Raidboat Pacific Proa

Discussion in 'Multihulls' started by BCowan, Sep 2, 2020.

  1. rob denney
    Joined: Feb 2005
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    Location: Australia

    rob denney Senior Member

    If you want to know anything about Harryproas, either ask me (harryproa@gmail.com) or join the Harryproa chat group: HarryProa@groups.io | Topics https://groups.io/g/HarryProa/topics
    where Rick Willoughby recently analysed the Harryproa set up, explaining why "The two large rudders near the beam give very close to ideal balance",
    "Another thing that I find nice in operation is close proximity of the two helms so both rudders can be used simultaneously",
    "When a standard HP is lifting the ww hull, the drive and drag are essentially aligned but there will be leeway if only the back rudder is working. It needs both rudders working to negate leeway. When the windward hull is loaded, it is pulling the boat to weather so the aft rudder has to pull the aft end to weather thereby reducing or negating leeway. There is a position of perfect balance for any particular conditions. "
    and a bunch of other observations from sailing and analysing an 18m Harryproa

    The forward rudder is not locked in position, although it can be. I have found the easiest way to steer upwind is to lock the aft rudder and steer with the front one. Reaching, use the aft one and downwind, lift the front one and as much of the aft one as you need.

    A board will make it harder to shunt, as it cannot be aligned with the water flow, so stalls, creating drag. 2 large, liftable, kick up rudders is the best solution.

    Any other questions, let me know.
     
  2. BCowan
    Joined: Aug 2020
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    Location: Colorado

    BCowan Junior Member

    Thank you Rob, this is hugely helpful. I have begun poking around the HarryProa discussion forum too, so thanks for the link. I wish I had the time and ambition for a larger project with IntelligentInfusion, but I currently dont even live next to a state that is next to the ocean......so for now I have to stick to my small boats and mountain climbing.

    I hadnt thought about steering with the forward rudder, and the idea that the drag from the windward hull makes some turning moment and weather helm is not something I had thought about either. Seems to me a multihull, and particularly a proa, has a more complicated dynamic of helm balance than a monohull heeled over. Figuring out when it is advantageous to lock a rudder, or leave it free, or steer with one or both rudders will be part of the sea trials and practice I need before committing to the Everglades Challenge. Learning to sail in a new way with my proa is going to be fun and interesting.

    For my proa, I have cannibalized a Hobie 16 rudder assembly, and the only challenge I see to this is the shallow water and frequent kicking up and needing to quickly and easily re-deploy. So the pressing question I have is about the placement of the rudders on the leeward hull.

    Do you think there is an ideal distance between the rudders as a percentage of the hull length? Certainly the HarryProa rudders are not mounted on the end of the bow/stern (100% of hull length), but your rudders look farther apart than dividing the hull into 3rds (33%). Im planning on a 21' (6.4m) leeward hull for my proa. I can conveniently place the hobie rudders about 12' (3.6m) apart, making the distance between the rudders about 55% of the hull length, though I can close the distance between the rudders with minor modification to the platform. Just wondering what your thoughts on rudder placement and helm balance.

    Right now my rig is looking like a pair of lugs, and I am absolutely sold on the schooner rig. Though Im sure many will scoff, my love for lug rigs has only grown with the 125sq ft mainsail I have for my yawl. A balanced lug rig to me looks like a lateen with part of the luff cut off, making it easier to reef. We'll see how it all comes together.....

    Thanks again for the ideas and passion. Were having a gnarly snowy day (slow) at work, so planning to really get to reading the HarryProa discussion forum.....
     
  3. rob denney
    Joined: Feb 2005
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    Location: Australia

    rob denney Senior Member

    Different rather than complicated. And less dynamic as the loads and directions stay pretty much the same unlike a heeling hull.
    Depends on the rig (schooner is more verstaile), windage, the load on and willingness to fly the windward hull, the rudder size and ease of lifting and the agility of the crew. 55% apart is as good a starting point as any. Helm balance should be a touch of weather helm.

