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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Re: Getting out on the water this year

Post by Manik » 14 Feb 2015, 22:31

A point which just crossed my mind as well, is that I always intended to install an emergency entry/escape hatch on the underside of the pod, in case of capsize. Without a pod it becomes difficult to find a spot to put such a hatch so that it's above the waterline both when the boat is the right way up, and when it's capsized...
"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 » 15 Feb 2015, 22:52

As you remind us Marco, there is also the possibility of detaching the safety ama and rolling the waka over in a worst case scenario of righting from capsize…….better to have enough buoyancy higher up to lee for prevention of such capsize in the first place.
I had a friend who made his own inflatable --– built up from a +- 6M rigid bottom, and it looked and worked as good as any “bought” inflatable. So the possibility of building your own tube with conical ends, certainly fits well into a plan.
Two of these tubes could be used with connecting booms/kiato (not ‘akas’ because of no bolts or glue to join structure) and will make a useful raft tender.

Talking about basic /centre section profile………….what I go for is a seating bench bulge on the w/ward side of waka , which can be close to water surface like the step seen on inside edge of just about any cruising condo catamaran. This helps to keep body weight to w/ward and blends into a deeper structure for stepping the mast…..also provides more knee space inside.
Stepped up yet again from this bench is the w/ward bunk pod, which 0.6M up from water surface.
Cabin extends to leewards from a step same height as the bunk base (0.6M) but is only a shelf 8 inches deep as a galley top workspace. Rather than a pod with half a dozen extra sq M surface area. Extra area is only that of the shelf, since lee cabin side can be a curved panel meeting hull sides at each end (forw and aft or aft and forw ends)
This configuration allows sitting headroom in the cabin, with easy access to the w/ward bunk.
Standing headroom is through a hatch right in the middle of the waka………covered with a tent when at anchor, to make a fairly comfortable cabin for a 23 footer………I am now drawing the craft described as a 7M waterline proa with Eskimo type parkas fitted onto two other hatch apertures, allowing steering and sail control seated with lower body inside and upper body outside….Eskimo kayak style.
Will elaborate in another following message
=Jeremy
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Re: Getting out on the water this year

Post by old school » 16 Feb 2015, 18:45

Originally my quest in proa design was for low cost, seaworthiness and single-handed manageability. Motoring did not even come into the picture, but now with age creeping up, this has changed. So for me a twenty something footer is no longer of use, however, I find it rewarding putting together all the ideas from over the years to meet the design brief in this thread. Especially so since they all come together so well in the picture and plan I have in my mind.
Lines are fairly modern looking……. Nothing ‘old school’ but comparing a little to a newish catamaran I have just seen in the Whangarei town basin. This is mostly in the areas of flat/plumb hull sides, reverse sheer line and stem, with fractional sloop rig. These lines come from a flow-on when keeping the hull sides parallel and quite deep…….. boxy above water and easy to build, then crowned off with the cabin top of transverse axis curvature.
Cabin access is different to anything seen so far, being my favorite shape and having hatch configuration to suit a Bermudan sloop mast step and boom swinging arc.
As a shunter it is preferable to keep hatch openings not facing to w/ward, and this includes forwards. So I choose to have two access openings, besides the skylight standing room hatch, and close the forward one when on the move. Through draft ventilation is also provided for and can be a good thing in hot weather on a small boat.
Plan is to have a kayak type lip at the edge of a circular opening in each of these hatches, over which an Eskimo type parka is fitted, when sailing. Hatches are angled at close to 45 deg, so one can be seated inside the opening (on a temporary bench inside the cabin) with upper body outside and facing forwards. Arms are thus positioned to handle sail lines and tiller……….provided the design allows for this, and so far my drawings/sketches of SO7 look good in this respect.
Unlike other proas with sloop rigs (to my knowledge) both mast and control foils are on the same fore and aft line, with the helmsman/person seated just to lee of this line and placing the tiller directly in line with either right or left hand (depending on tack).
Sheets and other sail control lines are within reach, and it is feasible to fit an escape hatch on the underside of the w/ward pod bunk.
-Jeremy
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Re: Getting out on the water this year

Post by Manik » 17 Feb 2015, 14:05

Sounds like your boat is really taking shape Jeremy! Any chance of getting a peek at those sketches of yours? ;) I think it's great to hear from you, our two designs do have one or the other thing in common after all. Have you thought about starting a thread of your own for your design? :)

