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PostPosted: Wed Oct 31, 2018 3:54 am 
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Gregbenner wrote:

I do have a couple of the small skegs,like RR used, on order. I plan to try them when I get them. I used 3M 5200 Marine adhesive for the skeg on the well plug and it seems to be holding. Would this work well fastening the small skegs directly to the hull, flaming it first?


I would go the double sided stuff as recommend earlier, kayak plastic is notoriously difficult to bond to. Finding anything that is proven to work is the way to go. Combining these with the plug skeg should make a difference. Just keep in mind what will fail first if the weight of the kayak is put on the skeg plug if you forget to remove it, which you will.


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PostPosted: Wed Oct 31, 2018 10:00 pm 
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WAVERIDER wrote:



I would go the double sided stuff as recommend earlier, kayak plastic is notoriously difficult to bond to. Finding anything that is proven to work is the way to go. Combining these with the plug skeg should make a difference. Just keep in mind what will fail first if the weight of the kayak is put on the skeg plug if you forget to remove it, which you will.


Almost hailed it out today to fit my new seat, ended up not needing to take out, but never thought once about removing the skeg in the drive well.

I have to admit I get sort of confused reading thru so many posts and ideas. I get the flaming concept, but what else? Just dual sided tape?


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PostPosted: Thu Nov 01, 2018 3:21 am 
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Gregbenner wrote:





I have to admit I get sort of confused reading thru so many posts and ideas. I get the flaming concept, but what else? Just dual sided tape?


Just make sure its clean with isopropyl alcohol, small pump bottles from electronics stores. The tape contact bonds immediately so make sure you get it lined up before making contact


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PostPosted: Thu Nov 01, 2018 8:58 am 
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Thx WR, I ordered some 3m 5952 today.

I have noticed that apparently there is more that one size rudder available? I have no idea which size I have, assume it’s what it came with. Would a larger rudder help? I do have a sail kit, which I haven’t tried yet but definitely plan to once I get a bit more familiar with it.

I’m starting to get the hang of pedaling and paddling together, and really like it. Great exercise.


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PostPosted: Fri Nov 02, 2018 6:04 am 
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large rudders will turn you better, and help track better in strong crosswinds. But if you are paddling and trailing it like a skeg it will be more resistance and make it harder to manoeuvre the kayak with the paddle. I try not to drop the rudder when paddling unless I have to due to this. But yes when used in pedal mode and operating the rudder by hand it is a worthwhile upgrade.


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PostPosted: Fri Nov 02, 2018 6:45 am 
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That sailing rudder is awesome for pedaling use and sailing. I really don't know why Hobie doesn't make it a stock item instead... but you can save your stock small rudder and try to mount it to the drive well plugs I sent ya.


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PostPosted: Fri Nov 02, 2018 12:32 pm 
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The larger sailing rudder came stock on our 2016 Oasis.


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PostPosted: Fri Nov 02, 2018 12:47 pm 
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I was hoping the skeg mod would improve towing as well and I was recently able to test this out.
IT WORKS BRILLIANTLY! :D
When towing the Adventure behind our TI, before the skegs were added it would fishtail and crab sideways, ending up at almost 90deg at times to the direction we were travelling. Dropping the rudder helped but it wouldn’t stay locked straight ahead. Dropping, but not down cleating the rudder seemed to work best but it would still ‘tack’ when underway.
It now tracks straight as an arrow with no crabbing/fishtailing.
Such a great mod, thanks Staktup. 8)
I’ll be adding the skegs to our Oasis just for this towing benefit.
Image


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PostPosted: Fri Nov 02, 2018 2:05 pm 
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Holy cow, friggin’ outboard! Sick stuff. Did you just add the 2 small skegs to the Adventure? Glad to hear it worked out, and that the sailing rudder comes stock on some models now.


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PostPosted: Fri Nov 02, 2018 4:37 pm 
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staktup wrote:
Did you just add the 2 small skegs to the Adventure?


Yes, just the 2 small skegs as detailed in my earlier posts.


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PostPosted: Sat Nov 03, 2018 12:39 am 
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Got my original adventure patched up now mainly for paddling duty. i am thinking of adding the skegs to this also and bolting different sized home made ones onto them(plating) just to experiment what effect different sized ones will have.


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PostPosted: Tue Nov 06, 2018 6:13 am 
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I look forward to your testing results, WR. Old regular sized rudders might be good to cut down to try.


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PostPosted: Sat Nov 10, 2018 4:49 pm 
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One issue for large glued on offcenter fins is which way does the water flow. It probably isn't going parallel to the hull centerline, but it is probably mirrored left and right. Fins parallel to the flow should balance forces and give straightening with least drag.

The obvious approach of mounting parallel to hull centerline could give toe in or toe out snowplowing relative to water flow. It will still appear to work, but you could even glue tennis balls under the stern and get some caveman efficiency straightening effect. A solution for the retentive is to tape one end of bright yarn segments to the proposed glue points and aim an underwater gopro (clone) camera at indicated flow.

The kayak depicted below is making a bet the water flow under the stern quarter is highly divergent in the horizontal plane, suggesting snowplow fins may be best. I think there is a rising flow in the vertical plane too, in case your fins don't go straight down and want to align to that too.

Image

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PostPosted: Sun Nov 11, 2018 6:42 pm 
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daft wrote:
A solution for the retentive is to tape one end of bright yarn segments to the proposed glue points and aim an underwater gopro (clone) camera at indicated flow.



Interesting concept and experiment, I guess this could also vary with speed. On an adventure style hull they fairly close to rear 'keel' and in the shadow of the main hull displacement so the wave displacement angle may be minimal to nil

Reality is due to curve of hull and base pad of fins there is not a lot of area of adjustment. The spine of the fin is rigid and so can't follow the curve of the hull which would be required if you were to angle them as suggested.


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PostPosted: Mon Nov 12, 2018 2:59 am 
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Yeah, I probably nitpick too much (back injury keeping me out of kayaking). I remembered some surprising hull flow diagrams such as for Olympic kayaks or sculls, but can't find them again. Above boat has a diverging flow diagram which has a security block. I can insert flow diagrams for planing surfboards, which snowplow their fins around 2 degrees, and not just for turning:

Image

Above pic shows divergent water causing cancelled out side lift on the straight fins, which results in drag. I suppose a kayak would diverge water less than that, or even converge at low speed. Does anyone want those fins to help you "bank" your kayak turns? On a banked surfboard, you stick your toed in sidefin into the straight center of the flow and it helps turn, just like canted side fins which become straight down in a turn. Just food for thought:

Image Image Image

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