A Photo & Discussion Forum for Wharram Design Enthusiasts
After ten years on the built of my tiki 31, I have finally reached the point where I must make my decision on the deck layout. I am thinking on going for a one piece central pod (tiki 30 style) instead of the four pieces central platform in the plans (two deck boxes and two part central platform). The thing is I haven't really understood how this central pod is suspended from the crossbeams. The central platform in the plans is hanging on ropes that pass through holes on the crossbeam plywood web. Can the central pod be suspended in the same way? Any suggestions?
My first thought is that it would be better to run pod support beams under the main crossbeams and then run the lashings under the pod beams and over the main beams. I would extend the pod beams far enough past the main beams to effectively lash bot fore and aft. This will prevent the weight of rhe pod tending to twist tha main beams in towards each other. Another option is to set the pod beams higher on the sides of the pod and have them sit on the beam tops.
Thanks for the reply boatsmith
If I understood correctly from your blog on building the Tiki 30, the cockpit is hung on the main crossbeams from ledgers glued on the cockpits for and aft sides. Do you propose a different setup now because this didn't prove to be an effective way to hang the cockpit or do you think lashing the cockpit on the beams or set the pod beams to sit on the beam tops better suits the tiki 31 design? Also, if I decide to go for the pod beams on the sides of the cockpit how many layers of glass cloth do you think is enough in the corners of the pod to solidly attach the sides to its floor ? (I am using West System 200 gr plain cloth).
Rou are correct. The Tiki 30 cockpit sat on flanges on the inward faces of the beams. We did not have any problems with this set-up. But it does push down on the inward faces of these two beams twisting the beam tops towards each other. On the Ariki we passed te cockpit floor under these two beams and bolted the cockpit to flanges on the fore and aft flanges of both beams. 4 flanges total. This distributed the cockpit weight evenly on both faces of the beams. The flanges take a lot of stress and loading the flanges on both sides of the beam keeps the flexing of the flange at a considerably lower level. I will add the flanges on the most fwd and most aft beam on the Ariki where loads from the trampolines and the wooden decks needed reinforcement after the fact because they flexed enough to crack the paint and faring putty. We added layers of glass to increase the stiffness of the flange. These flanges were about 3/8" thick an we added about an 1/8" more glass to the flange to face area. when the load is all cantilevered the flange needs to be much stronger.
I see your point now. I think I will go for the pod support beams under the main crossbeams and far enough for and after to lash them on both sides of the main crossbeams. This set up will also suit my Tiki 31 better since I have changed the design and enclosed the center cockpits, so beams 2 and 3 go through beam throughs. This I think would make the positioning of a pod with flanges glued on its for and aft sides difficult because when beams 2 and 3 are in place there isn't much space to twist them so as to lift or lower the pod in place.
Thanks again boatsmith for the invaluable advice!