Connor.kainalu

Backwards Skiffs?

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Rather recently, reverse bows have become popular on keelboats, but do they have a place on skiffs?

I would think that it would be slower in light airs when you go bow down because it would reduce waterline

 

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I don’t see the benefit on skiffs. Speaking from Cats, they serve a lot of purpose in getting more buoyancy down lower in the bows as well as the rounded top sides of the bows then have the tendency to pull out of a stuff.

On a skiff I don’t see the same problems and thus it just looks cool.

As far as light air, atleast on an F18 cat, we dig those bows in and don’t lose any WL, minus the transom of course. Trying to get that clear of the water.

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37 minutes ago, OutofOffice said:

I don’t see the benefit on skiffs. Speaking from Cats, they serve a lot of purpose in getting more buoyancy down lower in the bows as well as the rounded top sides of the bows then have the tendency to pull out of a stuff.

On a skiff I don’t see the same problems and thus it just looks cool.

As far as light air, atleast on an F18 cat, we dig those bows in and don’t lose any WL, minus the transom of course. Trying to get that clear of the water.

I know the theory - first, it's not a waterline problem as the fullness is pulled forward down low.

We kinda blow through waves upwind these days, so the theory is it reduces wave drag upwind, and doesn't cost much in light wind. 

 

No idea if theory = reality in this case.

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11 minutes ago, Raz'r said:

I know the theory - first, it's not a waterline problem as the fullness is pulled forward down low.

We kinda blow through waves upwind these days, so the theory is it reduces wave drag upwind, and doesn't cost much in light wind. 

 

No idea if theory = reality in this case.

For sure. There's a reason they're called wave piercing bows. It's a wet ride.

I suppose it matters what the rest of the hull design is, as to how the reverse bow does its job. (Wide platform vs Slim)

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19 hours ago, Connor.kainalu said:

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Rather recently, reverse bows have become popular on keelboats, but do they have a place on skiffs?

I would think that it would be slower in light airs when you go bow down because it would reduce waterline

 

Conor,

I drew the yellow one and built a white sistership.

Considered rationale as follows: the i14 in particular benefits from VCG aft  - its a long story. Also, any opportunity to reduce windage is taken as a development class. So, I knew what "J" measurement" I wanted and decided to make the top half of the stem a continuation of the forestay to reduce weight and windage at this point. This extension of the forestay meets the vertical part of the stem half way up so you are never losing WL length.

Any gains are frankly immeasurably small, also it forces your hand into an aft mast position all things being equal, and also split moulds down centreline, both of which have some downside. The lord giveth and the lord taketh away and all that!

Not sure if my rationale holds true for other applications, the downsides / compromises probably do though! :-)

 

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I think it's probably a lot more valuable to ask if wave peircer style bows belong on anything as low aspect as the keelboats they're being put on today. 

DRC

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1 hour ago, Dave Clark said:

I think it's probably a lot more valuable to ask if wave peircer style bows belong on anything as low aspect as the keelboats they're being put on today. 

DRC

Less windage, less added resistance and motion in waves.

On flipside Less bowman real estate less reserve buoyancy in big conditions downwind. 

Less fwd cabin space. 

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Well to be fair, the Euros took some of my (and others--I wasn't the only person who thought bulbous bows and flare with bluff WL made no sense!) observations of stupid OSVs and ran with it. Why make flare when you can make waterline instead? And then might as well look cool save some weight and come up with some hifalutin explanations for how it is light years ahead of a plumb bow:

X-Bow.jpg
 

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1 hour ago, Daniel Holman said:

Less windage, less added resistance and motion in waves.

On flipside Less bowman real estate less reserve buoyancy in big conditions downwind. 

Less fwd cabin space. 

That flipside off the wind and most importantly on oceans is the one that scares the Bujeezus out of me. "Naw dood. It's fine to have waves the size of freight trains going right over the deck every 200 seconds. It'll make monohulls powered by lead cool again!". 

Meanwhile the Dali foil boats just bounce around on top of the swell and actual wave piercing multi don't ask crew to venture onto the hull that's doing the piercing.

 

Edit. Clearly I'm a bit opinionated about this. Didn't mean to drift the thread. It just intersects with one of my pet design peeves.

DRC

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Remember that new singlehanded dinghy that was getting all sorts of discussion here like 5 years ago? That had the reverse bow. And after the inaugural sail, the Shaw guys went dark on it and the new owner ran away from any and all inquiries...and the vids disappeared too!

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4 hours ago, fastyacht said:

Remember that new singlehanded dinghy that was getting all sorts of discussion here like 5 years ago? That had the reverse bow. And after the inaugural sail, the Shaw guys went dark on it and the new owner ran away from any and all inquiries...and the vids disappeared too!

