venturi bullets

Does anyone know if you can purchase venturi"bullets" like those on the red7 pro. There was some discussion at the time,
but I've never heard anymore.
Thanks

Dale Lippstreu here in Cape Town is building a mould. He fitted them recently to his Fenn double and is about to fit them to my Mako Elite...

I'll keep the group posted.

Ah - so you have your new boat - what layup?

Carbon

Speak to Andre Botha (red7 / republic sports durban)

email: This email address is being protected from spambots. You need JavaScript enabled to view it. (www.red7.co.za)
Tel: +27 (0) 31 564 8499 Fax: +27 (0) 31 563 8798
2 Lothian Rd Briardene Durban North 4051 South Africa


or gary clarke (erics canoes - Durban) who manufacture RED7's in Durban -

Tel(031) 563 0874
Fax (031) 563 6734
E-mail This email address is being protected from spambots. You need JavaScript enabled to view it.
Address 55 Marseilles Road,
Briardene Industrial Park,
Durban, 4001,
South Africa

Hi,
please post here if you have gotten some 'bullets' from any source. I am looking for some too, my Mako Elite is emtying so painfully slow when going into the chop.

RoJo

I made my own after finding that the cockpit of my home built wasn't emptying fast enough at low speeds (eg in a strong headwind). I sketched up what I wanted after studying that flow diagram on the Red 7 write up, then found some plastic tubing of the right diameter for a mold. Filled the mold with epoxy and microballoons, cut and shaped the blank with sand paper, glued them on with silicon (in case they didn't work and had to come off). They worked a treat first time. I now have a powerful slurping sound which definitely wasn't there before. Will post some sketches and/or photo if you like.

Hi Brad

Well done on your place at the Trans Taupo.

Cheers
John (#5)

I fitted venturi bullets to my new Fenn Elite double and found a noticeable improvement in baler performance. This was still however not enough to cope with the water volume in the rear so I fitted a 3rd baler as in the Red7 Surf70 with an increased diameter of 22mm. This produces a significant improvement in overall baler performance.

I used a piece of an Epic paddle centre join tubing with an OD of 25mm to join the hull and deck. I drilled a 28mm hole in the cockpit and 25mm hole in the hull.I cleaned the gap between hull and deck with a mini grinder so to get a clean bonding surface before injecting bonding paste (resin, aerosil and cotton flock)into the gap between hull and deck. I then inserted the linking tube and injected further paste into the gap between the 28mm hole and the 25mm tube. When all was cured I sanded flush and bonded the venturi cup and bullet in place. Finishing was done by 2 coats of MS primer followed by 2 sprayed coats of 2K paint.

Please do post the sketches/phots.

Thanks.

Here is a very rough sketch. I will take some photo's over the weekend and post them on Monday.
Cheers
Brad

I get this when I click on your link...

Forbidden
You don't have permission to access /media/kunena/attachments/legacy/files/20090417171603037_0001.jpg on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

... Oh the joy of trying to attach files to your forum posts !

Hmmm... not sure what's happening there - the permissions are definitely set correctly...

Sorry for the ignorance here...:

Do these get epoxied to the hull at the mouth of the venturi?

Having fitted 3 sets of venturi bullets and experimented with them a bit I have found that there are a number of variables which affect their effectiveness quite dramatically. These include the diameter of the drain hole (Red7 used 22mm which seems to be best) and the gap between the cup a bullet which has to be optimised quite precisely. Andre Botha has gone into this quite extensively and has promised to send me a set of his new injection moulded scuppers which will be available for sale shortly. I plan to photograph and write up the fitment process for Surfski.info as soon as I get the scuppers and I suggest you hold back for this. Even if you elect to make your own scuppers you will be able to benefit from the expertise and testing that went into the design.

After constantly complaining to my paddling buddy, Leon, about the poor performance of the bullet on my Red7 Surf 70, he took matters into his own hands.

Simply by using Pratley Putty, he built up the existing scupper by about 4mm at the lowest point, tapering it out to about 2mm on the sides. The result is that the scupper now stands about 2mm proud of the bullet, whereas in the past the bullet always seemed a bit big to me. Obviously this adds a measure of drag but this is really nothing when comparing an empty footwell to carrying around 10 litres of water.

The result has been incredible! I now hear a very satisfying sucking sound from around 7km/h where I only used to hear this when riding a big wave at around 14km/h! Even with only one drain, my footwell stays dry in most conditions (upwind included) and empties very quickly after being flooded.

I'm sure the problem I experienced was corrected on the Surf 70 Pro as I have paddled that boat and immediately noticed a difference but for those of you building your own bullets and scuppers, this may come in handy.

If anyone is interested, I can post a picture.

We seem to have a challenge with posting pics into the thread - email it to me & I'll put it up for you... Cheers
Rob

Dose the venturi vacume only work if the footwell holes are comletely covered in water and will air pockets effect it.
I am trying to make a venturi for a ski that will be used in a race with white water rapids and lots of rocks so the venturi can not go straight underneith the footwells otherwise they will get ripped off. I am thinking about running the inlet hole in the footwell wall at the lowest point then running a hose to behind the seat and having the venturi come out the back below the waterline. Will this work?