Venturi

How good works footwell drainages in OC?

Submitted by Heavywater on Tue, 03/13/2007 - 5:25pm



I assume you are referring to an oc1? My experience is that footwell drains vary in efficiency from simply leveling off the water level in the footwell to sea level while the OC1 is in motion (i.e., not effective at all) to draining the footwell until its bone dry. I've seen different drain systems in the same boat as the boat designer attempts to perfect the placement and design.

Snarfblat


#1 Tue, 03/13/2007 - 6:09pm


In my humble opinion Good works the footwell drainages in OC pretty well. There were originally some bureaucratic roadblocks standing in his way when the Governator was first elected - but much like his namesake, the venerable Good N. Plenty of old west six-shootin' fame, he worked those footwell drainages right into the 21st century - not only in Orange County, but San Diego and Los Angeles Counties as well.

Huh?

PS - HukiJude makes the best footwell drainages I've ever tried. They suck harder than a... well, you just finish that one yourself.


#2 Tue, 03/13/2007 - 7:12pm


Epic has CAD created a venturi pipe for the V10.
http://surfski.info/index.php?option=com_content&task=view&id=218&Itemid=80

By the way, have any the OC1 also stringers like the V10?


#3 Wed, 03/14/2007 - 8:00pm


möglicherweise sind die besten Entwässerungen die, die, als Geschwindigkeit eaqual zum Azimut eine Blüte Formen aplied. wenn du angenehm bist, die Blüte zu benutzen, dann ist Outriggeranschluß von allen für das Blühen am glücklichsten. danke.


#4 Tue, 03/13/2007 - 9:24pm


jc9_0 Thanks for performace, but I guess your dictionary sucks, Flowers and Cannabis needs Vodka


#5 Tue, 03/13/2007 - 10:19pm


sometimes you have to wonder how google translation works...watch as i translate to german and then back to english. not quite the same eh?

manchmal mußt du dich wundern wie google übersetzung Arbeiten… Uhr, während ich zum Deutschen und dann zurück zu Englisch übersetze. nicht durchaus die selben wie?

sometimes you must be surprised like google translation work… Clock, while I translate to the German and then back to English. not quite the same how?


#6 Tue, 03/13/2007 - 11:37pm


My Huki stays bone dry, and not just because I'm in Arizona.


#7 Wed, 03/14/2007 - 3:50am


I'd concur Huki's venturis work great. Stingrays worked great too for draining the wells bone dry but on mine were made, surprisingly to me, with those mother-of-toilet-seat-tortoise-shell type guitar picks which are rather fragile. Not sure if they still do that these days and I guess if one broke you could go down to the local guitar shop and glue a new one right back on. Huki's are beefy carbon and you could probably paddle them into a rock and not harm them much. Not sure how they'd hold up on stage as a guitar pick though. Probably break all your strings off.
Cheers,
Bob
Kanu The Rock


#8 Wed, 03/14/2007 - 8:27am


My OC-1 footwell drains suck...and that's with the normal guitar pick. Think how much more it would suck if you had the POD...

People say its Bernoulli effect, but I say nah, nah, nah, its m-a-g-i-c.


#9 Wed, 03/14/2007 - 11:46am


Bob,
so you don't have to try it yourself... You can NOT paddle the HUKI venturi drains into a rock without damaging them much... But, you can buy new ones and attach them yourself - from Jude, not the guitar shop.


#10 Thu, 03/15/2007 - 8:57am


Goto,
Thanks for the advice. How do you know this? Are you punching a venturi drain in that little video up there? Around here I am sure I'll have the opportunity to paddle my drains into a rock whether I want to or not. Rocks around here seem to proliferate like bacteria, unfortunately.
Cheers,
Bob
Kanu The Rock


#11 Thu, 03/15/2007 - 9:04am


Is John Martin the only OC builder makes stringers and safety buoyancy in his canoe?

http://www.onemancanoes.com/naiacanoe.html
Construction
..... A one-inch stringer of closed cell foam runs the length of the boat and is bound to the hull and deck for strength and flotation. ......


#12 Thu, 03/22/2007 - 7:49am


yo Heavy,

nope.. most manufacturers at the very least use a stringer underneath the seating area. here's why....
our canoe, the C-Lion has a closed cell foam stringer which extends from the footwells to just past the rear iakos.

this provides structural support for heavy paddlers,
reduces flex ( C-Lions and C-Lion ST's are 22' 8" long)
and I suppose in a catastrophioc failure, could provide some floatation for you to swim it in..

the Venturis we use are actually wing blade paddle shaft off cuts bonded on with 3M jetweld - no ukulele picks here!