Dare say the reverse bow least of their issues commercially / technically. 

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8 hours ago, Dave Clark said:

That flipside off the wind and most importantly on oceans is the one that scares the Bujeezus out of me. "Naw dood. It's fine to have waves the size of freight trains going right over the deck every 200 seconds. It'll make monohulls powered by lead cool again!". 

Meanwhile the Dali foil boats just bounce around on top of the swell and actual wave piercing multi don't ask crew to venture onto the hull that's doing the piercing.

 

Edit. Clearly I'm a bit opinionated about this. Didn't mean to drift the thread. It just intersects with one of my pet design peeves.

DRC

Accept all of that - was just playing devils advocate! In most cases the big downsides would outweigh the marginal at best benefits. 

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I like the aero side of it, but I really dislike the observation that the deeper the bow goes in the water the blunter the entry angle gets. I can't help thinking, too, that if a boat perpetually has 20 kilos of green water on the foredeck that is going to be no help at all. Couple that with a dished deck so all that water gets washed into the cockpit too and I wonder how much the practical displacement increases.

 

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1 hour ago, Connor.kainalu said:

And how much goes down the spin chute?

A lot on any i14.

Various mitigations, from flaps over hole... to half length socks which prevent the water going in sock. 

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6 hours ago, JimC said:

I like the aero side of it, but I really dislike the observation that the deeper the bow goes in the water the blunter the entry angle gets. I can't help thinking, too, that if a boat perpetually has 20 kilos of green water on the foredeck that is going to be no help at all. Couple that with a dished deck so all that water gets washed into the cockpit too and I wonder how much the practical displacement increases.

 

That’s the case on all boats less so on most “wave piercers” whatever that means.

Waves come over the front quarter or beam not dead into bow irrespective of bow rake, and any skiff type boat on non flat water will be perpetually wet on deck. 

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11 hours ago, fastyacht said:

Remember that new singlehanded dinghy that was getting all sorts of discussion here like 5 years ago? That had the reverse bow. And after the inaugural sail, the Shaw guys went dark on it and the new owner ran away from any and all inquiries...and the vids disappeared too!

was that the Shadow/Phantom or something? Being built somewhere around Seattle or Vancouver? That thing looked sweet... 

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5 hours ago, mustang__1 said:

was that the Shadow/Phantom or something? Being built somewhere around Seattle or Vancouver? That thing looked sweet... 

No.
It was being built by Shaw in some country on the other side of the Equator...

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17 minutes ago, fastyacht said:

No.
It was being built by Shaw in some country on the other side of the Equator...

well no wonder the bow was backwards. 

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5 hours ago, mustang__1 said:

was that the Shadow/Phantom or something? Being built somewhere around Seattle or Vancouver? That thing looked sweet... 

I found the owner of the boat--Fraser Guthries. But I can't find the original thread!  He called it the Shaw 4

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It has benefits when pidge poling. She goes deeper. Then pops upright. Its so fast you don't even know you capsized a 14 ft skiff.

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1 hour ago, Rohanoz said:

The Shaw 4 was/is a cluster fuck of great ideas unfortunately put together by a dishonest asshat. Fraser left it without paying a cent to Shaw, CTech, North's or any other supplier. Shaw sold it and got a few $ back, but is now in bumfuck no-where Central QLD and worth whatever someone is willing to offer the current owner who sailed it once and like Fraser just couldn't sail it.

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54 minutes ago, brett221 said:

The Shaw 4 was/is a cluster fuck of great ideas unfortunately put together by a dishonest asshat. Fraser left it without paying a cent to Shaw, CTech, North's or any other supplier. Shaw sold it and got a few $ back, but is now in bumfuck no-where Central QLD and worth whatever someone is willing to offer the current owner who sailed it once and like Fraser just couldn't sail it.

Holy shit.
Was that video we all watched briefly before it went dark, where the helmsman was having issues, Fraser?

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I reckon it would be a lot of fun with a set of stays, stubby wings and a trap, plus a bowsprit and asso. And probably winglets on the rudder.

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5 hours ago, Rohanoz said:

I reckon it would be a lot of fun with a set of stays, stubby wings and a trap, plus a bowsprit and asso. And probably winglets on the rudder.

That reminds me that I still need to build my old idea: a stepped sailing hydroplane...

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7 hours ago, Rohanoz said:

I reckon it would be a lot of fun with a set of stays, stubby wings and a trap, plus a bowsprit and asso. And probably winglets on the rudder.

A Cherub?

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8 hours ago, brett221 said:

Or a Musto Skiff?

 

 

19 hours ago, Dave Clark said:

A Cherub?

Sorry - should have put a sarcastic note after my comment - the original thread for that boat had every other permutation of a camel/horse/committee derivative!

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