Firstborne: 8m light cruiser
Manik,
Attached is a crude sketch as requested regarding the flip down seats.
One last thought….
Why have just one cargo pod? If you are careful with the geometry, you should be able to get 3 pods in different positions to suit loading and weather. So you can go from a no pod singlehanded sports boat through to a 3 pod 4 person cruising boat as per attached sketch.
Rob
P.S.: Skateboards are a great idea, and much less hassle to carry on board.
That drawing looks great Rob! The aka cargo pod with the folding sides is a work of genius; it’s simple to make and install, and it literally accomplishes 6 different tasks at once! (dry stowage, dynamic ballast, backrest, wind/spray cover, cargo transport to shore, and it’s a table) xD Absolute genius!
Where stowage space in general is concerned, I think that the stowage lockers under the foredecks have enough space to fit two hiking backpacks each, and if the aka cargo pod fits 4 (no problem in my opinion), then I don’t think that any additional stowage space is needed. Maybe I’m being too optimistic though, there’s bound to be something like a tarp, or perhaps fenders or something, which will require stowage volume somewhere.
What also occurred to me last night, is that my proposal for the open deck lee pod with bike stowage space would be quite heavy, at least if it’s built in plywood, with a plywood-foam sandwich for the deck, then we’re looking at no less than ~6.5 sheets of 4mm ply (2 for the bike floor, 4 for the deck sandwich above that) plus the weight of epoxy and foam. That would likely get me somewhere over 100kgs just for that structure. That means either:
(1) Sandwich construction is necessary to dramaticall reduce weight
(2) I made the deck significantly smaller
(3) Both of the above
The skateboards are an interesting idea in that regard, because then I don’t need all that space that 2 bikes would take up, and making the lee deck considerably smaller wouldn’t be such an issue. On the other hand, having full-sized bikes along would be a nice plus, because then you can also do some more extended inland exploring along the north sea or baltic coasts. You can’t take everything along though! I guess the decision depends mainly on how much the open lee pod with bike stowage would actually weigh. There was some talk about foam-plywood sandwich panels in the “Sweet Rhode Island Red”-Thread, but what about just foam-glass panels to make it even lighter? How light could a strcuture made of two 4000x1200mm floors spaced 250mm apart be built, without having to resort to carbon fiber or expensive honeycomb materials?
@Michel: The estimate for outboard horsepower is much appreciated! I’d had something like 3-3.5 HP in mind, though if you say at least 4, then I guess I’ll look into 4-5 HP outboards instead. As much as I dislike the idea of having an outboard, you’re probably right in that with those currents, it’s a safety consideration and not just a convenience factor.
Some dry storage and bunk is more than “nice to have” in our region. Its not funny living in a wet tent.
My intention was to camp in a tent on land, though Rob’s proposal for a tent on board would eliminate the need to find a port or campsite. Does it rain that much in the summer up there? Am I understanding you correctly in that you are proposing that the boat should have a closed “cabin” for the bunk? I’d be quite reluctant to add something like that because of the extra labor involved, for all intents and puposes it would start becoming more of a yacht than an open boat then… What did you decide on for the larger and/or newer variants of Kea? I’d love to see some pictures!
Marco
I used to work on a tjalk that sailed from Harlingen to West Terschelling, Vlieland and Texel. The currents and tide can either help you tremendously, or make your planned passage impossible. When you start out, you will learn quickly to time your passage during favorable currents. There are only a few channels that boats tend to follow, and they can become like rivers with current and at low tide there is land or shallow water on each bank. You can set the boat on the ground during low tide (droogvallen, I’m not sure what it is called in English), but you have to be very careful about not being in a place where there will be waves when the water comes back.
A shallow draft multihull is ideal to explore this area, you can find dune islands that no one else can get to.
I would place two beams across the akas and lash the bikes down there, next to the ama. Storage boxes will get heavy, and then when you fill them with stuff they will be very heavy. You have a high displacement hull that will make this possible, but be aware of performance issues. A lighter boat is generally better. Of course, easier said than done.
Thanks for sharing your plans with us, Manik. Erskin Childer’s The Riddle of the Sands was set in the Wadden Sea, so it’s always been an area I’ve wanted to visit. The general hull shape looks great, I like the flat bottomed trapezoid for all the reasons you have given.
My two cents: consider doing without a lee pod, this is a camp cruiser, not an offshore cruiser. It adds a lot of weight, right where you don’t want it, and strapping the bikes or skateboards between the beams is a much lighter way to go. That’s important when dragging the boat over mud flats (OK, that’s iffy for a boat this size) or for performance in general. The worst part is that the pod and any stuff stacked on it, such as bikes, will be constantly in the way of shunting the crab claw, catching lines, obstructing the yard, and causing general mayhem, especially when sailing single-handed. Not to say it can’t be done, but get the shunting all figured out before you decide you must have that pod!