Roscoe
www.outrigger.ca


#13 Thu, 03/22/2007 - 9:36am


I think all canoes have stringers. To what extent the stringers run varies. The stringers add stiffness and support but they also add some amount of weight, although I don't know to what extent. I once saw pictures of Hurricanes snapped in half and was once told by a canoe maker that these canoes were vulnerable to breaking in half because the stringer did not run the length of the canoe but rather, stopped after the seat area.


#14 Thu, 03/22/2007 - 11:32am


all,

any thoughts on single venturis over dual? my old Kolea didn;t even have covers over the drain holes but somehow magically stayed dry.

what's the expereince with single drains ( hurricane , Viper etc.. ) do they drain as well?

Roscoe


#15 Thu, 03/22/2007 - 4:58pm


I don't think dual venturi's have any special advantages over a single venturi provided, however, the size of the single venturi is matched to flow at same cfm as the dual venturi. The key to the venturi is its design. You can have a dual set up but if its not designed right, the venturi will only serve to allow water into the footwells. I have two venturi drainholes in my Vantage that do diddly squat. You can have a single venturi that will outperform a dual set up simply because of its design. The function of the "cover" over the hole is not so much to prevent water from going into the hole as much as it is part of the system designed to accelerate water as it passes the drain to create a vacuum.


#16 Fri, 03/23/2007 - 5:28pm


As I mentioned earlier, my Vantage has two drain holes---one hole for each of the two footwells (i.e., left and right). At rest, each footwell fills with water until the water level is at sea level ---about two cups worth in each footwell. When I paddle, the water level in the wells generally remain constant, at sea level. If water sweeps over the gunwale and fills the footwell, the water drains from the hole until the water level returns to sea level.

I wasn't satisfied with the way the drains worked so I did an experiment. Last April, I bought a pack of small plastic Easter Egg shells from Long's drugs for $2...the kind with two halves that snap together. I took one half of the eggshell and cut a piece using a hacksaw. The resulting piece looked like a large toenail that turned black and fell off your foot because your girlfriend stomped on it after she caught you foolin' around with another paddler. Since there are two drain holes on my canoe, I made an identical piece using another shell and then taped them over the drain holes on the bottom of the hull using clear strapping tape. I then did a run from HI Kai to Kaimana today to test my new set-up.

At rest, the wells filled up with water until the level reached sea level....just like before. However, once I started moving, the drains sucked out all of the water until the wells were bone-dry. A sucking sound could also be heard coming from the drain holes. I thought to myself, "Great, I should be able to move faster without the excess weight!" and proceeded with the run. Despite the loss of weight, I struggled to keep the hull speed up and the boat moving on the swells even though it was a spectacular day for a downhill run. The drag on the boat was quite noticeable. Coming off the face of a wave, the eggshell-venturis worked so well that when the footwells filled with water, the water drained from the footwells in a couple of seconds until the well was bone-dry. While my new set up was very effective in draining water the eggshell venturis cavitated so much that air was being sucked through the hole and I could hear a great deal of cavitation under the canoe. With the eggshells, the canoe's hullspeed was noticeably down and the boat lost its ability to glide as it did before. As a result, wave runs were shorter than normal.

Frustrated by the decrease in performance, I yanked the eggshells from the bottom of the hull when I got to Blackpoint. Normal hull speed and glide then returned.

Based on my experience, it appears that their is a direct correlation between the effectiveness of a venturi system and hull drag....at least when it comes to eggshells. With my set-up, the drag created by the venturis outweighed any benefit of the reduction of weight because cavitation and a disruption of the laminar flow created a noticeable drag on the hull. Also, if the venturis are so effective in sucking out water, the venturis may also suck air when their is no water in the wells to be drained, resuling in cavitation and a disruption of the laminar flow. In my case, running with about two cups of water in each footwell was better than running with no water while using the eggshell.

I'll continue to experiment by using smaller eggshell coverings to see if there is a difference and will report my findings here.

Snarfblat


#17 Sun, 03/25/2007 - 1:08pm


Snarf was like greased lightning once he took those eggshells off!

Seriously, after the run we discussed how the venturis were an absolute waste when the footwells were dry, since they were still creating drag when there was no need for it, and they kill the boat's glide.

Its nice to have the venturis when you take a wave and fill up your footwells, but once your boat is dry they are just creating wasteful drag, and as Snarf proved the drag is significant. There is no "free lunch," and you pay for the venturis' effect with increased drag on your hull.


#18 Mon, 03/26/2007 - 4:10pm


Those are some big venturis.


#19 Tue, 03/27/2007 - 1:26am


That's what she said. ;)


#20 Tue, 03/27/2007 - 9:02am


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