That is very interesting but makes perfect sense in hindsight. while the foils are working, there is smooth flow and little turbulence but if they are struggling they cause turbulence and perform even worse. ie paradoxically as soon as they are big enough to work they are more than you need.
--- In harryproa@yahoogroups.com.au, Doug Haines <doha720@...> wrote:
>
> i used 1.8m length from february /march this year and no handling problems at all. Actually amazingly good. Steer right up in to a luff and be able to come back down wind again while nearly stopped waay.
> Then thought to try back to 1.5m after breaking the mini mount. Dreadful handling, couldn't steer well at all. Lots of turbulence and couldn't get going at a normal speed.
> So went back t9 1.8m and perfefct again!
>
> Doug
>
> --- On Wed, 16/6/10, Gardner Pomper <gardner@...> wrote:
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>
> From: Gardner Pomper <gardner@...>
> Subject: Re: [harryproa] Re: Crazy rudder idea
> To: harryproa@yahoogroups.com.au
> Date: Wednesday, 16 June, 2010, 21:01
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> Doug,
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> You are definitly the long distance harryproa record holder! <grin>
>
> What are the dimensions of your rudder now? Did they steer ok with the full harrigami rig, or just now that it has been shortened? Were the rudders ok in light airs before you lengthened them?
>
> I am trying to get a rough idea of how big my rudders need to be for 400 sq ft of sail. I have been using 1% of sail area, but maybe I need to double that? 1% per rudder?
>
> Thanks!
>
> - Gardner
>
>
> On Wed, Jun 16, 2010 at 1:17 AM, Doug Haines <doha720@yahoo. co.uk> wrote:
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> Hi,
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> Gardner and rest:
> Rudder should be able to stand the forces of a hard beat with a hull lifting. Then times safety factor by 3 maybe. If that is still not too thick and heavy take it up to 5 or more. Solid carbon? would that weigh too much. Would the blade fairings rip apart from the shaft?
> As you would recall, a few months? ago i ripped the side mounted beam off the hull, but the blade was OK. So now I am probably oerbuilt with the mini beam, and so it could be the blade that would go if something of therudder gear went.
> Is it any use trying mini keels, dagger board keels or other leeway rsistors to ease the load on the rudders?
> Do BIG cats ever just break a dagger board keel from sailing pre3ssure?
>
> Doug
> Still at Albany
>
> --- On Wed, 16/6/10, Mike Crawford <jmichael@gwi. net> wrote:
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> From: Mike Crawford <jmichael@gwi. net>
>
> Subject: [harryproa] Re: Crazy rudder idea
>
> To: harryproa@yahoogrou ps.com.au
> Date: Wednesday, 16 June, 2010, 1:06
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> Carl,
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> <<What is the problem with the drum style for an ocean passage, given thats exactly what I plan to do>>
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> Depending upon your priorities, nothing is wrong with the drum rudders. It's a very subjective matter.
>
> ---
>
> If I were to purchase a monohull, I'd purchase an ETAP, because not only are they unsinkable, they can be actively sailed while full of water, and can even recover from a 90-degree knockdown while full of water.
>
> Most monohull sailors don't think this is an important feature. Some reviews say that unsinkability is nice, but not worth the loss of interior space due to the foam-filled double hull.
>
> Is it just a "nice" feature? For some, yes.
>
> For me, it's a requirement for any boat I intend to sail more than a mile off the coast (I don't mind swimming longer distances, but my crew might, and the water temp in Maine can put some people out of commission pretty quickly). I'd say that unsinkability is like a seatbelt and airbag. You'll probably never need them. But if you do, and you don't have them, things can get pretty ugly.
>
> But since people are accustomed to sailing very heavy boats that sink if there's a hole in them, unsinkability is seen by most as a novelty, not an important feature.
>
> ---
>
> Kick-up foils on multihulls are a similar nice feature to have that matters to some people and not to others.
>
> But for me, if hitting a whale, sandbar, log, or submerged container could render your foils useless until you find a boatyard, or even worse, sink the boat, that could make for an ugly day.
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> I want to be comfortable with what might happen if my kick-up foils collide with whatever lies unseen beneath the water. I'd love for a grounding out to mean nothing more than cursing, retrieving my foil on it's line, setting it back in place, and sailing away.
>
> Many people are more than happy to sail everywhere with tall daggerboards, and most never hit a thing. I've known a number of Corsair owners, and only one of them ever had issues with the daggerboard -- and he made the mistake of chartering the boat out to people who couldn't read charts, resulting in multiple repairs to the daggerboard and crash box.
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> Statistically, if you go with drum rudders in the hull, you'll probably be fine. Just as if, should you decide not to wear a seatbelt in a car, you'll also probably be fine.
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> To each his own.
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> I'd say that any harryproa on the water is a great thing, regardless of its foils, daggerboards, leeboards, mini-keels, and such.
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> - Mike
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>
>
> On 6/15/2010 10:16 AM, Omar Khayyam wrote:
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> Mike, in your last post you said "And if you want to go fast, avoid steering balance issues, have an easy up/down system, and stay away from experimental designs, the drum is a good choice. Especially if you're not going to make an ocean passage."
> What is the problem with the drum style for an ocean passage, given thats exactly what I plan to do.
> Thanks,
> Carl.
>