Where can I purchase bullets for my Epic Venturi ?

8 years 4 months ago #17526 by PeterS294
I would like to add bullets to the existing venturi on my Epic V10S and Epic V8 to improve the draining. I know that some have constructed their own. It will save me time if I could purchase bullets and cement them in place. Thanks!

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8 years 4 months ago #17528 by Kayaker Greg
Might help if you said where you were, Stellar in NZ and Fenn in NZ both have bullets available.

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8 years 4 months ago #17531 by Ranga
Don`t waste your time and money, it makes zero difference. I did this many years ago and then realized that if you reduce cavitation and drag you reduce suction.

They are designed to drain at 10 km/hr.

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8 years 4 months ago #17533 by Goldcoastkiwi
I have had a very different experience than Ranga, I found that when I made a bullet for my V10S, it gave a dramatic improvement, no longer did you get that half full footwell at lower speeds , and it drained quickly and completely at much lower speeds than previously.

I think it is worth perserving to find one , or alternatively they are very easy to make ( I used FIMO, and fitted it using silicon)

Skis past and present : New Epic V10 Ultra, Fenn Swordfish Carbon,
Stellar S2E Excel double, PRS 570 , V8 Club, V10 Sport Club,Stellar S2E Advantage double, Epic V10 Sport Performance, Think EVO II, Fenn Swordfish Vac Glass, Fenn LS, new model Stellar S2E double, Fenn Bluefin S Carbon Hybrid

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8 years 4 months ago - 8 years 4 months ago #17536 by Bolge
Guys please excuse my ignorance but what is a bullet and the theory behind them?

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8 years 4 months ago #17537 by PeterS294
I am in the US. If they are not available here, I would purchase them from overseas.

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8 years 4 months ago #17539 by PeterS294

Guys please excuse my ignorance but what is a bullet and the theory behind them?


The bullets or bullet scupper (located at the venturi outlet on the bottom of the hull) are added to improve the draining efficiency of the venturi bailer and improve draining at lower speeds. Some are designed including the bullet scupper, but many are not.

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8 years 4 months ago #17543 by nell

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8 years 4 months ago #17545 by Steve Hansen

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8 years 4 months ago #17547 by Kayaker Greg
Not everyone paddles at 10km/h all the time, the bullets help my scuppers drain just under 8km/h and made a huge difference to my SES when I fitted one, the Stellars now come std with the bullet and I also fitted them to my Swordfish before I even paddled it. The science is simple and perhaps Ranga did not fit his in the right spot or the bullet was the wrong size for the scupper? I remember my V10L had a concave type of channel where the bullet would need to go so perhaps a filler of some sort would need to go in there before the bullet if your Epic is the same. They are cheap and easy to fit.

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8 years 4 months ago #17548 by Newbflat
One thing to keep in mind with adding a bullet is that your blocking a perfectly good exit for an battery powered RC boat mini jet drive. Tired of getting dropped while in a V10s by the guy in the Uno? Its just the thing for that Very strong finish in that 30 k race. Or showing that 'Pro' what you got! It can also really help you catch your breath on those down winders as well.......... Just saying.




Bill

FENN Bluefin S
FENN Swordfish S carbon hybrid
Epic V8 double gen 2
Lot and lots of DK rudders.


Had:
Stellar SEL excel (gen 2)
Stellar SR excel (gen2)
Stellar S18s g1 (excel)
Epic V10 Double (performance)
Stellar SR (gen 1)
V10 sport (gen 2)
V10 (Gen 2)
Beater SEL (gen 1)

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8 years 4 months ago - 8 years 4 months ago #17549 by Kocho
The proper bullet installed in the right place does make a difference. You can see my video that clearly demonstrates the two benefits from a bullet: more suction at the same speed AND reduced turbulence at the same time. It is like a free lunch, sort of thing ;)





You can see the shape and placement of the best-performing bullet that I measured on this rig around the 2 minute mark in the video. The bullet has to be smaller than the outer diameter of the ventury and placed close enough to it but not too close: you want to make the water go around the ventury, speed-up to get away from it, but before it could eddy into the venturi it hits the bullet and slips smoothly over the bullet - the result is more suction than with out the bullet, where some of the water flow curves into the ventury, creates back flow and negates some of the suction and creates added turbulence at the hull... You don't want the bullet to block too much of the opening either. I eyeballed the area of the donut-shaped opening near the bullet to be similar to the area of circular area inside of the Venturi drain. This seemed to work well in practice this way the bullet it is not blocking the flow while it is still covering as much of the outflow area as possible for a smooth flow and still being lower than the Venturi for good suction...

