Ama daggar boards

including Amas (Floats), Akas (Beams) , Swing Wing system and all other hull related issues.
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Waltonsmith
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Joined: Thu 18 Mar 10, 14:38
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Ama daggar boards

Post by Waltonsmith »

Have any Dragonflies been modified with daggar boards in the amas? Would akas or water stays need re-engineering to strengthen them?
Mika Harju
Posts: 218
Joined: Thu 02 Nov 06, 13:19
Your Country: Finland, Turku

Re: Ama daggar boards

Post by Mika Harju »

Waltonsmith wrote:Have any Dragonflies been modified with daggar boards in the amas? Would akas or water stays need re-engineering to strengthen them?
I have studied this topic a little bit. I have wondered does it make any sense to install hydrofoils to reduce wet area and get more speed as all modern bigger trimarans have nowadays.
Is there anyone interested of this kind of project?
For sure you need to strengthen amas, but akas and water stays should be strong enough because they allow you to fly two hulls at the moment. Displacement will be slightly bigger, but they should carry the load.
Mika Harju
DF1000 Racing #8
Waltonsmith
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Joined: Thu 18 Mar 10, 14:38
Your Country: USA, San Francisco Bay Area

Ama daggar boards

Post by Waltonsmith »

Mika;
Thanks for the reply.
My question does not introduce the idea of flying two hulls, but just the ability to add lift to the amas for increased pointing ability, and sail carrying.
For flying two hulls, one has to think about adding rudders to the amas; and this then gets pretty complicated, especially with a folding tri.
"Cheekee Monkee, a famous, -42 PHRF, F31 now in Florida, has straight daggar boards in the amas. It also has water ballast, a custom main-hull daggar board, and a canting mast.
http://www.cheekeemonkee.com/cheekeeMods.php
Double Horizon
Posts: 440
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Re: Ama daggar boards

Post by Double Horizon »

Waltonsmith wrote:Mika;
Thanks for the reply.
My question does not introduce the idea of flying two hulls, but just the ability to add lift to the amas for increased pointing ability, and sail carrying.
For flying two hulls, one has to think about adding rudders to the amas; and this then gets pretty complicated, especially with a folding tri.
"Cheekee Monkee, a famous, -42 PHRF, F31 now in Florida, has straight daggar boards in the amas. It also has water ballast, a custom main-hull daggar board, and a canting mast.
http://www.cheekeemonkee.com/cheekeeMods.php
The cheekeemonkee story is quite impressive, but it reads more like an addiction than a project. :) If you want a flat-out racer why don't you just start with that? If you want a Formula 1 why start with a BMW?

The 920 and larger Dragonfly boats are performance weekenders/cruisers, and the smaller ones are performance daysailors -- with appropriate compromises for human comfort and luxury accomodation. If you want pure performance you should go for that, IMHO.
Larry - Former Owner DF-1200
Waltonsmith
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Joined: Thu 18 Mar 10, 14:38
Your Country: USA, San Francisco Bay Area

Racer/cruiser vs flat-out racer

Post by Waltonsmith »

The Pacific Cup race (San Francisco to Hawaii) has specific requirements for multihulls: 33' min. length, crew of 4, 60 gallons of water in tankage, etc. Flat-out racing tri's of the size for ocean (40-50') crossings do not have the carrying capacity for this race. Even the Dragonfly 35 is a bit small for this event, with regard to carrying capacity. 1200 looks to be good size for speed and safety.
A racer can take a twenty-year-old Olsen 30, doublehanded, in the Pacific Cup; but the rules for multihulls are stricker, for reasons not yet explained to me.

Rick
tpaliwoda
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Joined: Fri 03 Nov 06, 3:05
Your Country: USA, Raritan YC, Perth Amboy, New Jersey

Post by tpaliwoda »

If you are looking for a tri that can fly the main hull, look at a SeaKart 30.
Why reinvent the wheel? This would cost you less in the long run.
Welcome aboard!
Ted
Ted Paliwoda
D'Fly 1000 ; HN #1
Nice Tri
Raritan YC, Perth Amboy, NJ, USA
Double Horizon
Posts: 440
Joined: Wed 09 May 07, 0:18
Your Country: USA

Re: Racer/cruiser vs flat-out racer

Post by Double Horizon »

Waltonsmith wrote:The Pacific Cup race (San Francisco to Hawaii) has specific requirements for multihulls: 33' min. length, crew of 4, 60 gallons of water in tankage, etc. Flat-out racing tri's of the size for ocean (40-50') crossings do not have the carrying capacity for this race. Even the Dragonfly 35 is a bit small for this event, with regard to carrying capacity. 1200 looks to be good size for speed and safety.
A racer can take a twenty-year-old Olsen 30, doublehanded, in the Pacific Cup; but the rules for multihulls are stricker, for reasons not yet explained to me.

Rick
I love the 1200 but it's designed as a luxury fast cruising boat. It's amazing for that purpose, and I can't help but feel that any future boat I might own will be a step down in sailing performance if not comfort. The finish level is equivalent to the best quality monohulls, and it would be a shame to strip it out for racing. It's light but not ultra-light and would not make a great racer compared with a tri that's designed from the start for racing. Some of the more obvious features of a racing tri would be more carbon-fiber, stripped out interior and lighter overall weight, narrower main hull, and be built to fly the center hull.

There's a Corsair 37 based near me that's all carbon-fiber. That is a very fast boat and would be a better choice for racing, but not as comfortable for cruising nor as nice (unless you prefer molded FRP, glued "mouse fur" carpet headliner and minimalist upholstery over Danish teak cabinetry, teak/holly sole, fully padded headliners, and tailored leather seating).
Larry - Former Owner DF-1200
choppy
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Hydrofoils

Post by choppy »

As stated dont think the Dragonfly quite the right boat to modify- but the theory is very interesting.

Good "production" start is to check out the Catri boats which utilise the principle. ~ Ingenious from Mr Eglais (Hope i got that right) They dont lift out in same way as Hydrocopter but plane (or very close to)with minimal wetted area - so more like a farrier or Df than Hydrocopter et al.

As well as speed benefits - reduced drag, no centre board etc they (ama foils) can produce lift as you come down a wave so boat stays level fore & aft as well as laterally - all great design stuff loads to look into.
Mika Harju
Posts: 218
Joined: Thu 02 Nov 06, 13:19
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Re: Hydrofoils

Post by Mika Harju »

As well as speed benefits - reduced drag, no centre board etc they (ama foils) can produce lift as you come down a wave so boat stays level fore & aft as well as laterally - all great design stuff loads to look into.[/quote]
Here is one excel sheet to estimate forces and lift of hydrofoils:
www.hydrofoils.org/Lift/lift.xls
I do not have enough experience to say is the calculation right or not.
Anyhow this is an interesting topic and all boats including DF's are worth of tuning; it is a part of this hobby too.
Mika Harju
DF1000 Racing #8
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