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overdraft

Kite Kat... Bat5h!t crazy?

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Had a Melges 24. Loved the speed off the wind. Hated: Stupid forstay-doubles as jib halyard-wants to destroy itself on furling / Having to find 5 guys for weight when there was only work for 3 / Fighting the kite around the forestay on jibes... 

Latest crazy idea... Get an old Melges, shift the mast forward a foot to move the CoE forward and lengthen the spreaders, delete the backstay to make room for huge-ass square head main, delete flaky forestay and jib altogether in favour of a baby stay to keep the mast from falling backwards. The result is a Kat boat with a Kite (get it?) which is a two or three person boat which will give up some upwind performance to a conventionally rigged Melges but be just as fast/fun downwind, except way easier to jibe because the absence of an 'out to the bow' forestay would make the jibes blow throughs with much diminished crew effort over hauling a loaded sail across the forestay. So here's the Kite Kat... what do you think?

 

 

melges.jpg

Kite Kat.jpg

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You're not concerned you'll pitchpole at every gust?

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i wasn’t until you said that... why exactly would that happen? the CoE is probably net in the same place as the pinhead main plus jib and all the cool kids are leaving their jibs up down wind in a blow.... you get that they don’t run down wind, they vmg reach, right?

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If your boat doesn't have enough bow volume moving your mast forward with a larger main and smaller foresail - you may find the mail driving your how into the water. 

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Oh. Ya, unconcerned. Carbon mast mast weighs  28kg, so like 60 pounds. Jib is being deleted so center of effort is unlikely to be any further forward than it was.

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actually seems pretty workable if you're trying to address what you don't like about the stock boat, I'd go for it. but in a blow without bodies aft and the new rig configuration my guess is it probably will be harder to keep the bow up. 

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Thought about old surf skis use to have either a spoon or wing shape attached to the bow for anti-pearling help.   I guess modern surf skis have more volume forward to prevent that.  

Maybe would want to add that to the equation?

- Stumbling

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The newer skis have volume arranged more vertically and are narrower.  What you could do[it will be a lot of work] is make a concave tunnel in the bow area to use the water to generate lift.  I did it in the 70s in small craft and endurance outboards.  You see it in a diluted version on noserider surfboards.  The concave surface for lift was made illegal by most of the governing bodies in water sport. I liked it except when I had to do the tooling, then it was very time consuming.  Good luck.

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14 hours ago, Miffy said:

If your boat doesn't have enough bow volume moving your mast forward with a larger main and smaller foresail - you may find the mail driving your how into the water. 

 

12 hours ago, overdraft said:

Oh. Ya, unconcerned. Carbon mast mast weighs  28kg, so like 60 pounds. Jib is being deleted so center of effort is unlikely to be any further forward than it was.

The  centre of effort may be longitudinally in the same place, but will it be a lot higher than it was, so a lot bigger lever arm for pitchpoling. Plus the mast shift.... 

Does you mast 28 kg include rigging and halliards?

You will also need more righting moment upwind as well?

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To my eyeball it’ll have less upwind sail area then the stock setup... remember I’m not pretending this is some kind of performance improvement, it’s a way for 3 old guys to go for a Wednesday night race and still get a double digit ride instead of trying to get 3 additional  guys and working hard to go 8 knots on some lead mine... so do I think upwind with only 3 crew it would have more than optimal heel? Sure, but at least we’d get to plane when we turned the corner...

I'm fascinated that there is so much concern about pitchpoling... We never stuffed the bow in my Melges... got knocked down for sure, but never saw green water over the bow... I guess if we’d left the beer cooler and spare sails and anchor in the forepeak it would have morphed into a submarine but it seems unlikely it was that close to the edge.

Thanks for the comments everyone!

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3 hours ago, guerdon said:

The newer skis have volume arranged more vertically and are narrower.  What you could do[it will be a lot of work] is make a concave tunnel in the bow area to use the water to generate lift.  I did it in the 70s in small craft and endurance outboards.  You see it in a diluted version on noserider surfboards.  The concave surface for lift was made illegal by most of the governing bodies in water sport. I liked it except when I had to do the tooling, then it was very time consuming.  Good luck.

My old sailboard wave boards had lift a dimple in the nose area.

- Stumbling

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Looks like a worthwhile experiment to me, and if it's not right then keep tweeking. Love the design goal: three old guys looking for double digits on a Wednesday night.

The mods look quite complex (to me), need to move the mast step support post forward and maybe add a new bulkhead. Masthead (to my eye) might be almost a foot lower so standard sails fit no more ?

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7 hours ago, overdraft said:

To my eyeball it’ll have less upwind sail area then the stock setup......

I'm fascinated that there is so much concern about pitchpoling... We never stuffed the bow in my Melges... got knocked down for sure, but never saw green water over the bow... 

You may have slightly less sail area, but the CE will be higher, so you will need the same amount of weight on the rail?

With extra swept back shrouds, there is less dumping ability and a reduction in efficient down wind angles?

I haven’t stuffed the bows of a Melges into a wave either, I am only saying that it could be more likely to happen?