The first bullet I made was not good - it either made no difference or was worse than without it. I figured, I don't have time to experiment multiple times on the water, so I built that rig you see in the video. Within a couple of hours I had tested several shapes and sizes and experimented with placement - the water level would change and tell me how well the bullet and placement worked. When I found something that seemed to maximize the suction, I stopped, glued it to the boat, and it worked on the water too.

The physics is seemingly simple - same effect that we get without the bullet, except amplified by the presence of the bullet, which allows for faster local velocity of the water and thus more suction, while the hydrodynamic shape minimizes the turbulene that otherwise the non-bulet ventury creates...
The following user(s) said Thank You: owenfromwales

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8 years 4 months ago #17551 by PaddleFaster
I had a bullet that I took the time to hand carve from mini-cell foam, encapsulate in epoxy, wet sand and polish to near perfection and then installed on my V10 Sport.

Back in the day, I produced approx. 1000 custom fishing lures a fishing season to provide to local fishing buddies, so my home shop is set up well to do this kind of manly-man, the fate of the world depends on me, kind of creative task! :laugh:

I have two boats, a V8 and a V10 Sport that I alternate in use.
The Sport had a bullet, the V8 did not. I used the bullet for about 400 - 500 miles of paddling last season( A lot of km's) and removed it prior to this season.

I found that the only genuinely "noticeable" difference the bullet made in my circumstance, is that it allowed far less water to flow into the cockpit when slowing, stopping and starting again. Less water in the cockpit in those situations, meant a faster draining cockpit.

In my situation, a bung/plug attached to a bungee and placed in the venturi that is removed and reinstalled to drain the on the fly, makes much more of a difference all around than the bullet ever did.

Personally, I felt that the bullet had about the same effect on my ski that a playing card and clothes-pin had when I put them on the frame of my bicycle as a kid so that the playing card made a motorcycle like engine noise as it hit my spokes.

Because it made a cool noise, it HAD to mean things where moving faster. :laugh:

Kidding aside, I really believe it falls under the "to each his own" category and will be one of those things that is forever debated; simply because the differences between having a bullet and not having one are so negligible, there really is no right answer.

If you want to make one it is a pretty non complicated task that takes a few morning hours of patience. Just ask and I am sure Kocho and others will be more than happy to outline the process.


Sidenote: My current project that I just finished up was using gas tank repair two part epoxy putty, to reform/replace a 1 inch chunk on the front of my surf rudder that was removed by a submerged boat engine that my rudder intimately met one day as I was gliding along in the shallows.

The repair, painting and epoxy top-coating worked out well.

Speaking of which... It makes absolutely no sense to me that the large Epic surf rudder is made in such an extremely buoyant fashion. I mean this thing seriously floats, rod and all, and wants more than anything to be lying flat on the water's surface.

I would think that a non-buoyant one of similar weight, might offer a tad more stability in refractory waters at lower speeds.

Damn it, there I go rambling on again! Cold beer on a hot day seems to do that to me! :laugh:

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8 years 4 months ago #17552 by Kocho
Non-buoyant rudder of similar weight would have to have a different size and shape. I'm pretty sure they shaped and sized it then let the weight and buoyancy fall where they may... It has to be a foil shape to work well and that means some volume. And because we don't want it to be heavy, it might float...

