Brian Bennett's VX from the FP

Sail IC

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Don't get hang up on the Libra example. I wrote it as I was suprised to see such a high SA/ballast for such a big boat. The Libra is a very extreme boat and not representative for sportsboats in general.

Even if comparing SA/ballast is not a one for one between different boats, I do think it tells a lot comparing boats of similar size. Sure, if you compare an RSK6, VX, and and Open 5.70, different dynamics comes into play when sailing upwind. Both the Open and the RSK6 hullshapes are designed to sail with some degree of heel, where the VX should be sailed more upright.

What purpose does the ballast have on a sport boat. I can see three going from less ballast to more.

1, Make the boat selfright

2, Make the boat easier to sail

3, Contribute to the RM when sailing

#1 is the bare minimum. When knocked down and the mast top is in the water, the RM from the keel must be bigger than the negative RM from the rigg. The negative RM from the rigg should be proprtional to the SA, not linier, less than square, probably somwhere in between.

What is interesting with the VX is that it seems to be designed to fulfill #1 but no more. I think this is quite rare for sportsboat, and the only other boat in this sie (around 20') to have similar objective is the Shaw 650, especially in its first configuration with a 70kg ballast (if I remember right.

So in summary, in the 20' size, only the VX and the Shaw 650 seems to be designed to fulfill criteria #1 but no more where all other boats have higher ballast and to some degree contribute to criteria #2 and #3.

I'm actually from now ignoring what Gybeset writes. He tends to look at a post and rather to try to understand what it is saying just try to find something that he can disagree to and put all is efforts into that. Highly unproductive. He fits the steriotype "grumpy old men" very well. People who have tried hard but failed to achieve any level of success, hence they got grumpy. Best to leave them by themselves.

 

RonK

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What purpose does the ballast have on a sport boat. I can see three going from less ballast to more.
To make it a sportsboat. The heavier sportsboats broach but don't capsize (mostly). People can sail them without an expectation of swimming. When people start wearing wetsuits, you're in a dinghy (moderate generalisation).

Some of the fleet don't want to go swimming. Some don't mind, but some will always pick something more stable; with good reason, not everyone has the energy or inclination for an extreme ride all of the time.

Sportsboats sail with the keel down permanently, they can be left on a mooring or against a dock overnight (e.g. for weekend events), they don't fall over on the dock if the crew aren't careful when walking around the boat. They don't collapse to windward in lulls. You don't swim if the crew are too tired to hike.

That's what the ballast does, it gives the boat manners. It's not about going faster, it's about being stable and still going pretty quick.

It's not clear to me exactly how the VX will fit, whether it will have enough stability for that market, but there's probably another one out there anyway.

 

timber

Super Anarchist
As a fan of the i550 I expect the VX to be faster than my boat given its weight and other numbers. The Viper will be faster , too. no surprises there. But in the bang for buck department the i550 is untouchable. Either as a home build or as a one off built to order. They are simple and simply fast.

If I keep this up I might begin to sorta follow the viper crowd in cross pollinating threads... help me.

T

 

Steveromagnino

Super Anarchist
What purpose does the ballast have on a sport boat. I can see three going from less ballast to more.

1, Make the boat selfright

2, Make the boat easier to sail

3, Contribute to the RM when sailing

What is interesting with the VX is that it seems to be designed to fulfill #1 but no more. I think this is quite rare for sportsboat, and the only other boat in this sie (around 20') to have similar objective is the Shaw 650, especially in its first configuration with a 70kg ballast (if I remember right.
Just commenting on the Shaw 650; the original wooden boats had 85kg bulb; the class standard and all production boats are bulb 108kg/235lb now; similar situation to the Vipers when they changed bulb sizes.

The reason is the boat sails almost as well downwind, the same upwind and the manners are improved in both directions; important when you consider that much of the world are not used to sailing at planing speeds or are coming from earlier generation sporties that used to have pretty massive amounts of lead under them. For the same reason, that's why carbon rigs work so well on sportsboats; it's like the benefits of more bulb weight while making the boat lighter.

Most of these boats go best when sailed flat; so most of the time the bulb doesn't do much; it does however make the boat more forgiving when things aren't spot on, provides peace of mind, and makes the characteristics a little more sedate. I think that's the reason why people sail sportsboats, not dinghies.

The bigger the boat, the more stable the boat will tend to be; for instance on a smaller size boat a crew on the wrong side of the boat (especially when there is less crew to combat the one person flailing on the low side out of a gybe) in a mess up gybe will have a bigger effect than a boat with the same righting moment that has a much bigger bulb, even though the ratios are the same.

Will be great to see some more of these little speedsters around.

 
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Sail IC

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Great post above.

I think in a nutshell explains why there is a need for more than one boat in each length category.

