Very close to Launch

That's really beautiful ! I must apologise for my previous remarks about your boards - I was sure that you had the covers on them <img src=

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thanks for the photos of your very impressive boat. enjoy!

Ok an A class. The term Acat is not familiar to me sorry (Ozy). It doesn't look 18ft in pics. When are you planning to launch?

Bill, Congrats! That boat is beautiful! What a joy it must be! Make sure to get good insurance.

Any follow-up on this lovely little project now that the New England sailing season has come and gone?

The followup on this project is that my DK17 is one of 4 DK's launched this year.
http://www.sailinganarchy.com/forums/index.php?showtopic=37584&hl=DK17
I raced twice in Bristol RI with the Acat fleet at the very beginning of the season. My first outing I capsized 4 or 5 times while tacking. I kept getting caught up in the midboom sheeting. The second outing I faired better, I wrapped a scrap of sail material around the boom as a way to keep getting caught in the sheet. I didnt come close to the veterans... These guys are fast. Its not the boat, by the way, its the sailor. In June, work kicked into high gear and I wasnt able to make any more Tuesday night races. I cant believe its almost the end of the year and I only raced this thing twice.

I did sail it regularly on the LIS out of New Haven, no major issues, no major breakages. I am still learing how to go downwind and thats going to take some practice.

I'm planning on attending the Jan regatta in FL, they are forecasting 50 boats.

I did have a couple issues with the tramp attachment, I used a plastic mast and slugs in a track to loop into and tighten the tramp. The plastic track failed, it wasnt stiff enough to hold my weight, so I think that I'll just add some carbon tabs and knot some spectra loops in it.

Other than the tramp track its been great. Its still underweight so this winter I might add some wings - the hulls are canted in, and I could add 2-3 inch wings at the deck so that I could trap out at max beam.

The only other thing, is that i'm not sold on the midboom sheeting, but I'm not going to change it right away.
Bill

My Cat has been launched <img src=

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Thanks for that laugh but I gotta ask.. Did the cat catch the bird and did you get in a LOT of touble?

Still laughing .... Hahahahahah.

classic.

I'll see your launched cat with a flying dog.

I'll raise you one Superman. Known as BOD (Almost GOD), Brian O'Driscoll, (Famous World Class Irish Rugby Player)
This is especially for the Welsh and English cat sailors <img src=

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What form!!!!

A likely stupid question from a soon-to-be mono convert:

Why ARE the hulls oriented that way versus the opposite (i.e. Tornado, Hobie, etc.)? Isn't there some (more or less) ideal hull shape for a small cat?

Nice job, BTW...look really sharp!

It's the latest design rage -

Wave Piercing

. The idea is that you go through the chop instead of hobby-horsing over it. I think the result of many of the recent designs that have the reverse raked bows do some wave piercing but it's a bit more complicated than simply punching through. I don't think the angle of the bow really plays much of a role in this effect either - but it's a sexy look. It's about where the hull volume is placed vertically and longitudinally resulting in a boat that is 'tuned' to a certain frequency chop such that it bobs over one wave and punches through the next. This results in half the hobby-horsing...i.e. a smoother ride and less 'tomahawking' of the rig while not spending quite so much time with a lot of hull under a wave. It's a difficult concept to design without making the boat very pitchpole prone - but some seem to have accomplished that.

Actually the reason for this bow shape is extremely down to earth and simple. I've disclosed it a
couple of times in the past on this forum.

Forget about windage or even wave-piercing.

Wouter

Oh com'on Wouter! Don't make us all search your ramblings... just spit it out and tell the ignorant yet again!... We are all sitting around the fire waiting quietly for a bed time story... why do late model cat shapes feature ever more radically droopy bows?

Because they have moved hull volume to the keel line. If you want to keep the overall volume of the hull about the same (as you must or risk bouncing over the waves) then you must take away volume under the deck. In effect the keel line becomes wider, while the deck become narrower. The sides of the hull now don't V-out anymore when going from keel line to deck but rather V-in. Together with the bow wedge (hull sides meeting eachother at the bow) this creates a intersecting line between the two sides of the hull that is raked back on the bow rather then raked forward as is the case with side that V-out towards the deck. Most easy way of producing these hulls is to just have this intersecting line be the bow itself. You could add a piece (triangular) to the bow to give is a straight appearance but this section will both be very thin (breakable), difficult to make, add weight and be pretty much useless as the waterline is further down on the hull. So why make things more complicated, just cut the bow back under an angle and be done with it.

So now the true question becomes why all the new hulls want more volume to be concentrated on the keel line while older boats had rather narrow keel lines. When this is decided then the raked back bow is nothing more then a result.

Wouter

Wouter's dead on, good description.

Its less about wave piercing and more about moving the volume down low so that the boat can be pressed harder downwind. Remember the Acat doesnt have a spin, so the main drives the boat downwind. Anyone who's gone downwind or on a hot reach in a uni-rig without a spin knows that the mast wants to push forward at the top, and the bows want to stick in and stop. So its more about preventing a pitchpole than wave piercing thru waves even though thats how this bow is described.

The bows also wont stick underwater when you bear away or if you press them hard downwind like a flat top deck will. Once a flat top deck goes underwater its all over, you either stop or pitchpole. I've actually done bear aways too agressively and the sterns come out of the water the boat bears away with the bows underwater and just the tips of the rudders in the water. Pretty scary the first time I did that. But it didnt stop, it just kept going.

Bill

Wouter I am ignorant about this so bare with me.
I have used several cats these last years and one stood out as very fast on a reach and VERY stable. It planed like a speadboat. IT was an 18 foot Tiger Shark designed by Ron Given in NZ. IT has hard chines and a vee hull at the rear section.
I am presuming these new hulls are also trying to pierce waves but then convert that displacement as effectively as possible toward the rear of the boat.
This would help planing up wind and certainly keep it more stable downwind.?
Do I make sense?

You mean like this?

Ow wait...never mind <img src=

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Yeah, I've noticed exactly the same thing on the Blade, compared to the Tiger. I've also had a similar experience on an FX-one.

One of the more convincing descriptions I've read of why

wave-piercing

hulls work talks about making the buoyancy

active

. By putting more buoyancy low down, you reduce the amount by which the boat pitches in response to a given force. With a V shaped bow, the boat has to pitch a long way in order to find all the reserve buoyancy, by which time the boat is way out of trim.

The downside, is that it doesn't feel as progressive. On a wave-piercer, you can be using most of your reserve buoyancy and the boat will still be relatively close to normal trim. I suspect that this is why people talk about the Capricorn as being easy to pitchpole: it's not, it's just harder to

read

how hard you're pushing the boat.

Paul

You are spot on there, Paul.

Wouter

I have witnessed same kind of difference between H16 (very strong V shape) and TheMightyHobie18 Formula (traditional but more curved). Next summer I can compare these to Blade. Hopeully the difference is not as big as it was between my previous cats, otherwise I will capsize so fast that I wont even notice it <img src=

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Valtteri