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8 years 4 months ago #17553 by Dicko
Unfortunately Ranga has missed the whole point of adding a bullet to your ski. They weren't designed to improve drainage. They do improve drainage which is a bonus.
The original bullets were designed by red7 to reduce drag, so they could add 3 venturis with no increase in drag.
Just cos epic don't use them doesn't mean they don't work. Epic opted to use a bailer that opens and shuts to reduce drag. Other manufacturers use bullets to reduce drag.
Heres the link www.surfski.info/reviews/surfskis/story/...-red7-surf70pro.html

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8 years 4 months ago - 8 years 4 months ago #17559 by PaddleFaster
I genuinely hope that no one takes the following comments as being smug or combative, I really don't mean them that way. I am typing it all with a smile and a playful chuckle and in no way do I wish to, or mean to, offend anyone's opinions, knowledge, experience or expertise.

I am just confused by what appears to be an obsessive need for everything on a boat to be it's absolute lightest and hydro dynamically efficient at the cost of all else; basically, meaning comfort, practicality and possibly even stability.

I guess that because I am looking at things from a non-racing perspective when it comes to paddling that I often don't understand why so much time and effort, is often devoted to topics about possibly making a boat a tenth of a kilogram lighter or doing things hydro-dynamically that "may" increase a boats speed by .001 kph.

I mean...

Unless every paddler competing is of the exact same weight and stature, the exact same strength and experience, and makes the exact same amount of correct paddling decisions and strokes along the way, I can't for the life of me understand how a .085 kg (3 ounce) lighter rudder, or more hydrodynamic bullet makes any difference whatsoever in the greater scope of things.

I wish I could see something that supports the opinion that during every race run, a more hydrodynamic bullet combined with the boat being a tenth of a kilogram lighter than all of the other boats, always wins. I can't understand how for 99.99% of us, it all makes a squat of difference.

A large surface area, lighter weight, highly buoyant rudder that is always wanting to make it's way to the surface because of it's buoyant nature, as opposed to a heavier, none buoyant rudder, that would probably give better tracking possibly improving stability, somehow doesn't matter and has never even been talked about.

What's next, sailboat keels made of lightweight and highly buoyant materials...( Okay that comment was a bit smug, I admit it! Feel free to throw spoiled fruit in my direction. :laugh: )

For some reason, the negligible gains from adding a bullet to the back of a venturi seem to be highly significant when it comes to improving a boats overall hydro-dynamics and speed. I say so because it is very often discussed a few times each and every season.

The truth is, I have never actually read anything, or had an experience that actually proves that a bullet's increase in performance actually really matters enough to make a difference in the grand scope of things.

As far as a boat being a few percentages of a kg lighter...

Truth be told, If I want my boat to be a kilogram or two lighter and faster, it seems far easier to drink a few less beers and eat a few less pizzas than to rely on bullets and buoyant rudders. ( smug again... Start throwing more fruit! :laugh: )

Ahhhhhhhhh who am I kidding, I love pizza and beer far too much.

Buoyant rudder's and bullets it is!

I do wonder though, would the lowered center of gravity from a non buoyant, heavy, solid stainless steel rudder improve a boats overall stability enough in certain conditions to actually make a boat faster for some paddlers?

After all, the new catch phrase that seems to be stated everywhere is that, "The fastest boat is the one you are the most stable in."

A final note:(Stop cheering!) My apologies for my shameless, classless and unwarranted hijacking of this thread.

In my defense I have to say that my holiday weekend beer is still very, very, cold, and it's still pretty damn hot out! :laugh:

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8 years 4 months ago #17561 by grasshopper
For most of us I think it's just a boys (and girls) with toys thing, we all want to make our skis as fast and efficient as possible to try to beat our mates.

I still think the bullets do make a difference with drainage, the venturis do seem to drain faster with the bullets and make more noise and I believe that noise is caused by extra suction?

Don't believe the buoyant rudder would make much difference when you consider the weight of the human on board and the rudder being near to vertical most of the time i.e. it's buoyant force would be pushing up through the center of the ski.

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8 years 4 months ago #17564 by Kocho
The reason I made the bullet was not to race faster, but because I was unhappy with how the V10 Sport drained at *slow* speeds, which is where I stay most of the time when on flat water. It did improve that for sure, bringing it from a speed that I had to push somewhat hard to a speed that was more comfortable. The suction was also improved - that nice gurgling noise would happen sooner and at lower speeds. I did have a plug too :)
The following user(s) said Thank You: ShaneS

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