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Nah, same height just crappy sketching.! The compression post lands on a saddle mounted over a big box section longitudinal keelson stringer so sliding it forward seems doable. Deleting the backstay for the fathead main requires more sweep on the spreaders so they’ll end up terminating at the same point so the bulkhead that takes the lateral loads stays in the same place. The only thing that seems tricky to me is going to be anchoring the baby stay... 

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Posted (edited)

Just omitting the jib will raise the overall CE. The fathead will raise it some more.....

i also wasn’t necessarily concerned about the structural integrity, just reduced mainsail sheeting/dumping angles....

Have fun!

PS: Buy a FarEast 23R!! Why fuck with a well designed and engineered boat?

Edited by Sidecar

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And you'll get a whole foot more usable cabin space below, liking this more and more. Where abouts is this happening ??

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Cool idea, but once you get tired of reaching back and fort, you may realise that upwind performance sucks. The angle of the baby stay looks wrong also, if you are pulling too hard on the vang or mainsheet, it may flip and the mast comes down... 

A very small self tacking jib would fix that. It may be a bit against your primary design goal, but it would help a lot going upwind without being too much in the way in a gybe. 

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On 7/3/2019 at 2:25 AM, 10thTonner said:

Cool idea, but once you get tired of reaching back and fort, you may realise that upwind performance sucks. The angle of the baby stay looks wrong also, if you are pulling too hard on the vang or mainsheet, it may flip and the mast comes down... 

A very small self tacking jib would fix that. It may be a bit against your primary design goal, but it would help a lot going upwind without being too much in the way in a gybe. 

This.  ^^^^^^    Wouldn’t need to move the mast.

You might need a drifter upwind in the light and add a smaller chute for the big stuff, but that could be fun,  I have an upwind drifter set flying on Amati that works as a deep downwind asymmetrical up to 15k  or so- just mess with the luff tension to get your shape so the luff rotates downwind, unless you really need dedicated sails.  Careful on the size of a drifter- I have a 160%, and it’s overpowered even close reaching in 5 knots, and we’re going fast enough in the light because of it that it seems like we’re always close reaching on apparent wind in the light. :)

I’d  consider a jib track or a dangly pole for a self tacking jib leach control.  Even a Hoyt jib spar might work- take look at the Schock Harbor classes, although you might have to beef up the deck, and deck placement of the sheet is important. They help downwind way more than you think, but leach control is something you need to consider. An athwartship jib track doesn’t help much downwind, and they can be complex little beasties.  

Anyway, a lot less $$$$ than moving the mast.  Watching your main pasted against really swept spreaders is frustrating....

 

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sounds a lot like the old Tripp Freedom 24 concept, although even that still had a small jib:

picfreedom24101a.jpg

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Yeah... The baby stay as shown won't do much other than add a bunch of compression on the spar when you crank on the main sheet! Also as stated, a fathead main an no jib is just going to make the boat even more tender!

Add a reef point to the main to keep the boat flat when there is breeze, put a self tacking jib on there to make that easier, and add longer sprit to make jibing easier. Much easier modifications that probably would do a better job addressing the stated issues!

You could also add water ballast to replace the extra crew (although not super helpful if short-tacking)

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4 hours ago, Airwick said:

Yeah... The baby stay as shown won't do much other than add a bunch of compression on the spar when you crank on the main sheet! Also as stated, a fathead main an no jib is just going to make the boat even more tender!

Add a reef point to the main to keep the boat flat when there is breeze, put a self tacking jib on there to make that easier, and add longer sprit to make jibing easier. Much easier modifications that probably would do a better job addressing the stated issues!

You could also add water ballast to replace the extra crew (although not super helpful if short-tacking)

+1. 

Might be interesting to try to understand if reducing sail (& where & how) with less weight results in better performance - little old school story- one of the small guys (John Christianson, IIRR) in the Finn class made himself a smaller sail for heavy airs, killed upwind, and got stomped downwind, but there was a lot of speculation about why it worked so well upwind, what with less righting moment, less sail area, a stiffer mast (in effect) and it was thought, less drag.  Low aspect pinhead sail with a little roach- on a not so light planing hull.  But low aspect sails, according to Marchaj do better in heavier air upwind and down, you’d have to look up info on planform distribution- like pin vs fathead- for example-  

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On 7/11/2019 at 10:54 AM, ryley said:

sounds a lot like the old Tripp Freedom 24 concept, although even that still had a small jib:

picfreedom24101a.jpg

:wub:

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On 7/13/2019 at 3:48 AM, Airwick said:

Yeah... The baby stay as shown won't do much other than add a bunch of compression on the spar when you crank on the main sheet! Also as stated, a fathead main an no jib is just going to make the boat even more tender!

Add a reef point to the main to keep the boat flat when there is breeze, put a self tacking jib on there to make that easier, and add longer sprit to make jibing easier. Much easier modifications that probably would do a better job addressing the stated issues!

You could also add water ballast to replace the extra crew (although not super helpful if short-tacking)

Just add ballast. You won’t get full benefit of a crew on the rail, but at least it will have less windage, have a lower CG overall and won’t malfunction or make mistakes whilst helping minimise yours.

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Stop wasting your time and just get a proper sports boat. At least your extra 2 crew will have something to do.

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An older Viper (without all the upgrades) might be almost the same price as a new larger main.

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