Philippines Banca 100 Islands

Discussion in 'Boat Design' started by 100islands, May 30, 2013.

  1. rxcomposite
    Joined: Jan 2005
    Posts: 2,555
    Likes: 477, Points: 83, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    I think you can keep your 3/4" shaft. Here is the preliminary results. Keep your prop at 10 or 11" dia. Lots of slip, not efficient but will reduce load on shaft. Watch out for bearing spacing as noted on the spreadsheet.

    I recommend 3 bladed prop to reduce vibration. It is always the odd/even rule. 2 blade/1 piston, 3 blade/2 piston. This is because the peak power of the engine coincides with the number of propeller blades. Not really significant if you can isolate the vibration.
     

    Attached Files:

  2. 100islands
    Joined: May 2013
    Posts: 36
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Philippines

    100islands Junior Member

    Excellent! We figured there would be some experimenting on the Propeller size, lets see how this one performs.

    Couple questions, available to us are 304 SS shaft and 316 SS shaft, is there any advantage to using 316 over the 304? In terms of corrosion or stiffness would one be better than the other? Do you recommend a 3rd Pillow block with this size shaft? Or would that be a waste of the 1.5% power as shown on the spreadsheet.

    Thanks again!
     
  3. rxcomposite
    Joined: Jan 2005
    Posts: 2,555
    Likes: 477, Points: 83, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    316 is slightly stiffer due to less iron content. Its main advantage is that it polishes well and good for high quality finish. Pricewise, I think it is twice the cost.

    The 20X-40X rule is to allow the shaft to flex without whipping. 20X is the minimum, 40X maximum. There is also a rule on how far the coupler extends on the fixed point (bearing area) but will have to dig up my files.

    Everytime you add a bearing or lengthen the shaft, it robs power.

    Allow enough propeller to hull clearance. You might benefit from using a larger prop. But of course, as we optimize the prop, the engine might not reach critical speed during starting as yours is a direct drive. No neutral. We had that problem once. The prop has too much "bite" we could not start the engine. As the engine turns, the prop bites.
     
  4. 100islands
    Joined: May 2013
    Posts: 36
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Philippines

    100islands Junior Member

    Great info, thanks again. We will be updating the pics soon.

    Rather than using the standard setup, we are wondering if anyone has suggestions on Optimal performance and rudder size? (should it be same height as the diameter of prop. In this case 10" How Long should the rudder extend out for the rudder shaft.

    Are there any specific rudder shapes/design or angles that would increase performance and decrease drag? Considering the outriggers we would like to get as much bite as possible for turning.

    Thanks again.
     
  5. rxcomposite
    Joined: Jan 2005
    Posts: 2,555
    Likes: 477, Points: 83, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    Before we leave the topic, check your bearing spacing. You have too much bearing there. I think you can eliminate 1 pillowblock, or at least two. You have three bearings already, the strut bearing, the stuffing box bearing, and the thrust bearing, all in a span of seven feet.

    As for the outriggers, the ama set up is that it is bowed and angled so that the front edge touches the water at roughly 1/3 of the hull with the full length nearly 3/4 of the hull. If you plot the wetted area, you will note that it is a an Arrow Tri configuration, an arrangement that Austal of Cebu is making. There is also the critical arrangement of the proximity of the amas to the main hull, where the transverse and the diverging wave creates the least interference or the interference is beneficial. If you want to learn more about this, read Leo Lazauskas paper of optimum spacing of multihulls and use his free program Michlet or Michlit. Search this forum.

    When this banca pitches forward, the immersed length of the ama increases and adds to the buoyancy preventing the narrow hull from "diving". Add to that the limber effect of the bamboo outrigger giving it a shock absorber ride. The outrigger's flexibility tunes the harshness of the ride. The front ones soft, the mid ones stiff, and the stern in between stiffnes.

    A modern approach would be to make the amas demihull, with the slab sided located inboard to reduce/eliminate divergent wave, bringing the amas closer to the hull, reducing weight. Google Austal Cebu to get an idea of this configuration.

    As for the rudder, there is an optimum nice s curve shape but only works if the rudder is close to the hull and does not ventilate. Gain is very very small. Works only on big ships.

    Keep the thrust line in the smallest angle possible for your use. Angled thrust line is only for racing boats.
     
  6. 100islands
    Joined: May 2013
    Posts: 36
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Philippines

    100islands Junior Member

    Updates: Installing Ribs, Found our bow and stern hardwood this morning.