Concerning the hatches, am I understanding you correctly in that the hatches don't face directly upwards, but instead are sloped about 45 degrees to leeward? The definitely sounds like a good way to try and keep at least some of the water out of the cabin. I myself am still pondering a bit about how best to use my plexiglass canopy / hexagonal cupola as a hatch. I don't know yet if I want to have the whole thing as a movable hatch (difficult to move around, especially when the wind is up) or if try to somehow make it possible to just open it on the top and the leeward side. Maybe I can adapt the idea of a hatch sloped to leeward though. Like always it's a game of tradeoffs, I'm trying to keep the windage and overall size as low as possible, I for instance couldn't have a windward pod (which is tall enough to turn around in) with anything close to 60cm of clearance to the water. At present I've only got 730mm of freeboard at the highest point (not including the canopy), with 270mm draft, fully loaded.

I've been thinking about having a single-bunk-pod to leeward, and a mini-pod/hull-step of some sort to windward, to have a bit more elbow room on both sides when seated at the steering station. The windward step would also be a great place to put the gas burner, VHF (right by the hatch), controls for lights, and the other electronics. I think that would provide an enormous benefit in single-handing the boat, because you'd have everything including the simmering pot of breakfast porridge or the boiling water for a hot cup of tea, within arm's reach while sitting at the steering station. You can stay on lookout then, and don't have to leave the boat unattended while you crawl over to the pot to stir a bit. ;)

Spillage safety is an issue though, and a paper chart + gas burner make for a bad combination too. Getting the steering station, nav. station, and galley all in one, may be asking for too much. That problem aside, something on the order of a 30cm wide hull step to windward should be enough, but I'm really having a hard time getting a satisfactory splay in there which is clear of the water, but has a steep enough angle to avoid excessive slamming from waves.

Marco
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Re: Getting out on the water this year

Post by Manik » 17 Feb 2015, 14:09

@Skip: Where did you cook on the P52, did you have a fixed VHF onboard?
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Re: Getting out on the water this year

Post by Manik » 17 Feb 2015, 14:44

Here's some renderings with a 200mm wide windward pod with a splay underneath which is 60° from the vertical. It has 100mm clearance to the flat water surface, and I rather like how it looks to be honest... :) Parts-count and construction time would go up though... :/

Cheers,
Marco

PS: a quick note, the extra edges at the pod-hull interface at the top, are just artifacts resulting from the way I defined the geometry in the CAD program.
Attachments
windward_top.png
leeward.png
bow.png
windward.png
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Re: Getting out on the water this year

Post by old school » 18 Feb 2015, 21:39

Starting a new thread sounds like a good idea because my solution to the design brief is pretty much defined by different enough features to yours, and there is no intention to detract from your ideas.
That way it will also give me time to make a quick 1/10 or even 1/5 scale mock-up to verify ideas produced in sketches, before I do a presentable drawing to show here.

Features that I have described will be made clear as well, like the +- 45 deg sloped hatchways......................they are not sloped to leewards, since the one similarity between our designs is the cabin top axis of curvature. But where you have a very low and large radius curvature, I have a higher structure with smaller radius and steeper angle where hatches are placed fore and aft.
What appeals to me about lines and structure I suggest, is the simplicity of form for construction ease, at the same time as habitability and aesthetic harmony with modern multihull lines after sleek cruisers rather than condomarans.
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Re: Getting out on the water this year

Post by old school » 19 Feb 2015, 01:45

>"getting the steering station, nav. station and galley all in one may be asking too much"

Given that we are talking about a shunter, and a small one at that, yes it is asking for a lot.

I have seen it done on a a very small boat -- Ahcroc Australis, which was the 12 ft boat Serge Testa sailed around the world. He had a full size chart table, a row of fishing reel type winches and a galley all to hand while sitting on his bunk......which was a normal single bed size mattress on the floor below the hatch.
Washboard and hatch were one piece with padding on the inside, so that it became a convenient cockpit seat when swung open on the hinges at the bottom of the 'washboard' part. He sat with legs dangling down through the opening when the weather allowed being outside, and could adjust the wind vane self steering just behind him. Steering from below was by joystick on the port side (opposite galley on Starb side) and self steering had control lines below as well.

