
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Re: Getting out on the water this year

Post by Amati » 31 Jan 2015, 06:43

Sometimes I think that actually sailing might be cheating.....
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Re: Getting out on the water this year

Post by petermirow » 31 Jan 2015, 11:40

Dear Marco,

that sounds like a neat design brief. And the targeted construction time of 500 hours seems suitable (3x8x22=528) to get a good result, if you can concentrate on building, and leave all the planning and pondering behind you once you start.

My contribution here would be that you also concentrate in the next months, until May, not only on the design planning, but also on the sourcing of the material. In my own experience, one can loose considerable amount of construction time to get stuff which does not seem obvious at first glance. Like rubber gloves, brushes, that odd stainless screws or fitting, sandpaper... you name it. It will also consume a surprising amount of your budget. Therefore, if you manage to plan ahead regarding these items, and stash them on the construction site, you win lots of time. Of course you should also have the more obvious items, like your wood, epoxi and other stuff ready at hand.

There is one relevant point which I did not see in your design brief, though, which seems very important to me. I is how you plan to store and launch your boat. Where are you going to keep it? In the water, on the dry, assembled, disassembled... If disassembled, can you manhandle the parts? Alone,... How many hands needed? This takes great influence on your end design, and will greatly impact on how you use your boat, on your maintenance cost, and on the overall life expectancy of your sailboat.

Keep us posted on your progress.
Cheers,

Peter
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claudio
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Re: Getting out on the water this year

Post by claudio » 31 Jan 2015, 15:47

Hi Marco, Aloha from Maui...
Your design parameters and your whole approach to building are right up my alley! A logical and do-able craft. I'm sure it will be a very enjoyable and successful project.
Peters' points are all well taken. Buying even the basic stuff...just to get started... ahead of time, can save a lot of running around. Moving the boat (and/or parts of it) can be amazingly simple with just a few bicycle wheels (or coasters) nailed to some wood braces.
I look forward to following your build.
Cheers for now,
claudio
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Re: Getting out on the water this year

Post by old school » 31 Jan 2015, 22:57

As stated beginning this thread "the mantra is to keep it simple, easy to build, stick to the essentials only.....etc" and as well the design has not yet been finished, the biggest challenge is in drawing up all details before starting the build.
So thinking about it all, you either need helpful ideas quickly or else no advise at all, because you know exactly what to do.

Now assuming the first point, a solution to Peter Mirrow's suggestion would be to rather build using foam cored polyester (maybe vinylester) and glass skinned panels made on a flat table. This way one delivery of materials will allow all panels to be made with minimum of tools or tooling as as and when needed.
Of course a plywood kit would produce similar results in roughly the same timeframe, but all the parts would need more finishing time, so the quicker build would favour composite panels.

Another big design challenge would be to have perfect geometry nailed in the design stage, unless you plan on going with the genuine outrigger concept where geometry is tune-able and variable.
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Re: Getting out on the water this year

Post by Manik » 01 Feb 2015, 23:00

I've been really strapped for time these last few days, but wow guys, thanks for all the support! And I haven't even posted any details yet. You guys are awesome! :) If anything I think encouragement is one of the two best things you can give someone who setting out on a venture -- solid advice being the other one. ;) There's definitely a couple of open points I'd like to hear some opinions and ideas on.

My starting point is John Harris' Mbuli, there's a lot I really like about that design. I think that at 6 meters it's a bit too short for what I have in mind though, and I don't like the relatively low L/B ratio (I think it was around 10-12). I think a higher L/B and greater LOA will give better seakeeping qualities and a bit more carrying capability, so I'm going to go for 8 meters instead. As Jeremy guessed, I have my sights fixed on plywood construction, chiefly because of the low build time and because I want a boat that will last, even if I do build another one in the not so distant future. Foam-core hulls can be built to last as well, but I can't afford the likes of Rohacell or Airex. A Cork/Fiberglass sandwich could be interesting too, but availability is a problem, so I'll stick with plywood for the time being.