    20130611_135612.jpg

    20130611_135620.jpg

    20130611_140650.jpg

    20130611_140722.jpg

    20130611_140733.jpg

    20130611_142611.jpg

    20130611_142702.jpg
     
  7. 100islands
    Joined: May 2013
    Posts: 36
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Philippines

    100islands Junior Member

    We reviewed stuffing box appears that it does not have a bearing its a gasket type i will attach specs on the stuffing box system made by (LASDROP) we creates a new question with a pillow block right before the stuffing box would the space between 1 pillow and the thrust bearing be to great?

    3/4" Shaft - 2" Stern tube

    89685F-p.gif


     
  8. 100islands
    Joined: May 2013
    Posts: 36
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Philippines

    100islands Junior Member

    Great! I will research try to come up with a drawing soon. We usually measure the circumference of the hull and base the offset from hull from that. However this taller than normal banca for handling larger waves, and has a wider planing bottom. Our output of the same formula puts the outriggers very wide... the boat might not turn very well. Ill come up with what i can on paper and post it for comments. Roger that on shaft angle we have some allowance with the Python CV to level it off.

     
  9. rxcomposite
    Joined: Jan 2005
    Posts: 2,555
    Likes: 477, Points: 83, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    It may be of interest to you if you can read some of the papers written by Dr, Glenn Doromal Aguilar. He is the expert here. He has a doctorate degree in Naval Architecture and Ocean Engineering and has written numerous papers for SNAME, Tokyo University, and other International publications. Here are some that might interest you. Bear with me as I search out the links.

    Aguilar, G. D. 1997. Comparative analysis of hull forms of selected Philippine indigenous fishing craft. UPV Journal of Natural Sciences 2(1):17-43.

    Aguilar, G. D. Shigehiro, R. Kuroda, T. September 2001. Resistance characteristics of the Philippine outrigger fishing crafts. UPV Journal of Natural Science 6(1-2):46-54.

    Aguilar, G. D., Yamato, H. and Koyama, T. December 1996. An approach to knowledge acquisition for the hull form design of fishing craft, (3rd report). Implementation of a hull form definition system using hull variation and shape aggregation techniques. Journal of the Japan Society of Naval Architects (178):755-765.

    Aguilar, G., Shigehiro R., Yamakoshi Y and Kuroda T. 2002. Safety related characteristics of Philippine indigenous outrigger crafts. Fisheries Science vol. 68 Supplement II, pp. 1819-1882.

    Shigehiro R, Aguilar GD, Kuroda T, Kawai A and Matsuda A. 2002. Characteristics of maneuvering motions of Philippine outrigger craft. Journal of the Kansai Society of Naval Architects, Japan No. 238, pp. 113-120 September 2002.

    Shigehiro, R., G. D. Aguilar and T. Kuroda. 2001. Turning performance of outrigger craft in the Philippines. UPV J. Nat. Sci. 6:55-68.
     
  10. 100islands
    Joined: May 2013
    Posts: 36
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Philippines

    100islands Junior Member

    Latest Update: Bow and stern attached (Mulawin Iron Wood)

    20130615_163109.jpg

    20130615_163216.jpg

    20130615_163224.jpg

    20130615_163540.jpg

    20130615_163548.jpg

    20130615_163554.jpg

    20130615_163612.jpg
     
  11. 100islands
    Joined: May 2013
    Posts: 36
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: Philippines

    100islands Junior Member

    Latest update: June 20 (Horizontal and Vertical Ribs)

    DSC_1013.jpg

    DSC_1015.jpg

    DSC_0982.jpg

    DSC_0984.jpg

    DSC_0986.jpg
     
  12. noli
    Joined: Jul 2012
    Posts: 32
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: New York

    noli Junior Member

    .

    Wow, real artisans right there!

    Looking good!

    Please keep the pics comin'






    .
     
  13. viking north
    Joined: Dec 2010
    Posts: 1,868
    Likes: 92, Points: 48, Legacy Rep: 1146
    Location: Newfoundland & Nova Scotia

    viking north VINLAND

    Why not move your post over to "Boatbuilding" where many more people interested in such projects will find it. Many will not be looking here and as such miss this most interesting project. Nice work and great photos ---
     
  14. raf pali
    Joined: Mar 2012
    Posts: 71
    Likes: 1, Points: 8, Legacy Rep: 12
    Location: Australia

    raf pali Junior Member

    Excellent work. keep us posted
     

  15. noli
    Joined: Jul 2012
    Posts: 32
    Likes: 0, Points: 6, Legacy Rep: 10
    Location: New York

    noli Junior Member

    .



    updates please :)
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.