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Streamlined Extension Downhaul Slipping when Wet
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norcom



Joined: 16 Jun 2008
Posts: 132

PostPosted: Sat Mar 23, 2013 1:20 pm    Post subject: Reply with quote

I decided to go ahead and mod the extension. I first tried replacing both pulleys but they barely fit and would seize up when torqued. I then ground off about 1mm from one of the pulleys and left the pulley in the back an original one. The brass pulleys did not need to be drilled and were a perfect match for the pulley bolt. The moded pulley's definitely not as smooth as the ball bearing one but I don't think I'll have any slipping issues with this extension now. Smile

If anyone has any busted streamlined extensions they want to donate the europin retention mechanisms from so I could try making my own, that'd be sweet. Wink



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kevinkan



Joined: 07 Jun 2001
Posts: 1149
Location: San Francisco

PostPosted: Sat Mar 23, 2013 3:51 pm    Post subject: Reply with quote

FWIW, the extension with ball bearing sheaves is no longer made by Streamlined. They were discontinued last year, and the new extensions have larger diameter delrin pulleys with deeper grooves. That said, the ball bearing extensions are still very popular with all the formula racers around here. Of course most of these are SDM models, so the cleat and pulley assembly is a bit further out than with the RDM models. But I used the exact extensions you have in the picture for several years, even with Ezzy Sails up to about 5.8. The only thing I noticed is that the stainless washers in between the ball bearing sheaves look smaller than usual to me. It's hard to tell from the angle.

norcom wrote:
Below is the actual picture of my extension. The previous pictures were not mine.

Now that I look at it closer, I may be able to replace the washers next to the pulleys with something a little bigger that might stop the slipping and give the channel a little more depth. But since I have two other extensions now that work, I'm just keeping this one as a spare.

Edit:
It seems to me that my pulleys seem a bit shallower than other pulleys in the pictures posted earlier. I was upgraded to the "ball bearing" pulleys for free because the cheaper model wasn't available at the time.

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mikecole



Joined: 21 Sep 2000
Posts: 146

PostPosted: Sat Mar 23, 2013 8:18 pm    Post subject: Reply with quote

norcom,

Your mod looks like it should solve the problem. Well done! I just had a look at my extensions and both use the deep brass pully wheels. Guess that's why I was not having the issue you we're having.

Mike
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isobars



Joined: 12 Dec 1999
Posts: 14166

PostPosted: Sun Mar 24, 2013 1:41 pm    Post subject: Reply with quote

gregnw44 wrote:
just the same anywhere, that you have strong wind and water current going against each other. ... the combo. of the strong wind pushing and or lifting the board "up" (on the upwind side of the crash)... while the current grabs the rig, taking it "down"

Getting off topic now, but I have never seen any argument, let alone been convinced, that WSers or their gear when we're not standing on the ocean or river bottom know we're in a current. i.e. The only effects of the current I can think of are a vector addiction to the ambient wind, a free trip downstream when not sailing, and swell/chop effects. I do not believe a lateral current "pulls the sail under" anything unless that thing is hooked to the planet ... just as we don't feel the effects of our planet's hurtling through space.
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gregnw44



Joined: 23 Jul 2008
Posts: 246

PostPosted: Mon Mar 25, 2013 12:44 am    Post subject: Reply with quote

"pulls the sail under". Ok... possibly a poor choice of words to use.

Hey, I'm not a scientist... just a guy blabbing away like most of us... chatting about one of our fav sports Smile

I guess what I mean is.
Say you have 20 knot winds, blowing across a "still water" lake. And you get catapulted on your FW. So that now your 10M sail is on the leeward side of the board, and you're lying on it. You carefully slide off it, so as not to damage your $ investment. But now your big rig is pointing at a 45* angle down, under the water. At the same time as this... the 20 knot wind is blowing hard on that light, big and wide FW... wanting to blow it downwind like a styrofoam cup. But, it's attached via a mastbase to the rig... so it wants to blow past (over the top of) the underwater rig. And it will likely do this... and when it does, it may push the sail farther down under the water. Next, it'll blow passed the underwater rig... so now the board on the leeward side of the rig, which is starting to rotate and float back up to the surface. The speed which it floats back up, is also dependant on how much air is trapped in your mast and boom.

Experiment #2 - Now perform the exact same stunt, with the same gear and the same wind... but this time, in "moving water" where the water is flowing exactly opposite the direction of the wind. And my thought is that, now... the rotation of all that gear will be faster.

So... if that is correct. Then, how does this "feel" to the guy who's trying to get his gear up and sailing again? And I'd guess that it feels like his sail is getting pulled "down and under and passed" his floaty board which the wind is pushing upriver (in the case of the gorge). Therefore, the whole kit is being rotated. The light and wide FW is bing blown up-current by the wind, while the attached sail under the water, is being dragged down-current by the flowing water.

And again, if this same thing happened in a "still water" lake... the strong wind would still blow the light and wide FW over the top of the sail, which is under the water.
So... the same rotation would still occur. But... the rotation would be slower, because the water is not moving opposite the wind.

Hey maybe I'm wrong about this Smile
No big deal... It doesn't matter to me... I was just commenting on the previous post, regarding gear getting rolled... and how this can cause great damage to mastbases and other parts.
Greg Smile
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kevinkan



Joined: 07 Jun 2001
Posts: 1149
Location: San Francisco

PostPosted: Mon Mar 25, 2013 1:55 am    Post subject: Reply with quote

well, dunno if it technically qualifies as a windsurfer, but the Oracle AC72 got torn to shreds when it catapulted and was caught in 25-30kt winds and an opposing 5 knot ebb.

also, anybody who's tried to waterstart in the delta or get out of the water at the sign or powerlines knows what trouble a little current can cause.

here's an interesting video of a big ebb tide at the South Tower GGB

http://www.youtube.com/watch?v=A8BjJSfP-L4

isobars wrote:
gregnw44 wrote:
just the same anywhere, that you have strong wind and water current going against each other. ... the combo. of the strong wind pushing and or lifting the board "up" (on the upwind side of the crash)... while the current grabs the rig, taking it "down"

Getting off topic now, but I have never seen any argument, let alone been convinced, that WSers or their gear when we're not standing on the ocean or river bottom know we're in a current. i.e. The only effects of the current I can think of are a vector addiction to the ambient wind, a free trip downstream when not sailing, and swell/chop effects. I do not believe a lateral current "pulls the sail under" anything unless that thing is hooked to the planet ... just as we don't feel the effects of our planet's hurtling through space.

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dhmark



Joined: 04 Sep 2007
Posts: 215

PostPosted: Mon Mar 25, 2013 11:29 am    Post subject: Reply with quote

Brain and physics class tells me that current should only affect magnitude and direction of apparent wind, but life experience tells me otherwise, sail handling in the water and clearing the sail way different when there is current-- there is something different, I think it is the chop. dhmark
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isobars



Joined: 12 Dec 1999
Posts: 14166

PostPosted: Mon Mar 25, 2013 6:08 pm    Post subject: Reply with quote

Not convinced yet ("getting out of the water" at powerlines or anywhere else involves walking on the bottom, which has nothing to do with floating/drifting freely with the current). I can imagine no connection between the Oracle's demise and the current. And I brought it up only because it's been claimed many times, always without any proof, logic, or physics.
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