The vaka will have a flat bottom. The penalty in wetted surface area compared to a semicircle or half-hexagon is not that large, but the savings in build time are significant. The 5.4m ama will be tortured plywood, a deep-v, but as full as I can make it with that construction method (the goal is a pretty aggressive deadrise angle of 25° at the center of the ama). Last autumn I started working on a series of 1:12 models using the Gougeon Brother's tables for thicknesses, on the basis of a tornado catamaran hull, but modified to be double-ended. To date that's still a work in progress (I've broken 3 models so far) but for the duration of the cold winter temperatures, that project is on hold. I'm optimistic about the 4th set of panels that are lying around waiting to be glued though. ;)
"Man's mind and spirit grow with the space in which they are allowed to operate." - Krafft A. Ehricke, rocket pioneer
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Re: Getting out on the water this year

Post by Manik » 01 Feb 2015, 23:25

There's more from Mbuli though. This article in WoodenBoat magazine about Mbuli says a few important things, specifically concerning time:
He devoted some 400 evening and weekend hours to creating the boat.
And from the CLC page on Mbuli:
Construction is of quarter-inch okoume plywood covered with epoxy and fiberglass. Plans are not extravagantly detailed and are intended for builders who may have built a small boat or two. The lifting rudder-daggerboards and the hollow masts are the most challenging part to tackle. Total cost of the project, including the best materials, high quality sails, and a lightweight trailer should be under $5000.
400 hours and $5000 sound like pretty good news to me, but my boat is going to be bigger, so I'll have to make sure the hours and costs don't creep away from my target. The second thing that really got me thinking, was the bit about the construction time of the masts and daggerboards/trunks. The rig had me particularily concerned. My preference would have been a Tornado rig (or similar), but to get at a Tornado mast, I'd have to buy an entire Tornado for >2500€. Building my own mast is out of the question due to the time involved in construction and design. There aren't many other dinghies that have ~20m^2 of sail area, but ever since I got a somewhat broken 470 dinghy for free a few months ago, the solution was pretty much staring me in the face: a schooner with two 470 mainsails. At ~9m^2 each that provides the sail area I want, and I can get the masts easily and cheaply. Upwind performance will suffer, but I think from a handling and balance standpoint a schooner rig has its advantages.

The next point to tackle was steering. As they said on the CLC site, rudderboards take a lot of time to build. For very shoal waters I need another steering solution anyway, so I'm going to drop the rudderboards altogether, and go for sidehung kickup casette rudders. It gets better, I don't even have to build the rudders, I can just buy two used 420 daggerboards. With their pretty much rectangular planform they should be perfect for that, and availabilty is even better than for 470 parts. ;)

As it stands, I'm well underway in securing the hardware. I could have everything on hand a couple of weeks from now. :)
"Man's mind and spirit grow with the space in which they are allowed to operate." - Krafft A. Ehricke, rocket pioneer
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Re: Getting out on the water this year

Post by Manik » 02 Feb 2015, 00:35

What that really leaves, is the vaka and cabin, and all the requirements they have to fulfill, and that is still very much a work in progress.

Another feature I definitely want is a lee pod or safety ama to prevent capsize. Sven Stevens recommended an angle of 15° for the pod to make contact in one of his posts, and I think that makes a lot of sense. If I get hit by a gust while I'm catnapping, I'd really rather have it heel to 25° than say 45°. To meet the 15° criterion with a pod clearance of 0.3m (which I think is reasonable), the pod has to be about 1.1m wide though, which is huge for a boat of this size. There's a couple of options I'm thinking about:
  1. Make the pod 1.1m wide
  2. Make the pod 0.7m wide (single berth) and...
    a.) add an inflatable safety ama next to it to get the necessary width for a low cost in weight
    b.) leave it as it is and lives with the rude awakenings at higher heel angles
  3. Make a very small pod which only provides some extra elbow room, and go for a safety ama
    a.) either inflatable
    b.) or a light plywood hull
Overall it seems like a good idea to get the width to leeward, not just so that heeling over isn't as dramatic, but also for the extra room for sail-handling on deck. The boom on a 470 is 2.7m long, and even with the masts set to windward of the vaka, having the extra deck/trampoline space seems like a very very good idea. Getting at least a little extra elbow room in the vaka seems wise as well. My initial CAD model of the vaka (see below) features a ~65cm wide pod, and the vaka itself, without the pod, is also only about 65cm wide at the top, so leaving out the pod altogether would make for a tight fit indeed.

-- One more post coming up... ;)
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"Man's mind and spirit grow with the space in which they are allowed to operate." - Krafft A. Ehricke, rocket pioneer
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