I have not begun to imagine how all this could be duplicated to meet shunting requirements, and so am working on the theory of shifting between two control stations for the sailing part, both within reach of halyards, sheets, furling lines and tillers. Chart work will have to be done on a board stowed under the w/ward bunk.
Cooking at the same time as hands on sailing in a small space is a risky business.......Serge had the worst incident of his circumnavigation when his alcohol fuelled stove flared up and burned him badly. So I a think a galley arrangement with a little more space to separate me from flames is good.......this is possible when the cooker is in the mini pod on the lee side and seating is on the w/ward side. This is about the same distance between me and my kitchen stove in a house, so is not bad for a proa of little more than 20 ft.
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Design Decisions & Some Observations

Post by Manik » 23 Feb 2015, 23:04

On Sunday I had a bit of time to dig out the old midsection frame from my full scale cabin mockup of my previous design Firstborne, measure it, sit down in the frame, and play around with it a bit. It turns out the new design is smaller than the old one in most of its dimensions (see added wooden blocks in the picture), which initially had me a bit troubled, because it seemed like that wasn't going to work out at all -- until after some playing around I had added the seat ~30cm off the ground. I found that sitting at that height was way more comfortable than sitting on the ground legs outstretched, and I also found that suddenly there was a more than acceptable amount of elbow room on either side. My head was obviously above the deckline at that point (total height of that frame is only 105cm) but with the planned plexiglass canopy ontop it'd be a perfect fit. Bottom line: I don't need the windward pod, and with the seat, I imagine the boat will actually be rather comfortable to helm from inside the cabin, despite its very small size. :)

I am going to have to figure out another solution for steering from inside the cabin though. Having a steering stick along the windward wall would not be practical at all, especially when wearing thick clothing. Something that could be quite comfortable and would require very little space would be to have a tiller-extension running to the front of the cabin, with some sort of linkages to connect it to the rudder from there. I havenÄt figured out a simple way to do that yet though... :| Mainsheet cleats will be placed on the (inside) leeward wall of the cabin, just below the pod, a bit more than arm's length from the seat. I think from the standpoint of ergonomics it'll be a lot like sailing a dinghy overall. Having a removable backrest of some sort on the seat (with the seat itself being removable as well) would be really good though. -- Any ideas? ;)

Marco
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IMG_20150222_174814.jpg
Center frame of my old full scale mockup, but with some blocks inserted to better correspond to the new design.
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Re: Getting out on the water this year

Post by Skip » 24 Feb 2015, 17:02

Manik wrote:@Skip: Where did you cook on the P52, did you have a fixed VHF onboard?
Sorry for the delay in replying, somehow missed the post then had to stop and replace my 25+ yr old keyboard (an original IBM clackity clack).
Cooking was originally a single burner propane stove usually used on the seat beside me at rest. VHF was a handheld clipped to vest while operating.

Stovewise I graduated to a jetboil which I cherish almost as much as my recently departed keyboard (I can always get another jetboil).

I'll go ahead and talk a little about general operation on P52 tandem and solo. The only extended operation tandem was the Everglades Challenge with Chuck Leinweber. At the time boat had oar steering and a 160s.f. crab claw which was too much for the existing conditions so we ran with a 48s.f. last minute polytarp staysail. Clothing was in drybags stowed in respective ends of boat along with inflatable camp pads and sleeping bags. Mummy style bags are best for the tapered end berth flats and tapered inflatable pads would have been better but we had rectangular pads and they worked OK. The drybags were usually held up out of the way off the berth flats on shockcords run along the sides. Anchor was kept bungeed to one of the swing arms. There were three compartments behind the backrest of the windward seating pod ~20" wide x 10" x 10" access thru 8" quarter turn hatches, stuff was stored in rectangular lightweight kitchen storage containers 6 per compartment I think. Middle compartment held common stuff, tools, spare parts, batteries and the like. We each had a personal compartment for our own food as we had separate needs. Compartments at each end of the seating pod held spare line, stove and propane canisters and the like. Water was carried in 1 gallon containers carried in the end that would mainly be the stern for a particular days run. Opposite end would carry fenders. There was storage space in the float accessible thru a couple of the ubiquitous 8" hatches but we didn't store anything there. The one time we ran at night the off watch slept in the sternward berth.

ran out of space, more to follow
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