Chris Grill’s crab claw rigged Desesperado was cruised successfully along the Mexican coast with no pod.
I like Rob’s cargo pod with flip down boards. Easily built and easily left on the dock for day sailing.
The cargo pod doesn’t have to be solid if it ends up being too heavy in itself, Make a waterproof sausage bag on a stretcher. Depending on what is inside and how you pack it, it will be a lot softer on the back as well…......
If you put some thought into it, you might be able to get it to double up for other uses like a canopy, tent component or camp bed frame.
Obviously everything that Marcel says regarding tides etc is absolutely spot on…you will learn that you will have to move between camping spots at all sorts of strange times to suit tidal times and heights. Planning ahead is everything.
Chris Grill’s Mexican podless oddessey obviously worked but everything was a lot warmer. Waddensea can get seriously cold even in the middle of summer, and you would not want to restrict your sailing season too much because if you like solitude, out of holiday season, Waddensea is even more beautiful and haunting (apart from friendly Dutch girls). So you will need extra gear. There might be up to 4 people on board, not 1 or 2.
I just read about Chris Grill’s adventures a bit; this post caught my eye. He capsized out in a chop:
I detached the capsize recovery stick and got it into position and began to lever the boat over, sitting on the stick as far out as I could, my feet on the keel, pulling hard on a rope out to the ama. Slowly, very slowly it came up and over then I was back in the water with the ama coming down on my head but I’d been here plenty of times before and submerged myself to avoid being conked. I’d been capsized for over twenty minutes and it was a huge relief to be the right way up again.
I think if this boat capsizes, then getting it upright again will be next to impossible, and I would definitely not want to spend 20 minutes in the water in the north sea (can that be fatal?), at least not without a wet-suit. Having something on the lee side to prevent capsize in most situations, whether that be a pod or a safety ama, is an absolute must! For similar reasons I’m very keen on having a lot of sealed or foam volume in the hull, to ensure the boat floats relatively high even in the event of a capsize. If it floats high, then hopefully everyone can more or less stay out of the water, or only have their feet in the water, standing on the underside of the akas essentially, until we can get a tow or be rescued by another vessel. I don’t want anyone freezing to death out there, even if we do capsize and it’s late (or early) in the season. You can’t cover all eventualities, but I want to do my best to provide at least one layer of safety for most of them.
Just as skyl4rk said, lots of weight is a bad idea. I’m really liking the idea to just lash the bikes out onto the akas, near the ama. If I can get some large and relatively tough waterproof sacks which fit a bike each, and then just lash the whole thing to the aka/ama out there, then that’s probably by far the best solution. No extra weight, the weight of the bikes is out on the ama stabilizing the boat, they don’t get in the way at all, and thanks to the waterproof sacks the bikes are not exposed to the salt water either.
With the bikes out of the way, the size of the lee deck can be reduced, drastically cutting down on weight. I’m thinking of just running the akas out to the lee side a bit, and putting a 1200mm wide lee deck (ply-foam-ply sandwich) on there, with sidewalls (an open-top pod like before), followed by a lightweight but large safety ama & leeward cargo pod. The lee deck could sleep 2 and the vaka would sleep 1. That would all be open though, so sleeping on board is for good weather only, unless a tent could be rigged over the whole thing.
As the cutout of the updated vaka shows, the vaka stowage lockers are actually becoming quite small, due to the distance between the akas, and my desire to run the aka bolts into the open part of the vaka, to make assembly easier. At the moment they look like a good spot for the rudderboard trunks, so it looks like the safety-ama / lee cargo pod is the way to go where stowage is concerned. I’m hoping that a simple arced guide-batten, permanently installed, will be enough to cleanly guide the foot of the rig over / around the lee structure cleanly.
If I get rid of the stowage lockers in the vaka, I can also just divide the hull into its 3 sections at the aka-support-bulkhead, instead of at the bulkhead closer to the bows. That makes the central hull component shorter and lighter and thus easier to transport and manually move around, saves a little labor because I only have to reinforce 2 bulkheads with timbers instead of all 4, and it makes the boat easier to assemble because having the bolts in the open part of the vaka makes them easy to get at. 😊
I’ll try to finally get rough CAD models of the akas, ama, and windward cargo pod done tomorrow.
The other thing that might help and save weight is to have another look at the basic proportion of the vaka underwater cross section. Bearing in mind that you need extra load carrying capacity, widening a vaka is a more efficient way to do it than deepening it. Your design seems to be on the narrow side anyhow.
On a wider hull, when you max out the load extra immersion will be less and freeboard will remain higher.
