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 Post subject: Re: SURFBOARD SAILS
PostPosted: Sat Oct 10, 2015 8:28 pm 
Brotherhood of the Golden Paddle
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Location: Arlington, VA (i.e. Wash DC)
john allsop wrote:
I think we brought out the idea of outriggers on both sides to make our craft more stable and less likly to go over no matter where the wind comes from and most of us dont seem to make much effort to keep the outrigger which is in or on the water clear of it by balancing, as suggested we could use chidren but i don,t think they are disposable any more.

No, the Filipinos have been using trimarans (bangkas) for millenia. Westerners didn't invent them. Filipino bangkas have much less substantial amas than the ones we are using, though-- thin and long, of bamboo.

john allsop wrote:
What we might be getting back to is have both outriggers clear of the water when on an even keel and try to keep it that way by leaning out or hiking so increasing speed, if we want to.

Yes, exactly-- that is what I have meant when I have referred to "sailing it like an IC10".

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Chris T.
~'91 Klepper A2 w/ BSD schooner rig.
'64 Klepper Passat/Tradewind and T12 restoration projects.
Non-folding: Early '90s Old Town Canoe.
Previously owned '04 Pakboat Puffin II and '05 Swift (prototype), as well as an '84 Hobie 16.


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 Post subject: Re: SURFBOARD SAILS
PostPosted: Sat Oct 10, 2015 11:18 pm 
Brotherhood of the Golden Paddle

Joined: Sun Aug 16, 2009 10:05 pm
Posts: 1398
Location: South Salem, NY
The problem is that the window for balance is so small with our outriggers. It's harder to keep the two amas out of the water than it is to sail without them altogether. Unfortunately that one mistake can put you in the drink.

That window can be expanded by raising the amas or shortening the akas or both... but is the trade-off worth it? I'm not sure I'm willing to risk cutting my tubes down just to find that 'there aint much difference.'

I do really like the idea of those big Solway Dory akas and amas. Big upswept wood akas and streamlined solid amas. Great system, but you'll never tuck all that in under the front deck.

d

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 Post subject: Re: SURFBOARD SAILS
PostPosted: Sun Oct 11, 2015 8:58 pm 
Brotherhood of the Golden Paddle
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Location: Arlington, VA (i.e. Wash DC)
I'm not suggesting cutting down the amas-- the Filipino amas are braced in two places and angled to trail the rear tips in the water. If the boat lists or leans for some reason, more ama would go in the water and (I think) increase the righting on the that side for that reason. BSD amas are an entirely different design.

I agree about the Solway Dory concept. I've been studying trimarans, recently, and apparently one of the keys to taking them from just being faster than monohulls in the 70s to the astonishing speeds of the 90s (20+ knots on 18-24 foot boats) was to substantially increase the volume of the amas and to get a significant portion of the buoyancy of those amas forward. Thinking of that and looking at the Solway design makes a few things come together in my head.

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Chris T.
~'91 Klepper A2 w/ BSD schooner rig.
'64 Klepper Passat/Tradewind and T12 restoration projects.
Non-folding: Early '90s Old Town Canoe.
Previously owned '04 Pakboat Puffin II and '05 Swift (prototype), as well as an '84 Hobie 16.


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 Post subject: Re: SURFBOARD SAILS
PostPosted: Sun Oct 11, 2015 10:23 pm 
Brotherhood of the Golden Paddle

Joined: Sun Aug 16, 2009 10:05 pm
Posts: 1398
Location: South Salem, NY
Two excellent concepts here Chris. The idea of an angled ama like the Filipinos have is genius. Like a wing it will create more lift the deeper it's pushed into the water. Love that idea. I'll try googling some images... I am curious to see how big these are.

The idea of more buoyancy forward is what I was wondering about in my BOSS thread. I'm guessing that you have a traditional rig with the aka/ama set in the center of the boat, yes? Mine are up front. That forward position gets them up a little higher without the blocks, maybe not much but let's face it, every little bit counts... and I don't know why but I got the impression that they weren't creating as much drag up front as they might further back. There really is no logical reason for this other than height, but that thought came to me while out on the boat watching the ama bounce along the surface.
I'll need to spend more time with the BOSS rig out on the water to get a good sense of the speed difference. On a nice long run it may even be evident on the GPS. After the little spin on the lake the other day I'm ready to hit the big water with the outriggers and have some fun - I'll definitely do some testing if I can.

I wonder if increasing the angle of the BOSS ama; pointing the nose up more, would be helpful? Seems to me that it would respond similar to the Filipino ama but less efficient when the nose is driven down. The instructions of the BOSS rig tell you to rig the ama in an upward position. I don't see a lot of angle on mine but I'm sure it's there. Mark seems to be pretty accurate about this stuff. I like that idea though.

I'll go take another look at the Solway Dory setup now as well.

Too bad the summer is coming to an end Chris. It would have been nice to meet up somewhere between the two of us to do some sailing together.

d

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 Post subject: Re: SURFBOARD SAILS
PostPosted: Sun Oct 11, 2015 10:59 pm 
Brotherhood of the Golden Paddle
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Location: Arlington, VA (i.e. Wash DC)
DLee wrote:
Two excellent concepts here Chris. The idea of an angled ama like the Filipinos have is genius. Like a wing it will create more lift the deeper it's pushed into the water. Love that idea. I'll try googling some images... I am curious to see how big these are.

Bamboo-- narrow, but long.

Quote:
The idea of more buoyancy forward is what I was wondering about in my BOSS thread. I'm guessing that you have a traditional rig with the aka/ama set in the center of the boat, yes?

Yes.

Quote:
There really is no logical reason for this other than height, but that thought came to me while out on the boat watching the ama bounce along the surface.

Actually, without the forward buoyancy, the tri can "trip" over the ama when it's going fast and it hits a wave. Catamarans have had very similar problems-- the Hobie 16 is notorious for it's propensity for pitch-poling.

Quote:
I wonder if increasing the angle of the BOSS ama; pointing the nose up more, would be helpful? Seems to me that it would respond similar to the Filipino ama but less efficient when the nose is driven down.

Maybe, but the bangkas have two akas. The BOSS rig has only one. When you add the different hullforms of the amas, I think we're dealing with apples and oranges.

Quote:
Too bad the summer is coming to an end Chris. It would have been nice to meet up somewhere between the two of us to do some sailing together.

:D Can't find that little emoticon for a beer mug being toasted...

_________________
Chris T.
~'91 Klepper A2 w/ BSD schooner rig.
'64 Klepper Passat/Tradewind and T12 restoration projects.
Non-folding: Early '90s Old Town Canoe.
Previously owned '04 Pakboat Puffin II and '05 Swift (prototype), as well as an '84 Hobie 16.


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 Post subject: Re: SURFBOARD SAILS
PostPosted: Sun Oct 11, 2015 11:01 pm 
Brotherhood of the Golden Paddle
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Joined: Thu Apr 14, 2005 4:47 pm
Posts: 1716
Location: Arlington, VA (i.e. Wash DC)
Filipino bangka images
https://www.google.com/search?q=filipino+bangka&tbm=isch&tbo=u&source=univ&sa=X&ved=0CB8QsARqFQoTCMKlssH4u8gCFYsmHgodB80GdA&biw=1600&bih=736

_________________
Chris T.
~'91 Klepper A2 w/ BSD schooner rig.
'64 Klepper Passat/Tradewind and T12 restoration projects.
Non-folding: Early '90s Old Town Canoe.
Previously owned '04 Pakboat Puffin II and '05 Swift (prototype), as well as an '84 Hobie 16.


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