Generic rudder upgrade (Terrapin XL)

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Tim399
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Generic rudder upgrade (Terrapin XL)

Post by Tim399 »

Gday guys and gals, after paddling with some of the guys that are in the hobies and watching them turn much sharper then my yak could, i wanted to try and improve the turning responsivness of my own yak.. The obvious answer: buy one of the well built name brand models (of course, you get what you pay for). The practical answer for the moment: have a crack at turning chopping boards into a bigger rudder! Well actually a sleeve to go over the existing rudder.

To start off, materials i needed: 2 chopping boards
4 stainless steel bolts and nuts
8 stainless steel washers
A small amount of selleys quick grip gel

Tools: jigsaw
Drill & drillbit to make a hole the bolts can go through
Router
Electric plane
Sander
F clamps

Picked up a couple of packs of plastic chopping boards about 4mm thick from k-mart. Ill use one of the left over boards to make a bait board.
IMG_454.jpg
Trace the rudder onto the chopping board, i wanted to double the surface area of the rudder, so i doubled the length but didnt want to increase the height, as it would only get in the way in shallow water
IMG_456.jpg
Once i had the shape of the new rudder i cut it out with the jigsaw
IMG_455.jpg
Trace the shape to the next chopping board and cut that out too. With the tracing of the origional rudder still on the board use the router to cut out a channel half the thickness of the old rudder. This way when the two chopping boards are glued together you can slide it over the old rudder. Be sure to rout them on opposite sides so it is mirrored when put together.
Note: you have to be fast with the router, as if you go too slow it melts the plastic rather than cutting out a channel. Its harder to rout neat quickly than i thaught haha the second one was better :)
IMG_457.jpg
When both halves of the board are routed out theyre ready to be glued together using selleys quick grip gel. Do not glue the channelled out area.
IMG_458.jpg
Clamp the halves together, then drill two holes for the bolts toward the back end of the rudder where it has NOT been channelled out, then put the bolt nuts and washers in and tighten up, to help hold them together.
After 24 hours drying time use the planer to take away the square edges on the front and back of the rudder so it cuts through the water, reducing drag.
IMG_461.jpg
The origional rudder
IMG_459.jpg
The rudder with the sleeve over the top.
Note: once i slipped the sleeve over and had it in place i drilled another two holes, through the sleeve and rudder and bolted tight to hold it in place. I also made a small nick in the bottom of the rudder for the bungee to tie it down onto. I put two bolts through the rudder sleeve and rudder to hold it in place, which can be undone and removed.
IMG_460.jpg
So does it work? Ill post up the next time i get on the water.
What do i have to lose? It only cost about $15 or so and took an hour of my time. If it doesnt work out, i can unbolt it and will be left with two 6mm holes in the rudder blade, i dont think i will notice and drag from them. It was worth having a go.

Thanks for reading :up:
Tim
Last edited by Tim399 on 15 Aug 2017, 22:30, edited 1 time in total.
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laneends
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Re: Generic rudder upgrade (Terrapin XL)

Post by laneends »

Good to see a bit of DIY :thumbsup:

When you increase rudder area, it becomes more important to lift the rudder at anchor for 2 reasons, increased risk of line snagging and second current catching it and causing it drag yak to one side, more important the higher the tide flow. This will also increase strain on rudder and mechanism.

How does the up/down mechanism operate with the extra weight, especially as it is triple thickness as well as increased area.?
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Tim399
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Re: Generic rudder upgrade (Terrapin XL)

Post by Tim399 »

Thanks keith. I didnt think about the effect in higher tide areas with the rudder down.. It was always a bit average to pull up, i tested it with the sleeve on and it was a little heavier, but still doable.. It is now about 2cm lower than before hand, so ill have to be cautious of line snag. Ive just got to remove two nuts if i dont want it on. The rudder system looks like it should be able to take the strain, other than the pedals and line to the pedals the whole unit on the back it made from some sort of metal. Looking faward to finding out if its a flop or not!
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Re: Generic rudder upgrade (Terrapin XL)

Post by laneends »

Tim399 wrote:Thanks keith. I didnt think about the effect in higher tide areas with the rudder down.. It was always a bit average to pull up, i tested it with the sleeve on and it was a little heavier, but still doable.. It is now about 2cm lower than before hand, so ill have to be cautious of line snag. Ive just got to remove two nuts if i dont want it on. The rudder system looks like it should be able to take the strain, other than the pedals and line to the pedals the whole unit on the back it made from some sort of metal. Looking forward to finding out if its a flop or not!
It will be an interesting experiment, things are often a lot harder on the water
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Re: Generic rudder upgrade (Terrapin XL)

Post by Seasherpa »

Nice ingenuity Tim, between you and Shane you can start up an aftermarket rudder company.
If it doesn't work out as planned you can always learn to steer on your paddle, when you are on the move you'd be surprised how quickly a little lean and one blade in the water will bring the nose around.
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Re: Generic rudder upgrade (Terrapin XL)

Post by Wind Waker »

Looks good. You might want some surface area in front of the rudder blade to help make the effort a little less. Balance of that ratio is gonna be trial and error. Well done though!
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Re: Generic rudder upgrade (Terrapin XL)

Post by laneends »

Wind Waker wrote:Looks good. You might want some surface area in front of the rudder blade to help make the effort a little less. Balance of that ratio is gonna be trial and error. Well done though!
Good point. As per hobie sailing rudder, that way pivot point is centered. water flow pushes leading edge in direction you are turning, rather than taking all strain mechanism
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Tim399
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Re: Generic rudder upgrade (Terrapin XL)

Post by Tim399 »

Cheer eion, has shane modified his rudder too? Ill have to have a search and see if theres a thread for what he did :) i think ill have to pay closer attention to other paddlers and see how they handle their yaks.. I might also book myself in for a kayak lesson to learn more.

Thanks wind, i thaught about that but then thaught once the rudder caught enough water it might try to turn by itself and be annoying, but ive never tested or tried it and know nothing about hydrodynamics (is that even a word?) so that might be the way to go! Version 2 wont cost much if its needed :)

Also, if the rudder has too much surface area (without going a rediculous size) would it be a hinderance catching too much water and being hard to control whilst on the move? As i now realise it would be in high tidal flow areas but other than in that situation?

As always i do appreciate any advice fellas :up:

Tim
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Re: Generic rudder upgrade (Terrapin XL)

Post by Ghurkin »

nice bit of diy, I'm impressed :up:
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Re: Generic rudder upgrade (Terrapin XL)

Post by laneends »

Tim399 wrote:Cheer eion, has shane modified his rudder too? Ill have to have a search and see if theres a thread for what he did :) i think ill have to pay closer attention to other paddlers and see how they handle their yaks.. I might also book myself in for a kayak lesson to learn more.

Thanks wind, i thaught about that but then thaught once the rudder caught enough water it might try to turn by itself and be annoying, but ive never tested or tried it and know nothing about hydrodynamics (is that even a word?) so that might be the way to go! Version 2 wont cost much if its needed :)

Also, if the rudder has too much surface area (without going a rediculous size) would it be a hinderance catching too much water and being hard to control whilst on the move? As i now realise it would be in high tidal flow areas but other than in that situation?

As always i do appreciate any advice fellas :up:

Tim
The principle of balancing the pivot point is that if it is not balanced the entire water resistance is being exerted on the rudder control, either straining it or making it too hard to pull. Being balanced means water resistance pressure is not transferred to operating mechanism as it is cancelled out, hence it is easy to operate regardless of water flow.
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