You really do want to be as shallow as is reasonably possible. There are times when you might be able to tow the boat wading through the shallows to cheat tide rather than motoring painfully slowly against it with an outboard screaming at you.
My intention was to camp in a tent on land, though Rob’s proposal for a tent on board would eliminate the need to find a port or campsite. Does it rain that much in the summer up there? Am I understanding you correctly in that you are proposing that the boat should have a closed “cabin” for the bunk? I’d be quite reluctant to add something like that because of the extra labor involved, for all intents and puposes it would start becoming more of a yacht than an open boat then… What did you decide on for the larger and/or newer variants of Kea? I’d love to see some pictures!
Hi Marco,
Forget full size bike’s on a boat. I carried one on a Dragonfly 800 Trimaran and this one has really big trampolines. It was in the way all the time. Either you use foldable bikes or skateboards. Bikes lashed near the ama are exactly at the wrong place if you have to hike out- or recover your boat from a capsize.
Weather: Lets say so. If you want to have good weather its always raining. No, that was a joke, we normally have better weather than inland 100km away from the coast.
As soon as I have sent my post yesterday I thought that I have too much of my own thinking and wishes in it. I did a couple of dinghy tours when I was young and we always had lots of fun. But very early in my cruising career it was clear that Iam a guy who wants to have a dry bunk and stores without building up a tent first.
Your camp cruiser is a different breed and thats more than ok. You will save a lot of wheight, plywood, costs and manhours to build it.
My Kea design is a little “yachty” with high freeboard and a small “cabin. Thats just because i want to delay the wet- or drysuit for one windforce more than with a low hull (again, like a beachcat.). The inside is like James Wharrams “flexi space” concept. Just a subdeck to sleep on with footholes in it to sit. Storing bags at the sides and the cooker in a moveable “kitchen box”. Even the nav Table is moveable and can be operated on the trampoline. There is no fixed furniture built in to keep labour and wheight down and make things simple. But of course the plywood bill rises a little as the workhours do ... 3 to 5 working days more I think.
For your boat you should have your trampoline minimum 60cm above the water. Even if you use a system with struts as the Hobie 16 to bring the beams up.
And forget the comfortable cockpit seating. If the wind goes up you will have to hike out on the trampoline to stabilize your boat. And you should be able to cover your cockpit from overcoming water. These are real facts as the one that you have to wear a neoprene suit as soon as you are sailing in conditions where your boat can capsize! Safety first!
Anyway, I looked after my design list and found some good hulls for a vaka that should suit your wishes and thoughts. I will post them on monday or tuesday, because in the moment Iam with my girlfriend and writing on her pc.
Short thoughts:
3 or 4 horsepower will do it. I had the old Evinrude /Johnsen 2-cycle 4 horsepower motor in mind, a very light and simple unit with an integrated tank. Just right to power your small boat. The “modern” 4-cycle motors have a very bad power to wheight ratio.
Make your trampoline big eneugh that you can build up a “throwing tent” on it. It is as you said: With the tent on board you can anchor outside the habour safely and quiet, drying out at low tide. There are such places (I know of) on Wangerooge, Spiekeroog, Langeoog, Norderney.
Best Regards, Michel
I really like the lower picture in post #5. It makes me think you could have quite long machined foam bows. Maybe 1-2m each? That *could* get the vaka small enough to cartop. Bonus points if the foam bows fit inside.
My wife and I can flip my 16’ wa’apa onto the roof of the car. Maybe the middle 12’ of a longer hull could be doable too.
The machined bows could be really nicely shaped getting the entry the way you want it before transitioning to the hard chined middle. And you could play with different shapes on the same vaka/rig. Sounds fun.
Nice project!
chris
Forget full size bike’s on a boat. I carried one on a Dragonfly 800 Trimaran and this one has really big trampolines. It was in the way all the time. Either you use foldable bikes or skateboards. Bikes lashed near the ama are exactly at the wrong place if you have to hike out- or recover your boat from a capsize.
I have been sketching cartoons (I’m no designer) of ndrua of approx 30 feet for a while now, to go with full-size bikes that have gone through S&S conversion. My 30ish-foot length, plus my voluminous second hull, are 100% determined by bike storage. I want to have two kid bikes along with the two adult bikes, and that is a lot of bicycle to store aboard.
If you want full-size bikes (and as a long-term bike tourer, I think you do) then the S&S conversion is pretty much the only way to go. The Bromptons are great for city riding but I don’t think they are right for your intended usage. Also the price-performance ratio on Bromptons leaves a bit to be desired, at least from my cheapskate point of view. The Montague fullsize folding frames are okay, but they usually come with substandard components.