 
The displacement goes down by 150 lbs and the same platform becomes a big powerful dinghy.
That'd make it 45 pounds lighter than a 505 (though extra kit would probably account for that). Put in that context we can really see what a different beast this is to a Viper or other 20ft sportsboat.

Good luck with it. I think there's definitely room for it in the market without eating into too many other classes.

Down my neck of the woods 1720s have been converted into training vessels. There's a demand there for sportsboat sailing for younger sailors. In the right circumstances there could be some competitive kids.

I'm probably the only person who'll ever suggest this but I think there's a lot to be said for putting in a slab reefing point (and then banning it for racing). Makes the boat a bit more flexible for daysailing or taking out guests for a burn or when the wind gets up to 40 knots and you're wrecked tired with a 3 mile beat back to the harbour. The fact that it's a lightly ballasted boat will favour reducing sail area for less experienced sailors.

At this kind of weight and size it shouldn't be too hard to trailor double or even triple-up. Makes a big difference when you want to run a fleet of them and you can have team racing (including rib) travelling to events behind 3/4 cars compared to 6/7 you'd need with SB3s or J80s.
This sounds very light (fragile?) to me. If the boat (without bulb) is lighter than a 505 (which is partially reinforced with carbon) but carries significanly more sail area particularly downwind, I wonder how the boat will handle the additional loads that come with the increased sail plan. Is there anything special in the construction that ensures durability and longevity of the boat?

 

GybeSet

Super Anarchist
loads are governed by RM not SA

and yes in any breeze it will need more of that, it won't be a 2 up boat in a fresh breeze

that model (2-up hiking) tops out with a rs400 or tasar, tho the proportionately wider hull of this larger dinghy has form stability to go toward providing that

 

jh26

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Georgia
/monthly_09_2011/post-14139-056931400%201316741316_thumb.jpg

Brian has just confirmed that The VX One will be at the Annapolis Boat Show October 6-10.

He's also planning to be at Lake Sinclair on Saturday and Lake Lanier Sailing Club this coming Sunday afternoon.

 

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Sail IC

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This sounds very light (fragile?) to me. If the boat (without bulb) is lighter than a 505 (which is partially reinforced with carbon) but carries significanly more sail area particularly downwind, I wonder how the boat will handle the additional loads that come with the increased sail plan. Is there anything special in the construction that ensures durability and longevity of the boat?
Yes, that seems very light. To make another comparison, an RSK6 is 165Kg excluding keel (20kg) and ballast (100kg). Even if similar in length, the VX has more sqm of panelst (laminate), so its a bigger boat.

My bet is that the 175kg in the VX specification is without keel/ballast even if it states its the displacement. That would be about right. Btw, a "naked" 505 (no fittings, just hull and deck put together) is 70-75kg, making a total sail-up weight of 127kg.

 

MauganTornado

Super Anarchist
/monthly_09_2011/post-14139-056931400%201316741316_thumb.jpg

Brian has just confirmed that The VX One will be at the Annapolis Boat Show October 6-10.

He's also planning to be at Lake Sinclair on Saturday and Lake Lanier Sailing Club this coming Sunday afternoon.
Line up that new boat of your against the Nacra Formula 20 Carbon. It'll be racing on Lake Lanier this weekend (from what I've heard).

 

RonK

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This sounds very light (fragile?) to me. If the boat (without bulb) is lighter than a 505 (which is partially reinforced with carbon) but carries significanly more sail area particularly downwind, I wonder how the boat will handle the additional loads that come with the increased sail plan. Is there anything special in the construction that ensures durability and longevity of the boat?
Yes, that seems very light. To make another comparison, an RSK6 is 165Kg excluding keel (20kg) and ballast (100kg). Even if similar in length, the VX has more sqm of panelst (laminate), so its a bigger boat.

My bet is that the 175kg in the VX specification is without keel/ballast even if it states its the displacement. That would be about right. Btw, a "naked" 505 (no fittings, just hull and deck put together) is 70-75kg, making a total sail-up weight of 127kg.
Maybe a different way of looking at it would be to look at the 49er. Same 215 square feet upwind SA, the fractional is slightly smaller than on the 49er. The VX is a bigger boat and needs structure to support a small keel, but it also weighs 75kg.

If you start at a Viper and then shave weight, the VX looks very light. If you start from skiffs and add structure, it's a little less unrealistic.

 

Dervish

Member
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Boston, PRM
Brian really wants to run a class his own way- from design and construction, to marketing, sales and class management. The VX is his means to attempt to do that.
Reminds me of an old joke.

Enoch Harris bought the old Wiggins farm, which was quite run down, and proceeded to restore it to its' former vigor. The local parson came out to visit.

"Fine farm you have here, Enoch," said the Reverend, "Just goes to show what God and Man can do, once they get together."

"That may well be, Reverend," said Enoch "But you should have seen the place when God was runnin' it by himself."

 


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