     
  4. BCowan
    Joined: Aug 2020
    Posts: 16
    Likes: 4, Points: 3
    Location: Colorado

    BCowan Junior Member

    I started building my shunting outrigger canoe in earnest in May. Started with the ama, not sure why. About 2 months of tinkering in the garage for the ama to be 95% complete. It weighs 64lbs, has space for my 7gallon water jug and my anchor. I doubt I'll need to shorten the braces but I may depending on how the hulls ride together
    - 16' CLC night heron double ender made with 3mm ply
    - Monocoque shell glass inside and out, i left a couple glassed bulkheads inside. It's full of xps foam. And has a couple drain holes for air circulation

    The canoe is 4mm ply bonded to 11mm plascore sheet. I bought a pallet of panels 10 years ago and have slowly used them. Canoe also has a significant amount of catastrophe foam under the floor mostly toward the bows. The middle space in the bilge under the hatch is open for some gear, heavier camping stuff. I plan to launch first and be sure that loaded with gear the floor is above the waterline and then I'll cut a few drain holes to avert the need for any bailing. Hull will get a 2"thick layer of foam on the bottom to radius the corners and fair it out. needs glass inside and out and i have a piece of kevlar to go on last for the hull PXL_20211008_035149664.jpg PXL_20211008_035011070.jpg PXL_20211008_035027675.jpg PXL_20210930_200431275.jpg PXL_20210907_191249607.jpg PXL_20210901_164140794.jpg PXL_20210902_035758776.jpg PXL_20210901_164130534.jpg PXL_20210810_194427158.jpg PXL_20210728_165625519.jpg PXL_20210728_165551094.jpg PXL_20210718_033444118.jpg PXL_20210530_192550012.jpg PXL_20210530_192441474.jpg PXL_20210517_231435585.jpg PXL_20211008_035149664.jpg PXL_20211008_035011070.jpg PXL_20211008_035027675.jpg PXL_20210930_200431275.jpg PXL_20210907_191249607.jpg PXL_20210901_164140794.jpg PXL_20210902_035758776.jpg PXL_20210901_164130534.jpg PXL_20210810_194427158.jpg PXL_20210728_165625519.jpg PXL_20210728_165551094.jpg d, so i won't cringe sailing up onto a beach.

    Im still devising the rig and beam attachments and floor, i have twin lug sails and all the spars. My aluminum tube masts are too thin to freestand, so I have learned lots about splicing dyneema for the bows stays and windward stay.

    Ive upload pictures from my phone which is a hassle so the order is messy.
     
    cracked_ribs and Will Gilmore like this.
  5. peterAustralia
    Joined: Mar 2006
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    Location: Melbourne Australia

    peterAustralia Senior Member

    very well done, dont forget that if you try the shunting rig and it is too difficult, you could convert it to a tacking rig. Just add a little weight to that ama (water jug) and you would be set. Note that I am biased having a website on tacking outrigger canoes
     
  6. upchurchmr
    Joined: Feb 2011
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    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Did you really put all that foam in the outrigger?
    Do you know what the foam weighed?

    What kayak design was the ama made from?
     
  7. BCowan
    Joined: Aug 2020
    Posts: 16
    Likes: 4, Points: 3
    Location: Colorado

    BCowan Junior Member

    The kayak design is a clc night heron. I made 16' panels for 2 bow sections.
    The foam was a sheet and a half of pink home depot xps foam board insulation. I doubt a panel weighs 5 lbs, so im guessing 8 lbs total.

    Your first question is rhetorical, but I'll humor you. Yes, what I'll call catastrophe foam fills most of the volume of the ama. Im guessing it's unlikely I'd ever crack a seam in the hull hitting something hard, but if I did it would likely sink, or suck bad anyways with it half sunk. The outrigger is but a shell.

    And I'm building a shunting pacific proa. A little mass in the ama only helps my righting moment. The night heron has 300lbs max payload, so a jug of water, some gear, 64# of boat, and my skinny butt doesn't come close to over loading it.
     

  8. BobBill
    Joined: Oct 2009
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    Location: Minnesotan wakes up daily, in SE MN, a good start,

    BobBill Senior Member

    Mr. Upchurch, what swab-built boat is ever "done," as you put it...?

    My rig sails fine, but finished? Needs outrigger made of foam and the main hull needs to have cockpit, to make paddling easier...also, since spars are carbon, might later alter the attachment scheme...using hook and loop now...maybe add lazy jack to keep Dacron dry...life is good...

    I have perused OPs plan and it seems solid, save proa part...might steer him to using older hulls and a more conventional plan...like a MO.
     
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