Thanks for all the feedback guys!
I’ve finally got my last exam for the summer semester behind me (was kind of busy the last few days as a result), and now I’ve got 8 weeks off from uni to focus on this boat. Here two images of the present state of the CAD model. I decided to drop the whole thing with the large lee platform because of the excessive weight. The trampoline and a trampoline tent will just have to do.
The lee pod is intended as a cargo pod. I think I’ll still play around with the shape a bit for aesthetic reasons though, and I’ll have a look if the width is ok in terms of pod buoyancy and heel angle at which it touches the water. Where bikes are concerned I’m kind of resigning here; lashing them onto the lee pod is a conceivable option. If they fit, they fit, if not, too bad.
Concerning the akas: does anyone know what sort of bend-radius I can expect from 6mm Okoume? My gut feeling is that the radius which I just sort of arbitrarily chose to use for the akas, is way too small to bend even 4mm ply around. (I’m planning to make the box-beam akas, with 3x 6mm ply laminated together for the top and bottom panels of the box beam.
Personally I’m really liking how modular this entire design is becoming as a result of the dis-assembly requirements though. As Luomanen pointed out, you could have CNCed foam bows, or swap out the bows and try something different at a later stage if you like (or a different bow on each end so you can compare?).
I’ll try to get the aka cargo pod, rudderboard trunks, and daggerboard trunk(s) in today or tomorrow, and move the position where the vaka is divided into sections from the forward bulkhead to the bulkhead which supports the akas. The vaka would then consist of 3 roughly 2700mm long sections, with the rudderboards in the bow/stern sections.
The rig is what has me most worried about the design at the moment. Getting the foot of the yard to travel across the boat to the other end cleanly, could turn out to be really tricky. I’m looking forward to finally getting to that sometime soon as well! 😉
Marco
I remember this random text file that I once found in a random place on the internet. It’s from the guy that has the LU-LOONIE one sheet boat design. Unfortunately his site is gone now. Anyway:
=========================================================
Bending Plywood
The following rough guide for the maximum bend in a sheet of dry
plywood comes from “Boatbuilding Manual 3rd edition” by Robt. M.
Steward (1987). The bend is given as the smallest radius of
curvature to which the plywood should bend without deforming. I
developed a formula to answer the question, “I want to bend a
sheet of plywood 3 inches in 6 feet, what’s my radius of
curvature?”. The formula I came up with is explained following the
guide.
Bending guide - all measurements in inches.
plywood min across min with
thickness grain radius grain radius
1/4 24 60
5/16 24 72
3/8 36 96
1/2 72 144
5/8 96 192
3/4 144 240
The table tells us 1/4 inch plywood sould bend into a 4 ft circle
across the face grain and a 10 ft circle with the face grain.
The formula for radius of curvature in inches (r”) is:
b” l”**2
r” =—- + ——-
2 8b”
where b” is the inches depth of the bend and
l” is the inches straight line length of the bend
(not the curved length of the bend)
and “**2” means “squared”
The calculation for the radius of curvature for 3 inches in 6 ft
is as follows:
raduis = 3”/2 + [(6’x12”)**2 / 3"x8]
= 6” + [5184 / 24]”
= 222”
what’s below is how I got the formula for anyone who wants to
check it out. all it requires is high school geometry and algebra.
—————————————————————————————————
1. draw a circle and a chord. draw the radius from the centre of
the cirle through the centre of the chord and a raduis to one end
of the chord. the arc of the chord is the bent plywood. the length
of the chord is “l”, the raduis of the circle is “r”, and the
length along the radius between the arc and the chord is “b”.
2. the raduis to the end of the chord is the hypotenuse of a right
angled triangle whose three sides are of length r, l/2, and r-b.
The Pythagorean theorum says the square of the hypotenuse is equal
to the sum of the other two squares, ie r**2 = (r-b)**2 + (l/2)**2
3. use algebra to rearrange the sums of squares equation.
r**2 = (r-b)(r-b) + (l**2 / 4) , squaring right side
= (r**2 - 2rb + b**2) + (l**2 / 4)
0 = (-2rb + b**2) + (l**2 / 4) , subtracting r**2
2rb = b**/2 + (l**2 / 4) , adding 2rb
r = (b**2)/2b + [(l**2 / 4) / 2b] , dividing by 2b
= b/2 + l**2/8b
r = b/2 + l**2/8b
- END -
—————————————————————————————————-
-Thomas
Forgot to say, design looks good! Definitely keep the self-bailing foot well.
-Thomas
Why do you have risers between the main hull and aka?
If you want to reduce the angle of the bend on the aka, you could build the receiver box on the side panel of the ama, so that the angle is not vertical, but at the same angle as the side panel of the ama.